Thoracic Outlet Syndrome: Diagnosis, Treatment & Rehabilitation
Thoracic Outlet Syndrome (TOS) can be challenging to diagnose because symptoms in the neck, shoulder, arm, and hand can resemble several other musculoskeletal and neurological conditions. Patients may report pain, numbness, tingling, weakness, fatigue, heaviness, or, in vascular cases, changes in circulation.
TOS is not a single condition. It describes a group of disorders involving compression or irritation of the brachial plexus, subclavian vein, or subclavian artery as these structures travel from the neck toward the upper extremity.
Three major forms are recognized:
Neurogenic Thoracic Outlet Syndrome (nTOS) involves the brachial plexus and accounts for the majority of clinical presentations.
Venous Thoracic Outlet Syndrome (vTOS) involves compression or thrombosis of the subclavian vein.
Arterial Thoracic Outlet Syndrome (aTOS) involves the subclavian artery and is much less common but potentially serious.
Distinguishing between these presentations is essential because their examination, investigation, treatment, and urgency can be very different.
For the practitioner, the first challenge is therefore not simply determining whether a patient has TOS. It is answering three questions:
What structure appears to be involved? What else could be producing these symptoms? And does this patient require conservative management or further medical investigation?
Once those questions are addressed, treatment can focus on the factors that are relevant to the individual, including activity and loading demands, neurological function, mobility, strength, and the patient's ability to return to work, recreation, or sport.
Article Index
Understanding the Three Types of Thoracic Outlet Syndrome
Thoracic Outlet Syndrome is classified according to the primary structure being affected: the brachial plexus, subclavian vein, or subclavian artery. Although symptoms can overlap, distinguishing between neurogenic, venous, and arterial TOS is essential because the clinical implications and treatment pathways are quite different. Current international consensus continues to recognize these as three distinct forms of TOS.
Neurogenic Thoracic Outlet Syndrome
Neurogenic Thoracic Outlet Syndrome (nTOS) involves irritation or compression of the brachial plexus as it passes from the neck toward the upper extremity. It is the most commonly encountered form of TOS.
Patients may experience:
Pain in the neck, shoulder, upper chest, arm, or hand
Numbness or tingling in the arm or hand
Arm heaviness or fatigue
Weakness or reduced grip strength
Symptoms aggravated by overhead positions or prolonged and repetitive use of the arm
Unlike a single peripheral nerve entrapment or cervical nerve-root lesion, symptoms may extend beyond one clearly defined nerve or dermatome. This variability is one reason nTOS can be challenging to diagnose.
Symptoms are often influenced by position and activity. Raising the arm overhead, repetitive upper-extremity activity, carrying loads, or maintaining certain positions for prolonged periods may reproduce symptoms. However, these findings are not unique to TOS, making the differential diagnosis particularly important.
Venous Thoracic Outlet Syndrome
Venous Thoracic Outlet Syndrome (vTOS) involves compression of the subclavian vein. In some cases, repetitive compression and vascular injury can contribute to thrombosis.
Patients may present with:
Swelling of the arm or hand
A feeling of heaviness or fullness
Bluish or dusky discoloration
Prominent superficial veins around the shoulder or chest
Pain or aching in the affected extremity
Symptoms may appear after strenuous or repetitive upper-extremity activity.
A swollen, discoloured, or unusually heavy arm should not simply be treated as a musculoskeletal presentation. Suspected venous TOS requires appropriate medical and vascular assessment.
Arterial Thoracic Outlet Syndrome
Arterial Thoracic Outlet Syndrome (aTOS) involves compression of the subclavian artery and is much less common than neurogenic TOS.
Possible findings include:
A cool or pale hand
Arm or hand fatigue
Pain associated with reduced circulation
Changes in pulses
Numbness or weakness associated with ischemia
In more significant cases, evidence of arterial injury, embolization, or compromised blood flow
Because arterial compromise can threaten the circulation to the upper extremity, suspected aTOS requires prompt vascular investigation and appropriate specialist referral.
Why the Distinction Matters
From a clinical perspective, simply diagnosing “TOS” is not enough.
A patient with position-dependent numbness and arm fatigue may be appropriate for a trial of conservative management for suspected nTOS. A patient presenting with substantial arm swelling, cyanosis, or signs of arterial insufficiency requires a very different pathway.
This is also why the history and physical examination remain central to evaluating suspected nTOS. Recent expert consensus emphasizes the combination of local findings, peripheral neurological symptoms, symptom behaviour, provocative examination, and consideration of competing diagnoses, rather than relying on one definitive test.
Understanding these differences provides the foundation for the next question:
Where Can Compression Occur?
Anatomy of the Thoracic Outlet
The term thoracic outlet describes the region through which the nerves and blood vessels supplying the upper extremity travel from the neck toward the arm. These structures pass through several relatively confined anatomical spaces where their relationship with surrounding muscles, bones, and connective tissues can become clinically important.
For TOS, three regions deserve particular attention: the scalene triangle, costoclavicular space, and retropectoralis minor space.
The Scalene Triangle
The scalene triangle is bordered by the anterior scalene, middle scalene, and first rib.
The brachial plexus and subclavian artery pass through this space. The subclavian vein does not. It travels anterior to the anterior scalene muscle, an important anatomical distinction when considering neurological versus vascular presentations.
Variations in scalene anatomy, fibrous bands, a cervical rib, previous trauma, or changes associated with repetitive loading may alter the mechanical environment surrounding the brachial plexus or subclavian artery.
