Posterior Cranial Fossa Meningioma Causing Tonsillar Herniation and Giant Cervicothoracic Syringomyelia, Case Report and Review of Literature

Background Syringomyelia is a fluid-filled cyst within the spinal cord and usually associated with Arnold-Chiari malformation. Posterior cranial fossa tumours are a rare cause of tonsillar herniation and secondary syringomyelia. Case Presentation: We report a rare case of a 56-year-old female with posterior cranial meningioma and secondary syringomyelia, admitted with headache, nausea, vomiting, and ataxic gait. MRI demonstrated a large posterior fossa lesion causing early ventriculomegaly and syrinx within the upper spinal cord extending from the hindbrain inferiorly to the level of T8. She underwent a posterior fossa craniectomy with left C1 hemilaminectomy and complete excision of the tumour. In 6 months following her procedure, MRI scan showed a significant reduction in the calibre of the syringomyelia throughout its length and there was a significant improvement in symptoms. Literature review: A PubMed literature search was carried out with keywords: “syringomyelia”, “posterior fossa” and “tumour”. 120 articles were reviewed. The inclusion criteria for this study was posterior fossa meningioma causing syrinx formation. A total of 9 isolated similar cases were identified. Discussion Tonsillar herniation and syringomyelia secondary to posterior cranial fossa meningioma are rare. The alteration in the dynamic flow of CSF is likely to be the cause for the formation and enlargement of the syrinx. Conclusion Although the pathophysiology of syrinx formation is still poorly understood, the alteration of CSF dynamic has been implicated, but a common unifying cause appears to be increased transcranial difference in intracranial pressure across the foramen magnum causing tonsillar herniation, irrespective of location in the posterior fossa. Posterior fossa craniotomy and excision of the lesion is the mainstay treatment.