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

To report a case of atypical positional vertigo revealing a fourth ventricle epidermoid cyst.

We report a case of a thirty-year-old woman suffering from positional vertigo with downbeat nystagmus. Except for these symptoms, the physical examination was normal, apart from intermittent headaches. On videonystagmography, a decrease in the average speed of beats and lowered benefits obtained by slow motion were noted. MRI revealed a fourth ventricle epidermoid cyst.

Physical examination may provide several signs that are likely to enable the examiner to distinguish between central nervous system or peripheral vertigos. Atypical symptoms such as a downbeat nystagmus, a lack of reversal in nystagmus beats when returning to the sitting position and a lack of a latency period in vertigo and nystagmus occurrence during the Dix-Hallpike maneuver suggest a central nervous system etiology.

With atypical symptoms noted when questioning the patient or during physical examination, a central nervous system etiology should be mentioned and explored with cerebral MRI.