The Costoclavicular Space
After leaving the scalene region, the neurovascular structures pass through the costoclavicular space, between the clavicle and first rib.
This region contains the brachial plexus and subclavian vessels and is particularly relevant when considering both neurological and vascular forms of TOS.
The dimensions of this space change with upper-extremity position. This helps explain why some patients experience symptoms primarily during sustained or repetitive arm positions rather than continuously at rest.
The Pectoralis Minor Region
As the neurovascular bundle continues toward the arm, it passes beneath the pectoralis minor near its attachment to the coracoid process.
This region is increasingly recognized as clinically important in patients with upper-extremity neurological symptoms. Compression or irritation of the brachial plexus beneath the pectoralis minor may produce symptoms similar to those attributed to more proximal thoracic outlet compression.
Some clinicians distinguish this presentation as pectoralis minor syndrome, although symptoms and contributing factors can overlap with neurogenic TOS.
Anatomical Variations
Not everyone has exactly the same anatomy. Potential variations include:
Cervical ribs or elongated C7 transverse processes
Fibrous bands
Variations in scalene muscle attachments
Differences in brachial plexus anatomy
Variations in the relationship between nerves, vessels, muscles, and the first rib
These findings can be clinically relevant, but an anatomical variation does not automatically mean that it is causing symptoms. Cervical ribs, for example, can exist without producing TOS.
This distinction is important. Imaging may identify an anatomical feature, but the finding still needs to be correlated with the patient's symptoms and examination.
Anatomy Changes With Movement
The thoracic outlet is not a static space.
Movement of the cervical spine, clavicle, scapula, shoulder, and upper extremity changes the relationships between the brachial plexus, blood vessels, muscles, and surrounding structures.
For this reason, assessment should not focus solely on finding a structure that appears “tight.” The more useful question is whether particular positions, movements, or loads reproduce the patient's symptoms and whether those findings are consistent with neural or vascular involvement.
Symptoms and Clinical Presentation
The clinical presentation of Thoracic Outlet Syndrome can vary considerably depending on which structures are involved, where irritation or compression occurs, and which positions or activities provoke symptoms.
This variability is one reason TOS can be difficult to recognize. Symptoms may overlap with cervical radiculopathy, shoulder disorders, peripheral nerve entrapments, and other upper-extremity conditions.
For practitioners, the pattern and behaviour of symptoms are often more informative than any single complaint.
Neurogenic Symptoms
In neurogenic TOS, symptoms are typically related to the brachial plexus and may include pain, paresthesia, numbness, weakness, heaviness, or fatigue affecting the upper extremity.
Symptoms may involve the neck, supraclavicular region, shoulder, upper chest, arm, forearm, or hand. Although some patients experience more pronounced symptoms along the medial forearm and ulnar side of the hand, nTOS does not necessarily follow a single peripheral nerve or cervical dermatome.
A particularly important feature is that symptoms are often position- or activity-dependent. Patients may report increasing symptoms when:
Working with the arms overhead
Reaching or lifting repeatedly
Carrying objects
Driving for prolonged periods
Sleeping with the arm elevated
Performing repetitive occupational tasks
Swimming, throwing, climbing, or participating in other overhead sports
Some patients describe the arm simply becoming heavy or easily fatigued, which can be an important clue when conventional strength testing at rest appears relatively normal.
Weakness and Neurological Deficits
Subjective weakness or fatigue is relatively common, but objective neurological weakness deserves greater attention.
Marked weakness, muscle wasting, or progressive neurological deficits suggest more significant neural involvement and should not automatically be managed as a routine musculoskeletal presentation.
True neurogenic TOS associated with objective muscle atrophy is less common. When present, intrinsic hand muscle wasting may be particularly important and warrants appropriate neurological or surgical evaluation.
Vascular Symptoms
Vascular presentations tend to produce a different clinical picture.
With venous TOS, patients may develop arm swelling, heaviness, cyanosis or bluish discoloration, discomfort, and prominent superficial veins. Symptoms may appear relatively suddenly, particularly following strenuous or repetitive upper-extremity activity.
With arterial TOS, the hand or arm may become cool, pale, painful, or easily fatigued. Changes in pulses or other evidence of impaired arterial circulation may also be present.
These findings change the urgency of the assessment. Significant swelling, discoloration, ischemic symptoms, or suspected thrombosis requires medical and vascular evaluation rather than routine conservative treatment.
Symptoms Do Not Equal Diagnosis
One of the challenges with TOS is that many of its symptoms are not unique to TOS.
Numbness in the hand could arise from cervical radiculopathy, ulnar neuropathy, carpal tunnel syndrome, or other neurological conditions. Shoulder and upper-chest pain can originate from numerous musculoskeletal structures. Arm fatigue during overhead activity can have several explanations.
Even symptom reproduction with an elevated arm position is not diagnostic by itself.
This is why TOS should not be diagnosed solely because a patient has arm tingling and a positive provocative test. Current consensus emphasizes combining the history, symptom distribution, physical examination, provocative findings, and exclusion of other reasonable diagnoses when evaluating suspected neurogenic TOS.
Look for the Pattern
A useful clinical question is not simply:
“Where does it hurt?”
Instead, consider:
What does the patient feel? Where do they feel it? What positions or activities reproduce it? How long does it take to appear? What relieves it? And do the neurological or vascular findings support the suspected diagnosis?
