Effective Control of Neuropathic Pain With Amitriptyline in Neuromyelitis Optica Spectrum Disorder: A Case Report

We describe a neuromyelitis optica spectrum disorder (NMOSD) case with neuropathic pain (NP) that was successfully controlled by amitriptyline. A 48-year-old woman presented with progressive left lower limb pain, gait disturbance, and sensory deficits, alongside a history of bilateral posterior thigh numbness. Neurological examination revealed motor weakness, hyperreflexia, positive Babinski signs, sensory impairments, and bladder and rectal dysfunction. Laboratory tests showed elevated serum anti-aquaporin-4 (anti-AQP4) antibody levels, and MRI demonstrated longitudinally extensive spinal cord lesions consistent with NMOSD. The patient was treated with methylprednisolone pulse therapy, followed by maintenance immunosuppressive therapy with inebilizumab and prednisolone, resulting in neurological improvement. However, around 15 weeks after onset, the patient experienced worsening burning sensations and numbness from the umbilicus to the toes, significantly impairing sleep due to NP (Numeric Rating Scale, or NRS: 7-8). Despite stable neurological findings and no new MRI abnormalities, she was diagnosed with NP related to NMOSD. Commencing amitriptyline at 5 mg/day led to rapid symptom relief by the next day, effectively controlling her NP. The pain remained well-managed with continued amitriptyline, allowing a gradual reduction in steroid dosage without symptom recurrence. This case highlights the potential of amitriptyline as an effective treatment for NP in NMOSD, a common and often resistant symptom in this condition. Given the complex mechanisms underlying NMOSD-related pain, individualized management strategies that include pharmacological agents like amitriptyline are crucial for improving patient quality of life (QOL), and further research is needed to optimize these approaches.