The basic wave pattern of lumbar root potentials and clinical application

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We routinely use the morphological examination for an objective deagnosis assisting clinical examinations in lumbar root radicuropathy. We,however, not infrequently encounter the clinical cases in which the level diagnosed by clinical examination does not coincide the result of myelography. In these cases electrophysiological examination are needed. It is desirable to devise more direct electrophysiological examinations which allow us to record electrical activities of the nervous system revealing the actual state of nerve conduction. Requirements for such examination would be as follows; 1) easy applicability in the out-patient clinic, 2) minimal risk on execution, and 3) selective recording of the afferent and efferent nerve volleys, if possible.The investigation was carried out on 15 patients with the lumbar disc herniationand the spinal stenosis, and also five neurologically normal adult volunteers. Tibial or peroneal nerve was stimulated with the surface electrodes, and lumbar roo … More t potential was recorded in the epidural space L5/S1,L4/5 and L3/4. Evoked EMG responses were monitored simultaneously with SRP.Two kinds of potentials with aifferent latencies were recorded from the epidural electrodes by stimulation of the tibial nerve with the intensity evoking both H and M responses in the soleus muscle. The relationship of the amplitude between SRP and the corresponding H-reflex and M-response was examined. From these result the liminal stimulation at the M-threshold would allow us to monitor the conduction of the posterior root and the supra maximal stimulation of the M-response do that in anterior root.In posterior and anterior of LDH and LSS, 1)positivisation, 2)polyphasic wave and 3)pathological low amplitude were examined. 11 cases of the examined 15 cases had the positivisation and/or polyphasic potentials in the posterior or anterior root. The pathological waves were not observed in the remaining 4 cases. But 3 of those 4 cases showed the pathological low amplitude by using the quantitative method for estimating the low amplitude. We found the present examination satisfactory despite some problems still remained. Less