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SAKOVETS, TATYANA G., and NADEZHDA L. RYBKINA. "CLINICAL MANIFESTATION FEATURES OF CHIARI TYPE 0, 1, AND “BORDERLINE” MALFORMATIONS." Bulletin of Contemporary Clinical Medicine 17, no. 2 (2024): 112–17. http://dx.doi.org/10.20969/vskm.2024.17(2).112-117.
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Introduction. Introduction of advanced neuroimaging methods has made it possible to identify subtle structural features of the posterior cranial fossa and craniovertebral junction, as well as the dislocation of cerebellar tonsils into the foramen magnum, which have clinically overt and subclinical forms. Aim: To study the clinical manifestation features of Chiari type 0, 1, and “borderline” malformations. Materials and Methods. For literature analysis, the sources were used from international databases, such as Web of Science, Scopus, and PubMed, and the Russian library system, eLibrary. Results and Discussion. The most common pathology of the posterior cranial fossa is Chiari type 1 malformation associated with a mesodermal defect and with discrepancies between the sizes of the posterior cranial fossa and the neural structures that fill it. To assess the Chiari malformation grade, it is advisable to specify the dislocation grades of cerebellar tonsils. There is a common classification of cerebellar tonsil dislocations, in which the dislocation grade 1 of cerebellar tonsils is characterized by the descent of cerebellar tonsils below the foramen magnum level; grade 2 is inherent in dislocation of the cerebellar tonsils down to the C2 vertebra level in combination with displacing the pons and medulla oblongata below the Twining line. Grade 3 dislocation of the cerebellar tonsils is where the cerebellum tonsil displacement is combined with intracranial hypertension. In case of the degree 4 dislocation of the cerebellar tonsils, cerebellar hypoplasia is observed, accompanied by a displacement of the medulla oblongata. The occurrence of syringomyelia in Chiari type 0 malformation is associated with liquor dynamic disorders in the craniovertebral junction region; the similar liquor circulation disorders are detected in Chiari type 1 malformation. Chiari type 1 and “borderline”- type malformations manifest as persistent cranialgia, pain in the cervical spine, otoneurologic and visual disorders, respiratory, psychological, and cognitive disorders, damage to the cerebellar and stem structures of the brain, damage to the spinal cord, and other, more rare signs of damage to the central nervous system. Conclusions. Thus, it is necessary to further study the features of developing clinical symptoms in Chiari type 1, 0, and “borderline” malformations to assess the changes in the course of the disease and select an adequate treatment strategy.
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Huang, Paul P., and Shlomo Constantini. "“Acquired” Chiari I malformation." Journal of Neurosurgery 80, no. 6 (1994): 1099–102. http://dx.doi.org/10.3171/jns.1994.80.6.1099.
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✓ Tonsillar descent of the cerebellum in Chiari I malformations is often considered a congenital defect. A patient is presented in whom magnetic resonance (MR) imaging revealed normally positioned cerebellar tonsils; however, 1 year later MR imaging was repeated for evaluation of gait abnormalities and showed descent of the cerebellar tonsils. This case illustrates worsening symptoms with progressive descent of the cerebellar tonsils and suggests that Chiari I malformations can evolve postnatally.
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Oldfield, Edward H. "Cerebellar tonsils and syringomyelia." Journal of Neurosurgery 97, no. 5 (2002): 1009–10. http://dx.doi.org/10.3171/jns.2002.97.5.1009.
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Silva, José Alberto Gonçalves da, and Maurus Marques de Almeida Holanda. "Basilar impression, Chiari malformation and syringomyelia: a retrospective study of 53 surgically treated patients." Arquivos de Neuro-Psiquiatria 61, no. 2B (2003): 368–75. http://dx.doi.org/10.1590/s0004-282x2003000300009.
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The present study shows the results of 53 patients who have been treated surgically for basilar impression (BI), Chiari malformation (CM), and syringomyelia (SM). The patients were divided into two groups. Group I (24 patients) underwent osteodural decompression with large inferior occipital craniectomy, laminectomy from C 1 to C 3, dural opening in Y format, dissection of arachnoid adhesion between the cerebellar tonsils, medulla oblongata and spinal cord, large opening of the fourth ventricle and dural grafting with the use of bovine pericardium. Group II patients (29 patients) underwent osteodural-neural decompression with the same procedures described above plus dissection of the arachnoid adherences of the vessels of the region of the cerebellar tonsils, and tonsillectomy (amputation) in 10 cases, and as for the remainning 19 cases, intrapial aspiration of the cerebellar tonsils was performed. The residual pial sac was sutured to the dura in craniolateral position. After completion of the suture of the dural grafting, a thread was run through the graft at the level of the created cisterna magna and fixed to the cervical aponeurosis so as to move the dural graft on a posterior- caudal direction, avoiding, in this way, its adherence to the cerebellum.
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Di, Xiao, Mark G. Luciano, and Edward C. Benzel. "Acute respiratory arrest following partial suboccipital cranioplasty for cerebellar ptosis from Chiari malformation decompression." Neurosurgical Focus 25, no. 6 (2008): E12. http://dx.doi.org/10.3171/foc.2008.25.12.e12.
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Cerebellar ptosis is a rare complication following Chiari malformation decompression, and generally is the result of a very large suboccipital craniectomy. This can lead to the descent of the cerebellum through the craniectomy defect, which in turn may result in cerebellar herniation through the surgical defect as well as the reestablishment of contact between the cerebellar tonsils and the brainstem. In addition, dorsal adherence of the herniated cerebellum to the dura mater or dural patch and an associated obstruction of cerebrospinal fluid flow at the cervicomedullary junction may ensue. Such a result is not desirable, in that it reproduces or mimics the pathoanatomical relationships that existed prior to the surgical decompression.
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Qureshi, Imran, Ghazala Hamid, Jaweria Naqi, et al. "Cerebellar Tonsillar Herniation an Incidental Finding in Asymptomatic Patient." Journal of Medical Research and Surgery 5, no. 1 (2024): 10–12. http://dx.doi.org/10.52916/jmrs244128.
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Cerebellar tonsillar herniation, often associated with Chiari malformation, involves the downward displacement of the cerebellar tonsils below the foramen magnum. This condition can lead to significant complications due to the limited intracranial space within the rigid skull. Timely diagnosis is crucial given its potentially fatal nature, with brain structural displacement evident on imaging studies. We present a case of a 27-year-old female with continuous headaches and dizziness, diagnosed with tonsillar herniation through MRI revealing 16 mm of tonsillar descent without associated hydrocephalus or syrinx. Tonsillar herniation, characterized by inferior descent of the cerebellar tonsils, may be congenital or acquired, with measurements typically referenced from the McRae line to the displaced tonsil tip. Complications include brainstem compression, obstruction of cerebrospinal fluid flow, syringomyelia, impaired blood flow, and various neurological and psychological symptoms. Management options vary based on symptom severity and may involve observation, medication, or surgical intervention to alleviate compression and improve cerebrospinal fluid flow. Consultation with a neurologist or neurosurgeon is essential for comprehensive evaluation and tailored management plans aiming to relieve pressure on the brainstem and spinal cord in tonsillar herniation cases.
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Lazareff, Jorge A., Marcelo Galarza, Tooraj Gravori, and Theodore J. Spinks. "Tonsillectomy without craniectomy for the management of infantile Chiari I malformation." Journal of Neurosurgery 97, no. 5 (2002): 1018–22. http://dx.doi.org/10.3171/jns.2002.97.5.1018.
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Object. The authors report their experience with 15 pediatric patients who underwent resection or shrinkage of the cerebellar tonsils without craniectomy or laminectomy, for the management of Chiari I malformation. Methods. The procedure was performed in six boys and nine girls with a mean age of 10 years. Thirteen patients presented with the congenital form of this disorder and two patients with Chiari I malformation caused by lumboperitoneal shunting. Clinical complaints included headaches (seven patients), scoliosis (four patients), numbness of the extremities (four patients), and upper-limb weakness (two patients). Two patients presented with failure to thrive and one with vocal cord palsy. Eight patients (six girls and two boys) had syringomyelia. The patients' symptoms had developed within a mean time period of 21 months (range 1–70 months). In all patients the cerebellar tonsils were exposed through a dura mater—arachnoid incision at the occipitoatlantal space. In seven patients the tonsils were resected and in the remaining eight patients the tonsils were shrunk by coagulating their surfaces. All patients improved postoperatively. Gliosis with cortical atrophy was observed in the resected neural tissue. Syringomyelia was reduced in seven of eight patients. The mean length of the follow-up period was 7 months. Conclusions. Removal of herniated cerebellar tonsils can be sufficient for alleviating symptoms in patients with Chiari I malformations.
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Silva, José Alberto Gonçalves da, Maria do Desterro Leiros da Costa, Luiz Ricardo Santiago Melo, Antônio Fernandes de Araújo, and Everardo Bandeira de Almeida. "Impacted cisterna magna without syringomyelia associated with lancinating headache, throbbed nuchal pain and paraparesis treated byposterior fossa decompression." Arquivos de Neuro-Psiquiatria 65, no. 4b (2007): 1228–32. http://dx.doi.org/10.1590/s0004-282x2007000700027.
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A 29-year-old woman with acute lancinating headache, throbbed nuchal pain and subacute paraparesis underwent brain MRI in supine position that depicted: the absence of the cisterna magna, filled by non herniated cerebellar tonsils and compression of the brain stem and cisternae of the posterior fossa, which are aspects of the impacted cisterna magna without syringomyelia and without hydrocephalus. During eight days, pain was constant and resistant to drug treatment. Osteodural-neural decompression of the posterior fossa, performed with the patient in sitting position, revealed: compression of the brainstem, fourth ventricle and foramen of Magendie by herniated cerebellar tonsils, which were aspirated. Immediately after surgery, the headache and nuchal pain remmited. MRI depicted the large created cisterna magna and also that the cerebellar tonsils did not compress the fourth ventricle, the foramen of Magendie and the brainstem, besides the enlargement of posterior fossa cisternae. Four months after surgery, headache, nuchal pain and paraparesis had disappeared but hyperactive patellar and Achilles reflexes remained.
