Spinal Movement Disorders in Neuromyelitis Optica: An Under-recognized Phenomenon

Background: Spinal cord demyelination can cause several movement disorders. Although these abnormal movements could be the presenting symptom of the disease and, at times, the major source of disability, they are often overlooked, mislabeled, or undertreated. The aims of this study were to clearly define and establish common terminology for spinal movement disorders (SMDs) and characterize their full spectrum in patients with neuromyelitis optica (NMO). Methods: We chart reviewed 37 patients with NMO or NMO spectrum disorder. We classified spinal movement disorders under five categories: tonic spasms; focal dystonia; spinal myoclonus; spontaneous clonus; and tremors of spinal origin. We examined clinical, MRI, and medication data of symptomatic patients. Results: Of the 37 patients (86.4% female; mean age: 51 +/- 17 years; mean disease duration: 9.4 +/- 5.3 years), 16 (43.2%) had one or more form of SMDs. Compared to those without SMDs, patients with SMDs were generally older at presentation and were less likely to be African Americans. An abnormal movement was the main complaint in at least one posthospitalization visit in all symptomatic patients. Thirteen (35.1%) patients had paroxysmal tonic spasms, 2 (5.4%) had focal dystonia, 3 (8%) had postural/action tremors, and no patient had spinal myoclonus or spontaneous clonus. In 9 patients, spasms were painful. There was no signal abnormality in the basal ganglia or the brainstem/cerebellum in any of the symptomatic patients. Conclusions: SMDs are common in NMO and are often a major source of disability.Using clear, unified terminology to describe SMDs is crucial for both clinical and research purposes.