Study Of Electromyography And Clinical In Paraneoplastic Neurological Syndrome

Paraneoplastic neurological syndromes(PNS) are a group of rare neurological disorders caused by malignancy,but not by metastatic or direct invasion of the nervous system by cancer. These disorders may affect the nervous and/or muscular system and usually present months or years prior to the diagnosis of the underlying malignancy.Paraneoplastic neurological syndrome are difficulty to diagnose because of their complexity of clinical symptom. Generally, PNS have a poor result of treatment so that their prognosis are all not satisfied. So prior diagnosis and elimination of primary tumor are crucial point. At the present time, the clinical diagnosis of paraneoplastic neurological syndromes depend on the history, clinical manifestation, serum tumor markers and tumor-associated antibodies. Moreover, modern medical imaging, especially the application of PET-CT. PET-CT is an important inspection to screen tumor, especially the smaller tumor. With the increased awareness of PNS, electrophysiology play an irreplaceable role in prior diagnosis and distinguishing of PNS.Objective:The study was to analyze the characteristic of clinical manifestation and Electrophysiology in PNS. Looking forward to provide the objective electrophysiological evidence for diagnosis and differential diagnosis of PNS.Methods:We studied136cases with PNS and25cases of age-matched healthy subjects. Electromyogram was measured with the KEYPOINT myoelectric/evoked potential instrument.1. Electromyography and F-wave:The recording electrode was placed over the muscle belly and the reference electrode was placed distally over the muscle tendon. The stimulating electrode was placed over the nerve with the cathode close to the recording electrode and the nerve was stimulated. The current was increased until the CMAP no longer increased, then stimulation was increased by further20%-30%. CMAP was recorded with surface disc electrode and its latency and amplitude was analyzed. The F-wave latencies were obtained by stimulating the distal portion of the median and ulnar nerves using motor nerve conduction setups. SNAP were recorded by stimulation of the distal sensory fibers in the orthodromic sensory conduction test with the recording electrode placed close to the stimulator and its amplitude and SCV were analyzed.2. Repeated nerve electric stimulation(RNS):The check method is similar with the way of motor nerve conduction velocity. Starting to stimulate when the clinician adjust the stimulate area and intensity at the low and high frequency. The lower frequency are1Hz,3Hz,5Hz. To compare the changes of amplitude of the fifth wave and the first wave. However, it is essential to give higher frequency(10-50Hz) when one patient is considered Lambert-Eaton syndrome(LEMS), then carefully to investigate the changes of amplitudes.Results:1. The mean age in patients was60.11±10.01years and the proportion for male and female was1.8:1. Half of the PNS patients are lung cancer and neurological syndromes of86.11%patients are prior to diagnosis of underlying malignancy.2. Compared patients and the control group:the amplitude of CMAPs, the latency and MCV of median nerve, uInar nerve, tibial nerve and peroneus nerve were significantly decreased (P<0.05).3. Compared patients and the control group:when stimulated at wrist, the amplitude of SNAP in all of the examined nerve are markedly reduced or absent. And SCV of the examined nerve are in the normal range or reduced. There also has significant difference (P<0.05).4. Applying Pearson examination to analyze the correlation on nerve conduction and their influencing factors. But the outcome shows that there has not apparent correlation between them.5. Compared patients and the control group:the distal latency of F waves are prolonged or absent and there has difference (P<0.05).6. Outcome of RNS:Sixteen cases stimulate the abductor pollicis braves and abductor digital minimi. The outcome of half patients are positive, and the other cases are negative. Four cases are stimulated the deltoid, but only is positive at the low frequency. Other three cases are in the normal range.7. Abnormal rates of the electrophysiology:The abnormal rates of lower limbs are more than the upper limbs(X=1.049,P=0.306). Moreover, abnormal rates of sensory nerve are greater than motor nerve on the conduction velocity and SNAP amplitude(X2=10.288,P=0.001;X2=8.371,P=0.004).Conclusion:1. Paraneoplastic neurological syndrome are more pleasure to the olderly, and the range of sixty years old is the most susceptible age. PNS may affect the central or peripheral nervous system, peripheral-nerve joint and autonomic nerve. These neurological diseases mostly precede months or years prior to the diagnosis of the underlying malignancy. So that they are easy to cause missed diagnosis and misdiagnosis. Lung cancer is the most common tumor associated with PNS.2. The presentation of electrophysiology and F waves suggest that all the examined nerves(including nerves not felling change by patients) are damaged. MCV, CMAP, SCV and SNAP amplitude all have changes of different degree. But impairment of sensory nerves is markedly more serious than motor nerves, what’s more, the lower limbs are more serious than the upper limbs. And the SNAP amplitude are seriously reduced or absent, which is the major traits of PPN; however conduction velocity are in the range of normal values or lightly reduced. The distal latency of F waves are prolonged or absent. But there has not apparent correlation between conduction velocity/amplitude and their influencing factors. In addition, the electrophysiology outcome are more serious than the clinical manifestation.3. Repeated nerve electric stimulation suggest that RNS is one examination which has a confirmed significance. The outcome of RNS show that the fifth waves amplitude is lower more fifty percentage than the first wave amplitude at the lower frequency. However, the waves amplitude show markedly increasingly trend, generally above100%.4. The other clinical information indicate that PET and tumor associated antibody play an important role in the diagnosis of PNS. They can complement each other so that they may improve early diagnosis rates. So clinicians conduct a comprehensive inspection when they consider PNS. In the hope of confirming PNS early and finding the underlying malignancy at primary stage.