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Öğrenci, Ahmet, Orkun Koban, Murat Ekşi, Onur Yaman, and Sedat Dalbayrak. "Traumatic Transient Herniation Concomitant with Tonsillar Hemorrhagic Contusion in a Child." Open Access Macedonian Journal of Medical Sciences 5, no. 6 (2017): 771–73. http://dx.doi.org/10.3889/oamjms.2017.167.
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Downward displacement of cerebellar tonsils more than 5 mm below the foramen magnum is named as Chiari type I malformation and named benign tonsillar ectopia if herniation is less than 3 mm. It does not just depend on congenital causes. There are also some reasons for acquired Chiari Type 1 and benign tonsillar ectopia/herniation. Trauma is one of them. Trauma may increase tonsillar ectopia or may be the cause of new-onset Chiari type 1. The relationship between the tonsil contusion and its position is unclear. We present a case of pediatric age group with tonsillar herniation with a hemorrhagic contusion. Only 1 case has been presented so far in the literature. A case with unilateral tonsil contusion has not been presented to date. We will discuss the possible reasons for taking the place of the tonsils to the above level of the foramen magnum in the follow-up period, by looking at the literature.
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Morota, Nobuhito, and Satoshi Ihara. "Postnatal ascent of the cerebellar tonsils in Chiari malformation Type II following surgical repair of myelomeningocele." Journal of Neurosurgery: Pediatrics 2, no. 3 (2008): 188–93. http://dx.doi.org/10.3171/ped/2008/2/9/188.
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Object Postnatal improvement in Chiari malformation type II (CM-II) following surgical repair of myelomeningocele was evaluated. Methods The authors reviewed data obtained in 20 cases in which patients underwent postnatal myelomeningocele repair within the first 48 hours after birth between October 2002 and September 2006. In 14 patients (Group 1), myelomeningocele was diagnosed in utero and the infants were delivered by cesarean section at 35–39 weeks' gestation (mean 36.4). The 6 infants in Group 2 were born after full-term gestation (39–41 weeks), and their myelomeningoceles were diagnosed postnatally. In all 20 patients, the myelomeningoceles were surgically repaired postnatally. Dynamic change of the herniated cerebellar tonsils in CM-II before and after the myelomeningocele repair, associated hydrocephalus, and symptomatic CM-II were analyzed. Results In Group 1, the CM-II was confirmed before myelomeningocele repair in 13 cases (93%). The spinal level of the caudal end of the cerebellar tonsils ranged from C-2 to C-7. Ascent of the cerebellar tonsils was observed in 11 patients (range 1–4 spinal levels, mean 2 levels) and continued even after ventriculoperitoneal (VP) shunt placement in most patients. A VP shunt was required for the treatment of hydrocephalus in 12 patients (86%). Symptomatic CM-II developed in 8 of 13 patients (61%), 3 of whom required surgical decompression. In Group 2, CM-II was confirmed in 5 infants (83%), with the cerebellar tonsils at a spinal level of C-2 to C-4 or C-5. Ascent of the cerebellar tonsils was observed in 4 patients (range 1–1.5 spinal levels, average 1.1 levels), and no patient had symptomatic CM-II. A VP shunt was placed in 5 patients (83%). No patient was lost to follow-up during the 18-month follow-up period. The only statistically significant difference between the 2 groups was the presence of symptomatic CM-II in Group 2 (p = 0.02). Conclusions Patients showed ascent of the cerebellar tonsils after postnatal myelomeningocele repair. Placement of a VP shunt helped promote the ascent. However, postnatal myelomeningocele repair in the patients in Group 1 failed to consistently prevent development of symptomatic CM-II. This limited experience suggests that postnatal repair of myelomeningocele can partially reverse the anatomical CM-II, but symptomatic CM-II cannot be prevented in some patients when the repair is performed after 36 weeks' gestation.
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Smith, Brandon W., Jennifer Strahle, Erick Kazarian, Karin M. Muraszko, Hugh J. L. Garton, and Cormac O. Maher. "Impact of body mass index on cerebellar tonsil position in healthy subjects and patients with Chiari malformation." Journal of Neurosurgery 123, no. 1 (2015): 226–31. http://dx.doi.org/10.3171/2014.10.jns141317.
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OBJECT It is unclear if there is a relationship between Chiari malformation Type I (CM-I) and body mass index (BMI). The aim of this study was to identify the relationship between BMI and cerebellar tonsil position in a random sample of people. METHODS Cerebellar tonsil position in 2400 subjects from a cohort of patients undergoing MRI was measured. Three hundred patients were randomly selected from each of 8 age groups (from 0 to 80 years). A subject was then excluded if he or she had a posterior fossa mass or previous posterior fossa decompression or if height and weight information within 1 year of MRI was not recorded in the electronic medical record. RESULTS There were 1310 subjects (54.6%) with BMI records from within 1 year of the measured scan. Of these subjects, 534 (40.8%) were male and 776 (59.2%) were female. The average BMI of the group was 26.4 kg/m2, and the average tonsil position was 0.87 mm above the level of the foramen magnum. There were 46 subjects (3.5%) with a tonsil position ≥ 5 mm below the level of the foramen magnum. In the group as a whole, there was no correlation (R2 = 0.004) between BMI and cerebellar tonsil position. CONCLUSIONS In this examination of 1310 subjects undergoing MRI for any reason, there was no relationship between BMI and the level of the cerebellar tonsils or the diagnosis of CM-I on imaging.
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Smith, Brandon W., Jennifer Strahle, J. Rajiv Bapuraj, Karin M. Muraszko, Hugh J. L. Garton, and Cormac O. Maher. "Distribution of cerebellar tonsil position: implications for understanding Chiari malformation." Journal of Neurosurgery 119, no. 3 (2013): 812–19. http://dx.doi.org/10.3171/2013.5.jns121825.
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Object Prior attempts to define normal cerebellar tonsil position have been limited by small numbers of patients precluding analysis of normal distribution by age group. The authors' objective in the present study was to analyze cerebellar tonsil location in every age range. Methods Two thousand four hundred patients were randomly selected from a database of 62,533 consecutive patients undergoing MRI and were organized into 8 age groups. Magnetic resonance images were directly examined for tonsil location, morphology, and other features. Patients with a history or imaging findings of posterior fossa abnormalities unrelated to Chiari malformation (CM) were excluded from analysis. The caudal extent of the cerebellar tonsils was measured at the midsagittal and lowest parasagittal positions. Results The mean tonsil height decreased slightly with advancing age into young adulthood and increased with advancing age in the adult age range. An increasing age in the adult age range was associated with a decreased likelihood of a tonsil position 5 mm or more below the foramen magnum (p = 0.0004). In general, the lowest tonsil position in each age group was normally distributed. Patients with pegged morphology were more likely to have a tonsil location at least 5 mm below the foramen magnum (85%), as compared with those having intermediate (38%) or rounded (2%) morphology (p < 0.0001). Female sex was associated with a lower mean tonsil position (p < 0.0001). Patients with a lower tonsil position also tended to have an asymmetrical tonsil position, usually lower on the right (p < 0.0001). Conclusions Cerebellar tonsil position follows an essentially normal distribution and varies significantly by age. This finding has implications for advancing our understanding of CM.
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Antonucci, Michael U., and Alex Drohan. "Dynamic Cerebellar Tonsils in Chiari Malformation." Journal of Pediatrics 206 (March 2019): 295. http://dx.doi.org/10.1016/j.jpeds.2018.11.020.
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Mendonça, Rodrigo, Telmo Tibúrcio Fortes Lima, Paulo Petry Oppitz, and Sérgio Fernando Raupp. "Herniation of the cerebellar tonsils after suprasellar arachnoid cyst shunt: case report." Arquivos de Neuro-Psiquiatria 64, no. 2b (2006): 523–25. http://dx.doi.org/10.1590/s0004-282x2006000300033.
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It is known that the caudal dislocation of the cerebellar tonsils may occur associated with clinical conditions such as an intracranial mass lesion or Chiari I and II malformation. It may also be acquired after repeated lumbar punctures or lumboperitoneostomy. The occurrence of cerebellar herniation after derivation of intracranial arachnoid cyst is extremely rare, and there are only three cases reported in the medical literature. We present the case of a 9-year-old boy with precocious puberty and suprasellar arachnoid cyst who developed a symptomatic herniation of the cerebellar tonsils three years after a cystoperitoneostomy. The patient underwent a suboccipital craniectomy with duraplasty and partial tonsilectomy, showing afterwards, remission of the symptoms. We discussed the pathogenesis suggested in the literature.
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Stevenson, Charles B., James L. Leach, Anita Gupta, and Kerry R. Crone. "Cystic degeneration of the cerebellar tonsils in pediatric patients with Chiari Type I malformation." Journal of Neurosurgery: Pediatrics 4, no. 6 (2009): 557–63. http://dx.doi.org/10.3171/2009.7.peds09174.
