Acupuncture for Thoracic Outlet Syndrome: A Comprehensive Guide

Thoracic Outlet Syndrome is a series of syndromes resulting from compression of the brachial plexus and subclavian artery at the thoracic outlet due to certain causes.

The boundaries of the thoracic outlet are formed anteriorly by the medial third of the clavicle and the lower portion of the clavicle, posteromedially by the anterior third of the first rib and the attachment points of the anterior and middle scalene muscles, and posterolaterally by the superior border of the scapula. Cervical ribs, the anterior scalene muscle, a normal or congenitally malformed first rib, and prolonged heavy pressure on the ribs can all affect the thoracic outlet, compressing the brachial plexus and subclavian artery, leading to this condition. Cases caused by the anterior scalene muscle are termed Anterior Scalene Syndrome; those caused by the ribs and clavicle are termed Costoclavicular Syndrome; and those caused by cervical ribs are termed Cervical Rib Syndrome.

**Key Diagnostic Points**

This condition commonly occurs in female patients aged 30–50 years, with a gradual onset and variable severity. Pain is typically the initial symptom. In mild cases, there is periodic scapular pain radiating downward to the medial aspect of the arm; in severe cases, the pain may be sharp, drilling, or burning in nature. During episodes, pain is located posterior to the scapula and then radiates to the lateral neck, followed by the medial arm, forearm, and palm. Pain is aggravated by lying flat, shoulder and arm drooping, lifting objects, carrying objects on the back, holding objects, or turning the head to the unaffected side. Some patients develop weakness in the hand muscles, including weakness in finger adduction, abduction, and flexion. Severe cases may present with wrist drop, along with numbness, tingling, or other abnormal sensations on the ulnar side of the hand and forearm. Compression of the brachial plexus can lead to varying degrees of sensory impairment in the corresponding areas. In later stages, atrophy of the ulnar muscles and interosseous muscles may occur. The biceps reflex, triceps reflex, and radial reflex may be diminished or absent. The skin of the hand may become cold with reduced skin temperature, paroxysmal pallor and cyanosis, and occasionally hand edema. The radial pulse may be weak or absent. The brachial artery systolic blood pressure may be 2–2.6 kPa (15–20 mmHg) lower than normal. Some patients may present with Horner’s syndrome.

In some patients, the symptoms occur almost entirely at night, starting shortly after lying flat. This is known as “Static Paresthetic Arm Pain” (*Jingzhixing Ganjue Yichangxing Bitong*) and is commonly seen in middle-aged women.

During a physical examination, the following tests may be used to differentiate among cervical rib syndrome, anterior scalene syndrome, and costoclavicular syndrome. Method: The patient sits upright, takes a deep breath, hyperextends the head, and then turns the head as far as possible to the left and right. If the radial pulse on the affected side disappears or is markedly diminished during this process, and a murmur is heard in the right supraclavicular fossa at the same time, this suggests cervical rib syndrome. If the radial pulse disappears when the affected limb is raised vertically overhead and the head is turned as far as possible toward the affected side, this suggests anterior scalene syndrome. For costoclavicular syndrome, because the shoulder is often injured by prolonged downward pressure from load-bearing, pulling downward firmly on the drooping shoulder can aggravate symptoms. Combined with a history of heavy load-bearing, and if firm pressure on the anterior scalene muscle does not worsen symptoms, costoclavicular syndrome may be considered.

X-ray: reveals a cervical rib or an elongated transverse process.

Subclavian artery angiography: stenosis of the subclavian artery near the thoracic outlet, with collateral circulation forming around it, and distal vascular dilation.

【Treatment】

I. Acupoints and Acupuncture Techniques

1. **LU2 (Yunmen)** (affected side): Located on the anterior-lateral aspect of the clavicle, 6 *cun* lateral to the midsternal line, in the depression medial to the coracoid process of the scapula. Use a 30-gauge, 2-*cun* filiform needle. Perform routine local disinfection. Insert perpendicularly about 1.8 *cun* toward the posterior shoulder. Needling sensation: local distension and pain.

2. **SI9 (Jianzhen)** (affected side): Located 1 cun directly above the posterior axillary crease, directly below SI10 (Naoshu). Using a 30-gauge, 2-cun filiform needle, after routine local disinfection, insert obliquely into the shoulder joint to a depth of approximately 1.8 cun. Needling sensation: local distension and pain.

