Diagnosing neurogenic thoracic outlet syndrome with the triple stimulation technique

Objective: We assessed the diagnostic value of triple stimulation technique (TST) in eight patients with neurogenic thoracic outlet syndrome (TOS) by revealing the conduction block of the proximal lower trunk of the brachial plexus and locating the compression site. Methods: Eight patients fulfilling the conventional criteria of the lower-trunk neurogenic TOS were enrolled in our study. TST along with the central motor-conduction time was evaluated. The parameters including the TST amplitude ratio and the TST area ratio were compared between patients and controls. Results: The amplitude ratio was significantly lower in the patient group than in the control group (patients: 0.518 +/- 0.113; control: 0.954 +/- 0.020, P < 0.01), so was the area ratio (patients: 0.453 +/- 0.194; control group: 0.955 +/- 0.192, P < 0.01). No significant difference of central motor-conduction time (CMCT) was seen between the patient group and the control group (patients: 6.62 +/- 0.36 ms; control: 6.54 +/- 0.36 ms; P = 0.528). Surgical procedures proved the compression of the lower trunk in all patients. Conclusion: Our results indicated that there was conduction block besides axon loss in neurogenic TOS patients, and the conduction block was located between the nerve root emerging site and the supraclavicular stimulation site. Significance: We first applied TST in diagnosing neurogenic TOS, and we showed that the patient's TST ratio was significantly lower than normal. Combined with clinical manifestations, TOS can be more precisely diagnosed. (C) 2015 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.