What are the common causes of left scapular pain?

Common Causes of Left Shoulder Blade Pain

Left scapular pain most commonly arises from musculoskeletal trauma (rotator cuff injuries, acromioclavicular sprains, fractures), nerve entrapment syndromes (dorsal scapular nerve, long thoracic nerve, spinal accessory nerve), cervical radiculopathy (particularly C6-C7), and neuralgic amyotrophy.

Traumatic and Musculoskeletal Causes

Trauma represents the predominant cause of acute shoulder and scapular pain 1. The key traumatic etiologies include:

• Fractures: Scapula, clavicle, or proximal humerus fractures
• Soft tissue injuries: Rotator cuff tears, acromioclavicular ligament injuries, labral tears
• Osseous contusions: Often visible only on MRI, not plain radiographs

These injuries disproportionately affect young adults and males, with incidence varying by activity level and sport participation 1.

Neurogenic Causes

Nerve-related pathology accounts for approximately 85% of cases presenting with scapular winging and pain 2, making this a critical diagnostic consideration:

Spinal Accessory Nerve Palsy (Most Common Neurogenic Cause)

• Accounts for the majority of neurogenic scapular dysfunction
• Most frequently occurs after neck surgery (17 of 29 cases in one series) 2
• Causes trapezius weakness and scapular winging

Long Thoracic Nerve Palsy (Second Most Common)

• Often follows strenuous physical activity (4 of 9 cases) 2
• Can occur as part of neuralgic amyotrophy with acute nocturnal shoulder pain followed by persistent weakness 3
• Causes serratus anterior weakness

Dorsal Scapular Nerve Entrapment

• Under-recognized and frequently overlooked cause of medial scapular border pain 4
• Most commonly entrapped where the nerve traverses the middle scalene muscle
• Presents with medial scapular pain, scapular dyskinesis, rhomboid weakness, and subtle winging 4
• Clinically mimics cervical radiculopathy, thoracic outlet syndrome, myofascial pain, and rotator cuff pathology 4

Cervical Radiculopathy

Cervical nerve root compression is an important cause of scapular pain that is often underappreciated:

• 72% of cervical radiculopathy studies report scapular pain as a symptom 5
• C7 radiculopathy shows the highest percentage of scapular pain descriptions, followed by C6 and C8 5
• Scapular pain may precede arm pain by several weeks in cervical radiculopathy 5
• Look for associated neck pain (88%), arm pain (85%), sensory disturbances, and reflex changes 5

Diagnostic Approach

Initial Evaluation

Plain radiographs are the preferred initial diagnostic modality 1. Look specifically for:

• Fracture patterns (scapula, clavicle, proximal humerus)
• Joint alignment abnormalities
• Scapular asymmetry or positioning

Advanced Imaging When Radiographs Are Normal or Indeterminate

MRI without contrast is the preferred next study 1 because:

• Acute trauma typically produces joint effusion, eliminating need for contrast
• Detects rotator cuff tears, osseous contusions, acromioclavicular sprains
• Identifies bone marrow edema and soft tissue injuries
• Superior for extraarticular soft tissue pathology 1

CT is best for characterizing scapular fracture patterns, particularly for assessing intraarticular extension, angulation, and lateral border offset 1.

Neurophysiological Testing

When neurogenic causes are suspected:

• Electromyography and nerve conduction studies support diagnosis but are operator-dependent and technically challenging 4
• High-resolution ultrasound may demonstrate nerve edema or muscle denervation 4
• These studies are essential to avoid misdiagnosis and inappropriate local treatment 3

Critical Pitfalls to Avoid

1. Do not assume all scapular pain is local shoulder pathology - systematic neurological assessment is essential 3
2. Do not overlook cervical spine pathology - examine for radicular symptoms, particularly when scapular pain precedes arm symptoms 5
3. Do not miss iatrogenic nerve injury - specifically inquire about recent neck surgery or procedures 2
4. Do not dismiss dorsal scapular nerve entrapment - it mimics multiple other conditions and requires high clinical suspicion 4

Examination Specifics

Examine the patient with torso uncovered, assess from front and back 6:

• Inspect for scapular winging at rest and with arm elevation
• Test trapezius strength (shoulder shrug against resistance)
• Test serratus anterior (wall push-up or forward punch)
• Test rhomboids (scapular retraction against resistance)
• Assess for sensory changes in dermatomal distribution
• Check reflexes (biceps for C6, triceps for C7)
• Perform scapular assistance test to predict treatment outcomes 6