3. LI15 (Jianyu) on the affected side: located at the midpoint of the deltoid muscle, in the depression anterior to the acromion when the arm is abducted to a horizontal level, between the acromial end of the clavicle, the acromial end of the scapular spine, and the greater tubercle of the humerus; use a No. 30 filiform needle, 2 cun in length, routine local disinfection, and insert obliquely downward approximately 1.8 cun. Needling sensation: local distension and soreness, or radiation to the elbow.

4. **Jugu point (LI16) (affected side):** Located on the shoulder, in the depression between the acromial end of the clavicle and the acromion of the scapula. Use a 30-gauge, 2-cun filiform needle. Perform routine local disinfection. Insert approximately 1.8 cun obliquely toward the shoulder joint. Needle sensation: local distension and pain.

5. LI11 (Quchi, affected side): Located in the depression at the midpoint of the line connecting the radial end of the elbow crease and the lateral epicondyle of the humerus. Use a 30-gauge, 2-cun filiform needle. Perform routine local disinfection. Insert perpendicularly toward Shaohai (HT3) to a depth of approximately 1.8 cun. Needling sensation: local distension and pain.

II. Methods

The patient is seated. The above points are inserted as per technique. Retain needles for 40 minutes before withdrawal, with one intermediate needle-twirling session. Upon withdrawal, apply cupping for about 1 minute. Treatment is administered once daily; 6 sessions constitute one course, followed by a 3-day rest before resuming needling.

【Commentary】

Acupuncture for pain relief in Thoracic Outlet Syndrome has shown good results, typically alleviating or resolving nocturnal pain within 3–5 sessions. However, for patients with more severe compression, surgical intervention such as resection of the cervical rib or anterior scalene muscle may be necessary. For residual sequelae following surgery, acupuncture treatment also yields quite satisfactory outcomes. In cases of muscle atrophy that develop over a long period and persist after surgery, using the aforementioned method of acupuncture combined with electrical stimulation can also achieve relatively satisfactory results.

Anatomical Basis and Pathophysiology

Thoracic outlet syndrome (TOS) encompasses a group of disorders arising from compression of neurovascular structures traversing the thoracic outlet. The boundaries of this confined space are formed anteriorly by the medial third of the clavicle, posteromedially by the anterior third of the first rib along with the attachment points of the anterior and middle scalene muscles, and posterolaterally by the superior border of the scapula. A cervical rib or fibrous bands can further narrow this passage, predisposing individuals to symptomatic impingement. The most critical pathological process is brachial plexus compression thoracic outlet, which can lead to a spectrum of neurogenic and vascular manifestations. Understanding this anatomy is essential for correlating thoracic outlet syndrome symptoms with specific compression sites. The brachial plexus roots (C5–T1) are particularly vulnerable as they pass between the anterior and middle scalene muscles, and any hypertrophy, trauma, or anomalous band can trigger irritation. Subclavian artery involvement, though less common, may produce vascular signs such as Raynaud phenomenon or distal emboli. Recognizing the interplay between structural constraints and dynamic postural factors is the first step toward accurate clinical assessment.

Clinical Presentation and Shoulder Pain

Patients with TOS frequently present with thoracic outlet syndrome shoulder pain, which may radiate down the arm or into the neck. This pain is often exacerbated by overhead activities, prolonged arm elevation, or carrying heavy loads. In neurogenic TOS, the most common subtype, symptoms additionally include paresthesias, numbness, and weakness in the ulnar nerve distribution, reflecting compression of the lower trunk of the brachial plexus. The variability of thoracic outlet syndrome symptoms can lead to diagnostic confusion with cervical radiculopathy, rotator cuff tendinopathy, or peripheral nerve entrapment such as cubital tunnel syndrome. A thorough history and systematic physical examination, including provocative maneuvers (e.g., Adson’s test, Roos test, and the upper limb tension test), are critical for raising clinical suspicion. Shoulder pain in TOS may be accompanied by a dull ache over the supraclavicular fossa or referred pain along the medial arm and forearm. Because the presentation overlaps with many musculoskeletal disorders, clinicians must maintain a high index of suspicion, especially in younger, active patients with repetitive overhead activities or a history of cervical rib.