Late onset tic disorder: A rare occurrence

To the Editor

Tic disorders have classically been considered to be childhood onset disorders. International Statistical Classification of Diseases and Related Health Problems–10th Revision (ICD-10) does not accommodate tic or related disorders occurring outside of childhood except Tic Disorder, Unspecified (World Health Organization [WHO], 1993). A majority of tics found in adults are considered to be a continuation or recurrence of childhood tics, and cases without such history are assumed to have forgotten about childhood occurrences. However, adult onset tic disorders have been identified in literature reviews (Chouinard and Ford, 2000).

A 57-year-old housewife from a middle class urban family was admitted to our department with sudden onset brief repetitive arrhythmic jerking movements in neck with progressive course over 18 months. These movements would exacerbate when the patient was tired, or attempted to eat. Sleep and conscious effort reduced the movements. She also had paraesthesias in neck region that would precede the movements and be relieved once the movements started. The patient had anxiety and distress owing to these movements. She was being treated as a case of Dissociative Disorder with a combination of Amitryptiline 37.5 mg/day and Chlordiazepoxide 15 mg/day but with no relief.

The patient’s past, family and personal history were non-contributory and she had a well-adjusted premorbid personality. A careful evaluation did not reveal any temporally associated stressor either. Her general physical examination and a comprehensive neurological examination were unremarkable except for the earlier described repetitive movements. She was provisionally diagnosed as a case of Tic Disorder, Unspecified as per ICD-10 (WHO, 1993) and, considering the patient’s associated anxiety, was treated with clonazepam 2 mg/day which was later on increased to 3 mg/day. Over the following week, the frequency and intensity of the movements decreased along with resolution of the paraesthesias in the neck region. She did not have excessive sedation or any other side effects. The patient was discharged and, on the follow-up visits, was found to be asymptomatic.

Tics in elderly are very rare; a review of 411 cases of tic disorder found only 22 presenting in adult age for the first time (Chouinard and Ford, 2000), out of which only 13 were found to have no prior history of tics. The average age of such patients was 47 years, ranging from 25 to 63 years.

Clonazepam has been found to be effective in tic disorder, albeit used infrequently (Shprecher and Kurlan, 2009). The current case represents a rare occurrence of late onset tic disorder, treated with an equally unconventional agent, clonazepam.