Posturally-evoked vomiting; Association with posterior fossa lesions.

Posturally-evoked vomiting (PEV) dissociated from vertigo was present in two patients with proven posterior fossa mass lesions. In both instances PEV was a major aspect of the patients' symptomatology before other findings clearly indicated the presence of an infratentorial mass lesion. A distinction is drawn between benign postural vertigo, which almost always indicates a benign disorder of the peripheral vestibular apparatus, and PEV which indicates a central lesion within the posterior fossa. A possible anatomic-physiologic basis is offered for PEV, based on the dissociation of the "vestibular syndrome," in which PEV increases while vertigo and nystagmus diminish.