Pulsed electrical stimulation protects neurons in the dorsal root and anterior horn of the spinal cord after peripheral nerve injury

Most studies on peripheral nerve injury have focused on repair at the site of injury, but very few have examined the effects of repair strategies on the more proximal neuronal cell bodies. In this study, an approximately 10-mm-long nerve segment from the ischial tuberosity in the rat was transected and its proximal and distal ends were inverted and sutured. The spinal cord was subjected to pulsed electrical stimulation at T10 and L3, at a current of 6.5 m A and a stimulation frequency of 15 Hz, 15 minutes per session, twice a day for 56 days. After pulsed electrical stimulation, the number of neurons in the dorsal root ganglion and anterior horn was increased in rats with sciatic nerve injury. The number of myelinated nerve fibers was increased in the sciatic nerve. The ultrastructure of neurons in the dorsal root ganglion and spinal cord was noticeably improved. Conduction velocity of the sciatic nerve was also increased. These results show that pulsed electrical stimulation protects sensory neurons in the dorsal root ganglia as well as motor neurons in the anterior horn of the spinal cord after peripheral nerve injury, and that it promotes the regeneration of peripheral nerve fibers.

DIAGNOSTIC VALUE OF NERVE ROOT STIMULATION METHOD IN CERVICAL RADICULOPATHY

By means of cervical nerve root stimulation(CRS) method, the amplitudes and latencies of compound motor action potential(CMAP) of brachial biceps and brachial triceps muscles in 41 patients with clinical symptoms and signs of cervical radiculopathy were observed. The amplitudes of CMAPs on the affected side in the patients were obviously lower than on the healthy side and control group, latencies of CMAPs on the affected side were also significantly prolonged. The results showed that CRS was a sensitive method for making a direct determination of proximal nerve roit cinductiin function, and a good aid for diagnosing cervical radiculopathy.

Basic mechanisms of peripheral nerve injury and treatment via electrical stimulation

Previous studies on the mechanisms of peripheral nerve injury(PNI)have mainly focused on the pathophysiological changes within a single injury site.However,recent studies have indicated that within the central nervous system,PNI can lead to changes in both injury sites and target organs at the cellular and molecular levels.Therefore,the basic mechanisms of PNI have not been comprehensively understood.Although electrical stimulation was found to promote axonal regeneration and functional rehabilitation after PNI,as well as to alleviate neuropathic pain,the specific mechanisms of successful PNI treatment are unclear.We summarize and discuss the basic mechanisms of PNI and of treatment via electrical stimulation.After PNI,activity in the central nervous system(spinal cord)is altered,which can limit regeneration of the damaged nerve.For example,cell apoptosis and synaptic stripping in the anterior horn of the spinal cord can reduce the speed of nerve regeneration.The pathological changes in the posterior horn of the spinal cord can modulate sensory abnormalities after PNI.This can be observed in cases of ectopic discharge of the dorsal root ganglion leading to increased pain signal transmission.The injured site of the peripheral nerve is also an important factor affecting post-PNI repair.After PNI,the proximal end of the injured site sends out axial buds to innervate both the skin and muscle at the injury site.A slow speed of axon regeneration leads to low nerve regeneration.Therefore,it can take a long time for the proximal nerve to reinnervate the skin and muscle at the injured site.From the perspective of target organs,long-term denervation can cause atrophy of the corresponding skeletal muscle,which leads to abnormal sensory perception and hyperalgesia,and finally,the loss of target organ function.The mechanisms underlying the use of electrical stimulation to treat PNI include the inhibition of synaptic stripping,addressing the excessive excitability of the dorsal root ganglion,alleviating neuropathic pain,improving neurological function,and accelerating nerve regeneration.Electrical stimulation of target organs can reduce the atrophy of denervated skeletal muscle and promote the recovery of sensory function.Findings from the included studies confirm that after PNI,a series of physiological and pathological changes occur in the spinal cord,injury site,and target organs,leading to dysfunction.Electrical stimulation may address the pathophysiological changes mentioned above,thus promoting nerve regeneration and ameliorating dysfunction.

ELECTRODIAGNOSIS OF LUMBOSACRAL RADICULOPATHY

For diagnosiug lumbosacral radicuiopathy precisely, electromyogram(EMG),nerve conduction velocity(NCV),conventional H reflex and H reflex by nerve root stimulation were done in 79 patients with clinical symptoms and signs of lumbosacral radiculopathy.The rate or appearance fibrillation voltage and/or positive sharp wave in the paraspinal muscles was the highest among them.In the comparison of the affected and the healthy sides in patients with S1 radlculopathy,and of affected side and control group,H-M wave interval of H reflex by nerve root stimulation were significantly prolonged(P<0.01,P<0.05);compared with control group,the dirference or H-M wave interval between the two sides was also significantly prolonged (P<0. 05).But the differences were not so significant in patients with L5 radlculopathy.The results suggest that the abnormal changes or EMG or the paraspinal muscles and H reflex by nerve root stimulation are reliable methods of diagnosing lumbosacral radiculopathy, H reflex by nerve root stimulation can be used to differentiate L5 and S1 nerve root lesions,and measure motor conduction velocity(MCV)and sensory conduction velocity(SCV) or the proximal sciatic nerve.