What could be causing my wrist to drop when I try to lift my hand, given my history of spinal cord injury and potential motor strength condition?

Wrist Drop: Radial Nerve Palsy

You have radial nerve palsy causing wrist drop, which is the inability to extend your wrist and fingers against gravity when your forearm is supported. This is a peripheral nerve injury, not a spinal cord problem, based on your isolated unilateral presentation 1.

Clinical Presentation Confirms Peripheral Nerve Injury

Your specific symptom pattern—normal wrist position when resting on a table but inability to lift the hand—is the classic presentation of radial nerve dysfunction 1. This differs fundamentally from spinal cord pathology, which would cause:

• Bilateral hand weakness affecting both hands simultaneously 2
• Lower extremity involvement with gait disturbance 2
• Hyperreflexia and sensory level changes below the compression 2
• Multiple muscle group involvement including biceps, triceps, wrist extensors, and finger flexors on both sides 2

The absence of these findings effectively rules out your spinal cord injury as the cause of this specific wrist drop 2, 1.

Immediate Diagnostic Steps

Obtain high-resolution ultrasound of the radial nerve from the spiral groove through the forearm to identify the exact site and nature of injury 1. If ultrasound is equivocal, proceed to MRI with dedicated neurography sequences for superior soft-tissue detail 1.

Key examination findings to document:

• Test for isolated wrist drop without upper motor neuron signs (no hyperreflexia, no Babinski sign) which confirms peripheral rather than central pathology 1
• Assess all upper extremity myotomes systematically to ensure no other nerve roots are involved 2
• Check for sensory changes in the radial nerve distribution (dorsal first web space) 1

Management Protocol

Initiate aggressive physical therapy immediately focusing on wrist and finger extension exercises 1. The American Heart Association emphasizes starting rehabilitation without delay, as physical exercise promotes neuronal recovery through elaboration of neurotrophic factors even in nerve injuries 3.

Splinting Requirements

• Maintain wrist in 20-30 degrees of extension to prevent overstretching of denervated muscles 1
• Use wrist splinting in neutral position to prevent contractures 1
• Splinting is critical because denervated muscles are vulnerable to permanent shortening

Pain Management

Use topical NSAIDs as first-line treatment for localized pain and inflammation if there was a precipitating injury 1.

Common Causes to Investigate

The most frequent etiologies of radial nerve palsy include:

• Compression in the spiral groove from prolonged pressure (Saturday night palsy) 1
• Post-injection injury if recent intramuscular injections were administered 1
• Fracture-related injury particularly humeral shaft fractures 1
• Compression at the radial tunnel in the forearm 1

Critical Pitfall to Avoid

Do not assume this wrist drop is related to your spinal cord injury history 2, 1. Central cord syndrome from your prior injury would affect hands bilaterally with lower extremity sparing, not cause isolated unilateral wrist drop 1. The presence of isolated wrist drop without upper motor neuron signs definitively points to peripheral nerve injury 1.

Prognosis Considerations

Recovery depends on the severity and mechanism of nerve injury. Nerve conduction studies should be normal acutely but may show abnormalities after 2-3 weeks if axonal injury occurred 1. Most compressive radial neuropathies recover with conservative management over 6-12 weeks if the nerve remains in continuity 1.