Disorders affecting the fourth ventricle: etiology and clinical correlates.

Objective: The fourth ventricle encompasses many vital structures including the brainstem as its floor and the cerebellum as its lateral wall and roof. Therefore, lesions affecting the fourth ventricle may present as cerebellar or brainstem manifestations. Herein, we presented our experience in the diagnosis of disorders affecting the fourth ventricle during the past 15 years.
Study Design: Retrospective study.
Setting: University hospital.
Subjects: From September 1995 to August 2010, 24,838 patients with vertigo/dizziness visited the clinic. Of them, 13 patients (0.5%) had tumor/stroke affecting the fourth ventricle.
Main Outcome Measures: All patients underwent a battery of audiovestibular function test.
Results: All patients had vertigo (100%) and then ataxia (92%) and nausea/vomiting (85%). Eight patients (68%) displayed persistent nystagmus. Most (>75%) patients showed central signs in electronystagmographic recordings and abnormal caloric coupled with visual suppression test. Three patients underwent both ocular and cervical vestibular-evoked myogenic potential tests, and abnormal results were noted in all 3 patients indicating a brainstem involvement. However, magnetic resonance imaging failed to demonstrate brainstem lesion in these 3 patients. Final diagnoses consisted of the following: cavernoma, n = 3; metastatic cancer, n = 3; astrocytoma, n = 2; meningioma, n = 2; epidermoid cyst, n = 1; ependymoma, n = 1; and lymphoma, n = 1. The prognosis was poor as 10 patients (77%) died within 2 years.
Conclusion: When a vertiginous patient displayed ataxia, persistent vomiting, and persistent nystagmus, lesion affecting the fourth ventricle should be kept in mind because its prognosis is poor. Abnormal results in electronystagmography and in ocular and cervical vestibular-evoked myogenic potentials may serve as a supplementary to magnetic resonance imaging to delineate the involvement of the lesion.