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Object The operative indications and treatment algorithms for pediatric patients with Chiari Type I malformation (CM-I) vary widely. When an intradural approach and duraplasty are thought necessary at the time of surgery, neurosurgeons may elect to fulgurate or resect a portion of the cerebellar tonsils. Histological analyses of cerebellar tonsils resected during decompression in pediatric patients with CM-I have revealed multiple abnormal findings including extensive ischemic and degenerative changes. The authors describe an interesting phenomenon of cystic degeneration in the distal ends of the cerebellar tonsils in children undergoing operative treatment of CM-I. Methods The authors reviewed the clinical database of 440 pediatric patients who underwent surgical decompression for CM-I performed by a single surgeon. The clinical course, preoperative MR imaging and intraoperative ultrasound characteristics, and histological findings in 3 children found to have tonsillar cystic degeneration were analyzed and detailed. Results Cystic changes were subtle but uniformly evident on preoperative MR imaging and were more readily apparent on intraoperative ultrasonography. In each patient, the tonsillar cyst was resected. Histological examination revealed areas of cystic degenerative change characterized by distortion of the normal cerebellar architecture with absent Purkinje and internal granular cell layers. All children experienced improvement in their symptoms, without complication, postoperatively. Conclusions Cystic degeneration of the tonsils in pediatric patients with CM-I is an uncommon pathological process most likely resulting from long-standing and excessive compression. Based on their experience, the authors advocate expeditious surgical treatment, including intradural exploration and capacious duraplasty, for patients in whom there is evidence of this phenomenon on preoperative imaging.
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SÜRÜCÜ KARA, İlknur, and Tayfun ÇAKIR. "Pediatrik bir hastada eş zamanlı medulloblastoma ve Chiari Tip-I deformitesi." Cukurova Medical Journal 48, no. 3 (2023): 1187–89. http://dx.doi.org/10.17826/cumj.1315981.
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Concurrence of medulloblastoma and Chiari deformity (type-1) in a pediatric patient is extremely rarely seen. 10 years old girl. She had first complained of nausea, abdominal pain, and vomiting. She had a mild headache for three days. Computed tomography was taken. There were sequelae related to her previous illness and noticed the appearance of the left cerebellar tonsils down to the foramen magnum level and mild prominence in the third ventricle. Cranial imaging was performed with magnetic resonance imaging. There was a lesion as a solid mass, about 60 mm sized in the level right cerebellar, a cerebellar tonsil hernia (11 mm), and ventricular dilatation in magnetic resonance imaging. Histologically, the lesion was a classic type of medulloblastoma. The coexistence of two diseases may occur in the same patient. Magnetic resonance imaging, which indicates the craniovertebral junction can be used singly.Because MRG is the first method to be selected for diagnosis.
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Oldfield, Edward H., Karin Muraszko, Thomas H. Shawker, and Nicholas J. Patronas. "Pathophysiology of syringomyelia associated with Chiari I malformation of the cerebellar tonsils." Journal of Neurosurgery 80, no. 1 (1994): 3–15. http://dx.doi.org/10.3171/jns.1994.80.1.0003.
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✓ The mechanisms previously proposed for the progression of syringomyelia associated with Chiari I malformation of the cerebellar tonsils are controversial, leave many clinical observations unexplained, and underlie the prevalence of different operations currently used as initial treatment. To explore the mechanism of syringomyelia progression in this setting, the authors used anatomical and dynamic (phase-contrast and phase-contrast cine) magnetic resonance (MR) imaging, and intraoperative ultrasonography to examine the anatomy and dynamics of movement of the cerebellar tonsils, the wall of the spinal cord surrounding the syrinx, and the movement of cerebrospinal fluid (CSF) and syrinx fluid at rest, during the respiratory and cardiac cycles, and during Valsalva maneuver in seven affected patients. In all patients the cerebellar tonsils occluded the subarachnoid space at the level of the foramen magnum. Syringomyelia extended from the cervical to the lower thoracic segment of the spinal cord. No patient had evidence of a patent communication between the fourth ventricle and the syrinx on anatomical MR images, dynamic MR images, or intraoperative ultrasound studies. Dynamic MR images of three patients revealed abrupt downward movement of the spinal CSF and the syrinx fluid during systole and upward movement during diastole, but limited movement of CSF across the foramen magnum during the cardiac cycle. Intraoperative ultrasound studies demonstrated abrupt downward movement of the cerebellar tonsils during systole that was synchronous with sudden constriction of the spinal cord and syrinx. Decompression of the foramen magnum was achieved via suboccipital craniectomy, laminectomy of C-1 and C-2, and dural grafting, leaving the arachnoid intact. Immediately after surgery, the pulsatile downward thrust of the tonsils and constriction of the spinal cord and syrinx disappeared. Syringomyelia resolved within 1 to 6 months after surgery in all patients. Observations by the authors suggest the following previously unrecognized mechanism for progression of syringomyelia associated with occlusion of the subarachnoid space at the foramen magnum. The brain expands as it fills with blood during systole, imparting a systolic pressure wave to the intracranial CSF that is accommodated in normal subjects by sudden movement of CSF from the basal cisterns to the upper portion of the spinal canal. With obstruction to rapid movement of CSF at the foramen magnum, the cerebellar tonsils, which plug the subarachnoid space posteriorly, move downward with each systolic pulse, acting as a piston on the partially isolated spinal CSF and producing a systolic pressure wave in the spinal CSF that acts on the surface of the spinal cord. This causes progression of syringomyelia by abruptly compressing the cord and propelling the fluid in the syrinx longitudinally with each pulse, and may be responsible for the origin and maintenance of syringomyelia by the pulsatile pressure waves forcing CSF into the cord through the perivascular and interstitial spaces. Effective treatment occurs when the systolic pressure wave transmitted by the cerebellar tonsils is eliminated by relieving the obstruction to rapid movement of subarachnoid CSF across the foramen magnum. The presence of this mechanism can be detected preoperatively on dynamic MR images and during surgery on ultrasound studies by the pulsatile excursion of the wall of the spinal cord surrounding the syrinx and by its immediate disappearance and the expansion of the syrinx during forced inspiration after decompression of the tonsils. Effective treatment is achieved with bone and dural decompression of the foramen magnum alone, without entering the arachnoid.
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Silva, José Alberto Gonçalves da, Maurus Marques de Almeida Holanda, Cristiana Borges Pereira, Maria do Desterro Leiros, Antônio Fernandes de Araújo, and Everardo Bandeira. "Retropulsion and vertigo in the Chiari malformation: case report." Arquivos de Neuro-Psiquiatria 63, no. 3b (2005): 870–73. http://dx.doi.org/10.1590/s0004-282x2005000500030.
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We describe a rare case of a 30 year-old woman with intense vertiginous sensation, lack of body balance and a tendency to fall backwards, making it necessary for two people to sustain her. The magnetic resonance imaging of the craniocervical junction evidenced tonsilar herniation at the inferior level of C1, and during the operation performed in sitting position, we observed crowding of the cerebellar tonsils at the level of C3. After the osteo-dural-neural decompression, the symptomatology remitted on the same day of the operation.
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Heiss, John D., Giancarlo Suffredini, Kamran D. Bakhtian, Malisa Sarntinoranont, and Edward H. Oldfield. "Normalization of hindbrain morphology after decompression of Chiari malformation Type I." Journal of Neurosurgery 117, no. 5 (2012): 942–46. http://dx.doi.org/10.3171/2012.8.jns111476.
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Object Chiari malformation Type I (CM-I) is characterized by hindbrain deformity. We investigated the effects of craniocervical decompression surgery on the anatomical features of hindbrain deformity with a prospective MRI study of patients with CM-I. Methods A prospective longitudinal study was conducted in 48 patients with CM-I (39 with syringomyelia) treated with craniocervical decompression. Clinical examinations and cervical MRI were performed before surgery and 1 week, 3–6 months, and annually after surgery. Hindbrain deformity was defined by tonsillar ectopia, pointed cerebellar tonsils, and/or cervicomedullary protuberance. The length of the clivus, basiocciput (sphenooccipital synchondrosis to basion), supraocciput (internal occipital protuberance to opisthion), and anteroposterior (AP) width of CSF pathways at the foramen magnum were measured and compared with those from 18 healthy volunteers (control group). Results Before surgery, the patients' posterior fossa bones were short and their CSF pathways were narrow. All patients had tonsillar ectopia (mean [± SD] 12.3 ± 5.1 mm; normal 0.3 ± 1.0). The majority of patients had pointed tonsils and more than two-thirds exhibited a cervicomedullary protuberance. Clivus and basiocciput lengths were significantly shorter than the values obtained in the control group. However, the supraocciput length did not differ significantly from control measurements. The mean bulbopontine sulcus distance superior to the basion was 9.5 ± 2.6 mm (vs 13.6 ± 2.8 mm in controls; p < 0.0001). The AP widths of the CSF pathways at the level of the foramen magnum were significantly narrowed. After surgery, CSF pathways significantly expanded both ventrally and dorsally. By 3–6 months after surgery, pointed tonsils became round, cervicomedullary protuberance disappeared, and tonsillar ectopia diminished by 51% (to 6.0 ± 3.3 mm; p < 0.0001). Conclusions The cerebellar tonsils and brainstem assumed a normal appearance within 6 months after craniocervical decompression. These findings support the concept that the CM-I is not a congenital malformation of the neural elements but rather an acquired malformation that arises from pulsatile impaction of the cerebellar tonsils into the foramen magnum. Clinical trial registration no.: NCT00001327.
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Huber, Aric, Matthew Driben, and Eduardo Espiridion. "Arnold-Chiari Malformation-I Borderline Personality Disorder." Transformative Medicine 2, no. 2 (2023): 25–28. http://dx.doi.org/10.54299/tmed/wgdh6653.
