A young weightlifter feels a pop during an overhead press. Within hours his arm is swollen, faintly blue, and the veins across his chest look like a roadmap. He’s told it’s a “shoulder sprain.” It isn’t. It’s a vascular emergency — and it’s also a good entry point into one of the more underdiagnosed conditions in sports medicine: thoracic outlet syndrome.
What Is the Thoracic Outlet?
The thoracic outlet isn’t one space — it’s a series of three narrow passageways the nerves and blood vessels of the arm must travel through on their way out of the neck and chest toward the shoulder:
- Interscalene triangle — bordered by the anterior and middle scalene muscles; contains the brachial plexus trunks and subclavian artery
- Costoclavicular space — between the clavicle and first rib; contains the subclavian artery, subclavian vein, and brachial plexus
- Retropectoralis minor space — beneath the pec minor tendon; contains the brachial plexus trunks and axillary artery/vein
Any of these spaces can become too tight for what’s passing through them. When that happens, you get thoracic outlet syndrome (TOS): compression of nerve or vascular structures as they exit the chest toward the arm.
Who Gets It, and Why
TOS affects women roughly three times more often than men. The classic board-exam description is a woman with a long neck and “droopy” shoulders — a body habitus that narrows these spaces at baseline.
Beyond that, it shows up heavily in overhead athletes: swimmers, pitchers, rowers, weightlifters — anyone repetitively reaching overhead. Whiplash-type hyperextension neck injuries can also trigger it by causing scalene muscle hypertrophy.
Risk factors fall into two buckets:
- Bony (~30%) — cervical ribs (present in under 1% of the population), abnormal clavicle or first rib anatomy, often from prior injury
- Soft tissue (~70%) — scalene muscle hypertrophy, anomalous fibrous bands, and rarely, a Pancoast tumor
Three Flavors of TOS
Neurogenic TOS (90–95% of cases) is by far the most common. Patients describe pain across the trapezius, neck, and shoulder, along with weakness, numbness, tingling, and a sense of heaviness in the arm. In rare, longstanding cases, there can be visible atrophy of the forearm and hand muscles — a finding known as Gilliat-Sumner hand.
Venous TOS is uncommon (~1% of cases) but dramatic: episodic blue discoloration of the hand or arm, distended chest veins, and a heavy feeling in the limb. This is the form that can progress to Paget-Schroetter syndrome (more on that below).
Arterial TOS is the rarest subtype, usually associated with a bony abnormality compressing the subclavian artery directly.
The Diagnostic Challenge: No Gold Standard
TOS is genuinely hard to diagnose, and this is worth being upfront about with patients. Physical exam maneuvers that have been taught for decades — Roos/elevated arm stress test, Adson’s test, Wright’s test — all have significant limitations:
| Test | Sensitivity | Specificity |
|---|---|---|
| Roos/EAST | 84% | 30% |
| Adson’s | 79% | 76% |
| Wright’s | 70% | 29–53% |
The uncomfortable reality: several studies have found these provocative maneuvers positive in up to 90% of healthy, asymptomatic people. A “positive” Adson’s test on its own proves very little.
Imaging has to be matched to the suspected subtype:
- Chest X-ray — a reasonable first step, useful for identifying cervical ribs or other bony anomalies
- CT angiography — the test of choice for suspected arterial TOS, ideally performed dynamically (arms up and down)
- EMG — can show abnormal conduction in the medial antebrachial cutaneous nerve or median motor nerve to abductor pollicis brevis, though many consider it unhelpful except in late-stage disease as usually normal.
- Brachial plexus MRI — can identify compressive lesions
- Ultrasound (duplex) — the modality of choice for suspected venous TOS, with excellent performance characteristics (92% specificity, 95% sensitivity) for detecting subclavian vein obstruction or thrombosis. It also has the advantage of being dynamic — the sonographer can watch venous flow change in real time as the patient moves the arm into provocative positions.
Treatment: Start Conservative
Physical therapy is the first-line treatment for most patients — scapular retraction work, pec minor stretching, gentle cervical range of motion. Most guidelines recommend a dedicated 3-month trial of PT before considering more invasive options.
