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.