You have done everything right. You wore a wrist brace. You stretched. Maybe you even had a nerve conduction study that said "mild carpal tunnel." But the tingling in your arm is still there, it travels in a pattern that does not quite match carpal tunnel, and the brace made zero difference.
One of the most underdiagnosed explanations for this pattern is thoracic outlet syndrome (TOS). It is a compression of the nerves and, in some forms, the blood vessels that pass through a narrow corridor just below the collarbone on their way from the neck into the arm. The anatomy is tight. The symptoms are easy to misread. And the treatment is completely different from what works for carpal tunnel.
Here is what TOS actually is, how it produces the symptoms it does, and how Dr. Banman evaluates it at our Lakewood Ranch clinic.
What Is the Thoracic Outlet?
The thoracic outlet is not a single structure. It is a space, or more precisely a series of overlapping spaces, through which the brachial plexus (the bundle of nerves supplying the arm and hand), the subclavian artery, and the subclavian vein all pass on their way from the neck and chest into the shoulder and arm.
Three zones within this pathway are the most common compression sites:
- The scalene triangle: The space between the anterior and middle scalene muscles of the neck, through which the brachial plexus and subclavian artery pass. Forward head posture and tight scalene muscles from desk work are the most common culprit here.
- The costoclavicular space: The gap between the first rib and the clavicle (collarbone). Repetitive overhead activity, carrying heavy bags on one shoulder, or a history of clavicle fracture can narrow this space.
- The subcoracoid space: The region under the coracoid process of the shoulder blade. This area is compressed by certain arm positions and is common in overhead athletes.
When any of these spaces narrows, it squeezes the structures passing through it. The symptoms that follow depend on what gets compressed: nerves, the artery, the vein, or a combination.
Three Types of TOS and What Makes Each Different
Clinicians organize TOS into three subtypes based on which structure is compressed. Knowing which type a patient has changes everything about how you approach treatment.
Neurogenic TOS (by far the most common)
Neurogenic TOS involves compression of the brachial plexus. It accounts for somewhere between 90% and 97% of all TOS cases, depending on which literature you reference. It is also the most frequently missed because nerve symptoms are diffuse, the nerve conduction studies used to diagnose carpal tunnel are often normal in neurogenic TOS, and the symptoms can look like a dozen other things.
Typical presentation: aching pain in the shoulder, arm, or neck; tingling or numbness that runs down the arm into the ring and little fingers (the ulnar distribution); hand weakness that makes grip tasks difficult; symptoms that worsen with overhead arm positions or prolonged forward head posture.
Venous TOS
Venous TOS involves compression of the subclavian vein, the vessel that drains blood from the arm back to the heart. It accounts for about 3 to 5% of cases. When the vein is compressed, blood backs up and the arm may become swollen, heavy, and discolored with a bluish or reddish tint. The condition is sometimes called "effort thrombosis" because it is often triggered by sudden, intense overhead activity in an otherwise healthy young person.
Venous TOS is a medical urgency. If the swelling is acute, rapid, and accompanied by visible discoloration, the patient needs vascular evaluation the same day, not chiropractic care first.
Arterial TOS
The rarest form, arterial TOS involves compression of the subclavian artery. It produces symptoms of reduced blood flow: the arm turns white or pale with activity, the hand feels cold, and there may be cramping pain in the forearm during exertion. Arterial TOS is almost always associated with an anatomical anomaly like a cervical rib (an extra rib that develops from the C7 vertebra), and it typically requires surgical evaluation. It is the least common presentation but the one with the most serious potential consequences if missed.
The vast majority of patients who ask about TOS at our clinic have the neurogenic variety. The neurological symptoms are real and often quite disabling, but they respond well to conservative care when the compression is accurately identified and addressed at the right level.
What TOS Feels Like: The Symptom Pattern
Neurogenic TOS produces a constellation of symptoms that is distinctive once you know what you are looking for. The challenge is that no single symptom is unique to TOS, which is one reason the condition is so often delayed in diagnosis.
The most common complaints we hear:
- Aching, dull pain in the neck, shoulder, and upper arm that worsens by end of day
- Tingling or numbness running down the arm into the ring finger and pinky (ulnar nerve distribution, the same pattern as cubital tunnel syndrome)
- Heaviness or fatigue in the arm with overhead activity: blow-drying hair, painting a ceiling, reaching into overhead cabinets
- Hand weakness, especially with fine motor tasks like buttoning a shirt or holding a pen
- Symptoms that are worse when carrying a bag on the affected shoulder or sleeping on that side
- Temporary relief when raising the arm above the head (which opens the costoclavicular space) but worsening with arm held out to the side or behind the back
- Neck pain and stiffness, often accompanied by headaches at the base of the skull
One clinical clue: TOS symptoms typically worsen when the arm is in certain positions and improve in others. Carpal tunnel symptoms are more consistent across arm positions; they tend to worsen at night and improve with wrist movement. If your tingling gets worse the longer you hold your arm overhead at a specific angle and then clears quickly when you drop the arm, that pattern suggests the thoracic outlet rather than the wrist.
