Why is my left arm feeling heavy after a recent needle injury to the forearm and complaints of paresthesia?

Left Arm Heaviness Following Forearm Needle Injury with Paresthesia

You need urgent evaluation to rule out compartment syndrome, nerve injury, or vascular compromise—this presentation with heaviness and paresthesia after forearm trauma requires immediate clinical assessment for the "4 P's" (pain, pain with passive stretch, paresthesia, and paresis) and should not be dismissed as benign. 1

Immediate Clinical Assessment Required

Critical Warning Signs to Evaluate NOW

• Pain with passive stretch of fingers/wrist - This is an early and reliable sign of compartment syndrome, far more important than late signs like pulselessness or pallor 1
• Progressive paresthesia - Worsening numbness or tingling suggests evolving nerve compression or ischemia 1
• Muscle weakness (paresis) - Test grip strength and finger/thumb extension immediately 1, 2
• Compartment tension - Palpate the forearm for firmness or swelling 1

Critical pitfall: Do not wait for pulselessness or pallor—these are late signs indicating irreversible damage has likely occurred 1

Repetitive Monitoring Protocol

If any compartment syndrome risk factors are present (needle injury causing hemorrhage or tissue trauma), clinical signs should be investigated every 30 minutes to 1 hour during the first 24 hours 1

Differential Diagnoses to Consider

1. Compartment Syndrome (Most Urgent)

• Needle injury can cause hemorrhage into a closed fascial compartment 1
• Compartment pressure >30 mmHg or differential pressure (diastolic BP minus compartment pressure) <30 mmHg confirms diagnosis 1
• Treatment is early fasciotomy if diagnosed—delay leads to permanent nerve and muscle damage 1

2. Direct Nerve Injury from Needle

• Penetrating injuries to the forearm can cause peripheral nerve transection or partial injury 2
• Loss of finger/thumb extension with intact wrist extension suggests posterior interosseous nerve (PIN) injury 2
• Paresthesia patterns help localize which nerve is affected 3

3. Hematoma with Nerve Compression

• Needle injury can create expanding hematoma compressing adjacent nerves 1
• Presents with progressive heaviness, swelling, and paresthesia 1
• Ice application immediately after injury may limit hematoma size 1

4. Vascular Compromise

• Though less likely with isolated needle injury, arterial or venous injury must be excluded 1
• Check radial pulse, capillary refill, and skin color/temperature 1

Diagnostic Workup

Initial Imaging

• Plain radiographs of the forearm (AP and lateral views) to exclude occult fracture or foreign body 1, 4
• Radiographs should be obtained even if no obvious bony injury suspected 1

Advanced Imaging if Indicated

• Ultrasound can evaluate for hematoma, nerve continuity, and vascular flow 1
• MRI without contrast if soft tissue injury (tendon, nerve, muscle) is suspected and initial workup is unrevealing 1

Compartment Pressure Measurement

• If clinical suspicion for compartment syndrome exists, measure compartment pressure directly 1
• Threshold for fasciotomy: pressure >30 mmHg or differential pressure <30 mmHg 1

Immediate Management

If Compartment Syndrome Suspected

• Remove any constrictive dressings immediately 1
• Do NOT elevate the limb—this reduces arterial inflow and worsens ischemia 1
• Urgent surgical consultation for fasciotomy if pressure criteria met 1
• Fasciotomy effectiveness decreases dramatically with time; benefits decline and complications increase the longer it is delayed 1

If Hematoma Present

• Apply ice to reduce swelling and pain 1
• Direct compression to any active bleeding sites without occluding distal outflow 5
• Rest the arm for at least one treatment cycle if significant infiltration occurred 1

If Nerve Injury Suspected

• Urgent referral to hand surgery or peripheral nerve specialist 2
• Complete nerve transection requires surgical exploration and repair for optimal functional outcome 2
• Document baseline motor and sensory function carefully 2

Common Pitfalls to Avoid

• Do not assume "just a needle stick"—penetrating forearm injuries can cause serious nerve damage requiring surgical repair 2
• Do not wait for classic "5 P's"—focus on the early "4 P's" (pain, pain with stretch, paresthesia, paresis); pulselessness and pallor indicate irreversible damage 1
• Do not elevate the limb if compartment syndrome suspected—this worsens ischemia 1
• Do not delay fasciotomy—every hour of delay increases risk of permanent disability 1

When to Seek Emergency Care

Go to the emergency department immediately if:

• Pain is severe or worsening, especially with finger/wrist movement 1
• Numbness or tingling is spreading or worsening 1
• You cannot move your fingers or grip objects 1, 2
• The forearm feels tight, swollen, or increasingly firm 1
• Skin color changes or the arm feels cold 1