Factors correlating with positive electrodiagnostic findings for neurogenic thoracic outlet syndrome

Diagnosis of neurogenic thoracic outlet syndrome (nTOS) remains a challenge. The role of electrodiagnostic studies (EDX) in the workup of nTOS remains controversial. The aim of this study was to report the EDX findings in a cohort of patients who underwent surgery for nTOS and also analyze patient-related and intraoperative factors associated with positive EDX findings supportive of nTOS diagnosis.

Baseline characteristics of patients, including age, sex, duration of symptoms, type of nTOS, and pattern of brachial plexus involvement, were gathered and analyzed. All patients received a preoperative EDX evaluation and were divided into two groups based on positive or negative EDX results for comparison.

A total of 30 consecutive patients were included in this study comprising 11 (36.7%) men and 19 (63.3%) women, with a mean age of 44.6 ± 17.6 years. Twenty-two (73.3%) patients had type 1 nTOS with muscle weakness and atrophy, followed by 7 (23.4%) patients with type 3, and 1 (3.3%) patient with type 2 nTOS. In terms of nTOS pattern, 26 (86.7%) patients had lower plexus pattern of involvement (C8-T1), followed by 17 (56.7%) with upper-middle plexus pattern (C6-C7), and 13 (43.3%) with upper plexus pattern (C5-dorsal scapular nerve (DSN)). When comparing the characteristics of patients with positive and negative EDX findings suggestive of nTOS, only older age and type 1 nTOS (P < 0.05) were significantly associated with positive EDX findings.

Currently, EDX assessment may not be the best modality for diagnosis of nTOS. Interindividual variation in findings reported by different clinicians performing the EDX remains a significant limiting factor. Older patients and those with more severe nTOS (type 1) are more likely to have positive results with EDX.