Why TOS Gets Mistaken for Carpal Tunnel (and Why It Matters)
Carpal tunnel syndrome and neurogenic TOS share significant symptom overlap: both cause hand tingling, both can wake you up at night, and both affect a working-age population sitting at desks for most of the day. The mistake happens because:
- Standard nerve conduction studies often look normal in TOS. NCS measures conduction velocity across the wrist. If the compression is at the thoracic outlet, the wrist measurements may appear normal, leading to a false-negative result and a carpal tunnel diagnosis by exclusion.
- Mild carpal tunnel can coexist with TOS. This is sometimes called "double crush" syndrome: the median nerve is already mildly compressed at the wrist, so any additional compression upstream at the thoracic outlet makes symptoms dramatically worse. Treating only the wrist gives partial, unsatisfying relief.
- The ulnar distribution is often misread. When tingling travels into the ring and little fingers, many clinicians correctly identify ulnar nerve involvement, then look to the elbow (cubital tunnel syndrome) rather than the thoracic outlet. All three possible culprits (the elbow, the thoracic outlet, and the cervical spine) are worth evaluating when the ulnar distribution is the presenting pattern.
Why the distinction matters: carpal tunnel treatment (splints, steroid injections, sometimes surgery at the wrist) does not address TOS. Decompressing the carpal tunnel when the actual compression is at the thoracic outlet typically produces minimal benefit. Worse, if the diagnosis is wrong and surgery is performed, the patient is left with a surgical scar and unchanged or worsening symptoms.
A careful physical examination that includes provocative TOS tests can identify the correct compression site without surgery and without waiting for failed wrist treatment to reveal the error. For more on how cervical spine issues produce similar hand symptoms, see our post on carpal tunnel versus cervical spine as the source of hand numbness.
How Dr. Banman Evaluates Thoracic Outlet Syndrome
The evaluation for TOS is largely clinical. There is no single imaging study that diagnoses neurogenic TOS in a straightforward way. MRI of the brachial plexus and dynamic ultrasound are sometimes used, but the physical examination remains the foundation for the initial working diagnosis.
The key provocative tests used in our evaluation:
The Roos Test (Elevated Arm Stress Test)
The patient raises both arms to 90 degrees, elbows bent, as if holding a goalpost. They then slowly open and close their fists for three minutes. A positive test is when the symptomatic arm develops fatigue, heaviness, tingling, or weakness significantly faster than the opposite arm, and the patient cannot complete the full three minutes without dropping that arm. Most healthy individuals can complete the full test with minimal discomfort.
Adson's Test
The patient turns their head toward the affected side and takes a deep breath. Dr. Banman monitors the radial pulse at the wrist. A significant reduction or loss of the pulse with this maneuver suggests compression of the subclavian artery in the scalene triangle, indicating possible vascular TOS involvement. A positive Adson's test is supportive evidence, not diagnostic on its own.
Wright's Test (Hyperabduction Maneuver)
The arm is brought up and back (into hyperabduction). A positive result is reproduction of the patient's symptoms combined with a change in radial pulse. This test stresses the subcoracoid space particularly.
Cervical and Shoulder Examination
Because TOS symptoms overlap with cervical disc radiculopathy and shoulder impingement, we always examine the cervical spine range of motion, perform Spurling's compression test (for cervical nerve root involvement), assess first rib position and mobility, evaluate scalene muscle tension, and check shoulder girdle strength. The pattern of which tests are positive and which are negative together point to the actual compression level.
For context on how cervical disc problems produce a pattern similar to TOS, see our detailed breakdown of pinched nerve in the neck versus the shoulder.
Conservative Care for Neurogenic TOS
The good news about neurogenic TOS is that the majority of patients respond well to conservative care when the treatment is focused on the actual compression site. The goal is to restore space in the thoracic outlet: reduce scalene tension, mobilize a hypomobile first rib, correct forward head posture, and strengthen the muscles that support the shoulder girdle and keep the clavicle elevated off the first rib.
The approach at our clinic typically involves several components:
First Rib Mobilization
A first rib that has shifted superiorly (upward and forward) is one of the most common structural contributors to costoclavicular TOS. Chiropractic mobilization of the first rib involves a specific technique that restores normal rib position and increases the costoclavicular space. Many patients report noticeable symptom change within the first few sessions when first rib restriction is the primary driver.
