Identification of alpha-motor nerve fiber potentials in lumbar epidural space and its clinical significance.
The alpha-efferent component of spinal root potentials (SRPs) was recorded in the lumbar epidural space stimulating the tibial and peroneal nerves for clinical diagnosis and clinical treatment. Five normal volunteers and 15 clinical cases with lumbar disc herniation (LDH) were examined. The SRP by the tibial nerve stimulation in the normal control group consisted of two kinds of potentials with different latency. Simultaneous electromyogram (EMG) recording from the stimulated muscles indicated that the shortest latency potential (first potential) was the ascending volley, including orthodromic afferent and antidromic alpha-efferent volleys; and that the long latency potential (second potential) was the descending volley of reflexively evoked alpha-efferents by the Group Ia afferents. The component of alpha-efferent fiber potential was recorded in the following two methods by changing the intensity of stimulation: 1) identifying alpha-efferent components in the first potential and 2) recording the second potential. Conduction blockage of spinal roots in 15 clinical cases was demonstrated as abnormal positivity and prolonged duration of the potentials. New methods were introduced to estimate two parameters quantitatively. The present study showed either of these signs in all patients tested. The examination was helpful to determine the level(s) of lumbar motor radiculopathies, and the extent of pathologic neuropathy.
Watanabe
J
J
Department of Orthopaedics, Saitama Medical School, Japan.
Tanaka
H
H
D000328:Adult; D004525:Efferent Pathways / Q000502:physiology; D004576:Electromyography; D004824:Epidural Space; D005073:Evoked Potentials, Somatosensory / Q000502:physiology*; D005260:Female; D006801:Humans; D007405:Intervertebral Disc Displacement / Q000175:diagnosis*; D008159:Lumbar Vertebrae; D008297:Male; D009046:Motor Neurons / Q000502:physiology*; D009412:Nerve Fibers / Q000502:physiology; D010543:Peroneal Nerve / Q000502:physiology; D013126:Spinal Nerve Roots / Q000502:physiology*; D013979:Tibial Nerve / Q000502:physiology