Short latency somatosensory evoked potentials in patients with painful dysaesthesias in peripheral nerve lesions.

Abnormally delayed and attenuated short latency somatosensory evoked potentials after electrical stimulation in the distribution of painful dysaesthesias after peripheral nerve lesions are reported in 4 selected patients with lesions in very proximal parts of the peripheral nerves. These included painful spondylopathic cervical radiculopathy, meralgia paraesthetica, pyriformis syndrome and allodynia after injury of the femoral nerve. Locally developed techniques for testing musculocutaneous, lateral femoral cutaneous and saphenous nerves were used in 3 patients. Possible pathophysiological mechanisms causing evoked potential abnormalities are discussed.