Internuclear ophthalmoplegia: causes and long-term follow-up in 65 patients

OBJECTIVES: To analyze the causes and long-term clinical outcome of internuclear ophthalmoplegia (INO) in a consecutive series of 65 patients. PATIENTS AND METHODS: From a clinical registry of a neuroophthalmological department, patients with diagnosis of INO were retrospectively identified. Patients were classified into three groups: unilateral INO, bilateral INO, and one-and-a-half syndrome. RESULTS AND CONCLUSIONS: Thirty-three men (50.8%) and 32 women (49.2%), with a mean age of 38.4 years were included in the study. INO was unilateral in 36 patients (55.4%), bilateral in 22 (33.8%) and one-and-a-half syndrome in seven (10.8%). The most common causes were vascular (36.9%), multiple sclerosis (32.3%), and infectious diseases (13.8%). Resolution of INO was documented in 32 patients (49.2%): 15 patients showed INO resolution during the first 3 months and 17 patients in 3-9 months. INO persisted in 33 patients (50.8%) even after a follow-up longer than 12 months.