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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.

Purpose: Abducens schwannomas are rare tumors that are not known to present with acute haemorrhage. We present a case of a 59 year-old female on warfarin who presented acutely with a sudden onset headache, nausea and photophobia. Neuroimaging revealed an acute haemorrhage into a lesion that entered Dorello's canal and was consistent with an abducens nerve schwannoma.Materials and methods: The patient's case notes, imaging, histology and operative recording were reviewed retrospectively to compile this case report.Results: The tumor was resected via a retro-mastoid approach with sacrifice of the abducens nerve. Removal of the haematoma intra-operatively provided more space in the surgical corridor to facilitate resection. Final histological examination confirmed the diagnosis of schwannoma and the patient made a good post-operative recovery.Conclusion: We conclude that accurate pre-operative radiological diagnosis can facilitate surgical planning and removal of haematoma at an early stage during the operation can create space and facilitate resection. Furthermore, abducens schwannoma should be considered in the differential diagnosis of any heamorrhagic cerebello-pontine angle lesion.