Electrophysiological Study And Clinical Significance Of Median-Ulnar Nerve Communications

ObjectiveAccording to the electrophysiological detection principle of the anomalous median-ulnar nerve communications,To clarify the practical steps and specific parameter settings;to probe the specificity and relevance in different detection methods;to complement and define the electrophysiological diagnostic criteria of communications;to investigate the incidence of communications in Chinese;to further analyze the clinical application value of communications in hand functional compensation after upper limb nerve injury.MethodsRandom 50 healthy upper limbs are contributed to detection for median-ulnar nerve communications with two different methods:1.Routine motor nerve conduction measure 2.Collision blocks.Particular precautions are undertaken to avoid false positive results due to stimulus spread to the neighboring nerve.The following data should be measured and observed:(A) the amplitude,latency and stimulus intensity of CMAP.(B) the morphological character especially initial deflection of CMAP.The comparison of CMAP between elbow and wrist stimulation and the investigation of the intrinsic relevance are to deduce the electrophysiological diagnostic criteria of communications.The differential comparison of the positives with two methods is to inspect whether the testing power of collision blocks is good or bad.Results1.The positive incidence of Martin-Gruber Anastomosis(MGA) was 24%using routine motor nerve conduction measure and 8%using the collision blocks.2.No case of Reverse Martin-Gruber Anastomsis(RMGA) was found with two different methods.3.The difference in the side of extremities and gender has no statistical significance for the communications.4.Unintended supramaximal intensity of stimulation and overlong stimulus interval of the collision block may induce false positive results.Case Report It is essential to follow up the patients of forearm nerve injury with real occurrence of median-ulnar nerve communications and to observe the special clinical manifestations and electrophysiological feature.We can learn that communications can play an important role in hand functional compensation after upper limb nerve injury.ConclusionWhile the MGA is very common,the RMGA is a rarity.The attention of the electrophysiological detection for median-ulnar nerve communications should be paid to the exclusion of false positives due to the volume-conducted effect from stimulus spread.Compared to routine motor nerve conduction measure,the collision blocks can separate and amplify the small potentials of MGA from normal large action potentials.Therefore,such technique is of great clinical application value.The communications play important role in the diagnosis and treatment of nerve injury in the forearm.