Neurogenic Thoracic Outlet Syndrome (nTOS)

When nerves between the neck and shoulder come under pressure

Tingling in the fingers, pain in the neck, or a sense of weakness in the arm – such symptoms can have many causes. One possible explanation is neurogenic thoracic outlet syndrome (nTOS). In this condition, certain nerves in the area between the neck, collarbone, and upper chest become compressed. The result: sometimes burdensome and difficult-to-interpret symptoms.

Depiction of the brachial plexus on the left side. Central view of the collarbone. — The brachial plexus is formed by nerve roots from the lower cervical and upper thoracic spine. In this illustration, it is shown after passing through the scalene muscles, running beneath the clavicle toward the axilla. The image shows the left side of the body, viewed from a slightly elevated angle centered on the clavicle. The nerve structures are highlighted in yellow.

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What is neurogenic thoracic outlet syndrome?

The thoracic outlet is an anatomical narrow space located between the cervical spine, the first rib, and the clavicle. Important nerves, blood vessels, and muscles pass through this area. If this space becomes narrowed, the condition is referred to as thoracic outlet syndrome (TOS).

Schematic illustration of the brachial plexus with compression between the rib cage and clavicle in neurogenic thoracic outlet syndrome (nTOS). — Schematic illustration of the brachial plexus: The yellow nerve fibers pass through a narrow anatomical space between a lower circle (representing the rib cage) and an upper circle (representing the clavicle). The central constriction symbolizes the typical nerve compression seen in neurogenic thoracic outlet syndrome (nTOS), occurring at the transition from the neck to the shoulder.

In neurogenic TOS, the compression mainly affects the nerves of the brachial plexus – a nerve network that controls movement and sensation in the arm. This is the most common form of TOS, but it is often difficult to diagnose.

Possible causes

Neurogenic TOS can have various underlying factors, such as:

Anatomical variations (e.g., cervical ribs or hypertrophic muscles)
Injuries or scar tissue following trauma or surgery
Postural strain, particularly from prolonged computer use
Sports involving overhead activity, such as swimming, climbing, or volleyball
Muscular imbalances or skeletal misalignments that further narrow the thoracic outlet

The condition often develops gradually as a combination of individual predisposition and repeated mechanical stress.

Typical symptoms of nTOS

Symptoms can vary significantly and are often inconsistent:

Tingling or numbness in the hand, fingers, or forearm
Pain in the neck, shoulder, or along the arm
Weakness when gripping or lifting (e.g., carrying shopping bags)
Worsening symptoms during certain movements (e.g., raising the arm to dry hair or open a window)
Nonspecific sensations that are difficult to localize

Because these signs can also occur in other conditions, nTOS is often diagnosed late.

How is nTOS diagnosed?

Diagnosis of neurogenic thoracic outlet syndrome can be challenging. The symptoms are often non-specific and may resemble other disorders. Routine diagnostic tests frequently do not provide clear findings.

The role of high-resolution nerve ultrasound

A modern, non-invasive approach is high-frequency nerve ultrasound. This imaging technique uses a specialized probe to examine the relevant area – it is painless and does not involve radiation.

Abstract heatmap illustration shows a nerve constriction during dynamic nerve ultrasound. — Movement made visible: Color gradients highlight a nerve constriction.

Advantages of nerve ultrasound in nTOS:

Direct visualization of the brachial plexus in the supraclavicular and infraclavicular regions, starting at the neuroforamen
Dynamic examination: nerves can be assessed in different arm and head positions, including signs of compression or restricted mobility
Identification of surrounding structures, such as thickened muscles, bony anomalies (e.g., cervical ribs), or scar tissue that may displace the nerve
Distinction from other conditions, such as entrapment syndromes or peripheral nerve injuries
Monitoring over the course of treatment

Nerve ultrasound can be a valuable tool in clarifying unclear symptoms in the shoulder and arm region.

Other diagnostic methods

Depending on the individual case, additional tests may include:

X-rays or CT scans: to detect cervical ribs or bone changes after injury
MRI of the cervical spine and possibly MR neurography: to evaluate alternative diagnoses
Electrophysiological testing (e.g., electromyography or nerve conduction studies)
Clinical provocation tests, such as the Adson or Roos test or Hoffmann-Tinel Sign

A combination of these findings, especially when dynamic nerve imaging is possible, can help assess the presence of nTOS.

Treatment options – tailored to the individual

The appropriate treatment depends on the underlying cause, severity, and impact on daily life.

Conservative management:

Physiotherapy to improve posture and strengthen muscles
Manual therapy to reduce muscular tension
Education on ergonomic movement patterns
Ultrasound-guided injections, e.g., local anesthetics or botulinum toxin to relax overactive muscles

Surgical treatment:

In selected cases, surgery may be considered. This decision should be based on thorough evaluation in a specialized center.

Why early evaluation is important

Without treatment, prolonged compression of the nerves can lead to persistent irritation or nerve damage. The longer the pressure remains, the more difficult full recovery may become. Early and accurate evaluation is therefore advisable – ideally by specialists experienced in peripheral nerve diagnostics.

Summary

Neurogenic thoracic outlet syndrome is an often-overlooked cause of pain, numbness, and weakness in the shoulder and arm. Symptoms may range from mild discomfort to significant impairment in daily activities.

High-resolution nerve ultrasound offers a dynamic and individualized assessment – without radiation or invasive procedures – and may assist in clarifying the underlying cause.

Disclaimer: The information provided on this page is for general informational purposes only and does not constitute medical advice. It is not a substitute for personal consultation, examination, or treatment by a physician or other qualified healthcare professional. No guarantees of healing or cure are made. While we strive for accuracy and completeness, we cannot guarantee that all content is up to date or free from errors, and we accept no liability for any inaccuracies.