Tremor in reflex sympathetic dystrophy.

Postural hand tremor was quantitatively investigated on both sides in 21 patients suffering from unilateral reflex sympathetic dystrophy of the upper extremity. On the affected side, enhanced tremor amplitude, with a mean tremor frequency of 7.2 Hz, was found in 57% of the patients. The appearance of tremor did not correlate to the occurrence of a single clinical symptom of reflex sympathetic dystrophy. On loading with increasing weight, the frequency of this pathological tremor shifted toward lower values, as it is found in physiological tremor. However, the peak frequencies of the electromyogram remained more or less stable. On recovery from this condition, the reflex sympathetic dystrophy tremor disappeared. Acute sympatholytic intervention could normalize reflex sympathetic dystrophy tremor. This would suggest that the sympathetic supply of the affected extremity contributes to the tremor in reflex sympathetic dystrophy. In conclusion, it is suggested that reflex sympathetic dystrophy should be included among the causes of tremor. According to our findings, tremor in reflex sympathetic dystrophy should be regarded as an enhanced physiological tremor.