Transient improvement of writing tremor by holding breath in volition: a case report]

We report a 76-year-old Japanese woman who had tremor of her hand during writing. Her past and family histories were unremarkable. On neurological examination, there was no abnormal finding except the writing tremor and the postural tremor of her lips and jaw. Surface EMG studies revealed that regular grouped discharges, at a frequency of about 5 Hz, appeared in the wrist flexor and extensor muscles soon after she start writing; these grouped discharges were inhibited while holding breath. Her postural tremor improved after consumption of a small amount of alcohol, suggesting that she had essential tremor. Thus, she may be diagnosed as having a variant of essential tremor. On the other hand, this tremor may be interpreted as a variant of writer's cramp, since her writing tremor transiently improved when she hold breath, just like a trick. In patients with dystonia, it is well known that dystonic symptoms can be temporally ameliorated by geste movement like a "trick". Although the pathophysiological relationship between primary writing tremor and writer's cramp are unclear, the unique characters of this tremor may suggest that a focal task-specific tremor and essential tremor can co-exist.