Objective: To determine the frequency of the association between tonic spasms and neuromyelitis optica (NMO) at our center.
Design: An institutional review board-approved retrospective study of clinical, serological, and radiographic characteristics of patients with NMO.
Setting: Multiple sclerosis center.
Patients: Patients with NMO treated at our center between 1990 and 2008.
Main outcome measure: Records were examined for documentation of tonic spasms.
Results: Of 110 patients with International Classification of Diseases code 341, 57 patients met diagnostic criteria for NMO. Of these, 8 patients (14%) had documented typical tonic spasms (median age at onset, 39.5 years; range, 13.8-54.2 years). Of those patients, 4 were African American, 3 were Hispanic, and 1 was white. Only 1 was male. The NMO-IgG antibody was found in 1 of 6 patients tested. Tonic spasms appeared after a mean of 24.6 months (range, 0-91 months). In 2 of 57 patients meeting NMO criteria, tonic spasms accompanied their initial episodes. Seven of 8 patients who had tonic spasms responded to treatment with carbamazepine within 1 week.
Conclusion: Tonic spasms are associated with NMO more commonly than with multiple sclerosis and may be a presenting sign in both diseases.