Central positional nystagmus associated with cerebellar tumors: Clinical and topographical analysis.

Purpose: Positional nystagmus is usually caused by peripheral vestibular disorder, mostly benign paroxysmal positional vertigo (BPPV). However, positional nystagmus is also encountered in central lesions. We aimed to determine clinical characteristics of the structures responsible for central positional nystagmus (CPN) associated with brain tumors.

Methods: All four patients (3 men; range=19-77years) had an evaluation of spontaneous and positional nystagmus using video-oculography. Brain MRIs were performed in all patients.

Results: All patients showed apogeotropic positional nystagmus during supine roll tests, and had an initial diagnosis of BPPV. Except for the positional nystagmus, findings of neurological examination were normal. Because all subjects were initially diagnosed with BPPV, canalith repositioning maneuvers were applied repeatedly but without a success. Brain MRI finally disclosed brain tumors involving the midline cerebellar structures around the fourth ventricle and the nodulus. The pathological diagnosis was hemangioblastoma in two and metastatic tumor in the others.

Conclusions: An apogeotropic type of CPN may be an isolated finding in patients with a cerebellar tumor. Even in patients with isolated apogeotropic positional nystagmus, a central lesion should be sought especially when refractory to repeated canalith repositioning maneuvers.