Electrical stimulation of the motor tracts in cervical spondylosis.

Motor action potentials evoked by percutaneous electrical stimulation of the scalp and of the cervical (or lumbar) vertebral region were recorded from the biceps, thenar and tibialis anterior muscles in 30 patients with cervical spondylosis. Twelve normal controls were matched for age and height. Abnormalities of central motor conduction (absence or increased central delay of cortical responses) for at least one muscle were observed in all (but one) the patients with myelopathy alone or combined with radiculopathy. An increase in latency of the responses evoked by cervical stimulation occurred in 40% of patients with radiculopathy or myelo-radiculopathy. Changes of motor conduction occurred even in the absence of abnormalities of somatosensory evoked potentials, while the opposite was never observed. Direct stimulation of the motor tracts may be of value in the functional assessment of the motor pathways in cervical spondylosis.