Scalene Release
The anterior and middle scalene muscles form the walls of the scalene triangle. When these muscles are chronically tight from forward head posture or repetitive stress, they narrow the triangle and compress the brachial plexus. We address this through directed soft-tissue work and guided stretching, combined with cervical manipulation where indicated to restore normal joint mobility in the lower cervical segments (particularly C5-C7, which contribute to scalene muscle tension).
Postural Correction
Forward head posture is the single most common mechanical driver of TOS in our patient population. Every inch the head moves forward from the neutral position adds load to the scalenes and shortens the available space in the scalene triangle. Correcting the pattern requires: cervical spine mobilization to restore joint mobility, strengthening of the deep neck flexors and lower trapezius (both of which are typically inhibited in forward head posture), and patient awareness about workstation setup.
You can read more about how forward head posture develops and what it does structurally in our post on tech neck and the cervical spine.
Therapeutic Modalities
Depending on the level of inflammation and nerve irritation, we may use Class IV laser therapy to reduce soft tissue inflammation along the brachial plexus pathway, or EMS to address inhibited muscle function in the shoulder girdle. These are adjuncts to the structural correction, not replacements for it.
Activity Modification During Recovery
Certain activities reliably aggravate TOS and slow recovery: carrying heavy bags on the affected shoulder, sleeping on that side with the arm under the head, and repetitive overhead work. We work with patients to identify the specific postures and activities that are loading the thoracic outlet during their daily routine, and we make specific modifications accordingly.
Who Gets TOS and Why
Certain groups are at significantly higher risk for TOS, and understanding this helps explain why a specific patient developed it.
- Desk workers with forward head posture: The most common pattern we see in Lakewood Ranch. Hours of screen time tightens the scalenes, inhibits the lower traps, and narrows the scalene triangle gradually. TOS in this population tends to develop slowly over months or years before it reaches the threshold of obvious symptoms.
- Overhead athletes: Swimmers, baseball pitchers, volleyball players, and tennis players repeatedly stress the thoracic outlet during arm extension and overhead movement. In young athletes, venous TOS (effort thrombosis) is more common in this group than in the general population.
- People with cervical ribs: Approximately 0.5 to 1% of the population has an extra rib that develops from the seventh cervical vertebra. A cervical rib is strongly associated with arterial TOS and is often discovered incidentally on X-ray when TOS is being evaluated.
- People with a history of clavicle fracture: Callus formation at the fracture site can permanently narrow the costoclavicular space.
- Those with drooping shoulders: Some individuals have a naturally low shoulder girdle that chronically narrows the costoclavicular space, particularly with the weight of a bag or heavy arm pulling the shoulder further down.
Red Flags That Warrant Urgent Evaluation
Neurogenic TOS is almost always a condition for conservative management. But there are warning signs that should move a patient toward vascular surgery consultation rather than chiropractic care:
- Acute arm swelling with rapid onset, especially after overhead exertion (possible venous thrombosis)
- Arm or hand that turns pale or white with activity, or feels cold relative to the other hand (possible arterial compression)
- Visible skin color change: bluish, reddish, or mottled pattern in the hand or forearm
- Sudden severe pain in the shoulder and upper arm without a trauma history
- Progressive hand muscle wasting (atrophy) that is worsening over weeks
These presentations require imaging and vascular evaluation. We will not provide conservative chiropractic care for these patterns without ruling out a vascular emergency first.
What to Do If You Think You Have TOS
If you have been dealing with arm tingling, hand numbness, or shoulder pain that has not responded to wrist-focused treatment, TOS is worth exploring as an explanation. A few practical steps:
- Note which fingers are affected. Tingling in the thumb, index, and middle finger points more toward the median nerve (carpal tunnel, C6). Tingling in the ring and little finger points toward the ulnar nerve (cubital tunnel, C8/T1, or TOS). Tingling in the entire hand, or the whole arm, points toward the brachial plexus level, which includes TOS and cervical disc pathology.
- Notice the position dependency. Do symptoms worsen with arm overhead? With carrying a bag? With head turned a certain direction? Position-sensitive nerve symptoms suggest a mechanical compression site that physical examination can often locate.
- Get a cervical spine evaluation alongside the wrist evaluation. Many patients presenting with hand numbness have compression at two levels simultaneously. Addressing only one rarely resolves both.
- Seek a provider familiar with TOS provocative testing. This is the key step. Adson's, Roos, and Wright's tests take about 10 minutes total and give a clear clinical picture in most cases. If your provider has not performed these, TOS has not been properly assessed.
At Spine and Wellness Center Lakewood Ranch, we evaluate TOS as part of our comprehensive neuropathy program, and we see it more often than many clinicians recognize because we actively look for it when the symptom pattern does not fit the more common diagnoses. For related neuropathy conditions affecting the hands and arms, see our full guide to peripheral neuropathy: causes, symptoms, and treatment.
