Neurosurgical Management of Writer's Cramp

Abstract

Background : Writer's cramp is NOT a mental disorder but a type of focal dystonia due to dysfunction of the pallido-thalamo-cortical circuit. Not only writing but other tasks such as playing musical instruments and using chopsticks may induce dystonic contractions of the hand. Therefore, it may be called task-specific focal hand dystonia. The symptom is refractory to most conservative treatment, though botulinum toxin injection is generally used for symptomatic relief. As a neurosurgical treatment of dystonia, we have performed stereotactic nucleus ventro-oralis (Vo) thalamotomy for dystonic cramp of the hand. Methods : Twenty-two patients (15 men, 7 women; age 22-57 years, mean 32.1 years) with medically intractable task-specific focal dystonia of the hand underwent Vo thalamotomy. The stereotactic target was chosen at the junction of the anterior and posterior Vo nuclei. The procedure was performed with MRI/CT fusion stereotaxis under complete local anesthesia. Results : The duration of the symptom ranged from 3 to 6 years (mean 4.5 years). All patients had complained of difficulty in writing. Ten patients were professionals, such as a comic artist, guitarist and barber, and, because of the dystonic symptoms occurring during their work, they had stopped pursuing their profession. All but one patients showed significant improvement of dystonic symptoms immediately after the operation. The effect sustained during the follow-up period (1-44 months, mean 13.1 months), except in three cases. The three patients showed partial recurrence of the symptom and underwent second thalamotomy 5-6 months after the initial surgery. There was no mortality or permanent morbidity. Conclusion : With modern stereotactic method, Vo thalamotomy is a useful and safe therapeutic option for writer's cramp. The ventro-oralis nucleus receiving the pallidal input is considered to be a key structure in task-specific focal hand dystonia.