DISTURBANCES OF ANTAGONISTIC NECK INNERVATION IN PATIENTS WITH CEREBELLAR DEFICITS

Fast 60 degrees head rotations of nine patients with cerebellar defici ts were analysed and compared with those of nine normal subjects. The surface EMG activity from both Splenii capitis muscles were recorded. The triphasic pattern of reciprocal innervated neck muscles with regar d to the duration, amplitude and onset of the pulses were analysed tog ether with the dynamic features of head rotation, i.e. position and ac celeration profiles. The deviation of the onset of the antagonistic (B ) pulse of the EMG-pattern flow was substantially increased. In most c ases the onset of the B-pulse was delayed, less premature and sporadic regular onsets occurred. The number of co-contractions and multiple a ntagonistic pulses was significantly increased. Half of the movements of patients were found to be dysmetric, with an irregular flow of posi tion and acceleration functions. From these, mainly hypermetric moveme nts occurred. The number of irregular pulse patterns was higher than t he number of dysmetrias. In this context cocontractions, multiple anta gonistic pulses and cortical control can be discussed as strategies of the cerebellar patients to improve their dynamic output. Our experime nts support the notion of the cerebellum playing an important part in the temporal integration of an antagonistically innervated movement. T he measurement of electromyographic burst patterns can be used as a cl inical tool to demonstrate an insufficient timing of the activities of muscles involved. (C) 1998 Elsevier Science B.V.