The Development of Abnormal Spontaneous Activities in the Experimental Radiculopathy in the Rat

OBJECTIVE: Through a animal study using rats, we investigated whether abnormal spontaneous activities (ASAs) could be observed in the radiculopathies of biochemical and mechanical model. METHOD: A total of 30 Sprague-Dawley male rats were randomly assigned into sham, nucleus pulposus (NP) and ligation groups. In the sham group, the right L4 and L5 nerve roots were exposed by laminectomies. In the NP group, nucleus pulposus was transplanted onto nerve roots from tail. In the ligation group, exposed nerve roots were ligated by silk ligatures. All rats were evaluated by mechanical allodynia, motor paresis, and the needle electromyography (EMG) examination. RESULTS: Mechanical allodynia was observed on the 4th and 7th postoperative days in NP and ligation groups. Motor paresis was observed only in the ligation group. The needle EMG showed ASAs on the 4th postoperative day, but decreased in incidence and amount on the 7th postoperative day in the NP and ligation groups. CONCLUSION: The ASAs can be observed by the biochemical action of nucleus pulposus as well as the mechanical compression. The results of this study may help explain the discrepancy between radiologic and electrodiagnostic findings.

Change of Abnormal Spontaneous Activities According to Time Course in Hemiplegic Upper Limb

OBJECTIVE: To evaluate the change of abnormal spontaneous activities according to the clinical and radiologic findings, and to the time course after onset in hemiplegic upper limb. METHOD: We scored abnormal spontaneous activities of hemiplegic upper limb muscles (infraspinatus, deltoid, extensor carpi radialis, abductor pollicis brevis, abductor digiti minimi) in 100 hemiplegic patients without peripheral neuropathy. The abnormal spontaneous activities were evaluated according to their radiologic findings and to Brunnstrom stage and the presence of reflex sympathetic dystrophy (RSD), and the time course after the onset (A cross-sectional study). In addition we repeatedly examined 40 hemiplegic patients until 12 weeks after the onset to define the pattern of change (A prospective study). RESULTS: There was no significant difference in the score of abnormal spontaneous activities according to the radiologic findings. The score of abnormal spontaneous activities decreased while Brunnstrom stage progressed. In both the cross-sectional and prospective studies, we found that the abnormal spontaneous activities decreased according to the time course after the onset in the limb without RSD, but sustained in the limb with RSD. CONCLUSION: Abnormal spontaneous activities decreased according to the progression of Brunnstrom stages. The hemiplegic patients with RSD showed more profuse and sustained abnormal spontaneous activities at needle EMG study of hemiplegic upper limb than the patients without RSD.

Abnormal Spontaneous Activities According to Type of Herniated Lumbar Disc and Anteroposterior Diameter of Dural Sac in MRI

OBJECTIVE: To assess the abnormal spontaneous activities in needle electromyography (EMG) according to the type of herniated lumbar disc and anteroposterior the diameter of dural sac in magnetic resonance imaging (MRI). METHOD: We performed the MRI on 120 patients with low back pain (LBP) and measured the midline anteroposterior diameter of dural sac in a MRI axial view. Fifty patients with a disc protrusion or extrusion in MRI were reviewed for the clinical findings on physical examination and assessed for the abnormal spontaneous activities (ASA) in needle EMG. RESULTS: Seventy cases with a normal finding in MRI did not have differences in a dural sac diameter regardless their age or sex. Fifty cases with a protrusion or extrusion in MRI showed that the dural sac size decreased more in an extrusion than in a protrusion, and more in a paracentral type than in a central type. The incidence of ASA in a needle EMG increased more in an extrusion than in a protrusion, and more in a paracentral type than in a central type. The incidence also increased according to the decrement of a dural sac diameter. The incidence of ASA were 100% in a group with both motor and sensory signs, 94% in a group with a motor sign, 86% in a group with a sensory sign, 26% in a group without motor or sensory sign. CONCLUSION: We concluded that the abnormalities in needle EMG must be correlated with the direction of herniated lumbar disc and anteroposterior diameter of the dural sac in MRI as well as clinical findings.