Bilateral Sixth Nerve Palsy

Bilateral abducens nerve pareses were nearly as common as unilateral cases in an inpatient setting (125:143). Cerebrospinal fluid abnormalities were more frequent among the bilateral cases, but generally the same causes produced unilateral and bilateral sixth nerve palsy. The relative ease of diagnosis was in contrast with the large number of undiagnosed or "vascular" cases in previous studies of outpatients. The degree of lateral rectus limitation proved to be of limited help in suggesting the cause or predicting recovery of oculomotor function. The etiology was of some prognostic value, with universal recovery of pressure palsies and rare improvement with tumor involvement. Myasthenia, orbital muscle entrapment, convergence spasm, divergence palsy, and pretectal pseudoconvergence entered into the differential diagnosis, but were only occasionally difficult to exclude.