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Introduction: Arnold-Chiari Malformation I (AM-I) is a congenital anomaly that manifests with cerebellar dysfunction. There is a displacement of cerebellar tonsils into the foramen magnum. Several mood disorders, personality disorders, and intellectual disabilities are associated with AM-I. Borderline personality disorder (BPD) is characterized by symptoms of mood lability, impulsivity, extreme efforts of abandonment, splitting and dysfunctional relationships. Case Description: The patient is an early aged adult with a past medical history of AM-I, hypothyroidism, Wolff-Parkinson-White syndrome, and diabetes mellitus type II. The patient was admitted to the hospital after ingesting foreign bodies. He/she presented with mood lability, sad mood, anhedonia, insomnia, panic attacks, ruminative worries, feelings of emptiness, and recurrent suicidal gestures and threats. The patient was eventually diagnosed with borderline personality disorder. This case suggests a possible connection between AM-I and BPD. Discussion: Emerging from contemporary research involving the cerebellum, it is important to acknowledge that the current definition of control of fine motor and balance is inadequate. Symptoms associated with AM-I and BPD may be better explained by Cerebellar Cognitive Affective Syndrome (CCAS), a condition that ties the cerebellum with the higher cognitive functioning in the brain.
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Lim, Sang Joon, Dae Sik Ryu, Seung Min Yoo, et al. "Normal Position of the Cerebellar Tonsils in Korean." Journal of the Korean Radiological Society 34, no. 3 (1996): 321. http://dx.doi.org/10.3348/jkrs.1996.34.3.321.
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Lazareff, J. A., John Kelly, and Michael Saito. "Herniation of cerebellar tonsils following supratentorial shunt placement." Child's Nervous System 14, no. 8 (1998): 394–97. http://dx.doi.org/10.1007/s003810050252.
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Derevyanko, Kh P., and Sh M. Safin. "Chiari malformation type I and syringomyelia as keys to understanding CSF circulation (literature review)." Vestnik nevrologii, psihiatrii i nejrohirurgii (Bulletin of Neurology, Psychiatry and Neurosurgery), no. 8 (August 16, 2022): 627–35. http://dx.doi.org/10.33920/med-01-2208-07.
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Pathophysiology of syringomyelia has not been understood completely. The basic «piston» theory is that the downward movement of the cerebellar tonsils that occurs during the cardiac cycle acts like a «piston» on the partially closed spinal subarachnoid space and results in the formation of a syringomyelitic cavity. However, this still needs to be confirmed by additional experimental data. The main pathogenetic question is how the cerebrospinal fluid enters and remains in the syringomyelic cavity, where the pressure is higher than in the subarachnoid space. Based on the literature data on the pathogenesis of Chiari I malformation with syringomyelia, we modeled and presented our vision of the pathogenesis. Our assumption about the formation of syringomyelia in Chiari I malformation is that there may be a CSF channel between the fourth ventricle and the syrinx. This channel takes on the function of a one-way valve when slightly squeezed and with cyclic movements of the cerebellar tonsils. Decompression of the tonsils turns off the one-way valve, collapsing the syrinx. Perhaps this assumption will serve as a working hypothesis for further study of the pathophysiology of Chiari malformation type I and syringomyelia.
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Chang, Han Soo. "Hypothesis on the pathophysiology of syringomyelia based on analysis of phase-contrast magnetic resonance imaging of Chiari-I malformation patients." F1000Research 10 (October 1, 2021): 996. http://dx.doi.org/10.12688/f1000research.72823.1.
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Background: Despite a number of hypotheses, our understanding of the pathophysiology of syringomyelia is still limited. The current prevailing hypothesis assumes that the piston-like movement of the cerebellar tonsils drives the cerebrospinal fluid (CSF) into the syrinx through the spinal perivascular space. However, it still needs to be verified by further experimental data. A major unexplained problem is how CSF enters and remains in the syrinx that has a higher pressure than the subarachnoid space. Methods: I analyzed phase-contrast MRI scans of 18 patients with Chiari-I malformation with syringomyelia undergoing foramen magnum decompression and 21 healthy volunteers. I analyzed the velocity waveforms of the CSF and the brain in various locations. The obtained velocity waveforms were post-processed using a technique called synchronization in situ. I compared between the preoperative data and the control data (case-control study), as well as between the preoperative and postoperative data (cohort study). Results: The syrinx shrank in 17 (94%) patients with good clinical improvement. In Chiari-I patients, the velocity of the tonsil was significantly larger than controls, but was significantly smaller than that of the CSF in the subarachnoid space, suggesting passive rather than active movement. The abnormal tonsillar movement disappeared after surgery, but the velocity waveform of the spinal subarachnoid CSF did not change. These results, contradicting the above mentioned hypothesis, required an alternative explanation. I thus hypothesized that there is a CSF channel between the fourth ventricle and the syrinx. This channel assumes one-way valve function when mildly compressed by the cyclical movement of the cerebellar tonsil. The decompression of the tonsils switches off the one-way valve, collapsing the syrinx. Conclusions: My hypothesis reasonably explained my data that clearly contradicted the existing hypothesis, and successfully addressed the above-mentioned theoretical problem. It will serve as a working hypothesis for further study of syringomyelia pathophysiology.
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Leung, Vannessa, John S. Magnussen, Marcus A. Stoodley, and Lynne E. Bilston. "Cerebellar and hindbrain motion in Chiari malformation with and without syringomyelia." Journal of Neurosurgery: Spine 24, no. 4 (2016): 546–55. http://dx.doi.org/10.3171/2015.8.spine15325.
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OBJECTIVE The pathogenesis of syringomyelia associated with Chiari malformation type I (CM-I) is unclear. Theories of pathogenesis suggest the cerebellar tonsils may obstruct CSF flow or alter pressure gradients, or their motion might act as a piston to increase CSF pressure in the spinal subarachnoid space. This study was performed to measure cerebellar tonsillar and hindbrain motion in CM-I and assess the potential contributions to syrinx formation. METHODS Sixty-four CM-I patients and 25 controls were retrospectively selected from a clinical database, and all subjects had undergone cardiac-gated cine balanced fast-field echo MRI. There were a total of 36 preoperative CM-I scans, which consisted of 15 patients with and 21 patients without syringomyelia. Nineteen patients underwent paired pre- and postoperative imaging. Anteroposterior (AP) and superoinferior (SI) movements of the tip of the cerebellar tonsils, obex, fastigium of the fourth ventricle, pontomedullary junction, and cervicomedullary junction were measured. The distance between the fastigium and tip of the tonsils was used to calculate tonsillar tissue strain (Δi/i0). RESULTS CM-I patients had significantly greater cerebellar tonsillar motion in both the AP and SI directions than controls (AP +0.34 mm [+136%], p < 0.001; SI +0.49 mm [+163%], p < 0.001). This motion decreased after posterior fossa decompression (AP −0.20 mm [−33%], p = 0.001; SI −0.29 mm [−36%]; p < 0.001), but remained elevated above control levels (AP +56%, p = 0.021; SI +67%, p = 0.015). Similar trends were seen for all other tracked landmarks. There were no significant differences in the magnitude or timing of motion throughout the hindbrain between CM-I patients with and without syringomyelia. Increased tonsillar tissue strain correlated with Valsalva headaches (p = 0.03). CONCLUSIONS Cerebellar tonsillar motion may be a potential marker of CM-I and may have use in tailoring surgical procedures. The lack of association with syringomyelia suggests that tonsillar motion alone is not the driver of syrinx formation. Tonsillar tissue strain may play a part in the pathophysiology of Valsalva headaches.
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Pandey, Aditya, Shenandoah Robinson, and Alan R. Cohen. "Cerebellar fits in children with Chiari I malformation." Neurosurgical Focus 11, no. 1 (2001): 1–4. http://dx.doi.org/10.3171/foc.2001.11.1.5.
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Object The authors describe a series of children with Chiari I malformation who presented with fulminating symptoms of “cerebellar fits” characterized by drop attacks with or without deterioration of consciousness, opisthotonic posturing, and varying degrees of respiratory compromise. Methods A retrospective analysis was undertaken of the medical records of 47 consecutive patients undergoing surgery for symptomatic Chiari I malformations at Rainbow Babies and Children's Hospital. Thirteen (28%) of the 47 patients presented with complaints consistent with cerebellar fits. Before the correct diagnosis was made, nine (69%) of the 13 children had previously undergone evaluation with electroencephalography and/or electrocardicography and Holter monitoring because of suspected cortical epilepsy or cardiogenic syncope. In each of the 13 children magnetic resonance imaging demonstrated pegged cerebellar tonsils herniated below the foramen magnum. A deep indentation or blanched discoloration of the cerebellar tonsils was noted in five (38%) of these 13 patients at the time of surgery. Of patients with symptomatic Chiari I malformations, the mean degree of tonsillar herniation was significantly less for those in whom cerebellar fits occurred than those in whom they were absent (8.8 mm and 13.9 mm, respectively; p = 0.007). In only one of the patients with cerebellar fits was a syrinx present, and this was a small focal lower thoracic collection. Spells resolved after surgery in all patients who presented with cerebellar fits. Conclusions Cerebellar fits may mimic other disorders such as cardiogenic syncope and epileptic seizures. The correct diagnosis may be delayed or the conditions may be misdiagnosed by those who fail to consider Chiari I malformation as a cause of drop attacks, abnormal extensor posturing, and apneic spells in children. The response to decompressive surgery in these patients is gratifying.
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Sahuquillo, Juan, Dulce Moncho, Alex Ferré, Diego López-Bermeo, Aasma Sahuquillo-Muxi, and Maria A. Poca. "A Critical Update of the Classification of Chiari and Chiari-like Malformations." Journal of Clinical Medicine 12, no. 14 (2023): 4626. http://dx.doi.org/10.3390/jcm12144626.
