Residual impairment in handgrip strength after unilateral frontal-lobe lesions.

The handgrip strength of 65 normal control subjects and 166 patients with unilateral frontal- or temporal-lobe excisions was assessed. Because of the known sex differences in strength, the results for the men and women were analysed separately. The grip strength of men with left frontal-lobe lesions was found to be within the normal range, but women with comparable excisions from the left frontal lobe had a residual impairment in strength on both hands. The men with right frontal-lobe lesions had a significant reduction in the strength of only the left hand, and the women in this group displayed a similar tendency. The deficits were interpreted in terms of a loss or disruption of input from the premotor area to the primary motor cortex.