Diagnostical value of electromyography in identifying responsible segments of multi-segmental lumbar degenerative diseases

English Keywords:Multi-segmental lumbar degenerative diseases  Responsibility segment  Electromyography

English Abstract:

  【Abstract】 Objectives: To explore the value of electromyography(EMG) in diagnosing responsible segments of multi-segmental lumbar degenerative diseases. Methods: A total of 342 patients(male 174, female 168; average age, 69.2) with multi-segmental lumbar degenerative diseases were enrolled in this study from January 2007 to January 2015. 180 patients had lumbar spinal stenoses, 95 with lumbar spinal stenosis with disc herniation, 55 with lumbar spondylolisthesis and 12 with degenarative scoliosis. The responsible segments in 224 patients were confirmed according to the symptoms, signs and imageological examination, and 118 were diagnosed by preoperational subarachnoid root block. 95 patients underwent single-segment surgery, 212 patients had double-segment surgery, and 35 had three-segment fixation. The nerve conduction velocity of lower limb motor nerve and sensory nerve were performed. Lower limb muscle and paraspinal muscle in lumbosacral region were detected by the electromyography of needle pole. And H reflex was examined in soleus muscle. The muscles detected by needle EMG appeared the denevated potentials, that were, fibrillation potentials, positive sharp waves and compound repetitive discharge(CRD), suggesting the nerve injury. The abnormal standards of motor nerve conduction velocity(MCV) and sensory nerve conduction velocity(SCV) were detected in the nerve conduction studies(NCS): MCV<40m/s, SCV<39m/s. The patients with affected H reflex disappearing or bilateral latency difference more than 1.5ms, suggesting that S1 nerve root might be damaged. Electromyography detection sensitivity=the number of segments positive in electromyography test and surgical decompression anastomosis/total number of segments undergoing decompression in electromyography detection; the specificity=the number of segments negative in electromyography test/all segments without decompression. Results: Needle electromyography showed that the sensitivity and specificity of the responsible segments were 72.5% and 87.2%, respectively. The complex repetitive discharges(CRD) showed a sensitivity of 8.7% and a specificity of 100% in the responsible segments. The sensitivity and specificity of motor unit potential(MUP) turned out to be 92.2% and 18.2%. Nerve conduction detection showed decreased compound muscle action potential(CMAP) in tibial nerves of 89 patients and common peroneal nerves of 101 patients. In those patients, CMAP of extensor digitorum could not be detected in 45 patients whose disease courses were longer than 3 years, however, CMAP with low amplitude and normal speed of tibialis anterior in those patients could be observed. In all of the patients, the motor conduction velocities of common tibial nerves and common peroneal nerves as well as the sensory conductions of superficial peroneal nerves and sural nerves were normal. H reflexes disappeared in 217 patients, and the latencies of H reflex were prolonged 1.5ms in 54 patients. Conclusions: This prospective study demonstrates the positive and sharp waves and fibrillation potentials have a higher sensitivity and specificity in analyzing the responsible segment of multilevel lumbar degenerative disease. However, it is of less value of MUP in defining responsible segment.