Those questions begin to separate TOS from the many other conditions that can produce similar symptoms.
Why Does Thoracic Outlet Syndrome Develop?
Thoracic Outlet Syndrome rarely has a single cause. In many patients, symptoms appear to develop through an interaction between individual anatomy, previous injury, repetitive loading, and the positions or activities regularly demanded of the upper extremity.
Anatomical Factors
Some individuals have anatomical variations that may reduce the available space around the brachial plexus or blood vessels. These can include a cervical rib, elongated C7 transverse process, fibrous bands, variations in the scalene muscles, or changes related to a previous clavicular fracture.
These findings may increase susceptibility to TOS, but they should not automatically be considered the cause of symptoms. Anatomical findings need to be interpreted alongside the history and physical examination.
Trauma
Symptoms may develop following trauma involving the neck, shoulder girdle, or upper chest. Examples include motor vehicle collisions, falls, clavicular or first-rib fractures, and other injuries that alter the tissues surrounding the thoracic outlet.
Trauma does not necessarily produce symptoms immediately. In some patients, pain, guarding, altered movement, or progressive sensitivity of neural structures may contribute to a more gradual presentation.
Repetitive and Overhead Loading
TOS is also seen in people whose work or sport repeatedly places the upper extremity in demanding positions.
Swimmers, throwing athletes, volleyball players, gymnasts, weightlifters, musicians, and people performing repetitive occupational tasks may repeatedly load the region around the brachial plexus and vascular structures. Repetitive arm stress and overhead activity are recognized features associated with nTOS presentations.
The important factor is not simply that an activity is “overhead.” It is the relationship between the frequency, duration and intensity of the activity and the individual's capacity to tolerate those demands.
What About Posture?
Posture deserves a more balanced interpretation than it has traditionally received in discussions of TOS.
Certain sustained positions may reproduce symptoms, particularly when the arms are elevated or when prolonged work positions increase neural or muscular loading. Current diagnostic frameworks recognize symptom aggravation with prolonged or repetitive upper-extremity use as clinically relevant.
However, this does not mean there is one universally “bad posture” that causes TOS or that treatment should simply involve pulling the shoulders back and down.
A more useful approach is to determine whether a particular position consistently reproduces symptoms and whether improving movement variability, strength, endurance, or tolerance to that position changes the patient's function.
A Load-and-Capacity Perspective
For many neurogenic presentations, it can be helpful to think beyond a simple model of a structure being permanently “pinched.”
Symptoms may emerge when the mechanical demands placed on the region repeatedly exceed what the surrounding neural and musculoskeletal tissues can comfortably tolerate. Anatomy, previous trauma, repetitive activity, mobility, strength, endurance, and recovery may all contribute to that relationship.
This perspective also changes the goal of treatment. Rather than trying to create a permanently “open” thoracic outlet or correct a supposedly faulty posture, rehabilitation can focus on reducing provocative loads when necessary and progressively developing the patient's capacity to tolerate the movements and activities they need to perform.
Physical Examination and Diagnosis
The diagnosis of neurogenic Thoracic Outlet Syndrome is based primarily on the history and physical examination. There is currently no single examination procedure, imaging study, or electrodiagnostic test that can independently confirm every case of nTOS. Recent international consensus therefore emphasizes the overall clinical pattern rather than reliance on one positive provocative test.
The examination should attempt to answer three questions:
Do the symptoms fit a neurogenic TOS presentation?
Can they be reproduced in a clinically meaningful way?
Is there another diagnosis that better explains them?
Begin With the History
The history should establish the location and character of symptoms, how they began, and which activities or positions reproduce them.
Particular attention should be given to symptoms associated with overhead activity, repetitive arm use, carrying, prolonged positioning, occupational demands, and sport. Previous trauma involving the neck, clavicle, shoulder, or upper chest may also be relevant.
Ask whether symptoms remain localized or radiate into the arm and hand, whether numbness or paresthesia follows a recognizable neurological distribution, and whether the patient experiences weakness, loss of endurance, heaviness, swelling, or changes in colour or temperature.
These details begin separating a primarily neurogenic presentation from vascular disease and other neurological or musculoskeletal conditions.
Neurological and Musculoskeletal Examination
A focused examination may include:
Cervical and shoulder range of motion
Upper-extremity strength
Sensory examination
Deep tendon reflexes when indicated
Grip and intrinsic hand muscle strength
Observation for muscle atrophy
Palpation of the supraclavicular/scalene region
Palpation around the pectoralis minor and coracoid region
Shoulder and scapular movement during relevant tasks
The cervical spine and shoulder deserve particular attention because disorders in either region can produce symptoms that closely resemble TOS.
Marked objective weakness, muscle wasting, abnormal reflexes, or progressive neurological findings should prompt consideration of cervical radiculopathy, myelopathy, significant brachial plexus pathology, or another neurological disorder rather than automatically attributing the findings to TOS.
Provocative Testing
Provocative tests can contribute useful information, but they should be interpreted as part of the examination rather than used as stand-alone diagnostic tests.
Elevated Arm Stress Test: EAST/Roos
During the Elevated Arm Stress Test (EAST), the patient holds the arms in an elevated position while repeatedly opening and closing the hands.
Reproduction of the patient's characteristic pain, paresthesia, heaviness, or fatigue may support the clinical suspicion of nTOS.
The 2024 INTOS consensus specifically recommends EAST as a provocative procedure for nTOS. However, a positive test should not be considered diagnostic by itself.
