In a child with acute shoulder pain, inability to use the arm, and normal plain radiographs, could this represent a traction (distraction) injury to the axillary nerve or brachial plexus?

Yes, this could absolutely be a traction (distraction) injury to the brachial plexus or axillary nerve

In a child with acute shoulder pain, inability to use the arm, and normal radiographs following a stretching mechanism, you must strongly consider and actively evaluate for a nerve injury—particularly to the axillary nerve or infraclavicular brachial plexus—as these injuries can occur without fracture or dislocation and require time-sensitive specialist referral.

Why This Diagnosis Must Be Considered

Traction injuries to the shoulder region nerves occur when the arm is forcefully stretched or pulled, causing excessive displacement of the humeral head relative to the glenoid. This mechanism can injure nerves through:

• Direct stretch/traction of nerve fibers beyond their elastic limit 1, 2
• Compression against bony or soft tissue structures during excessive displacement
• Ischemic injury if vascular structures are also compromised 3

The axillary nerve is particularly vulnerable because it wraps around the surgical neck of the humerus and can be stretched even without frank dislocation 4, 5. Recent evidence demonstrates that excessive dislocation distance (>49mm between inferior glenoid and humeral neck) significantly increases axillary nerve injury risk, and this can occur with rotator cuff tears even when the shoulder spontaneously reduces 5.

Critical Clinical Features to Assess

Immediate Neurological Examination Required:

Document these specific findings before any intervention:

• Deltoid function: Test shoulder abduction strength (axillary nerve motor)
• Lateral shoulder sensation: Pinprick over the "regimental badge" area (axillary nerve sensory) 4
• Elbow flexion/extension: Assess musculocutaneous and radial nerve function
• Hand intrinsic muscles: Test for lower trunk/medial cord involvement
• Wrist/finger extensors: Evaluate posterior cord function

The pattern of deficits localizes the injury:

• Isolated deltoid weakness + lateral shoulder numbness = axillary nerve injury 4, 3
• Multiple nerve deficits = cord-level or trunk-level brachial plexus injury 6, 3

Red Flags Requiring Emergency Escalation:

• Vascular compromise: Absent pulses, pallor, prolonged capillary refill (limb-threatening) 3
• Complete paralysis of the limb
• Progressive neurological deficit over hours
• Multi-nerve involvement suggesting cord/trunk injury 3

Imaging Algorithm After Normal Radiographs

Since radiographs are normal, MRI without contrast is the next appropriate study 7:

MRI Will Reveal:

1. Nerve signal abnormality: Increased T2 signal in injured nerves 8
2. Occult soft tissue injuries: Rotator cuff tears, capsular tears, labral injuries that accompany nerve stretch 7, 9
3. Bone marrow edema: Indicating occult fracture or contusion 7, 10
4. Muscle denervation changes: Edema in deltoid or other muscles suggesting nerve injury 8

MRI is superior to ultrasound for nerve injuries—ultrasound completely misses instability and has 0% sensitivity for detecting nerve traction injuries 9. MRI provides the global assessment needed and can identify the "terrible triad" (dislocation with spontaneous reduction + rotator cuff tear + nerve palsy) 5.

Management Timeline

Immediate (Emergency Department):

• Repeated neurological examination documented before and after any manipulation 3
• Gentle reduction if any subluxation present (do not delay for imaging if neurovascular compromise) 3
• Analgesia that allows examination without masking deficits 3
• Urgent orthopaedic consultation if red flags present

Early (Within 1 Month):

• Electrodiagnostic studies (EMG/NCS) at 3-4 weeks to confirm nerve injury and grade severity 4, 2
• Serial clinical examinations monthly to document recovery trajectory 11
• Physiotherapy and nerve stimulation during observation period 11

Surgical Window (3-6 Months):

Critical timing consideration: Most nerve injuries recover spontaneously (neurapraxia/axonotmesis), but complete nerve disruption requires surgery within 3-6 months for optimal outcomes 6, 3.

• If no clinical improvement by 3-4 months despite therapy, surgical exploration is indicated 11
• Nerve transfers (e.g., triceps nerve to axillary nerve) can restore function even in children 11
• Delayed surgery beyond 6 months significantly compromises recovery potential 6

Common Pitfalls to Avoid

1. Assuming normal radiographs exclude significant injury: Nerve injuries and spontaneously reduced dislocations are radiographically occult 9, 5

2. Failing to document baseline neurological exam: This is both a clinical and medicolegal necessity 3

3. Ordering ultrasound instead of MRI: Ultrasound misses nerve injuries and instability 9

4. Waiting too long for specialist referral: The 3-6 month surgical window is time-sensitive 6, 3

5. Missing concurrent vascular injury: Always assess pulses and perfusion—vascular compromise compounds nerve injury through ischemia 3

Pediatric Considerations

In children specifically:

• Physeal injuries may accompany nerve traction and are best seen on MRI 7, 10
• Earlier surgical intervention may be appropriate in selected pediatric cases for faster recovery 11
• Recovery potential is generally better in children, but complete disruptions still require timely surgery 11

Bottom line: Document detailed neurological examination now, obtain MRI shoulder without contrast as the next study 7, ensure monthly follow-up with repeat exams, and maintain a low threshold for specialist peripheral nerve service referral—particularly if no improvement by 3 months 6, 11, 3.