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Chiari malformations are a group of craniovertebral junction anomalies characterized by the herniation of cerebellar tonsils below the foramen magnum, often accompanied by brainstem descent. The existing classification systems for Chiari malformations have expanded from the original four categories to nine, leading to debates about the need for a more descriptive and etiopathogenic terminology. This review aims to examine the various classification approaches employed and proposes a simplified scheme to differentiate between different types of tonsillar herniations. Furthermore, it explores the most appropriate terminology for acquired herniation of cerebellar tonsils and other secondary Chiari-like malformations. Recent advances in magnetic resonance imaging (MRI) have revealed a higher prevalence and incidence of Chiari malformation Type 1 (CM1) and identified similar cerebellar herniations in individuals unrelated to the classic phenotypes described by Chiari. As we reassess the existing classifications, it becomes crucial to establish a terminology that accurately reflects the diverse presentations and underlying causes of these conditions. This paper contributes to the ongoing discussion by offering insights into the evolving understanding of Chiari malformations and proposing a simplified classification and terminology system to enhance diagnosis and management.
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Humphrey, Emily. "Chiari malformations in adults: their surgical and nursing management." British Journal of Neuroscience Nursing 15, no. 3 (2019): 130–36. http://dx.doi.org/10.12968/bjnn.2019.15.3.130.
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There are two categories of Chiari malformations that occur in adults: type 1 and type 2. Type 1 Chiari malformations are conditions where the bottommost parts of the back of the brain (called the cerebellar tonsils) descend below the skull and enter the spinal canal—the space around the spinal cord. In type 2 Chiari malformations, more of the brain descends below the skull. This means that, as well as the cerebellar tonsils, the lower section of the brainstem (the medulla) and the brain's lowermost fluid-filled cavity, the fourth ventricle, also descend. The descending structures cause pressure and disrupt the normal flow of fluid that circulates in the brain and spinal cord, known as cerebrospinal fluid (CSF). This article further explains the Chiari malformations, presents theories of how they are caused and describes their symptoms and complications. It also discusses Chiari malformations, theories of causation, symptoms, complications, treatment and nursing management considerations.
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Johncy, Anne, G. Rohini, and Lekha Shri. "NT scan: can it prevent second trimester MTP complications?" International Journal of Reproduction, Contraception, Obstetrics and Gynecology 7, no. 6 (2018): 2497. http://dx.doi.org/10.18203/2320-1770.ijrcog20182375.
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The NT scan (11 to 13 weeks+6 days) is used as dating scan and genetic scan. Now it is emerging as a basic checklist for examination of the whole fetal anatomy and also to identify congenital anomalies in early trimester. Arnold-Chiari malformation type II is the most common which is characterized by displacement of cerebellar tonsils, parts of the cerebellum- fourth ventricle, pons and medulla oblongata through the foramen magnum into the spinal canal. This is usually associated with hydrocephalus and myelomeningocele. This can be prevented by preconceptional folic acid supplementation. Second trimester MTP complications can be prevented if we diagnose congenital anomalies in first trimester itself.
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Etibarlı, S. A., and N. V. Najafbayli. "CHIARI MALFORMATION. BRIEF SUMMARY OF THE INFORMATION ABOUT DISEASE AND HISTORY OF DISCOVERY." National Journal of Neurology 2, no. 22 (2023): 9–13. http://dx.doi.org/10.61788/njn.v2i22.01.
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Chiari malformation is a congenital anomaly of the hindbrain and is characterized by descent of the cerebellar tonsils into the foramen magnum with compression of the medulla oblongata and the development of specific neurological symptoms. The whole concept of these malformations arose towards the end of the 19th century from the original descriptions by the German pathologist, Professor Hans Chiari (1851–1916), of changes in the cerebellum resulting from cerebral hydrocephalus. He also classified Arnold-Chiari malformations into 4 types. The aim of this study was reviewing of the literature and discussion of the anatomical forms, classification and history of the discovery of Chiari malformation.
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H, Rahul, and Aysha Juhi Amal Hafeez. "CASE REPORT ON MANAGEMENT OF CEREBELLAR TONSILLAR ECTOPIA- AN AYURVEDIC APPROACH." International Ayurvedic Medical Journal 12, no. 11 (2024): 2108–12. https://doi.org/10.46607/iamj2912112024.
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Cerebellar tonsillar ectopia is where the cerebellar tonsils protrude through the foramen magnum, often causing neurological symptoms. In this case, the patient mainly complained of weakness in both lower limbs, difficulty while walking, and lower body balance. Diagnosis of this case was challenging, but after the study of MRI of the cervical and dorsal spine, the case was diagnosed as Cerebellar tonsillar herniation. She was given Ayurveda medication internally, and Panchakarma procedures were done at the IP level. Throughout the entire course of treatment, physiotherapy was also done. There was a marked improvement in the symptoms, which helped her improve her quality of life.
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Gingold, Scott I., and Jeffrey A. Winfield. "Oscillopsia and Primary Cerebellar Ectopia: Case Report and Review of the Literature." Neurosurgery 29, no. 6 (1991): 932–36. http://dx.doi.org/10.1227/00006123-199112000-00026.
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Abstract Oscillopsia, the visual sensation of stationary objects swaying back and forth or vibrating, has been described in association with downbeat nystagmus in patients with primary cerebellar ectopia (Chiari I malformation). A patient with symptomatic oscillopsia without downbeat nystagmus, who was diagnosed by magnetic resonance imaging to have displaced cerebellar tonsils below the foramen magnum, is presented here. Suboccipital craniectomy and upper cervical laminectomy completely relieved the visual disturbance of the patient. The pathogenesis and surgical management of oscillopsia are discussed with respect to the current literature. Early recognition and surgical decompression of cerebellar ectopia may lead to complete recovery in patients with minimal symptomatology.
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De Souza, Illgner Alves, Matheus Borges Gomes, Guilherme Enares Ramires, Felipe Famelli de Campos, and Felipe Iankelevich Baracat. "MALFORMAÇÃO DE CHIARI I: RELATO DE CASO." Revista Uningá 56, no. 2 (2019): 44–49. http://dx.doi.org/10.46311/2318-0579.56.euj2714.
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RESUMO
 Introdução: A Malformação de Chiari tipo I é uma alteração congênita e pouco prevalente que é originária de anomalias estruturais da base do crânio com uma fossa craniana posterior hipoplásica que leva à herniação das tonsilas cerebelares pelo forame magno. Relato do caso: Relatamos um paciente com Malformação de Chiari tipo I diagnosticado após trauma crânio-encefálico com exames de imagem que não mostraram alterações relacionadas ao trauma, entretanto com achado da anomalia, evidenciada pela insinuação inferior das tonsilas cerebelares no forame magno por cerca de 1,8 cm, hidromielia e coleções císticas na fossa posterior. Correlacionados o achado de imagem com sintomas prévios do paciente característicos, indicou-se a cirurgia e foi submetido à descompressão da fossa posterior do crânio com boa evolução. Conclusão: O tratamento cirúrgico adequado é capaz de obter resultados satisfatórios e duradouros com melhoria da qualidade de vida dos pacientes.
 Palavras chave: Malformação de Chiari I, descompressão da fossa posterior, cefaleia occipital, hidromielia
 
 ABSTRACT
 Introduction: Chiari Malformation Type I is a congenital and less prevalent alteration that originates from structural abnomalities of the skull base with a hypoplasic posterior cranial fossa leading to herniation of the cerebellar tonsils by the foramen magnum. Case report: We report a pacient with Chiari Malformation Type I diagnosed after cranioencephalic trauma with imaging tests that showed no trauma-related changes, however with anomaly finding, evidenced by the inferior insinuation of the cerebellar tonsils in the foramen magnum for about 1.8 cm, hydromielia and cystic collections in the posterior fossa. Correlated the image finding with charateristics patient’s previous symptoms, the surgery was indicated and was submitted to decompression of the posterior fossa of the skull with good evolution. Conclusion: The adequate surgical treatment is capable of obtaining satisfactory and long-lasting results with improvement of patients quality of life.
 Keywords: Chiari malformation Type I, posterior fossa decompression, occipital headache, hydromyelia.
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Heiss, John D., Nicholas Patronas, Hetty L. DeVroom, et al. "Elucidating the pathophysiology of syringomyelia." Journal of Neurosurgery 91, no. 4 (1999): 553–62. http://dx.doi.org/10.3171/jns.1999.91.4.0553.