Supraclavicular Tinel Sign
Palpation or percussion over the brachial plexus in the supraclavicular region may reproduce neurological symptoms extending into the upper extremity.
A positive Tinel-type response in the supraclavicular fossa is another finding recommended by the INTOS consensus and may support the diagnosis when it reproduces the patient's familiar symptoms.
Upper Limb Tension Test
The Upper Limb Tension Test (ULTT) places mechanical load on neural structures of the upper extremity.
Reproduction of the patient's familiar symptoms may indicate increased neural mechanosensitivity, but this finding is not specific to TOS. It must be interpreted alongside the rest of the neurological and musculoskeletal examination.
Interestingly, ULTT appears in established diagnostic frameworks for nTOS, although the 2024 INTOS panel did not reach the same level of consensus for it as it did for EAST and supraclavicular Tinel testing.
What About Adson's Test?
Traditional TOS examinations frequently emphasize Adson's test and changes in the radial pulse.
Changes in pulse during positional testing do not necessarily indicate clinically meaningful neurovascular compression, and provocative vascular maneuvers should not be used to diagnose neurogenic TOS in isolation.
If vascular TOS is genuinely suspected, a proper vascular examination and appropriate vascular investigation are much more important than relying on disappearance of the radial pulse during a provocative maneuver.
Examine Above and Below the Thoracic Outlet
The examination should not stop at the scalene triangle.
Symptoms attributed to TOS may originate from or coexist with pathology involving the cervical spine, shoulder, brachial plexus, ulnar nerve, median nerve, or other peripheral nerves.
This is particularly important because TOS and distal nerve entrapments are not necessarily mutually exclusive. The presence of one condition does not automatically exclude another. The INTOS consensus specifically recognizes that other diagnoses may coexist with nTOS.
Vascular Examination When Indicated
When symptoms include swelling, discoloration, unusual temperature changes, vascular-type fatigue, or other findings suggesting impaired circulation, the examination should include an appropriate peripheral vascular assessment.
Suspected venous or arterial TOS should move the patient out of a routine musculoskeletal treatment pathway and toward appropriate medical or vascular investigation.
Clinical Perspective
A useful way to think about the examination is as a process of building or weakening the clinical hypothesis.
No single positive EAST, Tinel sign, tender scalene, or upper-limb tension test proves that a patient has TOS. The diagnosis becomes more credible when several findings tell the same story:
Compatible symptoms + characteristic symptom behaviour + meaningful reproduction during examination + relevant neurological findings + absence of a more convincing alternative diagnosis.
That approach is both more clinically useful and more consistent with current expert consensus than trying to diagnose TOS from one provocative test.
Differential Diagnosis
The differential diagnosis is a central part of evaluating suspected Thoracic Outlet Syndrome because many conditions can produce similar pain, numbness, tingling, weakness, or fatigue in the upper extremity. Current consensus specifically requires consideration of other reasonably likely diagnoses, while recognizing that another condition can sometimes coexist with nTOS.
Rather than treating TOS purely as a diagnosis of exclusion, the goal is to determine whether the overall clinical pattern is more consistent with TOS than with another condition.
Cervical Radiculopathy
Cervical nerve-root compression can produce neck and arm pain, paresthesia, sensory changes, weakness, and altered reflexes.
Symptoms following a recognizable dermatomal or myotomal pattern, changes in reflexes, and findings associated with cervical movement may increase suspicion of cervical radiculopathy. MRI and electrodiagnostic testing may be appropriate when the diagnosis remains uncertain or neurological deficits are present.
Peripheral Nerve Entrapment
Several peripheral nerve disorders can resemble nTOS.
Ulnar neuropathy, particularly at the elbow, may produce numbness and tingling involving the fourth and fifth fingers and weakness of intrinsic hand muscles.
Carpal tunnel syndrome primarily affects the median nerve and commonly produces numbness or tingling involving the thumb, index, middle, and radial half of the ring finger.
Other peripheral nerve entrapments should also be considered according to the distribution of symptoms and examination findings. Electrodiagnostic testing can be useful when distinguishing nTOS from distal nerve compression. PubMed Central (PMC)
Importantly, identifying a distal nerve entrapment does not automatically exclude TOS. More than one neurological condition can coexist.
Shoulder Disorders
Rotator cuff disorders, glenohumeral pathology, instability, and other shoulder conditions can produce shoulder and upper-arm pain that may initially resemble TOS.
A focused shoulder examination is therefore important, particularly when symptoms are strongly associated with shoulder movement or loading rather than neurological symptoms extending into the upper extremity.
Pectoralis Minor Syndrome
Compression or irritation of the brachial plexus beneath the pectoralis minor can produce symptoms very similar to neurogenic TOS.
Patients may experience pain or tenderness near the coracoid or anterior shoulder together with neurological symptoms extending into the arm or hand. Some specialists consider pectoralis minor syndrome a distinct condition, while others view it within the broader spectrum of neurogenic TOS.
Clinically, the distinction can still be useful because it encourages the practitioner to consider whether symptoms appear to arise predominantly from the supraclavicular region, infraclavicular region, or both.
Brachial Plexus and Other Neurological Disorders
Traumatic brachial plexus injury, brachial neuritis, cervical myelopathy, and other neurological disorders should be considered when the history or neurological examination does not fit a typical nTOS presentation.