It’s worth being honest about the evidence here, though: of 11 studies reviewing PT for TOS, only 2 showed a significant difference in long-term outcomes compared to patients who didn’t do PT. This doesn’t mean PT is useless — it remains the reasonable starting point — but expectations should be realistic.
Where Ultrasound-Guided Injections Fit In
This is where image-guided procedures earn their place in the TOS treatment algorithm, serving a genuinely dual purpose — diagnostic and therapeutic.
Ultrasound-guided lidocaine and/or botulinum toxin injections into the pec minor and/or scalene muscles can:
- Confirm the pain generator — if a diagnostic lidocaine block into the scalenes or pec minor reproducibly relieves the patient’s symptoms, it strongly supports that muscle as the compressive culprit and helps direct further treatment (including surgical planning, if it comes to that)
- Provide therapeutic relief — botox injection into the involved muscle(s) can reduce muscle bulk and tension over the neurovascular bundle
The reported numbers for botox: 46–63% of patients experience resolution of symptoms, with another 30–42% reporting improvement. Relief typically lasts 1–6 months, and the complication profile is favorable.
That said, the evidence isn’t uniformly enthusiastic. One commonly cited review concluded: “There is no evidence for considering BTX injection as a validated tool for the management of NTOS. There might be a slight effect on symptoms, but outcomes are very variable, which prevents further interpretations.”
Practically, this means botox/lidocaine injections are a reasonable tool — particularly for diagnostic clarification and as a bridge therapy — but should be framed to patients as adjunctive rather than curative, with variable and sometimes short-lived results. Ultrasound guidance is what makes these injections both safe and accurate, allowing direct visualization of the scalene muscles and the neurovascular bundle running alongside them, minimizing risk to the brachial plexus or subclavian vessels during needle placement.
When Surgery Enters the Picture
Surgery is reserved for patients who fail conservative treatment, or who show progressive neurologic deficits or muscle atrophy. The most common procedure is first rib resection, often combined with scalenectomy and/or neurolysis.
This isn’t a trivial undertaking — major complications (brachial plexus injury, subclavian vessel injury, pneumothorax) occur in 5–40% of cases depending on the series. That said, outcomes data is reasonably encouraging: one study found 54% of patients had complete symptom resolution and 90% had at least some improvement.
Less invasive options are also emerging — arthroscopic pec minor release has been described as safe and effective, though patient selection is critical; this approach only works if the compression is isolated to the retropectoralis space.
The Case That Started This: Paget-Schroetter Syndrome
Returning to our weightlifter: his ultrasound showed an occlusive thrombus extending through his subclavian, axillary, and brachial veins. This is Paget-Schroetter syndrome — “effort-induced” thrombosis of the subclavian/axillary vein, classically triggered by repetitive overhead activity in athletes and weightlifters.
The classic presentation: swelling, cyanotic discoloration, and distended collateral veins across the chest and shoulder (Urschel’s sign) — exactly what was seen on exam before the ultrasound confirmed the diagnosis.
Management follows a defined pathway:
- Anticoagulation plus a thrombophilia workup (our patient was found to have Prothrombin G20210A heterozygosity, nearly tripling his baseline clot risk)
- Thrombectomy, if caught early in the clinical course
- Definitive surgical decompression of the thoracic outlet — because simply treating the clot without addressing the underlying anatomic compression invites recurrence
Our patient underwent successful thrombectomy, was bridged to oral anticoagulation, and had surgical decompression a month later.
Bottom Line
Thoracic outlet syndrome deserves a place on the differential for any athlete — especially overhead athletes — presenting with arm pain, heaviness, swelling, or neurologic symptoms that don’t fit a cleaner diagnosis. Physical exam and imaging both have real limitations, so diagnosis often requires piecing together history, exam, targeted imaging based on suspected subtype, and sometimes a diagnostic injection. Ultrasound plays a role throughout — both in detecting venous thrombosis and in safely guiding diagnostic/therapeutic injections into the scalenes and pec minor. Most patients improve with conservative management, but it’s important to recognize red flags — particularly venous symptoms — that warrant urgent evaluation rather than a course of physical therapy.
This page is educational and general in nature and does not replace an individualized evaluation — see our medical disclaimer.