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Object. Syringomyelia causes progressive myelopathy. Most patients with syringomyelia have a Chiari I malformation of the cerebellar tonsils. Determination of the pathophysiological mechanisms underlying the progression of syringomyelia associated with the Chiari I malformation should improve strategies to halt progression of myelopathy.Methods. The authors prospectively studied 20 adult patients with both Chiari I malformation and symptomatic syringomyelia. Testing before surgery included the following: clinical examination; evaluation of anatomy by using T1-weighted magnetic resonance (MR) imaging; evaluation of the syrinx and cerebrospinal fluid (CSF) velocity and flow by using phase-contrast cine MR imaging; and evaluation of lumbar and cervical subarachnoid pressure at rest, during the Valsalva maneuver, during jugular compression, and following removal of CSF (CSF compliance measurement). During surgery, cardiac-gated ultrasonography and pressure measurements were obtained from the intracranial, cervical subarachnoid, and lumbar intrathecal spaces and syrinx. Six months after surgery, clinical examinations, MR imaging studies, and CSF pressure recordings were repeated. Clinical examinations and MR imaging studies were repeated annually. For comparison, 18 healthy volunteers underwent T1-weighted MR imaging, cine MR imaging, and cervical and lumbar subarachnoid pressure testing.Compared with healthy volunteers, before surgery, the patients had decreased anteroposterior diameters of the ventral and dorsal CSF spaces at the foramen magnum. In patients, CSF velocity at the foramen magnum was increased, but CSF flow was reduced. Transmission of intracranial pressure across the foramen magnum to the spinal subarachnoid space in response to jugular compression was partially obstructed. Spinal CSF compliance was reduced, whereas cervical subarachnoid pressure and pulse pressure were increased. Syrinx fluid flowed inferiorly during systole and superiorly during diastole on cine MR imaging. At surgery, the cerebellar tonsils abruptly descended during systole and ascended during diastole, and the upper pole of the syrinx contracted in a manner synchronous with tonsillar descent and with the peak systolic cervical subarachnoid pressure wave. Following surgery, the diameter of the CSF passages at the foramen magnum increased compared with preoperative values, and the maximum flow rate of CSF across the foramen magnum during systole increased. Transmission of pressure across the foramen magnum to the spinal subarachnoid space in response to jugular compression was normal and cervical subarachnoid mean pressure and pulse pressure decreased to normal. The maximum syrinx diameter decreased on MR imaging in all patients. Cine MR imaging documented reduced velocity and flow of the syrinx fluid. Clinical symptoms and signs improved or remained stable in all patients, and the tonsils resumed a normal shape.Conclusions. The progression of syringomyelia associated with Chiari I malformation is produced by the action of the cerebellar tonsils, which partially occlude the subarachnoid space at the foramen magnum and act as a piston on the partially enclosed spinal subarachnoid space. This creates enlarged cervical subarachnoid pressure waves that compress the spinal cord from without, not from within, and propagate syrinx fluid caudally with each heartbeat, which leads to syrinx progression. The disappearance of the abnormal shape and position of the tonsils after simple decompressive extraarachnoidal surgery suggests that the Chiari I malformation of the cerebellar tonsils is acquired, not congenital. Surgery limited to suboccipital craniectomy, C-1 laminectomy, and duraplasty eliminates this mechanism and eliminates syringomyelia and its progression without the risk of more invasive procedures.
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Thapa, Amit, and Sandeep Bohara. "Use of intraoperative ultrasonography in deciding the extent of surgical decompression for Chiari Malformation Type I." Nepal Journal of Neuroscience 19, no. 3 (2022): 17–23. http://dx.doi.org/10.3126/njn.v19i3.46064.
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Introduction: The optimal surgical treatment for Chiari Malformation Type I continues to be controversial with procedures ranging from posterior fossa bone decompression alone to release or resection of the cerebellar tonsils. Intraoperative ultrasonography can be a useful tool in deciding the least invasive procedure so as to reduce the complications and improve the efficacy of the procedure. Methods: A retrospective study over a period of seven years of patients who underwent surgery for Chiari Malformation type I under the guidance of intraoperative ultrasonography was done. The patients underwent three types of surgery based on the adequacy of decompression seen as free flow of CSF through foramen of magendie and free movement of cerebellar tonsils on intraoperative ultrasonography placed over the duramater: Group 1: foramen magnum decompression alone, Group 2: foramen magnum decompression and lax duraplasty and Group 3: foramen magnum decompression with lax duraplasty and release or resection of cerebellar tonsils. Outcome of the types of surgery were determined by the clinical outcome at post-operative six months and two years. Result: A total of 10 patients: four males and six females were included in the study. The mean age of the population was 32.7 +/- 14.57 years with range of 42 years. There were three patients in group 1, two patients in group 2 and five patients in group 3. 100% of the patients in group 1, 50% of patients in group 2 and 60% of the patients in group 3 had improved outcome as evidenced by resolution of symptoms and resolution of syrinx at six months and one year postoperative period. Conclusion: Intraoperative ultrasonography is an effective tool in deciding the extent of surgical decompression for Chiari Malformation Type I. A larger multicentre study would help statistically validate the findings.
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Gonçalves da Silva, José Alberto, Maurus Marques de Almeida Holanda, Maria do Desterro Leiros, Luiz Ricardo Santiago Melo, Antônio Fernandes de Araújo, and Everardo Bandeira de Almeida. "Basilar impression associated with impacted cisterna magna, spastic paraparesis and distress of balance: case report." Arquivos de Neuro-Psiquiatria 64, no. 3a (2006): 668–71. http://dx.doi.org/10.1590/s0004-282x2006000400029.
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We report on a 48 years-old man with basilar impression without syringohydromyelia, in which the cisterna magna was impacted by the cerebellar tonsils. Six months after posterior fossa decompression there was the disappearance of nuchal rigidity, vertigo, spastic paraparesis and improvement of balance. Nevertheless hyperreflexia and diminished pallesthesia of the lower limbs persisted.
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Venanzi, Maria Sole, Marco Pavanello, Mattia Pacetti, et al. "Surgical Management of Chiari Malformation Type I in the Pediatric Population: A Single-Center Experience." Journal of Clinical Medicine 13, no. 12 (2024): 3430. http://dx.doi.org/10.3390/jcm13123430.
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Background: Chiari malformation type 1 (CM-1) involves the cerebellar tonsils’ descent below the foramen magnum. In Chiari malformation type 1.5 (CM-1.5), both the cerebellar tonsils and the brainstem are herniated. Common symptoms include headaches and cervical pain, often associated with conditions like syringomyelia and hydrocephalus. Surgical treatment is not performed in asymptomatic patients, while the presence of syringomyelia represents an indication for surgery. Methods: This study retrospectively examined pediatric patients with CM-1 and CM-1.5 at Giannina Gaslini Hospital from 2006 to 2020, analyzing demographics, radiological findings, surgical interventions, and outcomes. Results: Out of 211 patients who underwent surgery, 83.9% were diagnosed with CM-1 and 16.1% with CM-1.5. Headaches were prevalent (69%) and cerebellar signs were noted in 29% of patients. Syringomyelia and hydrocephalus were present in 28.4% and 8% of cases, respectively. Intraoperative ultrasonography guided interventions, with 59.8% requiring bony and ligamentous decompression, and 27.1% undergoing duraplasty. Conclusions: The surgical treatment of CM-1/CM-1.5 involves posterior cranial fossa decompression. Choosing between bony decompression alone and its combination with duraplasty has always been controversial in the pediatric population. If we consider as surgical endpoint the restoration of cerebrospinal fluid (CSF) flux, intraoperative ultrasound may be a real-time helpful tool in orienting the surgical strategy, yet refinement with quantitative measures is needed.
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Vurdem, Ümit Erkan, Niyazi Acer, Tolga Ertekin, Ahmet Savranlar, and Mehmet Fatih İnci. "Analysis of the Volumes of the Posterior Cranial Fossa, Cerebellum, and Herniated Tonsils Using the Stereological Methods in Patients with Chiari Type I Malformation." Scientific World Journal 2012 (2012): 1–7. http://dx.doi.org/10.1100/2012/616934.
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Objective. The aim of this study was to determine the posterior cranial fossa volume, cerebellar volume, and herniated tonsillar volume in patients with chiari type I malformation and control subjects using stereological methods.Material and Methods. These volumes were estimated retrospectively using the Cavalieri principle as a point-counting technique. We used magnetic resonance images taken from 25 control subjects and 30 patients with chiari type I malformation.Results. The posterior cranial fossa volume in patients with chiari type I malformation was significantly smaller than the volume in the control subjects (P<0.05). In the chiari type I malformation group, the cerebellar volume was smaller than the control group, but this difference was not statistically significant (P>0.05). In the chiari type I malformation group, the ratio of cerebellar volume to posterior cranial fossa volume was higher than in the control group. We also found a positive correlation between the posterior cranial fossa volume and cerebellar volume for each of the groups (r=0.865,P<0.001). The mean (±SD) herniated tonsillar volume and length were0.89±0.50 cm3and9.63±3.37 mm in the chiari type I malformation group, respectively.Conclusion. This study has shown that posterior cranial fossa and cerebellum volumes can be measured by stereological methods, and the ratio of these measurements can contribute to the evaluation of chiari type I malformation cases.
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Heiss, John D., Nicholas Patronas, Hetty L. DeVroom, et al. "Elucidating the pathophysiology of syringomyelia." Neurosurgical Focus 7, no. 2 (1999): E1. http://dx.doi.org/10.3171/foc.1999.7.2.1.