Progressive weakness, muscle wasting, abnormal reflexes, widespread sensory changes, gait disturbance, or other upper motor neuron findings warrant further neurological investigation.
Vascular and Other Important Conditions
Arm swelling, cyanosis, pallor, coolness, diminished circulation, or other vascular findings should raise concern for venous or arterial disease rather than routine musculoskeletal nTOS.
Other less common but important conditions can also mimic aspects of TOS, including complex regional pain syndrome, lymphatic disorders, masses involving the brachial plexus, and apical lung lesions such as a Pancoast tumour.
Clinical Perspective
The purpose of differential diagnosis is not to generate an enormous checklist for every patient. It is to ask whether another condition provides a better explanation for the patient's symptoms and examination findings.
For many patients, the most clinically relevant distinctions will be between:
nTOS → cervical radiculopathy → peripheral nerve entrapment → shoulder pathology → pectoralis minor involvement
Imaging and Further Investigation
Imaging can be helpful in Thoracic Outlet Syndrome, but its role depends on which form of TOS is suspected and what clinical question needs to be answered.
For neurogenic TOS, the history and physical examination remain central. There is no single imaging study that definitively confirms nTOS, and anatomical narrowing or positional compression on imaging does not necessarily mean that it is responsible for the patient's symptoms. Current expert consensus supports using imaging selectively to identify anatomical factors and exclude competing diagnoses.
X-Ray
A cervical spine or chest X-ray can identify bony abnormalities such as a cervical rib, elongated C7 transverse process, previous clavicular fracture, or other skeletal changes that may be relevant to the thoracic outlet.
The 2024 INTOS consensus recommends cervical spine or chest radiographs as part of the workup for nTOS, particularly to identify a cervical rib.
MRI and CT
MRI may be useful when additional information about the brachial plexus, cervical spine, surrounding soft tissues, or another possible diagnosis is required.
CT provides excellent visualization of bony anatomy and, when combined with angiography, can help assess vascular structures and their relationship to the thoracic outlet. Specialized CT or MRI protocols may also examine the region with the arm in different positions.
These findings must still be correlated with the clinical presentation because positional neurovascular compression can sometimes be demonstrated in people without symptomatic TOS.
Ultrasound and Vascular Imaging
When venous or arterial TOS is suspected, vascular imaging becomes considerably more important.
Duplex ultrasound can assess blood flow and may help identify vascular obstruction or thrombosis. Depending on the presentation, CT angiography, MR angiography, or other vascular investigations may be required to define the location and severity of vascular compromise.
Significant arm swelling, cyanosis, ischemic symptoms, or suspected thrombosis should prompt appropriate medical or vascular referral rather than delaying assessment while pursuing routine musculoskeletal treatment.
Electrodiagnostic Testing
Nerve conduction studies and electromyography may be useful when neurological symptoms are present, particularly when trying to distinguish nTOS from cervical radiculopathy, ulnar neuropathy, carpal tunnel syndrome, or another peripheral nerve disorder.
However, normal electrodiagnostic findings do not necessarily exclude nTOS. Current expert consensus considers electrodiagnostic testing potentially useful for supporting the diagnosis and identifying other neurological conditions rather than a mandatory diagnostic test in every case.
Clinical Perspective
Additional testing should be driven by the clinical question:
Is there a cervical rib or other structural variation? Is another neurological condition more likely? Is there vascular compromise or thrombosis? Is there significant brachial plexus pathology? Would the result change management?
Conservative Management of Neurogenic TOS
For most patients with neurogenic Thoracic Outlet Syndrome without significant muscle weakness or atrophy, conservative management is the appropriate first step. The 2024 INTOS consensus recommends conservative treatment as first-line care, generally for three to six months before surgery is considered.
The objective is not simply to “open” the thoracic outlet or permanently correct posture. Rehabilitation should focus on reducing symptom-provoking demands when necessary, restoring comfortable movement, improving strength and endurance, and progressively increasing the patient's capacity for work, recreation, and sport.
Education and Activity Modification
Early management begins by identifying the positions and activities that consistently aggravate symptoms.
For some patients this may involve repetitive overhead work, prolonged computer use, carrying loads, sustained arm elevation, or high-volume athletic activity. Temporary modification can reduce irritability while rehabilitation begins. Activity-dependent and intermittent nTOS is commonly managed initially with rehabilitation rather than surgery.
The key word is temporary. The long-term goal should not be permanent avoidance of every provocative position. Whenever appropriate, rehabilitation should progressively prepare the patient to tolerate the activities they need or want to perform.
Mobility
Restrictions involving the cervical spine, thoracic region, shoulder, or surrounding musculature may be addressed when they are identified during examination and appear relevant to the patient's presentation.
This does not mean every patient requires increased mobility in every region. Treatment should be directed toward clinically meaningful findings rather than following a predetermined TOS protocol.
Strength and Endurance
Progressive strengthening is an important component of rehabilitation. Current clinical literature commonly incorporates shoulder-girdle strengthening, range-of-motion exercise, and progressive rehabilitation, although there is still no universally accepted exercise protocol for nTOS
Depending on the patient's findings and functional requirements, exercise may address the scapular musculature, rotator cuff, cervical and thoracic musculature, and the broader upper extremity.
Endurance can be particularly important because many patients experience symptoms not during a single movement but after prolonged or repetitive activity.
Neural Mobility
Neural mobilization or nerve-gliding exercises may be incorporated when examination suggests neural mechanosensitivity.
