Objective: Neuromyelitis optica spectrum disorder (NMOSD) is an inflammatory disease of the central nervous system characterized by optic neuritis and myelitis. NMOSD is more prevalent in the elderly than multiple sclerosis. In particular, optic neuritis of NMOSD is common in the elderly.Methods and Results: We report an 82-year-old female patient with no medical history who presented with optic neuritis as the first attack of NMOSD. On day X−15, she developed horizontal hemianopia and was referred to our department. On admission, her visual acuity was hand motion. Cerebrospinal fluid suggested pleocytosis. Magnetic resonance imaging revealed a hyper-intense lesion on the optic chiasm and optic tract. Steroid pulse therapy was performed, but from the night, delirium with visual hallucinations developed. She refused drug administration, removed the intravenous administration route, and was unable to continue in-hospital treatment.Conclusion: NMOSD often develops in the elderly with optic neuritis, and in addition to steroid therapy, plasma exchange or immunoglobulin therapy is expected to improve the prognosis. However, in our case, treatment was discontinued due to marked delirium accompanied by visual hallucinations. Visual hallucinations are more likely to occur in elderly patients with visual impairment, and clinicians should be careful and manage hallucination-associated delirium.

We report a case with disturbed consciousness and myoclonus, diagnosed as amantadine intoxication. Amantadine is widely used in the treatment of Parkinson's syndrome. However, in elderly patients and those with renal dysfunction, amantadine overdose is a rare complication, resulting in symptoms of intoxication such as impaired consciousness and myoclonus. In the present case, multiple amantadines prescribed by several medical institutions may have resulted in the observed intoxication. Our pharmacists and nurses checked the medications and found duplicate amantadine prescriptions.