Neurogenic Thoracic Outlet Syndrome (NTOS): Symptoms, Diagnosis & Treatment

Neurogenic TOS (NTOS) = compression/irritation of the brachial plexus (C5-T1) in the thoracic outlet (between clavicle, 1st rib, scalene muscles). Accounts for 95% of TOS cases.

Symptoms

• Pain: Neck, supraclavicular, shoulder, arm, ulnar forearm/hand
• Paresthesia: Ulnar distribution (C8-T1) – 4th/5th digits, medial forearm
• Weakness: Hand intrinsic muscles, grip strength
• Fatigue/heaviness with arm elevation/use
• Symptoms worsen: Overhead activity, carrying, prolonged sitting, night

Common Causes

• Cervical rib / elongated C7 transverse process (congenital)
• Scalene muscle hypertrophy/spasm (repetitive overhead, posture)
• Trauma (whiplash, clavicle fracture)
• Poor posture (forward head, rounded shoulders)
• Obesity, heavy breast tissue

Diagnosis

• Clinical: Provocative tests (Adson's, Roos/EAST, Wright's, ULTT)
• Imaging: X-ray (cervical rib), MRI (plexus anatomy, variant muscles), CT angiography (vascular)
• Electrodiagnostics: NCS/EMG – often normal; mainly excludes radiculopathy/neuropathy.
• Diagnostic block: Scalene/infraclavicular block – gold standard for surgical candidacy.

Treatment

Conservative (First-Line, 6-12 months)

• Physical therapy: Scalene stretching, postural re-education, nerve glides, scapular stabilization
• Activity modification, ergonomics
• NSAIDs, neuropathic agents (gabapentin)
• Weight loss if indicated

Surgical (Refractory Cases)

• Transaxillary or supraclavicular 1st rib resection + scalenectomy ± neurolysis
• Success rates 70-90% with proper selection (positive block response).