These exercises should generally encourage comfortable movement of the nervous system rather than aggressively stretching the brachial plexus or peripheral nerves. Symptoms should be monitored and the dosage adjusted according to the patient's response.
Breathing and the Scalene Muscles
Breathing strategies may also be relevant in selected patients.
The scalene muscles contribute to respiration as accessory inspiratory muscles as well as forming part of the anatomical boundaries surrounding the brachial plexus. In patients demonstrating excessive upper-chest or accessory respiratory muscle activity, breathing exercises may be incorporated as part of a broader rehabilitation program.
This should not be interpreted to mean that abnormal breathing causes TOS. It is simply another factor that may be clinically relevant in some individuals.
Progress According to Function
Rehabilitation should progress according to the patient's symptoms, neurological findings, strength, endurance, movement tolerance, and functional requirements, rather than according to an arbitrary timetable.
A desk worker, musician, swimmer, electrician working overhead, and competitive throwing athlete may all require very different rehabilitation programs even if each has been diagnosed with nTOS.
The endpoint is not simply fewer symptoms during treatment. It is the ability to tolerate the positions, loads, repetition, and duration required in everyday life.
Clinical Perspective
Conservative management of nTOS is best viewed as a process of gradually changing the relationship between symptoms and functional demand.
Reduce excessive provocation when necessary → restore comfortable movement → build strength and endurance → progressively reintroduce demanding positions and activities.
Manual Therapy and Motion Specific Release
Manual therapy may be incorporated into the conservative management of neurogenic Thoracic Outlet Syndrome when examination identifies pain, mobility restrictions, muscular sensitivity, or other findings that interfere with comfortable movement and rehabilitation.
The current rehabilitation literature includes soft-tissue techniques and joint mobilization among the approaches used for nTOS, but the evidence supporting specific manual procedures remains limited. A recent scoping review found manual therapy in 10 of the rehabilitation studies it examined, while also emphasizing substantial variation in treatment approaches and limited evidence regarding optimal protocols.
For this reason, manual therapy is best considered an adjunct to an active rehabilitation program, rather than a stand-alone method of permanently decompressing the thoracic outlet.
Applying MSR to Thoracic Outlet Syndrome
Within the Motion Specific Release (MSR) system, treatment is guided by the findings of the examination rather than applying the same protocol to every patient.
Depending on the presentation, clinically relevant structures may include the:
Anterior and middle scalene muscles
Sternocleidomastoid
Pectoralis minor and major
Upper trapezius and levator scapulae
Cervical and thoracic regions
First rib and surrounding articulations
Shoulder girdle
Brachial plexus and peripheral neural structures
The objective is not simply to identify every structure that feels tight. Treatment should focus on findings that appear relevant to the patient's symptoms, movement limitations, neural sensitivity, and functional demands.
Soft-Tissue Procedures
MSR soft-tissue procedures may be used when muscular or myofascial sensitivity and restricted movement appear to contribute to the patient's presentation.
Treatment of the scalene and pectoral regions deserves particular care because of the brachial plexus and major vascular structures passing through or near these areas.
Rather than claiming that soft-tissue treatment physically releases a compressed nerve, the clinical objective is more appropriately described as reducing symptoms, improving comfortable movement, and facilitating progression into active rehabilitation.
Joint Mobilization and Manipulation
Mobility of the cervical spine, thoracic spine, first rib, clavicle, and shoulder girdle may also be assessed.
When a clinically relevant restriction is identified, joint mobilization or manipulation may be incorporated according to the practitioner's training, clinical judgment, and the patient's presentation.
First-rib mobilization, for example, appears frequently in TOS rehabilitation literature, but that does not mean that every patient with nTOS has an “elevated first rib” that must be corrected. Recent rehabilitation literature includes first-rib and cervicothoracic mobilization while rating the supporting evidence for manual therapy relatively low.
The response should therefore be reassessed. Does the intervention improve movement, reduce familiar symptoms, or allow better tolerance of exercise or functional activity? If not, its relevance should be reconsidered.
Neural Mobilization
MSR procedures may also incorporate techniques directed toward the neural structures of the upper extremity.
Neural mobilization should generally encourage comfortable excursion of neural tissues rather than aggressively stretching the brachial plexus or peripheral nerves. Current rehabilitation literature includes median and ulnar nerve mobilization, but recommends caution when neural structures demonstrate significant tensile sensitivity.
The patient's neurological response during and after treatment should guide the intensity and progression.
Fascial Expansions
Fascial Expansions may also be incorporated within the MSR approach when clinically appropriate. These procedures integrate manual approaches to fascia with concepts derived from acupuncture and acupressure.
For TOS, Fascial Expansions should be presented as an adjunct for symptom management and movement tolerance, rather than as a method of structurally enlarging the thoracic outlet or permanently decompressing the brachial plexus.
From Manual Therapy to Active Rehabilitation
This is the most important connection to make.
If manual therapy reduces pain or improves comfortable movement, that change creates an opportunity to progress the patient into mobility, strengthening, endurance, neural mobility, and eventually the activities that previously provoked symptoms.
Exercise and Rehabilitation
Exercise is a central component of conservative management for neurogenic Thoracic Outlet Syndrome. Current rehabilitation literature most consistently includes strengthening, mobility, neural mobilization, and progressive restoration of functional activity, although there is no single standardized exercise protocol appropriate for every patient.
The program should therefore be based on the patient's examination findings and the activities that provoke symptoms.
