What are the potential causes and treatment options for an adult patient experiencing burning sensations in the axillary (armpit) region and tingling down the left arm, possibly related to underlying conditions such as thoracic outlet syndrome, cervical radiculopathy, or peripheral neuropathy?

Burning Axillary and Tingling Down Left Arm

Primary Diagnosis and Immediate Action

This presentation most likely represents neurogenic thoracic outlet syndrome (nTOS) or cervical radiculopathy, and requires urgent clinical evaluation with specific provocative maneuvers and imaging to differentiate these conditions and rule out vascular compromise. 1, 2, 3

Differential Diagnosis Framework

Most Likely Diagnoses to Consider:

• Neurogenic Thoracic Outlet Syndrome (nTOS): Compression of the brachial plexus (primarily lower trunk) as it passes through the interscalene triangle, costoclavicular space, or subcoracoid space, presenting with burning pain and paresthesias radiating down the arm 2, 4

• Cervical Radiculopathy: Nerve root compression at the cervical spine level causing radiating arm pain and sensory changes, which can mimic TOS 3, 5

• Axillary Nerve Injury: Less common but presents with axillary region symptoms and can result from traction or blunt trauma 6

• Vascular TOS (vTOS): Compression of subclavian vessels causing arterial insufficiency or venous obstruction symptoms 2, 4

Critical Clinical Assessment

Key History Elements to Obtain:

• Provocative positions: Symptoms worsening with arm elevation, overhead activities, or specific neck positions suggest TOS rather than radiculopathy 2, 4

• Trauma history: Recent shoulder trauma or traction injury points toward axillary nerve injury or traumatic TOS 6

• Pattern of symptoms: Constant burning in axilla with intermittent tingling suggests neurogenic compression; positional symptoms favor TOS 2, 3

• Hand weakness or wasting: Painless wasting of intrinsic hand muscles is pathognomonic for true neurogenic TOS 2

Essential Physical Examination Maneuvers:

• Adson's test, Wright's test, Roos test: Provocative maneuvers that reproduce symptoms by compressing neurovascular structures in different positions, highly suggestive of TOS if positive 2, 4

• Spurling's test: Neck extension with rotation and axial compression reproducing arm symptoms indicates cervical radiculopathy rather than TOS 3

• Vascular assessment: Palpate radial pulse during provocative positions; pulse diminution suggests arterial TOS requiring urgent vascular imaging 2, 4

• Dermatomal sensory testing: Specific dermatomal pattern (C5-T1) helps localize cervical radiculopathy level 3

• Motor examination: Test deltoid (axillary nerve), intrinsic hand muscles (lower trunk TOS), and specific myotomal patterns (radiculopathy) 2, 3, 6

Diagnostic Workup Algorithm

First-Line Imaging:

MRI chest with and without contrast in neutral and stressed positions is the preferred initial imaging for suspected TOS, as it directly visualizes neural structures, evaluates space narrowing, and assesses for anatomical variants (cervical ribs, fibrous bands, scalene muscle variations) 1

• MRI provides superior soft tissue resolution compared to CT and can demonstrate brachial plexus compression 1

• Dynamic imaging in abducted/stressed positions increases diagnostic yield for positional compression 1

Alternative/Complementary Imaging:

• CT chest with IV contrast: Quantifies costoclavicular and interscalene space changes with provocative maneuvers and identifies bony abnormalities (cervical ribs), though lacks neural structure resolution 1

• CTA/CTV chest: Essential if vascular TOS suspected based on pulse changes, color changes in extremity, or venous distension; obtained in neutral and stressed positions 1

• Cervical spine MRI: Mandatory if Spurling's test positive or dermatomal pattern suggests radiculopathy to evaluate for disc herniation or foraminal stenosis 3, 5

Electrodiagnostic Studies:

• EMG and nerve conduction studies: Should be obtained within 4 weeks if axillary nerve injury suspected, or to differentiate TOS from cervical radiculopathy and peripheral entrapment neuropathies 3, 6

• These studies help localize the lesion and establish baseline for monitoring recovery 3, 6

Treatment Approach

Initial Conservative Management (First 3-6 Months):

Conservative treatment with physical therapy and exercise programs should be initiated first for neurogenic TOS and cervical radiculopathy, as the vast majority of patients recover without surgery 2, 6

• Physical therapy focusing on posture correction, scalene muscle stretching, and shoulder girdle strengthening 2, 4

• Activity modification avoiding provocative positions (overhead activities, prolonged arm elevation) 2

• Pain management with NSAIDs or neuropathic pain medications as needed 2

Indications for Surgical Referral:

• Vascular TOS: Requires urgent surgical consultation for subclavian vessel compression or thrombosis 2, 4

• True neurogenic TOS with progressive weakness: Particularly painless wasting of intrinsic hand muscles warrants earlier surgical consideration 2

• Failed conservative therapy at 3-6 months: Persistent disabling symptoms despite appropriate physical therapy 2, 4

• Axillary nerve injury without improvement: If no clinical or electromyographic improvement at 12 weeks, surgery should be performed within 3-6 months from injury for optimal results 6

Surgical Options When Indicated:

• Supraclavicular approach with scalenotomy: Preferred for neurogenic TOS when anterior scalene muscle impinges on brachial plexus 2, 4

• Transaxillary first rib resection: Provides greatest field of view for decompressing both vascular and neurogenic structures 2, 4

• Combined approaches: May be necessary for complex cases with multiple compression sites 4

Critical Pitfalls to Avoid

• Do not assume TOS diagnosis without proper workup: TOS is often overdiagnosed when the actual problem is cervical radiculopathy or peripheral entrapment neuropathy 3, 5

• Do not delay vascular imaging if pulse changes present: Arterial TOS can lead to thrombosis, embolization, and limb-threatening ischemia 2, 4

• Do not proceed with cervical spine surgery without ruling out TOS: Cases exist where patients were planned for anterior cervical discectomy when the actual diagnosis was arteriogenic TOS 5

• Do not rush to surgery for neurogenic TOS: Most patients improve with conservative management; surgery is reserved for true neurogenic TOS with objective findings or failed conservative therapy 2, 4

• Do not delay surgical repair beyond 6 months for axillary nerve injury: Results deteriorate significantly after this window due to motor end-plate degeneration 6