Vertigo and masseter paresis. A new local brainstem syndrome probably of vascular origin.

Two patients are reported with symptoms and signs of peripheral vestibular dysfunction, including severe rotatory vertigo, abolished caloric response in the involved ear, and spontaneous nystagmus with the fast component away from that ear. In addition, paresis of the masseter, temporal, and pterygoid muscles and impairment of the masseter reflex were found on the affected side. It is suggested that the vertigo and masseter paresis syndrome is a brainstem syndrome which is probably due to a vascular lesion affecting a very small dorsolateral pontine area.