Research Article| Volume 404, P115-123, September 15, 2019

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Clinical, electrodiagnostic and imaging features of true neurogenic thoracic outlet syndrome: Experience at a tertiary referral center


      • Contrary to the traditional view, TN-TOS patients often present with sensory symptoms.
      • The decrease of SNAP amplitude of MABC nerve in NCS seems the most sensitive marker.
      • MRI and CTA findings could be used as an ancillary data for the diagnosis of TN-TOS.



      True neurogenic thoracic outlet syndrome (TN-TOS) is an extremely rare neuromuscular disease. We report clinical, electrodiagnostic and radiologic features of patients with TN-TOS.


      Retrospective chart review of patients satisfying criteria was done. Nerve conduction study (NCS) and needle electromyography (EMG) of upper extremity were reviewed. Brachial plexus MRI and computed tomography angiography (CTA) were also reviewed.


      Thirteen TN-TOS patients were identified. The most common neurologic signs were hypesthesia in the medial forearm or ulnar digits and weakness of the abductor pollicis brevis (APB) muscle. In NCS, medial antebrachial cutaneous (MABC) sensory nerve action potential amplitude was decreased in all tested patients. The APB muscle was most commonly involved in EMG. Among radiologic criteria, focal stenosis of subclavian artery in CTA was the most common finding.


      We confirmed that TN-TOS is T1 predominant lower roots/trunk brachial plexopathy with clinical and electrodiagnostic features. Radiologic studies may be used to detect structural abnormalities.


      As MABC NCS showed abnormal results in all tested patients, it should be added to electrodiagnostic study as screening method. If present, structural abnormalities might be confirmed with radiologic studies.



      ADM (abductor digiti minimi), APB (abductor pollicis brevis), CMAP (compound muscle action potential), CTA (computed tomography angiography), EIP (extensor indicis proprius), EMG (electromyography), FDI (first dorsal interossei), MRI (magnetic resonance imaging), MABC (medial antebrachial cutaneous), NCS (nerve conduction study), SCA (subclavian artery), SNAP (sensory nerve action potential), STIR (short tau inversion recovery), TN-TOS (true neurogenic thoracic outlet syndrome), TOS (thoracic outlet syndrome)
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