[Epidermoid cysts of the fourth ventricle mimicking benign paroxysmal positional vertigo]

Fourth Ventricular Epidermoid Cyst - Case Series, Systematic Review and Analysis

Background:

Epidermoid cysts are extra-axial, pearly white avascular lesions mostly found in the cerebellopontine region. They are slow-growing and mostly become symptomatic when they attain significant size. They do occur at other anatomical locations, but fourth ventricle is a rare location. Three representative cases with their outcomes are described here.

Methods:

The systematic review was done with adherence to predefined criteria. The studied variables were age, gender, duration of symptoms (DOS), clinical features, hydrocephalus (HCP), extent of resection, postoperative complications, outcome, follow–up, and recurrence. Statistical analysis was done to identify predictive factors for outcome.

Results:

Final analysis included 58 studies containing 131 patients. The most common clinical feature was cerebellar dysfunction (93%). The most common cranial nerve involved was the abducens nerve (n = 37, 28.46%). Preoperative HCP was present in nearly a third (35%) of patients. The outcomes were not different with age (P = 0.23), gender (P = 0.74), DOS (P = 0.09), and HCP (P = 0.50). Improved outcomes were associated with total resections (P = 0.001), absence of preoperative cranial nerve dysfunctions (P = 0.004), and presentation with features of raised intracranial pressure (P = 0.005). Longer DOS (mean 76.74 months) was associated with significantly increased cranial nerve nuclei involvement (P = 0.03). Aseptic meningitis was reported in 14.5% of cases. Recurrences were infrequently reported (n = 9).

Conclusions:

Although the fourth ventricular epidermoid lesions are difficult to detect in an innocuous stage, when found, they should be extirpated early and totally, as a longer DOS leads to cranial nerve dysfunctions and suboptimal outcomes.