We investigated cortical motor neuron excitability in patients with total brachial plexus injuries. The cortical motor neuron excitabilities were evaluated by the amplitude of spinal evoked potentials (SCEPs) following unilateral transcranial magnetic stimulation (TMS). Several components of SCEPs were recorded following TMS. The amplitude of these components were similar by right and left cortex stimulation in control subjects. In patients with brachial plexus injury, the amplitude of SCEPs following TMS was similarly recorded by right or left cortex stimulation. These results suggested that cortical motor neuron excitability is preserved in the early stages of peripheral nerve injury.
