Electromyographic studies on the flapping tremor, especially its relationship to hyperammonemia.

Abstract

Summary 1. Flapping tremor was observed in 10 cases with severe hepatic diseases. EMGs were recorded and analyzed in 5 of these cases. 2. The EMGs of the flapping tremor showed grouping discharges with definite irregular period and amplitude. The ratio of duration to interval of the grouping discharges ranged from 0.78 to 2.5 and the degree of fluctuation of period from 16.9 to 43%, considerably larger than any other grouping discharges due to various disorders. 3. Applying these analyzed results to the analytical coordinate of grouping discharges devised by Yoshii et al u), it was found that the napping tremor occupied a new position deviating to the right and upward, compared with tremor or clonus of other origin. From this fact, it is suggested that some cerebral or emotional factor and pyramidal factor were predominant in the mechanism of the flapping tremor. 4. All 10 cases with the napping tremor showed considerable disturbances of liver functions and EEG-changes corresponding to the degree of disturbance of consciousness (delta waves or triphasic waves). 5. All cases with the flapping tremor had outstanding hyperammonemia. It was also observed that the degree of the flapping tremor was affected by the blood ammonia level. 6. It was found that the flapping tremor was evoked or increased by oral administration of ammonium chloride in patients with severe hepatic diseases. 7. In patients with hepatic disease exhibiting the flapping tremor, the tremor disappeared following intravenous infusion of arginine in accordance with the decrease in blood ammonia level. 8. When ammonium chloride was administered orally to a patient with Wilson's disease, in whom the tremor was regular and typical of Parkinsonism, the tremor became more irregular and was transformed almost to the same pattern as the flapping tremor. 9. By slow infusion of ammonium chloride intravenously in the rabbit, an irregular tremor was evoked without producing convulsion. By analyzing the EMG, it was found that this tremor resembled the flapping tremor in man. 10. From the above results, it is well ascertainable that hyperammonemia plays the most important role in the development of the flapping tremor in hepatic disorders, and the participation of the limbic system of the brain and brain stem reticular activating system was discussed.