[Electrophysiological study on lumbosacral compression radiculopathy].

Using an electrophysiological approach, a functional diagnosis was attempted to evaluate lumbosacral compression radiculopathy. The cauda equina action potential (root-CEAP) and the somatosensory evoked potential (root-SEP) were measured by stimulating a single nerve root. The mixed nerve root action potential (MRAP) and the CEAP (P-CEAP) were recorded by stimulating a peripheral nerve. When a root was stimulated, reproduction of pain was also investigated. Seventy-four patients with lumbago and sciatica were examined. Nerve roots involved with neurological signs showed some abnormal conductivity in the order of P-CEAP, MRAP, root-SEP and root-CEAP. Subclinical involvement was also observed. It seems to be that the relationship between neurological signs and classification of root-SEP and root-CEAP are rather close. Pain was reproduced by stimulating the root in all cases of disc herniations irrespective of the neurological deficit. The above mentioned electrophysiological tests make it possible to identify and judge the extent of root involvement.