Causes of isolated recurrent ipsilateral sixth nerve palsies in older adults: a case series and review of the literature

PURPOSE The etiology of recurrent isolated sixth nerve palsies in older adults has not been well described in the literature. Sixth nerve palsies presenting with a chronic, relapsing, and remitting course are uncommon, but can herald a diagnosis of high morbidity and mortality in the older population. PATIENTS AND METHODS Our method was a retrospective case series study. A review of clinical records of 782 patients ≥50 years of age diagnosed with recurrent sixth nerve palsies was performed over a 10-year period from 1995-2005 in a neuro-ophthalmology clinic in Reno, Nevada. A review of the current literature regarding similar cases was also performed on PubMed. RESULTS Seven patients ≥50 years of age with chronic, recurrent sixth nerve palsies were identified. Five were males and two were females. Four of seven (57%) patients had structural lesions located in the parasellar or petrous apex cavernous sinus regions. One of seven (14.29%) had a recurrent painful ophthalmoplegic neuropathy (International Headache Society [IHS] 13.9), previously termed ophthalmoplegic migraine; one of seven (14.29%) presented with an intracavernous carotid artery aneurysm; and one of seven (14.29%) presented with microvascular disease. CONCLUSION The clinical presentation of an isolated recurrent diplopia from a sixth nerve palsy should prompt the neurologist or ophthalmologist to order a magnetic resonance imaging (MRI) scan of the brain with and without gadolinium as part of the initial workup to rule out a non-microvascular cause, such as a compressive lesion, which can increase morbidity and mortality in adults >50 years of age.