RESUMEN
BACKGROUND: Studies on frequency and underlying diseases causing binocular diplopia in patients presenting to the emergency department (ED) are lacking. OBJECTIVE: To evaluate the prevalence of different diseases causing diplopia and the role of medical history, clinical examination, and unenhanced head computed tomography (UHCT) in the identification of secondary diplopia. METHODS: Diplopic patients presenting to the ED were enrolled prospectively. Cardiovascular risk factors and associated neurological signs and symptoms were reported. UHCT was performed in the ED. RESULTS: Secondary diplopia was diagnosed in 93 of 260 (35.8%) diplopic patients. Among patients with secondary diplopia, the most frequent diagnoses were stroke (45.2%), multiple sclerosis (18.3%), brain tumors (11.8%), and cerebral aneurysms (7.5%). The prevalence of cardiovascular risk factors was similar in primary and secondary diplopia. Among the 118 (45.4%) patients without associated neurological signs or symptoms (isolated diplopia), secondary diplopia was diagnosed in 13 (11%); UHCT was negative in all 13 cases, with a derived null sensitivity. Eighty of 142 (56.3%) patients with associated signs or symptoms had secondary diplopia. The presence of signs or symptoms associated with diplopia showed a sensitivity of 87% [95% confidence interval (CI): 80-92%] and a specificity of 63% (95% CI: 59-66%) for the diagnosis of secondary diplopia. In this group, UHCT identified 30 of 80 (37.5%) cases, increasing the specificity to 98% (95% CI: 96-99%). CONCLUSION: One-third of diplopic patients had secondary diplopia. In patients with isolated diplopia, UHCT does not increase diagnostic sensitivity. In patients with associated neurological signs or symptoms, the prevalence of secondary diplopia was high and UHCT showed incremental diagnostic value.