Isolated shoulder palsy due to cortical infarction: localisation and electrophysiological correlates of recovery.

The corticospinal tract influences the distal musculature more than the proximal, and the mechanisms involved in recovery of proximal muscle strength after stroke are unclear. A 65 year old man developed right shoulder weakness due to infarction in the left precentral gyrus. MRI showed a 3 mm cortical-subcortical ischaemic lesion in the superior genu of the left precentral gyrus medially to the knob-like structure corresponding to the motor area of the hand. Two months after stroke, when the patient was able to abduct the right arm against gravity and seven months after stroke when the patient had almost completely recovered, maximal TMS of the contralateral and ipsilateral motor cortex during voluntary contraction did not evoke a MEP in the right deltoid either with a focal or a non-focal coil. Recovery of proximal muscles in these cases may be mediated by elements other than the fast corticospinal neurones responsible for MEP generation.