DYSAESTHESIAE INDUCED BY PHYSIOLOGICAL AND ELECTRICAL ACTIVATION OF POSTERIOR COLUMN AFFERENTS AFTER STROKE

Six of 48 stroke patients had functionally limiting dysaesthesiae indu ced by repetitive light touch, joint movement, or neuromuscular electr ical stimulation (NMS). Only one of these six patients had a thalamic lesion. Quantitative sensory testing showed substantial impairment of pain and temperature sensation in all six patients, whereas light touc h, vibration and position sense, and graphaesthesia were normal (three patients) or relatively spared (three patients). By contrast, none of 15 stroke patients in whom NMS did not evoke dysaesthesiae had clinic al evidence of dissociated sensory loss. Conscious perception of joint movement and light touch is mediated mainly by the population of larg e myelinated activated preferentially by low intensity electrical stim ulation. It is suggested that activation of these nonnociceptive, pres umably dorsal column, afferents may contribute to dysaesthesiae in som e patients with sensory loss after stroke.