Serious unexpected sinus infection discovered by CT scanning for presumed neurological disease.

Serious infection in the paranasal sinuses may present with symptoms suggestive of neurological disease and thus lead to delay in the diagnosis and subsequent treatment. We present three such cases in whom the initial diagnoses had been acute optic neuritis, a posterior communicating aneurysm and an intracranial space occupying lesion. The fourth patient had meningitis but the paranasal sinuses had not initially been considered as a possible source of infection. The current methods of diagnosing sinusitis are discussed.