Clinical Study Of Electrophysiological Diagnosis Of Neurogenic Thoracic Outlet Syndrome

Objective: Thoracic outlet syndrome (TOS) is a group of syndromes caused by thecompression of bone, tendon and abnormal fibrous band on the neurovascular trunk ofupper limbs at the thoracic outlet. Neurogenic thoracic outlet syndrome (NTOS) ismostly common in different types of thoracic outlet syndrome, but is also one of thediseases difficult to be diagnosed for lack of good specificity and sensitivity whetherin signs or symptoms. Most of electrophysiological detection methods are applicablein the diagnosis of peripheral nerve entrapment syndrome. Only a few of them aresuitable for brachial plexus neuropathy and spinal cord disease, and it is stillcontroversial about their roles in diagnosis of neurogenic thoracic outlet syndrome. Sothe role of electrophysiological examination in diagnosis of neurogenic thoracic outletsyndrome needs to be further investigated.Methods: The studies of EMG, nerve conduction, F wave, and conduction of themedial cutaneous nerve of the forearm were conducted using KEYPOINTmyoelectric/evoked potential meter (Medtronic, US). Each testing result wascompared between bilateral limbs. The electrophysiological data of27cases ofpatients diagnosed with neuropathic thoracic outlet syndrome that were screened outfrom January2010to January2013were retrospectively analyzed.Results: The abnormal rate of EMG of abductor pollicis brevis was33.3%(9/27), andthe abnormal rate of EMG of abductor digiti minimi was22.2%(6/27). There weretwo cases of median nerve sensory conduction with reduced amplitudes although thevelocities were normal. The abnormal rate of nerve sensory conduction of ring fingerof the ulnar nerve was62.9%(17/27). The abnormal rate of amplitude in theconduction of the medial cutaneous nerve of the forearm was66.7%(18/27). Therewere no abnormaliyies in motor conduction velocities of the median nerve and ulnarnerve. The abnormal rate of amplitude in motor nerve conduction of the median nervemiixed with muscle action potential was40.7%(11/27). The abnormal rate of amplitude in motor nerve conduction of the ulnar nerve miixed with muscle actionpotential was22.2%(6/27). The abnormal rate of the medial cutaneous nerve of theforearm was88.9%(24/27). The abnormal rate of F wave was81.5%(22/27). Thecoincidence rate of electrophysiological diagnosis was100%. The difference in theabnormal rate between F-wave detection and the conduction of the medial cutaneousnerve of the forearm was not statistically significant (X2=0.1467, P>0.05).Conclusion: Different electrophysiological examination methods must be combinedwith each other in comprehensive analysis for lack of independent diagnostic role, inorder to improve the sensitivity and specificity in the diagnosis of NTOS.Electrophysiological detection is therefore of diagnostic significance for NTOS. Thereare currently few clinical studies reported TOS, so a prospective clinical research witha larger sample size needs to be further conducted.