Arm Symptoms That Start at the Collarbone: Thoracic Outlet Syndrome

Arm pain that will not localise, a hand that keeps dropping things, and every scan of the wrist coming back normal. Sometimes the pressure is much higher up.

Here is what sits in that space, how the three types separate, and what the evidence says rehabilitation actually contains.

The space itself

The thoracic outlet is a passage at the base of the neck. The StatPearls overview of thoracic outlet syndrome describes the first rib, the scalene muscles, and the clavicle as the structures that comprise it.

Picture the route. Nerves leave the spine in the neck, gather into the bundle that supplies the whole arm, and travel outward and downward. The artery bringing blood to the arm and the vein draining it run alongside. All of them pass over the first rib and under the collarbone before reaching the armpit and continuing down the limb.

That passage is narrow, and it changes shape when you move. Raising the arm, pulling the shoulders back, turning the head, or taking a deep breath all alter the dimensions of the space, because the muscles and the rib that form its walls move too. This is why symptoms in this condition so often depend on arm position rather than being constant.

How often it occurs is genuinely unclear. Estimated incidence ranges from 3 to 80 cases per 1,000 population, a spread wide enough to tell you that different studies are counting different things. A 2026 scoping review in Hand Therapy found that 56 percent of the studies it examined, 9 out of 16, quoted either the Society of Vascular Surgeons or CORE-TOS diagnostic criteria, which leaves a sizeable group using something else.

Three types, and one of them dominates

The three types are named for the structure being compressed.

The neurogenic type involves the nerve bundle. It is the most prevalent by far, accounting for over 90 percent of all cases. Symptoms described in the clinical literature are vague pain, hand weakness, and atrophy of the intrinsic muscles of the hand. That word vague is doing real work. The pain often will not localise to a single point, and people describe it differently from one visit to the next, which is one reason the condition is often identified late.

The venous type involves compression of the vein draining the arm. Symptoms are upper extremity swelling, venous distention meaning visibly enlarged surface veins, and pain running from the hand to the forearm.

The arterial type involves the artery supplying the arm. Symptoms are colour changes in the upper extremity and diminished pulses.

The last two are much less common, and they are the reason this condition needs a careful first look rather than an assumption. Swelling that arrives suddenly, a limb changing colour, or a pulse that is hard to find are findings that belong to a physician the same day.

Anatomy plays a role in some cases. In a review of 47 neurogenic thoracic outlet syndrome operations involving abnormal ribs, 85 percent involved cervical ribs. A cervical rib is an extra rib arising from the lowest vertebra of the neck. It narrows the passage. Plenty of people have one and never develop symptoms.

Why it gets confused with other problems

Symptoms in the arm can come from several places along the route, and thoracic outlet syndrome sits in the middle of that route.

Nerve compression further down the arm produces overlapping complaints. Numbness in the thumb, index, and middle fingers points toward the pattern described in our article on carpal tunnel syndrome. Numbness in the ring and little fingers points instead toward the pattern in our guide to cubital tunnel syndrome at the elbow. Neck-driven symptoms and referred pain add another layer, which is why the assessment has to look at the whole route rather than one segment of it.

Position dependence is the feature that most often raises suspicion of the outlet. Symptoms that appear with the arm overhead, while carrying a bag on that shoulder, or after a long period at a keyboard with the shoulders rolled forward point toward a space that closes in those positions.

What the physical tests do and do not tell you

Clinical references name three tests: the Adson maneuver, the Roos stress test, and the Spurling test.

The 2026 scoping review counted how often each appeared across 18 studies. The Roos test, also called the EAST test, was used in 16 of 18 studies, or 89 percent. Upper limb tension testing appeared in 14 of 18, or 77 percent. Adson's maneuver appeared in 10 of 18, or 56 percent.

Those frequencies describe what clinicians and researchers reach for, and none of these tests settles the diagnosis alone. A positive test contributes to a picture built from the symptom pattern, the position dependence, the neurological findings in the hand, and the exclusion of other causes.

The review also recorded which outcome measures were used to track progress. The QuickDASH appeared in 12 of 18 studies, or 67 percent, and the CBSQ in 8 of 18, or 44 percent. Using a measure like that matters in a condition where symptoms fluctuate, because it gives a consistent way of asking whether things are genuinely better than they were two months ago.

What rehabilitation actually contains

The scoping review mapped what physiotherapy programmes for the neurogenic type are made of, which is more useful than a general instruction to strengthen the shoulder.

Stretching appeared in 15 studies. The most common targets were the scalenes and the pectoralis muscles, named in 10 studies. Both of those muscle groups sit directly at the walls of the passage or pull the shoulder into a position that narrows it.

Strengthening appeared in 14 studies. The scapula was the most common target, in 9 studies, with the trapezius and serratus anterior named in 5. Those are the muscles that position the shoulder blade and, through it, the collarbone. Changing where the shoulder sits changes the size of the space underneath it.

Posture improvement appeared in 13 studies and diaphragmatic breathing in 6. Breathing is relevant here because the scalene muscles assist with breathing. A pattern that recruits the neck muscles heavily on every breath keeps loading the exact structures involved.

Neural mobility exercises appeared in 7 studies. These work on the ability of the nerves to glide through the tissue around them rather than on muscle strength.

The timeframe matters for expectations. Six months was the most reported timeframe suggested for therapy, appearing in 6 studies. This is a slow condition, and there is a reasonable payoff for that patience: clinical references report that patients who undergo conservative therapy have symptoms resolve in about 90 percent of cases.

Load, posture, and the daily pattern

Because the size of the space depends on position, the ordinary parts of the day matter as much as the exercises.

Long periods with the shoulders rolled forward and the head in front of the body load the front-of-chest and neck muscles that form the walls of the passage. Overhead work does the same from a different angle. A heavy bag on one shoulder pulls the collarbone down toward the first rib. Our guide to desk ergonomics for neck and back pain covers the workstation half of that assessment.

The practical version is that a good programme has two halves. One is the exercise itself, done consistently over months. The other is finding the two or three positions in a person's day that repeatedly close the space, and changing them.

When to get it looked at

Arm pain, numbness, or hand weakness that keeps returning, especially when it depends on arm position and has not been explained by an assessment at the wrist or elbow, is worth having looked at properly. Difficulty with fine tasks or any visible loss of muscle bulk in the hand should be assessed sooner rather than later.

Some findings need urgent medical attention rather than a physiotherapy booking. Sudden swelling of the arm, a change in the colour of the limb, an arm that is cold or pale, or a pulse you cannot find are signs pointing toward the venous or arterial types. Those are reasons to go to Lions Gate Hospital or call your physician immediately rather than waiting for an appointment.

If your arm symptoms have been hard to explain and nobody has looked at the base of the neck, book a 30-minute assessment and we will test the whole route from the neck to the hand. You can see what we treat or reach the clinic here.

This article is general information, not personal medical advice. A regulated practitioner can confirm whether the patterns described apply to you.

Sources

• Thoracic Outlet Syndrome, StatPearls, NCBI Bookshelf
• Physical assessment and rehabilitation for neurogenic thoracic outlet syndrome (NTOS): A scoping review (Hand Therapy, 2026)
• College of Health and Care Professionals of BC public registry

This article is for general information only and does not constitute medical advice, diagnosis, or treatment. Individual presentations vary, and assessment findings and treatment plans differ from person to person. If you are experiencing severe symptoms, neurological changes (numbness, weakness, bowel or bladder changes), or a significant trauma, contact your physician or emergency services. Care at Medstar Sport Physio & Health is provided by practitioners registered with their respective British Columbia regulatory colleges.