Many individuals experience hand numbness or tingling during daily activities like computer usage, driving, or even upon awakening. Alongside these symptoms, some also report neck stiffness, shoulder tension, chest constriction, and pain radiating down the arms and hands. While several conditions might account for these symptoms, Thoracic Outlet Syndrome (TOS) stands out as one potential cause. Studies suggest its prevalence lies between 3 to 80 cases per 1,000 individuals.
TOS refers to conditions resulting from the compression of neurovascular bundles, which are groupings of nerves, veins, or arteries, held together by connective tissues for coordinated movement within the body. Specifically, TOS impacts the bundle that includes the brachial plexus, the subclavian artery, and the subclavian vein.
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Anatomy of TOS
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).
Symptoms of TOS
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).
Causes of TOS
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.
Examination Process
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.
RECOMMENDED ORTHOPAEDIC REFERENCE BOOKS
Orthopaedic Physical Assessment – David J. Magee https://amzn.to/3zgu0za
Dutton'sOrthopaedic: Examination, Evaluation and Intervention, Fifth Edition https://amzn.to/3st1AOv
Differential Diagnosis (DDx)
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.
Conclusion
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. BRIAN ABELSON DC. - The Author
Dr. Abelson's approach in musculoskeletal health care reflects a deep commitment to evidence-based practices and continuous learning. In his work at Kinetic Health in Calgary, Alberta, he focuses on integrating the latest research with a compassionate understanding of each patient's unique needs. As the developer of the Motion Specific Release (MSR) Treatment Systems, he views his role as both a practitioner and an educator, dedicated to sharing knowledge and techniques that can benefit the wider healthcare community. His ongoing efforts in teaching and practice aim to contribute positively to the field of musculoskeletal health, with a constant emphasis on patient-centered care and the collective advancement of treatment methods.
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