Frequency - Specific Study Of Transcutaneous Electrical Acupoint Stimulation For Postherpetic Neuralgia

Post-herpetic neuralgia (PHN) is a common complication of herpes zoster.Due to its intense pain and lingering, refractory disease process, PHN has an greatly effects on health and quality of life of patients. PHN is a typical neuropathic pain and the incidence of PHN increases with age, showing a significant positive correlation. The pathophysiology of PHN is not yet fully understood. Usually, there is a variety of mechanisms influencing each other and no specific treatment so far. Principles of treatment generallyadopted are full course and combination therapy as early as possible. Drug therapy combined with minimally invasive interventional treatment usually is recommended. Transcutaneous electrical acupoint stimulation (TEAS) is based on the principle of acupuncture analgesia, which has been invented by HAN Ji-Sheng of Peking University institute of neuroscience. Animal experimental studies have been shown that low frequency (2 Hz) electrical stimulation of HANS has a good analgesic effect for neuropathic pain in rats, while high frequency (100 Hz) electrical stimulation is to no avail. The principle may involve activation of endogenous opioid system, which accelerates the production and secretion of endorphins、enkephalins and dynorphin. So these neurotransmitters mediate analgesic. It may also involve synaptic transmission changing in long plasticity of the spinal dorsal horn nociceptive neurons, which are the long-term potentiation (LTP) and long-term depression (LTD). However, the clinical efficacy has not been verified, we uphold the idea of translational medicine toconduct the clinical observation of the subject in order to better serve results of basic research for clinical services and remove more pain.Objective:To observe the therapeutic effect of transcutaneous electrical acupoint stimulation (TEAS) for the treatment of post-herpetic neuralgia (PHN).Methods:A total of 60 patients with clinical diagnosis of PHN were randomly and evenly distributed into 3 groups:control group (n=20)、2 Hz group (n=20) and 100 Hz group (n=20),by using random numbers table.The control group received routine medical treatment (Vitamin B1, Mecobalamin Tablets, Gabapentin and Tramadol) only. The 2 Hz group and 100 Hz group received TEAS with a frequency of 2 Hz or 100 Hz, respectively, combined with routine medicine. TEAS was administered by using a Han’s acupoint nerve stimulator (HANS) model 200A with two output channels connected with 4×4cm self-adhesive skin electrodes. Stimulating site:An electrode of A guide is placed on Jiaji point near the midline of onset stage, while the other placed on Ashi point in the distal skin lesions. An electrode of B guide is placed on Hegu in the healthy side, while the other placed on Zusanli. Stimulus intensity 10-15 mA,30 minutes per day for 14 days. The VAS、NRS、HAMD and HAMA for therapeutic effect were taken as clinical outcomes.Results:58 completed the trial. All 3 groups showed significant reduction of pain scores over the period of 2 weeks. The 2 Hz TEAS group showed significantly enhanced reduction in pain scores compared with the other two groups (P<0.01). The 100 Hz TEAS group was not superior to the control group. There was no significant difference between the 3 groups in terms of the degree of anxiety and depression (P>0.05).Conclusions:The TEAS with frequency of 2 Hz, but not 100 Hz, showed significant enhancement of pharmacological intervention on pain for post-herpetic neuralgia.