Case of The Month – Thoracic Outlet Syndrome in a Competitive Tennis Player

Diagnosis, Rehabilitation and Return to Sport

As tennis season continues, with the US Open taking place next month, racket sport participation soars; closely mirrored by the incidence or upper limb and trunk injuries. Distinguishing between different upper limb pathologies can be challenging in clinical practice. 

This case describes a case of arm pain in a professional tennis player. 

Clinical Presentation

I had the pleasure of seeing this patient in my clinic this month. Here is an outline of the clinical presentation.

History

• A 27-year female presents with aching in the upper arm on dominant arm
• Occurs when playing tennis, particularly after >30mins of match play
• Feels that serve that and forehand specifically make the symptoms worse
• Pain is described as heaviness in upper arm and dull aching
• Patient first noticed symptoms over 6 months ago with gradual progression
• No history of vestibular symptoms or headaches

Activities of daily living

• Has also noticed similar sensations when carrying heavy tennis bag with strap over shoulder
• Sometime sleep is disrupted with heaviness in right arm, particularly when in “arm above head” position

Past Medical History 

• No history of trauma to neck, shoulder or upper limb.

Drug History 

• Nil of note
• Not on contraceptive pill

Exercise History

Professional tennis player with regular tennis training, match play and strength and conditioning. Player is increasing tennis volume as getting ready for grass court session. 

Clinical Examination

• Patient is right hand dominant. 
• Visual Inspection: Muscle hypertrophy in right upper scalenes, trapezius, deltoid and scapular girdle consistent with a right-handed tennis player
• Range of Motion: Marked restriction into internal rotation of the right shoulder (GIRD), protraction of the right scapular in resting position with medial winging of the inferior medial border of the scapular on abduction. Shoulder flexion and thoracic rotation maintained.
• Strength Testing: Force decks testing reveals shoulder ER:IR ratio of 1.4 (ideal ratio 1)
• Neurological Exam: 
  • No myotome weakness or loss of sensation in dermatomes of upper limb. No intrinsic hand wasting.
  • Full range of movement of the cervical spine pain free.
  • Upper limb tension tests (median bias in particular) are more symptomatic on the right than left side
  • Costoclavicular compression and Roo’s test reproduces symptom in right arm
• Vascular assessment:
  • Adson and reverse Adson test negative
  • No signs of venous congestion in the upper limb
  • No signs of peripheral arterial disease, strong pulses with arm down

Bedside Diagnostic Ultrasound 

• There is no abnormality of the right shoulder.
• The brachial plexus travels freely through the interscalene, subcostal and sub-coracoid spaces. 
• The anterior scalene muscle (ASM) appears bulky with greater cross-sectional area than middle scalene muscle. Manual pressure over the brachial plexus at the interscalene junction reproduces symptoms immediately. 

Differential diagnosis and clinical reasoning

1. Neurogenic thoracic outlet syndrome (nTOS). 

This seems the likely diagnosis given symptoms are correlated with use of the arm (particularly overhead activity), crescendo and with thoracic outlet clinical signs (Roo’s, Wright and costoclavicular compression). Softer clinical signs such as bag/bra strap compressing the subcoastal are also point to this diagnosis. Neurogenic TOS can either occur due to functional causes or structural. It is important to rule out and compressive brachial plexus lesions with imaging (e.g. cervical rib, neck/lung mass)

2. Venous thoracic outlet syndrome (vTOS). 

Although neurological thoracic outlet and venous usually coincide, this patient does not demonstrate any signs of significant venous compromise e.g. limb swelling, purple colour change. If these symptoms where present urgent investigation including venous doppler should be considered to rule out subclavian deep vein thrombosis (DVT). DVT is more commonly after trauma (e.g. tennis ball in the neck) or with patient on hypercoagulable medications (combined contraceptive pill being common in this age group).

3. Cervical nerve root injury.  

This must always be considered as nerve root impingement also presents with radicular pain also exacerbated by activity. Neural tension signs are also positive. Further examination and palpation of the cervical spine can help identify a localised impingement however imaging is usually required. 

4. Shoulder injury. 

Shoulder driven pathologies can also present with fatigue and sensation of numbness in the arm/hand. Common pathologies that need to be excluded in an elite tennis player include rotator cuff injury, labral pathology and humeral bone stress. 

Diagnostic Imaging

An MRI scan was recommended for further investigation. 

