Regression of syringomyelia and tonsillar herniation after posterior fossa arachnoid cyst excision: Case report and literature review

Progression of Pre-existing Chiari Type I Malformation Secondary to Cerebellar Hemorrhage -Case Report-

“…4,5,7,8) Venous congestion and the swelling of the posterior fossa structures arising from a supratentorial arteriovenous malformation can also cause tonsillar herniation. 6) Mechanism of the deterioration of preexisting Chiari type I malformation secondary to cerebellar hemorrhage is unknown, but the cerebellar hematoma could have displaced the tonsils in the spinal canal into a lower position in the present case.…”

“…4,[6][7][8] improvement after spontaneous disappearance of the hematomas. 5) In the present case, we chose conservative treatment rather than surgical decompression because we thought that the tonsillar herniation would improve after the disappearance of the cerebellar hematoma.…”

Bilateral Retrocerebellar Arachnoid Cysts Exerting Mass Effect and Associated With Cerebellar Tonsillar Ectopia in an Otherwise Healthy Adult

“…The theory that retrocerebellar ACs exert a mass effect on the tonsils, chronically inducing herniation, is supported by some cases of unilateral or midline cerebellar hemispheric AC in which TE and/or syringomyelia was reversed through foramen magnum decompression and excision or drainage of the AC. 5,11) It is tempting to infer that this patient's cysts, presumably harboured asymptomatically for several decades, gradually became symptomatic as a result of the significant blow to the occiput received when falling 6 years previously. ACs have been observed to expand (and in one case disappear 19) ) following trauma, often with a significant delay between injury and symptom onset.…”

“…4,5,10,16) These cysts are sometimes seen in conjunction with cerebellar tonsillar ectopia (TE), although the relationship between these two entities is unclear. 5,11) Bilateral ACs in the posterior fossa are virtually unprecedented. We describe the case of a 33-year-old man with a history of multiple minor head injuries found to harbour asymptomatic, bilateral ACs over the cerebellar hemispheres.…”

Symptomatic Syringomyelia Associated With a Dermoid Tumor in the Posterior Fossa -Case Report-

“…Cervical syringomyelia may be associated with intracranial lesions including posterior fossa tumors such as meningiomas, 1,3,6,9,10,22) gliomas, 13,16) medulloblastomas, 7,10) and arachnoid cysts, 2,11,14,21,23) and are occasionally associated with tonsillar herniation. Interestingly, cervical syringomyelia associated with supratentorial meningioma 20) or tectal arteriovenous malformation 17) has also been reported.…”