Nonneurologic causes of binocular diplopia for the neurologist.

PURPOSE OF REVIEW: To review several etiologies of nonneurologic diplopia that the neurologist should be familiar with. The pathophysiology, clinical presentation, neuroimaging findings, and treatment options are briefly summarized for each condition.

RECENT FINDINGS: Certain etiologies for diplopia can be associated with life-threatening neurologic conditions and should be investigated thoroughly for proper localization and immediate management of the underlying disease. However, nonneurological causes of binocular diplopia are very common and disabling, but are often nonemergent and may not require in-depth investigation or neuroimaging. Some of the etiologies of nonneurologic diplopia mimic cranial nerve palsies, making them confusing to evaluate when the physician is not familiar with these etiologies. Unfamiliarity with these diagnoses can lead to unnecessary neuroimaging, inefficient utilization of medical resources, and undue alarm to the patient. Recent advances in clinical diagnostic tools and neuroimaging have clarified our understanding of the diverse underlying mechanisms of nonneurologic binocular diplopia.

SUMMARY: Diplopia can be a difficult symptom for the neurologist to evaluate. A systematic approach to the evaluation of diplopia can help establish the urgency and necessity of an extensive workup.This review will help to familiarize the neurologist with nonneurological causes of binocular diplopia, minimize expensive and unnecessary evaluations, and reassure patients and physicians alike.