MRI is used for Thoracic Outlet Syndrome (TOS) because it provides detailed images of the soft tissues, including muscles, blood vessels, nerves, and surrounding structures in the thoracic outlet area. 

This helps identify any anatomical abnormalities, such as muscle hypertrophy, fibrous bands, or cervical ribs, that may be compressing the nerves or blood vessels. 

Additionally, MRI can assess vascular involvement and nerve inflammation, and also helps to rule out other potential pathologies and conditions.

MRI  

This MRI follow the cervical nerve routes from the cervical spine to the axilla with no evidence on compression. This would indicate a functional thoracic outlet syndrome over structural.  

Diagnostic Ultrasound

US shows a 50% reduction in arterial volume in the right subclavian artery in the arms up position and 20% in the left. Note: reduction in artery volume and flow is normal phenomena in the arms up position due to gravity. Anything above 50% however would usual indication a functional or structural obstruction. 

Discussion

This player presented with neurogenic thoracic outlet syndrome with no structural cause found on MRI. This is a relatively common phenomena in overhead athletes usually due to hypertrophy of the scalenes, sternocleidomastoid, trapezius and pectoralis of the dominant arm. Poor scapulothoracic mechanics also play a significant contributing factor. 

Neurogenic thoracic outlet can present with a variety upper limb symptoms including;

• Weakness/Fatigue in upper arm (e.g., when lifting objects)
• Weakness in hand and wrist (e.g., when gripping)
• Issues with fine control and hand dexterity (e.g., doing up buttons)

Other signs can be helpful in working out whether the cause is arterial or venous including

• Temperature change
• Colour change 
• Pins and needles
• Absent pulse
• Swelling in hand

A full clinical assessment of TOS must include:

• General observations
• Visual inspection
• Cervical and thoracic spine assessment
• Scapular and shoulder assessment
• Vestibular assessment
• Neurological assessment
• Vascular assessment
• Special tests and Functional movements 

When making a diagnosis it is important to consider whether nTOS is functional or structural in origin. The diagram below comments on some of the key consideration for both groups. 

Some patients have a mixed picture. 

Imaging modalities should include:

• MRI cervical spine and brachial plexus
• Arterial/Venous doppler scan upper limb with varying arm positions
• Veno/Arteriogram can be used in cases where severe vascular obstruction is note (see below)

Management and Rehabilitation

Rehabilitation of functional nTOS is multifaceted and complex. 

The principal aim is to reduce neural compression in:

• Inter-scalene triangle
• Thoraco-coraco-pectoral space
• Costoclavicular space

Common rehabilitation strategies used to treat nTOS include:

• Cervical and head posture
• SCJ and First Rib Mobilisation
• Improving strength and releasing tension of Scalene, SCM and Upper Trapezius
• Releasing tension of the Thoraco-pectoral space
• Improving Scapular/GHJ biomechanics range, movement and rhythm
• Neural flossing techniques
• Vestibular rehabilitation
• Persistent pain psychology and management

Medical management would include:

• Medication to desensitise the nervous system (SSRIs, Tricyclics, anti-convulsant) 
• Botox injections into scalene, upper trapezius and pectoralis minor depending on the site of neural compression
• Scalenectomy/1^st rib removal/pectorals minor release in extreme cases

Summary and Key Learning Points

This case highlights the complex and multifactorial nature of neurogenic thoracic outlet syndrome (nTOS) in an elite-level tennis player. Despite no structural cause on MRI, the patient’s presentation was consistent with functional nTOS, driven by muscle hypertrophy and altered scapular mechanics due to sport-specific demands. 

Key diagnostic learning points include the importance of thorough clinical examination, including postural, neurological, vascular, and scapulothoracic assessments, alongside the use of imaging to rule out structural or vascular causes.

For clinicians assessing athletes with upper limb pain, particularly those in overhead sports, nTOS should be considered as part of the differential diagnosis, especially when symptoms include fatigue, heaviness, or weakness in the arm during or after activity. 

Imaging such as MRI and diagnostic ultrasound can help distinguish between structural and functional causes and guide management.

Successful rehabilitation requires a holistic and multidisciplinary approach, addressing postural alignment, neural tension, scapular control, and strength imbalances. Awareness around patient pain perception and other neuromuscular drivers (e.g. stress, anxiety, poor diet) is also key.

Early recognition and referral can prevent chronicity and allow athletes to return to sport safely and efficiently.