Advances in primary writing tremor.

Primary writing tremor (PWT) is considered to be a type of task-specific tremor in which tremor predominantly occurs and interferes with handwriting. The pathophysiology of PWT is not clear. Primary writing tremor may be a variant of essential tremor, a type of focal dystonia such as writer's cramp, or a separate nosological entity. Botulinum toxin injections and deep brain stimulation may be treatment choices for primary writing tremor.