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Object Syringomyelia causes progressive myelopathy. Most patients with syringomyelia have a Chiari I malformation of the cerebellar tonsils. Determination of the pathophysiological mechanisms underlying the progression of syringomyelia associated with the Chiari I malformation should improve strategies to halt progression of myelopathy. Methods The authors prospectively studied 20 adult patients with both Chiari I malformation and symptomatic syringomyelia. Testing before surgery included the following: clinical examination; evaluation of anatomy by using T1-weighted magnetic resonance (MR) imaging; evaluation of the syrinx and cerebrospinal fluid (CSF) velocity and flow by using phase-contrast cine MR imaging; and evaluation of lumbar and cervical subarachnoid pressure at rest, during the Valsalva maneuver, during jugular compression, and following removal of CSF (CSF compliance measurement). During surgery, cardiac-gated ultrasonography and pressure measurements were obtained from the intracranial, cervical subarachnoid, and lumbar intrathecal spaces and syrinx. Six months after surgery, clinical examinations, MR imaging studies, and CSF pressure recordings were repeated. Clinical examinations and MR imaging studies were repeated annually. For comparison, 18 healthy volunteers underwent T1-weighted MR imaging, cine MR imaging, and cervical and lumbar subarachnoid pressure testing. Compared with healthy volunteers, before surgery, the patients had decreased anteroposterior diameters of the ventral and dorsal CSF spaces at the foramen magnum. In patients, CSF velocity at the foramen magnum was increased, but CSF flow was reduced. Transmission of intracranial pressure across the foramen magnum to the spinal subarachnoid space in response to jugular compression was partially obstructed. Spinal CSF compliance was reduced, whereas cervical subarachnoid pressure and pulse pressure were increased. Syrinx fluid flowed inferiorly during systole and superiorly during diastole on cine MR imaging. At surgery, the cerebellar tonsils abruptly descended during systole and ascended during diastole, and the upper pole of the syrinx contracted in a manner synchronous with tonsillar descent and with the peak systolic cervical subarachnoid pressure wave. Following surgery, the diameter of the CSF passages at the foramen magnum increased compared with preoperative values, and the maximum flow rate of CSF across the foramen magnum during systole increased. Transmission of pressure across the foramen magnum to the spinal subarachnoid space in response to jugular compression was normal and cervical subarachnoid mean pressuree and pulse pressure decreased to normal. The maximum syrinx diameter decreased on MR imaging in all patients. Cine MR imaging documented reduced velocity and flow of the syrinx fluid. Clinical symptoms and signs improved or remained stable in all patients, and the tonsils resumed a normal shape. Conclusions The progression of syringomyelia associated with Chiari I malformation is produced by the action of the cerebellar tonsils, which partially occlude the subarachnoid space at the foramen magnum and act as a piston on the partially enclosed spinal subarachnoid space. This creates enlarged cervical subarachnoid pressure waves that compress the spinal cord from without, not from within, and propagate syrinx fluid caudally with each heartbeat, which leads to syrinx progression. The disappearance of the abnormal shape and position of the tonsils after simple decompressive extraarachnoidal surgery suggests that the Chiari I malformation of the cerebellar tonsils is acquired, not congenital. Surgery limited to suboccipital craniectomy, C-1 laminectomy, and duraplasty eliminates this mechanism and eliminates syringomyelia and its progression without the risk of more invasive procedures.
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Won, Daniel J., Uma Nambiar, Cheryl A. Muszynski, and Fred J. Epstein. "Coagulation of Herniated Cerebellar Tonsils for Cerebrospinal Fluid Pathway Restoration." Pediatric Neurosurgery 27, no. 5 (1997): 272–75. http://dx.doi.org/10.1159/000121266.
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Nevzati, Edin, Bawarjan Schatlo, Ali-Reza Fathi, Javier Fandino, and Carl Muroi. "Intraoperative Visualization of Bilateral Thrombosis in the Posterior Inferior Cerebellar Artery Apparent in the Telovelomedullary Segment." Case Reports in Neurological Medicine 2014 (2014): 1–4. http://dx.doi.org/10.1155/2014/247652.
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Unilateral posterior inferior cerebellar artery (PICA) thrombosis is frequent. However, bilateral PICA thrombosis is rare. Herein we report about an intraoperative visualization of a bilateral thrombosis of the telovelomedullary segment of the PICA. A 74-year-old woman was admitted to our department on day two of a bilateral PICA thrombosis with developing cerebellar infarction. Her Glasgow Coma Scale score dropped from 15 to 13, and cranial computed tomography revealed compression of the fourth ventricle with consecutive occlusive hydrocephalus. After the insertion of an external ventricular drainage, the patient underwent urgent suboccipital decompressive craniectomy with removal of infarcted cerebellar tonsils, which allowed the bilateral visualization of the thrombosed telovelomedullary segments. The surgical access may offer surgical therapeutic options in a hyperacute occlusion, such as thromb-/embolectomy or bypass procedures.
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Bin Wan Hassan, Wan Muhammad Nazief, Francesco Mistretta, Stefano Molinaro, et al. "Overview of Spontaneous Intracranial Hypotension and Differential Diagnosis with Chiari I Malformation." Journal of Clinical Medicine 12, no. 9 (2023): 3287. http://dx.doi.org/10.3390/jcm12093287.
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Spontaneous intracranial hypotension (SIH) occurs due to a leakage of the cerebrospinal fluid (CSF) lowering the pressure of subarachnoid space, mostly caused by a dural breach or discogenic microspur. As a result of less support provided by CSF pressure, intracranial structures are stretched downward, leading to a constellation of more or less typical MRI findings, including venous congestion, subdural effusions, brainstem sagging and low-lying cerebellar tonsils. Clinic examination and an MRI are usually enough to allow for the diagnosis; however, finding the location of the dural tear is challenging. SIH shares some MRI features with Chiari malformation type I (CM1), especially low-lying cerebellar tonsils. Since SIH is likely underdiagnosed, these findings could be interpreted as signs of CM1, leading to a misdiagnosis and an incorrect treatment pathway. Medical treatment, including steroids, bed rest, hydration caffeine, and a blind epidural blood patch, have been used in this condition with variable success rates. For some years, CSF venous fistulas have been described as the cause of SIH, and a specific diagnostic and therapeutic pathway have been proposed. The current literature on SIH with a focus on diagnosis, treatment, and differential diagnosis with CM1, is reviewed and discussed.
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SAKOVETS, TATYANA G., and ENVER I. BOGDANOV. "HEADACHES IN CHIARI MALFORMATION." Bulletin of Contemporary Clinical Medicine 17, no. 6 (2024): 78–83. https://doi.org/10.20969/vskm.2024.17(6).78-83.
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Introduction. Chiari malformation type 1 is found incidentally in 0.7-1% of children and adolescents undergoing magnetic resonance imaging of the brain and spine, and in 0.5% of cases in the adult population. The most common posterior fossa condition associated with cough headaches is Chiari malformation type 1. This condition results from a mesodermal defect, leading to a disparity between the sizes of the posterior cranial fossa and the neural structures it contains. According to the latest international classification of headaches, established by the Committee of the International Headache Society, cough headaches are categorized into primary and secondary (symptomatic) types. Primary cough headaches typically have a benign course. In contrast, symptomatic cough headaches are associated with pathological changes in the bone structure of the posterior cranial fossa and its contents, particularly seen in Chiari malformation type 1. Aim: To identify the characteristics of headaches in Chiari malformation. Materials and Methods. Literature analysis was conducted using international databases, such as Web of Science, Scopus, and PubMed, as well as the domestic library system eLibrary. Results and Discussion. Headaches, along with hydrosyringomyelia, are considered an indication for neurosurgical intervention. However, if we look at headaches as the sole reason for surgery, we must consider their origin. In cases of Chiari malformation, headaches may be linked to migraine or other primary headache types due to their common occurrence. Cough and stress headaches are specific indicators of Chiari malformation. In some instances, Chiari malformation type 1 characterized by dislocation of the cerebellar tonsils, may be a secondary phenomenon resulting from fluctuations in intracranial pressure. This condition can also cause headaches that stem from the secondary dislocation of the cerebellar tonsils. Consequently, the question of whether the dislocation of the cerebellar tonsils, accompanied by headaches, is primary or secondary is particularly relevant. Conclusions. Chiari malformation type 1 is associated with headaches of various types, which can sometimes be challenging for distinguishing them from primary headaches. This necessitates mandatory neuroimaging and careful differential diagnosis by neurologists.
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Gonçalves da Silva, José Alberto, Maria do Desterro Leiros da Costa, Maurus Marques de Almeida Holanda, Luiz Ricardo Santiago Melo, Antônio Fernandes Almeida de Araújo, and André Pachelli Bezerra Viana. "Impacted cisterna magna without syringomyelia associated with spastic paraparesis: case report." Arquivos de Neuro-Psiquiatria 64, no. 3a (2006): 672–75. http://dx.doi.org/10.1590/s0004-282x2006000400030.
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We report on a 49 year old man with impacted cisterna magna without the presence of syringohydromyelie (SM). The clinical picture was characterized by spastic paraparesis. Magnetic resonance imaging depicted a cisterna magna filled by the cerebellar tonsils. Six months after osteodural-neural decompression of the posterior fossa there was resolution of neurological symptoms and signs with the exception of hyperactive patellar and Achilles reflexes.
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Mussi, Antonio C. M., and Albert L. Rhoton. "Telovelar approach to the fourth ventricle: microsurgical anatomy." Journal of Neurosurgery 92, no. 5 (2000): 812–23. http://dx.doi.org/10.3171/jns.2000.92.5.0812.
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Object. In the past, access to the fourth ventricle was obtained by splitting the vermis or removing part of the cerebellum. The purpose of this study was to examine the access to the fourth ventricle achieved by opening the tela choroidea and inferior medullary velum, the two thin sheets of tissue that form the lower half of the roof of the fourth ventricle, without incising or removing part of the cerebellum.Methods. Fifty formalin-fixed specimens, in which the arteries were perfused with red silicone and the veins with blue silicone, provided the material for this study. The dissections were performed in a stepwise manner to simulate the exposure that can be obtained by retracting the cerebellar tonsils and opening the tela choroidea and inferior medullary velum.Conclusions. Gently displacing the tonsils laterally exposes both the tela choroidea and the inferior medullary velum. Opening the tela provides access to the floor and body of the ventricle from the aqueduct to the obex. The additional opening of the velum provides access to the superior half of the roof of the ventricle, the fastigium, and the superolateral recess. Elevating the tonsillar surface away from the posterolateral medulla exposes the tela, which covers the lateral recess, and opening this tela exposes the structure forming the walls of the lateral recess.
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Goven’ko, F. S., B. V. Martynov, and A. S. Grishchenkov. "Acquired Chiari malformation type I (pseudo-Chiari malformation) and intracranial hypotension: Clinical observation and literature review." Russian journal of neurosurgery 26, no. 4 (2025): 65–74. https://doi.org/10.17650/1683-3295-2024-26-4-65-74.
