Noise-induced psychogenic tremor associated with post-traumatic stress disorder.

Tremors in post-traumatic stress disorders have not been previously well characterized. A 67-year-old man has a 46-year history of a noise-induced exaggerated startle reflex followed by a large amplitude rest, postural and kinetic tremor that may persist for up to 3 days. This tremor is superimposed on a continuous mild organic postural/kinetic tremor whose electrophysiological characteristics are different from those of the overlying tremor. We attribute the exaggerated startle reflex and the noise-induced tremor to Post-Traumatic Stress Disorder (PTSD) and postulate a psychogenic origin for the noise-induced tremor. The patient also believes the noise-induced tremor to be psychologically based and to be produced by the fear and anxiety he experiences when he hears loud, unexpected noises. The sudden onset of the noise-induced tremor, its intermittent character, its temporary disappearance on distraction despite the patient's inability to suppress it, inconsistencies in handwriting and figure drawing, and the fact that the noise-induced tremor is stimulus specific and persists long after the offending stimulus (noise) is no longer present all suggest a tremor of psychogenic origin.