Painful tonic spasms initially described in association with multiple sclerosis are actually more common in patients with neuromyelitis optica spectrum disorder. Characterized by fierce pain and tonic posture of limbs, painful tonic spasms are common in patients during the recovery phase after the first episode of myelitis. A 68-year-old man presented with painful tonic spasm after 2 months of diagnosis of neuromyelitis optica spectrum disorder. Eventual use of eslicarbazepine resulted in significant control of spasms. Early recognition of painful tonic spasms and appropriate therapeutic medications can significantly decrease the impact it can have on the quality of life among neuromyelitis optica spectrum disorder patients.