Posterior Fossa Cyst and Hydrocephalus

A Dandy-Walker malformation is an anatomical triad characterized by a large posterior fossa, agenesis of the cerebellar vermis, and dilation of the 4th ventricle. Up to 90% of patients will have hydrocephalus secondary to obstruction of fourth ventricular outflow through the foramen of Luschka and Magendie. The differential diagnosis of Dandy-Walker malformation includes Blake’s pouch cyst, a cystic structure originating within the roof of the 4th ventricle that herniates into the cisterna magna, and posterior fossa arachnoid cysts, which typically displace both the cerebellum and 4th ventricle anteriorly and demonstrate a propensity to enlarge. Brain MRI is the best diagnostic imaging modality to evaluate posterior fossa anatomy and cystic structures. Not all posterior fossa cysts require treatment. Indications for surgical intervention include enlargement, symptomatic mass effect and/or hydrocephalus.

Posterior Fossa Ependymoma

Pediatric posterior fossa ependymomas are typically well-delineated masses with heterogenous enhancement arising from the floor, lateral aspect, or roof of the fourth ventricle. Growth of tumor into the posterior fossa subarachnoid spaces, particularly into the foramen of Magendie and the cerebellopontine angles via the foramen of Luschka, is a radiological hallmark of this tumor. Clinical findings of elevated intracranial pressure and obstructive hydrocephalus are common at presentation. The current standard of care for children with ependymoma consists of gross total resection with subsequent focal radiotherapy. The extent of resection is the single most important determinant of outcome. Hydrocephalus typically resolves after resection, and it is uncommon to require cerebrospinal shunt placement after tumor removal.

Combined telovelar-minimal transvermian approach for a bleeding pontine cavernoma in a 48-year-old patient – case report and literature review

Symptomatic pontine cavernous malformations carry a high risk of recurrent bleeding, which may result in permanent neurological deficit. Such lesions require surgical management that can be challenging to the neurosurgeon due to their anatomical location and their proximity to delicate neural structures. An ideal surgical approach should provide maximal surgical resection with minimal morbidity. We present the case of a 48-year-old woman with a pontine cavernoma with repeated spontaneous intralesional hemorrhages, resected using a telovelar approach extended by a minimal incision of the inferior vermis, with good surgical outcome. The telovelar approach provided a good access to the lateral recesses and the foramen of Luschka, while the lower vermian incision provided a greater vertical working angle inside the ventricle.

Lateral inferior cerebellar peduncle approach to dorsolateral medullary cavernous malformation

Object Brainstem cavernous malformations (BSCMs) present a unique therapeutic challenge to neurosurgeons. Resection of BSCMs is typically reserved for lesions that reach pial or ependymal surfaces. The current study investigates the lateral inferior cerebellar peduncle as a corridor to dorsolateral medullary BSCMs. Methods In this retrospective review, the authors present the cases of 4 patients (3 women and 1 man) who had a symptomatic dorsolateral cavernous malformation with radiographic and clinical evidence of hemorrhage. Results All patients underwent excision of the cavernous malformation via a far-lateral suboccipital craniotomy through the foramen of Luschka and with an incision in the inferior cerebellar peduncle. On intraoperative examination, 2 of the 4 patients had hemosiderin staining on the surface of the peduncle. All lesions were completely excised and all patients had a good or excellent outcome (modified Rankin Scale scores of 0 or 1). Conclusions This case series illustrates that intrinsic lesions of the dorsolateral medulla can be safely removed laterally through the foramen of Luschka and the inferior cerebellar peduncle.