Shoulder and Scapular Strength
The shoulder girdle provides a foundation for upper-extremity movement. Rehabilitation may emphasize the serratus anterior, middle and lower trapezius, rotator cuff, and other muscles responsible for controlling the scapula and shoulder during movement.
Early exercises may use relatively light resistance and shorter lever arms, particularly when the arm fatigues quickly. Resistance, repetitions, range of motion, and arm elevation can then be progressively increased as tolerance improves. Current rehabilitation literature places particular emphasis on serratus anterior and middle/lower trapezius function.
The objective is not to force the shoulders permanently “back and down.” The scapula needs to move normally during elevation of the arm, including upward rotation and posterior tilt. Rehabilitation should develop control and capacity rather than impose a rigid postural position.
Mobility
Mobility exercises may be appropriate when examination identifies restrictions involving the cervical spine, thoracic region, shoulder, or surrounding musculature.
Stretching should be individualized. Aggressive stretching is not necessarily beneficial and may aggravate symptoms when neural structures are particularly sensitive. Current clinical recommendations specifically advise caution with stretching when it increases neural tension or reproduces neurological symptoms.
Neural Mobility
Median, ulnar, or other neural-mobilization exercises may be incorporated when examination identifies relevant neural mechanosensitivity or reduced neural mobility.
These exercises should generally be performed as gentle gliding movements rather than forceful nerve stretches. Increasing numbness, tingling, burning, or other neurological symptoms is a reason to reduce the intensity or reconsider the exercise.
Breathing Exercises
Breathing exercises may be useful in selected patients who rely heavily on the scalenes, sternocleidomastoid, and other accessory respiratory muscles.
Diaphragmatic breathing and improved rib-cage control can be incorporated when these findings are clinically relevant. This should not be interpreted as suggesting that breathing dysfunction causes TOS. It is one potential component of an individualized rehabilitation program.
Building Endurance
Strength alone may not reproduce the demands that trigger symptoms.
Many patients with nTOS tolerate individual movements but develop symptoms after repeated or sustained activity. Musicians, computer users, healthcare workers, tradespeople, and athletes may need to maintain upper-extremity positions for prolonged periods.
Rehabilitation should therefore develop endurance as well as strength. This may involve gradually increasing repetitions, resistance, duration, carrying tasks, reaching, or time spent in previously provocative positions.
Returning to Overhead Activity
For swimmers, throwers, climbers, weightlifters, and people who work overhead, rehabilitation eventually needs to reproduce the demands of those activities.
Progression may move from:
Controlled movement → strengthening → endurance → increasing arm elevation → repetitive overhead loading → work- or sport-specific activity
The progression should be based on symptom response, neurological findings, strength, endurance, movement quality, and recovery after activity, rather than a predetermined number of weeks.
Rehabilitation of overhead athletes with TOS particularly emphasizes restoring shoulder mobility and control before progressing toward the demands of the athlete's sport. However, much of the published return-to-sport literature remains based on lower-level evidence and individual clinical cases rather than large controlled trials.
Monitor the Response
Some muscular fatigue or effort is expected as rehabilitation becomes more demanding. Increasing neurological symptoms are different.
Exercise should be modified when it produces progressively increasing numbness, tingling, weakness, substantial arm heaviness, or symptoms that remain significantly aggravated afterward.
When Referral or Surgery Should Be Considered
Most patients with neurogenic Thoracic Outlet Syndrome begin with conservative management, but not every presentation should follow the same pathway. The decision to refer for specialist or surgical assessment depends on the type of TOS, neurological findings, severity and progression of symptoms, functional limitations, and response to conservative care.
Progressive Neurological Deficits
Significant or progressive muscle weakness, muscle wasting, or objective neurological loss changes the clinical picture.
The 2024 INTOS consensus recommends conservative management as first-line treatment for most nTOS presentations, but identifies significant muscle atrophy or weakness as reasons to consider surgery without first completing the usual three-to-six-month trial of conservative treatment.
These patients warrant timely specialist assessment rather than repeatedly extending conservative treatment while neurological function deteriorates.
Persistent Neurogenic TOS
For patients without significant motor deficits, conservative treatment is generally appropriate before surgery is considered. The INTOS expert group recommends approximately three to six months of conservative management for most patients.
Referral may become appropriate when:
The diagnosis of nTOS is reasonably well established.
Important competing diagnoses have been investigated.
Symptoms continue to substantially interfere with work, sleep, recreation, or sport.
An appropriate course of rehabilitation has not produced sufficient functional improvement.
Failure of conservative treatment does not automatically mean that surgery is required. It should prompt reassessment of the diagnosis, contributing factors, rehabilitation program, and available treatment options.
Venous TOS
Venous Thoracic Outlet Syndrome requires a different approach.
Sudden arm swelling, cyanosis, heaviness, prominent superficial veins, or symptoms suggesting upper-extremity venous thrombosis require medical and vascular assessment. In effort-related thrombosis, sometimes referred to as Paget-Schroetter syndrome, management may involve anticoagulation, thrombus-directed treatment, and subsequent thoracic outlet decompression depending on the individual presentation.
This is not a condition that should simply be treated as a musculoskeletal problem.
Arterial TOS
Arterial TOS is uncommon but potentially serious. Findings such as a cool or pale hand, ischemic pain, arterial insufficiency, or evidence of embolization or thrombosis require prompt vascular investigation.
