On the nature of normal tremor

Abstract

Under the proper circumstances of recording, normal tremor at rest has the amplitude, frequency, and wave form characteristics of a ballistocardiogram. Persistence of the tremor after complete neuromuscular blockade with succinylcholine precludes a neuro-muscular origin for normal tremor at rest. The frequency spectrum of tremor under succinylcholine, in spite of the total paralysis, resembles that seen on intentional movement of the limb rather than that recorded at rest. Normal tremor on intention may have both ballistocardiographic and neuromuscular components, but preliminary considerations suggest that the two cannot be readily separated on the basis of frequency, amplitude, and wave form of the oscillation. Our observations suggest that the transformation at surgery of the characteristic tremor pattern of parkinsonism to that of the lateral ballistocardiogram may be used as a monitor of the therapeutic procedure.