Movement-associated cortical potentials in unilateral cerebral lesions.

Movement-associated cortical potentials (MP) associated with thumb-opposition or fist-clenching were studied in 20 patients with unilateral cerebral lesions and in 8 healthy subjects. MP was abnormal in 16 patients. The most frequent abnormality was an attenuation of the N component or readiness potential, recorded on the central region contralateral to the contracting muscle, on the affected hemisphere. The occurrence and severity of MP abnormalities seem to be influenced by an intensity and extension of the lesion, rather than by how much disability is present in the affected limb. There was no significant correlation between the abnormalities of MP and of EEG. The most useful index of MP for comparing two hemispheres was shown to be the amplitude and wave form of the N component or readiness potential contralateral to the contracting muscle.