Chronic isolated abducens paresis from tumors at the base of the brain

A chronic sixth-nerve paresis, even if isolated, may be neither benign nor idiopathic. We describe five patients with tumors in the basisphenoid region manifested clinically by isolated, unilateral abducens paresis for five to 20 years. There were three meningiomas (one confirmed by biopsy, two presumed), a neurilemmoma, and a chondrosarcoma. Isolated abducens paresis may persist for years in both children and adults with tumors or aneurysms. All patients with chronic sixth-nerve paresis should undergo vigorous neuroradiologic investigations to rule out a petrous apex-cavernous sinus mass lesion.