top of page
  • Dr. Brian Abelson DC., Dr Evangelos Mylonas DC.

Overcoming Thoracic Outlet Syndrome: A Step-by-Step Guide – Part 1

Updated: 2 days ago

Numerous patients report experiencing hand numbness or tingling while using computers, driving, or even upon waking up in the morning. Many of these individuals also suffer from stiff neck muscles, tense shoulders, chest tightness, and pain that may extend down their arms and hands. While various conditions can cause these symptoms, one such condition is known as Thoracic Outlet Syndrome (TOS). The prevalence of TOS is estimated to range from 3 to 80 cases per 1,000 people, according to multiple studies.

TOS serves as an overarching term for conditions characterized by the compression of a neurovascular bundle. These bundles consist of nerves, veins, or arteries bound together by connective tissues, enabling them to move together throughout the body. In TOS, the affected neurovascular bundle comprises the brachial plexus, the subclavian artery, and the subclavian vein.



Within the neck and shoulder areas, the neurovascular bundle passes through the thoracic outlet region. This space begins at the scalene triangle, which consists of three neck muscles, and ends at the pectoralis minor muscle.

There are several anatomical structures that may potentially lead to the compression of the neurovascular bundle, such as:

  • Scalene Muscles: Entrapment mainly occurs in the anterior and medial scalene muscles, with the posterior scalene being less commonly involved (7).

  • Subclavian Muscle: In certain instances, this muscle can attach to the first rib, leading to compression in the costoclavicular space (6; 20).

  • Pectoralis Minor Muscle: A significant number of TOS cases involve various muscles, with recent research suggesting that the pectoralis minor muscle is implicated in 75% of cases (8). Due to the brachial plexus' location just beneath the pectoralis minor muscle, the resulting compression is primarily neurogenic (8).

  • First Rib: The shape of the first rib can influence whether it contributes to compression (9).

  • Ulnar Nerve: Comprising the C8/T1 nerve roots, the ulnar nerve is situated beside the first rib, making it more prone to compression. This explains why 70-90% of TOS cases present with ulnar nerve distribution in the 4th and 5th fingers (9).



TOS manifests in three distinct forms: Arterial, Venous, or Neurogenic, with each type involving compression of an artery, vein, or nerve, respectively. A vast majority of TOS cases, over 90%, are associated with nerve compression (neurogenic TOS) (9; 19).

Typical symptoms of Neurogenic TOS encompass:

  • Weakness: This may involve weakness and fatigue in the upper extremity.

  • Neck Pain: Lateral neck pain is most common, primarily affecting the trapezius (92%) and scalene muscles (21).

  • Headaches: Occipital headaches are experienced by 76% of TOS patients (10; 21). Shoulder or Arm Pain: Shoulder pain might indicate neurogenic TOS, as it is less common in arterial or venous TOS. Shoulder and arm pain affects 88% of TOS patients (21).

  • Chest Pain: Roughly 72% of TOS patients experience chest pain (21).

  • Altered Hand Sensation: Approximately 58% of TOS patients encounter altered sensations (paresthesias) in their hands (21).

  • Ulnar Nerve Distribution: Ulnar distribution is more prevalent in TOS than median or radial nerve involvement. Over 90% of TOS cases are neurogenic, with 70-90% presenting ulnar nerve distribution (9). This includes the medial arm and elbow, extending to the 4th and 5th fingers, and manifests as weakness, numbness, and tingling (paresthesias).

Arterial TOS symptoms

Arterial TOS symptoms involve reduced blood flow, coldness, and pain. In Venous TOS, swelling in the upper extremity may be present, along with increased pain or tingling during activity. Shoulder and neck symptoms are uncommon in both arterial and venous TOS cases (11).



TOS may result from various factors, such as prior trauma like a motor vehicle accident, a fall, sports injury, surgery, poor posture, repetitive arm and shoulder movements, or individual anatomical differences. Many cases can be linked to myofascial restrictions in the neck (scalene muscles), shoulder, and upper chest (subclavius, pectoralis minor), which can lead to nerve entrapment, muscle imbalances, and dysfunction.

Poor posture is another frequent contributing factor.

Generally, poor posture (anterior posture) tends to pull the shoulder forward, causing imbalances throughout the chest, upper back, and shoulder girdle. Furthermore, joint restrictions in the cervical and thoracic spine, between the collarbone (clavicle) and chest bone (sternum), and between the first rib and first thoracic vertebra can all result in reduced mobility and compensatory movement patterns in the neck, shoulders, and chest—further contributing to the development of TOS syndrome.

The precise cause of TOS is often uncertain, with symptoms typically developing gradually and sometimes of unknown origin.



