Objective: To review the causes and prognosis of sixth nerve palsies in patients who are 20 to 50 years of age.
Design: Retrospective, noncomparative case series.
Participants: All patients aged 20 to 50 years with a nontraumatic sixth nerve palsy seen in a neuro-ophthalmic practice from 1994 to 2000.
Intervention: Diagnostic testing to determine the cause of the palsy and surgical intervention to correct persistent stable strabismus.
Main outcome measures: Cause of the palsy. The patients' clinical courses were reviewed.
Results: The most common cause for a sixth nerve palsy in this age group was a central nervous system (CNS) mass lesion, although the most common cause for an isolated sixth nerve palsy in this age group was multiple sclerosis. Patients with a CNS mass lesion responsible for their palsy had the highest rate of nonresolution requiring strabismus surgery.
Conclusions: Sixth nerve palsies are unusual in young adults, but in the practice of author (GBK) most are secondary to CNS mass lesions and, when isolated, multiple sclerosis. Deferring neuroimaging or other appropriate investigations presuming a microvascular cause for the palsy in this age group is not recommended.