Ventral foramen magnum neurenteric cysts: a case series and review of literature.

Neurenteric cysts (NEC) are uncommon, benign, congenital lesions. Ventral foramen magnum (FM) location is very rare. The difficulties in diagnosis and management aspects are detailed with a review of the pertinent literature. We report four new cases of ventral FM NEC, all managed surgically and present a literature review of ventral FM NEC. A retrospective analysis of histopathologically confirmed cases of ventral FM NEC, operated from 2010-2013 at our institute, was performed. For review, only those cases of NEC extending from the lower clivus to the C2 level constituting the foramen magnum were included. Including our four cases, a total of 47 cases were identified. The male to female ratio was 1.2:1. Mean age was 33.5 years (range 1-60 years). Neck pain and occipital headache were the most common symptoms, followed by limb weakness and cranial nerve paresis. Recurrent meningitis was noted in three cases. Hyperintensity on both T1- and T2-weighted sequences with absent enhancement was the most common finding on MRI. Surgical approaches were as follows: suboccipital (n = 21), far/extreme lateral (n = 18), retrosigmoid (n = 6), and transoral (n = 4). The extent of resection was as follows: total, 26; near total, 6; subtotal, 9; and partial, 3 cases. Cerebrospinal fluid diversion was done in four cases for intracranial hypertension. Mean follow-up duration was 26.8 months (range 1 month-9 years). Recurrence was noted in four (8.5 %) cases. One (2 %) case had malignant transformation. Mortality rate was 4 %. Foramen magnum neurenteric cysts are rare, benign tumors of the central nervous system. Accurate preoperative diagnosis can often be established with MRI. Surgical removal is the treatment of choice. Complete excision is ideal but often not possible. Near total removal would suffice with good progression-free periods. A long-term follow-up with radiological studies is necessary as delayed recurrences can occur.