The following videos showcase a selection of common orthopedic and neurological techniques employed in the assessment of TOS cases:

Cervical Examination - Orthopaedic Testing

This video goes through inspection and observation, palpation, Active and Passive Ranges of motion, and orthopaedic examination of the cervical region.

Shoulder Examination - Orthopaedic Testing

This video teaches you some of the common causes of shoulder pain and how to diagnose them using orthopaedic examination procedures. This video is a summation of Parts 1 to 8 of the Shoulder Examination.

Upper Limb Neuro Exam

The upper limb neurological examination is part of the over all neurological examination process, and is used to assess the motor and sensory neurons which supply the upper limbs. This assessment helps to detect any impairment of the nervous system. It is used both as a screening and an investigative tool.

Cranial Nerve Examination - 12 Cranial Nerves

The Cranial Nerve examination is one of the ways that we assess sensory and motor dysfunction.

Peripheral Vascular Examination - Key Points

A peripheral vascular examination is a crucial method for identifying and ruling out indications of vascular-related issues. Detecting and treating Peripheral Vascular Disease (PVD) can potentially reduce cardiovascular and cerebrovascular complications. In this video, we demonstrate some of the standard procedures frequently performed in everyday clinical practice.


Orthopaedic Physical Assessment – David J. Magee

Dutton'sOrthopaedic: Examination, Evaluation and Intervention, Fifth Edition



Keep in mind that a TOS diagnosis is not definitive but rather a working diagnosis, particularly given that a comprehensive physical examination often requires the process of elimination to confirm TOS.

Numerous other syndromes exhibit symptoms similar to TOS and must always be taken into account. While some of these syndromes are rare, they could potentially coexist with TOS. These alternative conditions include:

  • Cardiovascular Disease: A class of diseases involving the heart and blood vessels.

  • Carpal Tunnel Syndrome: A condition causing pain, numbness, and tingling in the hand and arm due to a compressed median nerve in the wrist.

  • Cervical Radiculopathy: Involves nerve root dysfunction in the cervical spine, leading to pain and other symptoms.

  • De Quervain's Tenosynovitis: A painful condition affecting the tendons on the thumb side of the wrist.

  • Degenerative Disc Disease of the Cervical Spine: A progressive condition involving the degeneration of intervertebral discs in the neck.

  • Glenohumeral Joint Instability/Shoulder Instability: A condition where the shoulder joint is excessively loose or prone to dislocation.

  • Herniated Spinal Disc: A condition where the soft inner portion of a spinal disc bulges or ruptures, potentially causing pain and nerve irritation.

  • Horner's Syndrome: A rare neurological disorder characterized by a combination of symptoms, including drooping eyelid, constricted pupil, and loss of facial sweating.

  • Malignancies (Pancoast's Syndrome): A rare form of lung cancer that affects the top of the lung and can cause shoulder pain and other neurological symptoms.

  • Medial and Lateral Epicondylitis: Inflammation of the tendons at the elbow, commonly known as golfer's elbow (medial) and tennis elbow (lateral).

  • Peripheral Neuropathies (ulnar, radial entrapment): Conditions involving damage to the peripheral nerves, which can result in pain, numbness, and weakness.

  • Rotator Cuff Syndrome: A spectrum of shoulder conditions involving the tendons and muscles responsible for shoulder movement and stability.

  • Raynaud's Syndrome: A condition causing the blood vessels in the fingers and toes to constrict abnormally, resulting in coldness, numbness, and color changes.

  • T4 (Thoracic) Syndrome: A condition involving upper thoracic spine dysfunction, which can cause referred pain and other symptoms in the upper extremities.



Thoracic Outlet Syndrome can be a highly distressing and disabling condition. To address it effectively, a meticulous physical examination is necessary, encompassing a comprehensive history, orthopedic, and neurological testing. It is crucial to rule out various other syndromes that may present similar symptoms.

In the second part of "Resolving Thoracic Outlet Syndrome," I will explore recommended treatment approaches and exercise protocols. This will also feature demonstration videos for the recommended soft-tissue and osseous treatments, as well as examples of specific exercises often prescribed to patients to complement their TOS treatments.

Please Note: References can be found at the end of Part 2.




Dr. Abelson is committed to running an evidence-based practice (EBP) that incorporates the most up-to-date research evidence available. He combines his clinical expertise with the specific values and needs of each patient to deliver personalized care that is both effective and patient-centered.

As the developer of Motion Specific Release (MSR) Treatment Systems, Dr. Abelson operates a clinical practice in Calgary, Alberta, under the name Kinetic Health. He has authored ten publications to date and continues to offer online courses, in addition to his live programs, to healthcare professionals seeking to expand their knowledge and skills in treating patients with musculoskeletal conditions. By staying current with the latest research and offering innovative treatment options, Dr. Abelson is dedicated to helping his patients achieve optimal health and wellness.

599 views0 comments
bottom of page