Treatment of primary writing tremor with botulinum toxin type a injections: report of a case series.

Primary writing tremor is a rare motor disorder in which tremor occurs primarily during writing and is not accompanied by other neurological symptoms and/or signs. Its etiopathogenesis is unknown, and treatment approaches remain largely empirical. Based on the effectiveness of botulinum toxin injections in writing dysfunction, we effectively used botulinum toxin type A for the treatment of primary writing tremor in a series of patients seen over a period of 5 years. Of the 5 patients, four received injections and reported significant and sustained treatment benefit for a period of at least 1 year. One patient declined botulinum toxin injections and responded moderately when treated with trihexyphenidyl.