Neurogenic thoracic outlet syndrome (nTOS) is a condition where nerves in the brachial plexus, the bundle of nerves running from your neck to your arm, become compressed as they pass through the narrow space between your collarbone and first rib. It accounts for 95% to 99% of all thoracic outlet syndrome cases, making it far more common than the vascular forms that affect blood vessels in the same area. The compression typically involves the lower portion of the brachial plexus, which controls sensation and movement in your forearm, hand, and fingers.
Where the Compression Happens
The brachial plexus exits the chest through a tight corridor called the thoracic outlet. This region has very little room to spare. The nerves pass between the scalene muscles on the side of your neck, then travel beneath the collarbone and over the first rib before reaching the arm. Any narrowing in this corridor, whether from an extra rib, tight muscles, or scar tissue, can put pressure on these nerves.
The nerves most often affected are the lower trunk and the fibers coming from the lowest two nerve roots (C8 and T1). These fibers supply sensation to the inner forearm and hand, and they control many of the small muscles that let you grip and manipulate objects. That’s why symptoms tend to show up in the hand and inner arm rather than the shoulder or outer arm.
Causes and Risk Factors
Some people are born with anatomical features that make the thoracic outlet narrower than usual. The most well-studied is a cervical rib, a small extra rib that grows from the lowest neck vertebra. Cervical ribs appear in only about 1% of the general population but are found in roughly 30% of people diagnosed with thoracic outlet syndrome. About half of those symptomatic patients with a cervical rib have the neurogenic form. Fibrous bands, which are tough strips of tissue in the same area, can also compress the nerves without being visible on standard X-rays.
Beyond anatomy, repetitive overhead arm movements, poor posture, and trauma such as whiplash injuries or falls can contribute to nTOS. Jobs or sports that require holding the arms above shoulder height for extended periods are common triggers. The muscles in the neck and chest can tighten or enlarge over time, gradually squeezing the nerves.
What Symptoms Feel Like
The hallmark symptoms are pain and weakness in the shoulder and arm, tingling or numbness in the fingers (particularly the ring and little fingers), and an arm that fatigues quickly during overhead activities. You might notice that holding a phone, styling your hair, or reaching up to a shelf becomes uncomfortable or tiring much faster than it should.
In advanced cases, the pad of muscle at the base of your thumb can visibly shrink, a pattern sometimes called the Gilliatt-Sumner hand. This is rare and represents long-standing nerve damage. More commonly, people experience intermittent numbness, aching along the inner forearm, or a vague heaviness in the entire arm that worsens with certain positions.
Because the symptoms overlap heavily with other conditions, nTOS is frequently mistaken for carpal tunnel syndrome or a pinched nerve in the elbow. Carpal tunnel can even mimic nTOS when it causes shoulder pain, though the two conditions occurring together in the same patient is extremely rare. The key difference is location: carpal tunnel affects the thumb, index, and middle fingers through compression at the wrist, while nTOS affects the ring and little fingers through compression near the collarbone.
Why Diagnosis Is Difficult
There is no single test that reliably confirms nTOS, which is a major source of frustration for patients who sometimes see multiple specialists before getting an answer. Physical exam maneuvers like the Halstead maneuver (pressing the pulse point while adjusting arm position) and Wright’s test (checking for symptom changes with the arm overhead) have moderate accuracy for detecting upper extremity nerve problems in general, but they don’t reliably distinguish nTOS from other conditions. Notably, two of the older and more commonly used tests, the Adson’s test and the Roos test, have been found to have poor diagnostic accuracy and some researchers have recommended discontinuing their use for this purpose.
Nerve conduction studies and electromyography (EMG) can sometimes detect the damage, but they often come back normal in milder cases. When they do show abnormalities, the pattern is distinctive: nerve fibers from the T1 root are affected more than those from C8. A study of confirmed nTOS patients found that testing a specific combination of the inner forearm sensory nerve and the median motor nerve picked up abnormalities in 89% of cases. Comparing readings to the opposite, unaffected arm is essential for catching subtle differences.
Because no single test is definitive, diagnosis typically relies on a combination of your symptom history, physical exam findings, imaging to look for structural causes like a cervical rib, and nerve testing. This process can take weeks or months.
Physical Therapy and Conservative Treatment
Physical therapy is the first-line treatment for nTOS and centers on two goals: opening up the thoracic outlet by improving posture and stretching tight muscles, and strengthening the muscles that hold the shoulder blade in a healthier position. A typical program targets the scalene muscles on the sides of the neck, the pectoralis muscles across the chest, the upper trapezius, and the levator scapulae (the muscle running from your neck to the top of your shoulder blade). These muscles, when tight, can pull the thoracic outlet closed.
On the strengthening side, the focus shifts to the middle and lower trapezius, the serratus anterior (the muscle along your ribcage that stabilizes your shoulder blade), and the rhomboids between your shoulder blades. Exercises like scapular retraction, chin tucks, prone shoulder extension, and serratus push-ups are common components. Nerve gliding exercises, which gently mobilize the brachial plexus through its range of motion, are also frequently included. Most programs incorporate diaphragmatic breathing to help relax the scalene muscles, which double as accessory breathing muscles.
Rehabilitation protocols vary, but sessions are typically performed daily, with a combination of 30-second stretches and low-repetition strengthening exercises using light resistance or body weight. Consistency matters more than intensity, and most programs run for at least several weeks before results are reassessed.
Botulinum Toxin Injections
For patients who don’t respond well enough to physical therapy alone, injections of botulinum toxin into the scalene muscles are sometimes used. The idea is to temporarily relax the muscles that are compressing the nerve. Typical doses range from 12 to 20 units per muscle, with injections sometimes also targeting the pectoralis minor. Across multiple studies, 46% to 63% of patients reported symptom reduction after their first injection, with pain scores improving by 30% to 42%. Relief generally lasts one to six months. The evidence for this approach remains limited in quality, and results vary significantly from person to person.
When Surgery Is Considered
Surgery becomes an option when conservative treatment fails to provide adequate relief. The most common procedure is first rib resection, where the first rib is removed through an incision under the arm to widen the thoracic outlet. In a study of 62 procedures, this approach was used in 51 cases. When a cervical rib is present, it may be removed through an incision above the collarbone instead.
Outcomes after surgery are generally positive but not universal. About 54% of patients in one long-term study reported complete symptom relief, and 90% experienced at least some improvement. For neurogenic cases specifically, overall clinical success (defined as at least 60% symptom reduction) fell between 60% and 80% of patients.
Recovery and Return to Activity
Recovery after surgery varies depending on the type of procedure and the physical demands of your daily life. In a study of healthcare workers who underwent surgery for TOS, about 68% to 71% returned to work, with a median follow-up of nearly two years. The return rate depended heavily on the physical demands of the job: 93% of physicians returned to work, compared to 61% of nurses and 43% of allied health workers whose roles involved more repetitive physical tasks. Whether the injury was work-related did not significantly affect recovery outcomes.
For those managed conservatively, improvement is more gradual. Physical therapy typically requires several months of consistent effort, and some people continue a maintenance exercise routine long-term to prevent symptoms from returning. The muscles and posture that contributed to the compression in the first place don’t change overnight, so patience with rehabilitation is critical.