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One of the complications of latent intracranial hypotension is a dystopia of the tonsils of the cerebellum, which can lead to an erroneous diagnosis of “Chiari malformation type 1”. The aim of the work is to pay attention to the symptoms, course and diagnosis of acquired (pseudomalformation) Chiari in intracranial hypotension syndrome. The work is based on clinical and neurological data and magnetic resonance imaging of the brain and spinal cord of a woman aged 28 years, obtained during dynamic observation over a number of years. At the acute onset of the disease with severe postural headache, minimal neurological symptoms, magnetic resonance imaging revealed a dynamic dystopia of the cerebellar tonsils from the plane of the large occipital foramen 15 mm below it and stable hydromyelia in the thoracic region, which inclined to the diagnosis of Chiari malformation type 1. However, flattening of the bridge, thickening of the dura mater, the tendency to rounding of the sagittal sinus, narrowing of subarachnoid spaces, basal cisterns, prolapse of the bottom of the 3rd ventricle into the prebridge cistern indicated the possibility of intracranial hypotension caused by latent liquorrhea, which was confirmed by magnetic resonance imaging with intravenous administration of gadolinium containing contrast agent in the mode of a strongly weighted T2-three-dimensional image with inversion and weakening of fluid – revealed hidden liquorrhea at the cervical level. A diagnosis of Chiari pseudomalformation has been established, which excludes surgical intervention – decompression of the posterior cranial pit. When diagnosing Chiari malformation type 1 and detecting cerebellar tonsillar dystopia, it is always necessary to exclude Chiari pseudomalformation associated with other primary pathology, in particular, with latent cerebrospinal liquor, the consequence of which is intracranial hypotension, which has specific signs in magnetic resonance imaging, and requires a different therapeutic tactic.
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Markovic, Marko, Iva Berisavac, Vladimir Bojovic, Bojan Kostic, and Vuk Djulejic. "Surgical treatment of Arnold-Chiari malformation type I in an adult patient." Vojnosanitetski pregled 65, no. 8 (2008): 648–52. http://dx.doi.org/10.2298/vsp0808648m.
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Background. Herniation of the cerebellar tonsils through the foramen magnum into the cervical spinal canal with obliteration of the cerebellomedullary cistern is the primary feature of Arnold-Chiari type I malformation (ACM I). It is considered to be congenital malformation, although there have been reported cases of an acquired form. Case report. We presented a female patient, 45-year old, with ACM I without syringomyelia as a rare and unusual clinical image, as well as the effect of decompressive surgery in the treatment of this malformation. The patient was admitted to the Department of Neurosurgery with clinical signs of truncal ataxia worsening during the last six years. Moderate quadriparesis with predominant lower extremity involvement and the signs of the cranial nerves damages occured during the last seven months before admission, with progressive clinical course up to the date of admission. Neurosurgical treatment that included suboccipital medial craniectomy with resection of posterior arch C1 vertebrae and C2 laminectomy resulted in a significant clinical improvement and a much better quality of life. Conclusion. Posterior craniovertebral decompression with microsurgical reduction of the cerebellar tonsils and placement of an artificial dural graft is a treatment of choice in severe forms of ACM I without syringomyelia. .
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Kramar, Lyubov, Tatyana Larina, and Yuliya Khlynina. "MENINGOCOCCAL MENINGITIS WITH ARNOLD-CHIARI MALFORMATION: CASE REPORT." AVICENNA BULLETIN 26, no. 4 (2024): 685–93. https://doi.org/10.25005/2074-0581-2024-26-4-685-693.
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Arnold-Chiari malformation (ACM) is a developmental anomaly of the brain characterized by the descent of the cerebellar tonsils into the foramen magnum, leading to compression of the medulla oblongata and subsequent neurological symptoms. ACM can manifest at any age due to various provoking factors, such as toxic effects, head injuries, and congenital craniofacial anomalies. We present a case involving a 5-year-old boy who experienced clinical and radiological deterioration of ACM while undergoing inpatient treatment for meningococcal meningitis. Prior to hospitalization, the child had achieved critical developmental milestones and exhibited no neurological symptoms. Upon admission, a diagnosis of meningitis was established, and a diagnostic lumbar puncture was recommended. The patient had no clinical or laboratory contraindications for the procedure and showed no signs of cerebral edema. However, a complication arose following the lumbar puncture. An MRI scan of the brain revealed that the cerebellar tonsils had herniated into the foramen magnum (16 mm below the edge of the foramen) with compression of the brainstem, resulting in a diagnosis of ACM. Despite receiving comprehensive therapy in the intensive care unit, it was not possible to restore central nervous system functions. Unfortunately, on the 59th day of hospitalization, the patient succumbed to cardiac arrest. Keywords: Children, meningococcal meningitis, Arnold-Chiari malformation, rare diseases, clinical case.
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Lisboa do Vale, Bruna, Maurus Marques de Almeida Holanda, Diogo Berto Campos, Moisés Dantas Cartaxo de Abreu Pereira, and Érico Samuel Gomes Galvão da Trindade. "Subpial Aspirated Cerebellar Tonsils in Pediatric Chiari I Malformation: anatomopathological study." JBNC - JORNAL BRASILEIRO DE NEUROCIRURGIA 29, no. 3 (2019): 501–5. http://dx.doi.org/10.22290/jbnc.v29i3.1781.
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Introduction: Chiari Malformation (CM) is a condition in which ectopy or herniation of components of the posterior cranial fossa to theforamen magnum are present, and can be divided into four types. Type I (CM-I) occurs when there is protrusion of only the cerebellartonsils into the cervical spinal canal. One of the available therapeutic options is subpial aspiration. Previous anatomopathologicalstudies showed that the main alterations in the aspirated tonsils were the loss of Purkinje cells, Bergmann gliosis, cortical atrophyand neuronal changes due to hypoxia; all of them secondary to the aggression to the nervous tissue over time. These changes leadto gradual loss of function of the tissue, with compensation by other structures. Therefore, when subpial aspiration of the herniatedtonsil is performed in adults, there are no negative consequences to the patient in the future, as concluded by many studies targetingadults with CM. However, studies in children with CM are scarce, which means that we cannot affirm in which age the histologicalchanges occur. Hence, we cannot determine whether or not the surgical removal of this tissue in childhood leads to future losses tothe patient. Objective: To analyze the main histological aspects of cerebellar tonsils in children with Chiari I Malformation whounderwent subpial aspiration, to help clarify the natural history of this pathology, as well as to help determine the prognosis of thispopulation when treated with this technique. Method: We analyzed the histopathology of the tonsils removed with subpial aspirationtechnique, in several hospitals of João Pessoa, Brazil, from children diagnosed with Chiari I malformation. Results: The slides of alltonsils showed the same histological changes: Bergmann gliosis, loss of Purkinje cells, atrophy of the cerebellar cortex and meningealfibrosis. The obtained results were similar to the ones found in previous studies carried out in adults. Conclusion: The cerebellaranatomopathological alterations secondary to Chiari I Malformation, which leads to loss of tissue function, seem to appear early inlife, suggesting the safety of the subpial aspiration in pediatric patients. However, more extensive studies and long-term follow-up ofpatients are needed to establish with more precision the natural history of the disease.
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Heiss, John D., Giancarlo Suffredini, René Smith, et al. "Pathophysiology of persistent syringomyelia after decompressive craniocervical surgery." Journal of Neurosurgery: Spine 13, no. 6 (2010): 729–42. http://dx.doi.org/10.3171/2010.6.spine10200.
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Object Craniocervical decompression for Chiari malformation Type I (CM-I) and syringomyelia has been reported to fail in 10%–40% of patients. The present prospective clinical study was designed to test the hypothesis that in cases in which syringomyelia persists after surgery, craniocervical decompression relieves neither the physiological block at the foramen magnum nor the mechanism of syringomyelia progression. Methods The authors prospectively evaluated and treated 16 patients with CM-I who had persistent syringomyelia despite previous craniocervical decompression. Testing before surgery included the following: 1) clinical examination; 2) evaluation of the anatomy using T1-weighted MR imaging; 3) assessment of the syrinx and CSF velocity and flow using cine phase-contrast MR imaging; and 4) appraisal of the lumbar and cervical subarachnoid pressures at rest, during a Valsalva maneuver, during jugular compression, and following the removal of CSF (CSF compliance measurement). During surgery, ultrasonography was performed to observe the motion of the cerebellar tonsils and syrinx walls; pressure measurements were obtained from the intracranial and lumbar intrathecal spaces. The surgical procedure involved enlarging the previous craniectomy and performing an expansile duraplasty with autologous pericranium. Three to 6 months after surgery, clinical examination, MR imaging, and CSF pressure recordings were repeated. Clinical examination and MR imaging studies were then repeated annually. Results Before reexploration, patients had a decreased size of the CSF pathways and a partial blockage in CSF transmission at the foramen magnum. Cervical subarachnoid pressure and pulse pressure were abnormally elevated. During surgery, ultrasonographic imaging demonstrated active pulsation of the cerebellar tonsils, with the tonsils descending during cardiac systole and concomitant narrowing of the upper pole of the syrinx. Three months after reoperation, patency of the CSF pathways was restored and pressure transmission was improved. The flow of syrinx fluid and the diameter of the syrinx decreased after surgery in 15 of 16 patients. Conclusions Persistent blockage of the CSF pathways at the foramen magnum resulted in increased pulsation of the cerebellar tonsils, which acted on a partially enclosed cervical subarachnoid space to create elevated cervical CSF pressure waves, which in turn affected the external surface of the spinal cord to force CSF into the spinal cord through the Virchow-Robin spaces and to propel the syrinx fluid caudally, leading to syrinx progression. A surgical procedure that reestablished the CSF pathways at the foramen magnum reversed this pathophysiological mechanism and resolved syringomyelia. Elucidating the pathophysiology of persistent syringomyelia has implications for its primary and secondary treatment.