Why is my whole arm feeling heavy after a traumatic injury?

Arm Heaviness After Traumatic Injury: Urgent Evaluation Required

If your whole arm feels heavy after a traumatic injury, you need immediate evaluation to rule out compartment syndrome, vascular injury, or spinal cord injury—all of which can cause permanent disability or limb loss if not treated within hours.

Immediate Life-Threatening Concerns

Compartment Syndrome (First 24-48 Hours Critical)

• Most cases develop within the first 24 hours after trauma, but can occur up to 65 hours post-injury 1
• The "four P's" are your warning signs: pain (especially pain with passive stretch), paraesthesia (numbness/tingling), paresis (weakness), and pressure/tension in the arm 1
• Critical pitfall: Do NOT wait for pulselessness or pallor—these are late signs indicating irreversible damage 1
• Arm heaviness combined with progressive pain, numbness, or weakness requires emergency fasciotomy within 6-8 hours to prevent permanent muscle and nerve death 1

Vascular Injury

• Fractures and dislocations around the shoulder can injure the axillary or brachial arteries 2
• If you have arm heaviness with decreased pulses, coolness, or pallor, you need CT angiography immediately 2
• The ankle-brachial index (ABI) equivalent for arms—comparing blood pressure in the injured arm to the uninjured arm—should be <0.9 if vascular injury is present 2
• Vascular injuries require repair within hours to prevent limb loss 2

Spinal Cord Injury (Cervical Myelopathy)

• Arm heaviness with hand weakness, numbness in fingers, or burning sensations in the forearm suggests cervical spinal cord injury 2
• Even ground-level falls can cause spinal cord injury in patients with pre-existing cervical stenosis 2
• The illustrative case shows a 37-year-old who developed progressive arm weakness after a simple fall, requiring urgent decompression within 48 hours 2
• MRI of the cervical spine is mandatory if you have arm heaviness with hand dysfunction or bilateral symptoms 2

Secondary Urgent Concerns

Fractures Requiring Stabilization

• Plain radiographs are the mandatory first imaging study for any traumatic arm pain or heaviness 2
• Occult fractures can present initially as soft tissue swelling and arm heaviness before bruising appears 3
• If radiographs are normal but clinical suspicion remains high, CT without contrast is the next appropriate study 3
• Femoral and tibial shaft fractures should undergo definitive fixation within 24 hours, and similar principles apply to major arm fractures 2

Soft Tissue Injuries

• MRI without contrast is the gold standard for detecting muscle tears, tendon ruptures, and ligamentous injuries 2
• Distal biceps tendon rupture causes arm heaviness and weakness with elbow flexion 2
• Traumatic ruptures more commonly involve both heads of the biceps tendon compared to atraumatic ruptures 2
• MRI has 87.5% concordance with surgical findings for medial collateral ligament injuries and 90.9% for lateral collateral ligament injuries 2

Clinical Algorithm for Arm Heaviness After Trauma

Within First Hour:

1. Check for the "four P's" of compartment syndrome 1
2. Compare pulses and blood pressure between arms 2
3. Test hand grip strength and finger movements 2
4. Obtain plain radiographs of the entire arm 2

If Any Red Flags Present:

• Progressive pain despite rest → measure compartment pressures immediately 1
• Weak or absent pulses → CT angiography emergently 2
• Hand weakness with neck pain → MRI cervical spine urgently 2
• Obvious deformity or fracture → orthopedic consultation within hours 2

If Initial Workup Normal:

• Continue monitoring every 30-60 minutes for the first 24 hours 1
• Crush injuries, hemorrhagic injuries, or reperfusion scenarios require extended surveillance up to 65 hours 1
• If arm heaviness persists beyond 48 hours without improvement, obtain MRI without contrast to evaluate soft tissue structures 2

Special Populations

Sedated or Obtunded Patients

• Compartment pressure monitoring becomes critical when clinical examination is unreliable 1
• Threshold for surgical decompression should be lower in patients who cannot report pain 1

Patients with Pre-existing Cervical Stenosis

• Even minor trauma can cause devastating spinal cord injury 2
• The 76-year-old case demonstrates that some patients recover fully with conservative management, but the 37-year-old case shows others deteriorate despite surgery 2
• Early decompression within 48 hours may prevent permanent neurological deficit 2

Common Pitfalls to Avoid

• Never dismiss arm heaviness as simple muscle soreness after trauma—it can be the first sign of compartment syndrome 1
• Never wait for loss of pulses before acting—by that time, irreversible damage has occurred 1
• Never assume normal radiographs exclude serious injury—soft tissue injuries and early compartment syndrome have normal X-rays 2, 3
• Never delay imaging in patients with hand weakness after neck/shoulder trauma—cervical spinal cord injury requires urgent decompression 2