Acute arterial thrombosis or distal embolization can threaten the viability of the limb and may require urgent intervention.
What Does Surgery Involve?
Surgical treatment depends on the location and structures involved. Procedures may include scalenectomy, brachial plexus neurolysis, first-rib resection, removal of a cervical rib or fibrous band, and pectoralis minor tenotomy in selected patients.
There is not complete agreement about which procedure should be performed in every case. For example, the INTOS workgroup did not reach consensus that the first rib must routinely be removed during surgery for primary nTOS. Surgical strategy should therefore be individualized according to the patient's anatomy, examination findings, location of compression, and surgeon's assessment.
Rehabilitation Still Matters After Surgery
Surgery addresses the structures believed to be contributing to neurovascular compression, but it does not eliminate the need for rehabilitation.
Postoperative rehabilitation may include range-of-motion exercise, neural mobility, scar management, progressive shoulder-girdle strengthening, and gradual restoration of functional activity. The INTOS workgroup specifically reached consensus that rehabilitation is useful following nTOS surgery.
Conclusion
Thoracic Outlet Syndrome is best understood as a group of neurovascular disorders rather than a single diagnosis. Distinguishing neurogenic, venous, and arterial TOS is essential because the examination, investigation, treatment, and urgency can differ considerably.
For neurogenic TOS, diagnosis depends on the overall clinical pattern rather than any single provocative test or imaging finding. A careful history, neurological and musculoskeletal examination, appropriate differential diagnosis, and selective use of further investigations provide the foundation for clinical decision-making.
For most patients with nTOS, conservative management focuses on education, appropriate modification of provocative activities, restoration of comfortable movement, progressive strengthening and endurance, neural mobility when indicated, and gradual return to functional demands. Manual therapy, including Motion Specific Release procedures, joint mobilization, and Fascial Expansions, may be incorporated when clinically relevant, but should support rather than replace active rehabilitation.
Most importantly, treatment should reflect the individual patient. A desk worker, musician, tradesperson, swimmer, or overhead athlete may share the same diagnosis while requiring very different rehabilitation strategies.
The goal is not simply to create more space within the thoracic outlet. It is to identify the structures involved, understand what provokes the patient's symptoms, recognize when further investigation is required, and progressively restore the capacity needed for everyday life, work, recreation, and sport.
References
Chim, H., Hagan, R. R., & INTOS Workgroup. (2024). Consensus recommendations for neurogenic thoracic outlet syndrome from the INTOS Workgroup. Plastic and Reconstructive Surgery Global Open, 12(8), e6107. PubMed
Dessureault-Dober, I., Bronchti, G., & Bussières, A. (2018). Diagnostic accuracy of clinical tests for neurogenic and vascular thoracic outlet syndrome: A systematic review. Journal of Manipulative and Physiological Therapeutics, 41(9), 789–799. PubMed
Habibollahi, P., Zhang, D., Kolber, M. K., & Pillai, A. K. (2021). Venous thoracic outlet syndrome. Cardiovascular Diagnosis and Therapy, 11(5), 1150–1158. PubMed Central (PMC)
Hock, G., Johnson, A., Barber, P., & Papa, C. (2024). Current clinical concepts: Rehabilitation of thoracic outlet syndrome. Journal of Athletic Training, 59(7), 683–695. PubMed
Huang, J., Lauer, J., & Zurkiya, O. (2021). Arterial thoracic outlet syndrome. Cardiovascular Diagnosis and Therapy, 11(5), 1118–1124. PubMed Central (PMC)
Illig, K. A., Donahue, D., Duncan, A., Freischlag, J., Gelabert, H., Johansen, K., Jordan, S., Sanders, R., & Thompson, R. (2016). Reporting standards of the Society for Vascular Surgery for thoracic outlet syndrome. Journal of Vascular Surgery, 64(3), e23–e35. PubMed
Khalilzadeh, O., Glover, M., Torriani, M., & Gupta, R. (2021). Imaging assessment of thoracic outlet syndrome. Thoracic Surgery Clinics, 31(1), 19–25. PubMed
Li, N., Dierks, G., Vervaeke, H. E., Jumonville, A., Kaye, A. D., Myrcik, D., Paladini, A., Varrassi, G., Viswanath, O., & Urits, I. (2021). Thoracic outlet syndrome: A narrative review. Journal of Clinical Medicine, 10(5), 962. PubMed
Lim, C., Kavousi, Y., Lum, Y. W., & Christo, P. J. (2021). Evaluation and management of neurogenic thoracic outlet syndrome with an overview of surgical approaches: A comprehensive review. Journal of Pain Research, 14, 3085–3095. PubMed
Teijink, S. B. J., Pesser, N., Goeteyn, J., Barnhoorn, R. J., van Sambeek, M. R. H. M., van Nuenen, B. F. L., Gelabert, H. A., & Teijink, J. A. W. (2023). General overview and diagnostic (imaging) techniques for neurogenic thoracic outlet syndrome. Diagnostics, 13(9), 1625. PubMed
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DR. BRIAN ABELSON, DC. - The Author
Dr. Brian Abelson is a chiropractor, author, and educator with more than 30 years of clinical experience in musculoskeletal care, rehabilitation, and sports performance. His educational work focuses on musculoskeletal conditions, human movement, sports biomechanics, and evidence-informed approaches to treatment and rehabilitation.
He is the developer of Motion Specific Release (MSR) and Clinical Director of Kinetic Health in Calgary, Alberta, Canada.
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