Moxifloxacin-induced Abducens Nerve Palsy: A Rare Neurological Complication During Mycobacterium avium Complex Lung Disease Treatment.

Mycobacterium avium complex (MAC) lung disease requires prolonged multidrug therapy. We report the case of an 80-year-old woman with MAC lung disease who developed an isolated right abducens nerve palsy after approximately nine months of treatment with moxifloxacin, azithromycin, and ethambutol. The patient presented with horizontal diplopia, and ophthalmological evaluation confirmed sixth cranial nerve palsy. Although ethambutol-induced optic neuropathy was initially considered, clinical findings were not consistent with this diagnosis. Given the temporal relationship with moxifloxacin exposure and the absence of other identifiable etiologies, fluoroquinolone-induced neurotoxicity was considered the most likely cause. Partial improvement was observed during follow-up. This case highlights a probable rare neurological complication of moxifloxacin and the importance of considering drug-related cranial neuropathies in patients receiving prolonged treatment for MAC lung disease.