Isolated nontraumatic abducens nerve palsy.

Introduction: Abducens nerve palsy (ANP) is the most common isolated palsy. The injury of the abducens nerve can occur anywhere along its long course, so differential diagnosis of ANP occasionally demands thorough investigation to find the proper cause.

Patients: Ten patients with isolated ANP are presented. The causes included nasopharyngeal carcinoma, diabetes, cholesteatoma of the inner ear, carotid-cavernous fistula, subarachnoid bleeding, hydrocephalus, toxic ANP, multiple sclerosis, clinically isolated syndrome suggestive of multiple sclerosis, and Tolosa-Hunt syndrome.

Discussion: Based on the cases presented and review of the literature, we argue that every patient with isolated nontraumatic ANP requires brain MRI as an initial diagnostic tool. If this finding remains inconclusive, additional tests including angiography and CSF examination should be performed.