What are the possible causes of localized right-sided scapular pain?

Localized Right-Sided Scapular Pain: Differential Diagnosis

Localized right-sided scapular pain most commonly arises from musculoskeletal causes including rotator cuff pathology, levator scapulae syndrome, dorsal scapular nerve entrapment, or scapular fracture, though cervical radiculopathy and referred visceral pain must also be considered. 1

Primary Musculoskeletal Causes

Rotator Cuff Pathology

• Rotator cuff tears, tendinopathy, or dysfunction frequently refer pain to the scapular region, particularly during overhead activities or throwing motions 1
• Pain typically worsens with arm elevation and may be accompanied by focal weakness and decreased range of motion during abduction with external or internal rotation 2
• Adults over 40 years are at higher risk due to degenerative changes, while younger athletes may develop secondary impingement from rotator cuff weakness combined with ligamentous laxity 1, 2

Levator Scapulae Syndrome

• Pain localized to the upper medial angle of the scapula that radiates to the neck and shoulder (rarely to the arm) is characteristic 3
• The dominant shoulder is affected in 82% of cases, predominantly in young females 3
• Movements that stretch the levator scapulae aggravate symptoms, and a trigger point with crepitation may be palpable 3
• Thermography shows increased heat emission from the upper medial scapular angle in over 60% of cases 3
• Anatomic variations in the levator scapulae insertion and associated bursitis between the scapula, serratus, and levator contribute to this syndrome 3, 4

Dorsal Scapular Nerve Entrapment

• Dorsal scapular nerve entrapment accounts for 52.7% of unilateral interscapular pain cases 5
• Nerve entrapment occurs at the scalenus medius or from stretch during overhead activities, causing nerve trunk pain from nociceptor sensitization 5
• Myofascial pain syndrome of the rhomboids with nerve entrapment by taut bands is another mechanism 5
• Scapular winging may develop (16.4% of cases), causing stretch of cutaneous medial branches of dorsal primary rami of thoracic spinal nerves 5

Scapular Fracture

• Direct trauma from falls or impacts can cause scapular fractures that are easily missed on conventional radiography 1
• CT is the best imaging modality for identifying and characterizing scapular fracture patterns, including intra-articular extension, angulation, and lateral border offset 6
• Three-dimensional reformatted CT images optimally visualize fracture displacement and angulation 6

Neurological Causes

Cervical Radiculopathy

• Cervical nerve root compression can refer pain to the scapular region, particularly from C8 radiculopathy which corresponds to the interscapular area 7, 8
• The medial branches of the dorsal ramus of cervical nerve roots innervate the intrascapular region, explaining the referred pain pattern 8
• Associated symptoms include numbness, tingling, weakness, or radiation down the arm in dermatomal distributions 7
• Cervical spine imaging should be obtained if clinical examination supports radiculopathy, with electrodiagnostic testing (sensitivity >80%, specificity 95%) if imaging is equivocal 7

Biomechanical Factors

Scapular Position and Muscle Strain

• Scapular depression maintains the upper trapezius in a lengthened position, causing excessive strain and peripheral nociceptive nerve sensitization 9
• Individuals with depressed scapula position demonstrate significantly lower pressure pain thresholds (19.0 vs 26.1 N/cm²) in the upper trapezius region 9
• Scapular dyskinesis—poor coordination of scapular movements during arm elevation—contributes to pain by failing to properly rotate upward and tilt posteriorly 2

Diagnostic Approach

Physical Examination

• Assess for focal weakness, decreased range of motion during abduction with external or internal rotation, and tenderness to palpation 1
• Evaluate for scapular winging, trigger points at the upper medial scapular angle, and pain with movements that stretch the levator scapulae 3, 5
• Test for cervical radiculopathy signs including dermatomal sensory changes, motor weakness, and provocative maneuvers 7

Imaging Strategy

• Begin with plain radiographs to exclude fracture, though scapular fractures are frequently missed 6, 1
• CT is the definitive study for scapular fractures, with three-dimensional reformations for surgical planning 6
• MRI without contrast is preferred for soft tissue evaluation including rotator cuff tears, bone marrow contusion, and capsular/ligament injuries 6, 1
• Ultrasound can detect rotator cuff abnormalities with sensitivity of 85% and specificity of 90%, equivalent to MRI for this evaluation 2
• Electrodiagnostic studies should be performed if dorsal scapular nerve entrapment is suspected, evaluating motor conduction and electromyography of rhomboid major and levator scapulae 5

Common Pitfalls

• Scapular fractures are easily overlooked on conventional radiographs—maintain high suspicion after direct trauma and obtain CT when clinical concern exists 6, 1
• Do not assume all scapular pain is musculoskeletal—cervical radiculopathy must be excluded, particularly when pain radiates or neurological symptoms are present 7, 8
• Dorsal scapular nerve entrapment is frequently underdiagnosed—consider this in cases of persistent unilateral interscapular pain, especially with overhead activities 5
• Thermography may aid diagnosis of levator scapulae syndrome when clinical findings are equivocal, showing increased heat emission in over 60% of cases 3