Wrist Drop

Definition | Aetiology | Pathophysiology | Risk Factors | Signs and Symptoms | Investigations | Management

Definition

Wrist drop is the inability to extend the wrist and fingers due to dysfunction of the radial nerve, leading to a characteristic limp wrist posture.

Aetiology

Wrist drop is commonly caused by radial nerve injury, which may occur at different levels.

1. Peripheral Causes:

  • Radial nerve palsy: compression or injury along its course.
  • Saturday night palsy: prolonged compression of the radial nerve (e.g., sleeping with arm draped over a chair).
  • Humeral fracture: midshaft humerus fractures can injure the radial nerve.
  • Lead poisoning: can cause chronic radial nerve dysfunction.
  • Entrapment neuropathy: compression at the radial groove or wrist.

2. Central Causes:

  • Stroke: upper motor neuron lesion affecting radial nerve control.
  • Multiple sclerosis: demyelination affecting motor pathways.
  • Motor neurone disease: progressive muscle weakness affecting wrist extensors.

Pathophysiology

  • The radial nerve supplies the extensor muscles of the wrist and fingers.
  • Damage to the radial nerve disrupts these muscles, leading to an inability to extend the wrist.
  • Prolonged dysfunction can cause muscle atrophy and contractures.

Risk factors

  • Prolonged compression (e.g., sleeping on the arm).
  • Fractures of the humerus.
  • Alcoholism (associated with neuropathies and prolonged immobilisation).
  • Heavy metal exposure (e.g., lead poisoning).
  • Repetitive movements leading to radial nerve entrapment.

Signs and symptoms

Wrist drop is characterised by weakness in wrist and finger extension.

Motor Symptoms:

  • Inability to extend the wrist: the hand remains in a flexed position.
  • Weakness in finger extension: difficulty opening the hand.
  • Reduced grip strength: due to loss of wrist stabilisation.

Sensory Symptoms (If Sensory Fibres Are Affected):

  • Numbness over the dorsum of the hand.
  • Loss of sensation in the first web space (between thumb and index finger).

Investigations

  • Clinical examination: test wrist and finger extension strength.
  • Radial nerve conduction studies: assess nerve function and localise lesion.
  • Electromyography (EMG): detects denervation in affected muscles.
  • X-ray of the humerus: if fracture is suspected.
  • Lead levels: if lead poisoning is suspected.

Management

1. Conservative Management:

  • Physiotherapy: strengthening and stretching exercises.
  • Wrist splint: maintains functional position and prevents contractures.
  • Activity modification: avoiding pressure on the radial nerve.

2. Pharmacological Management:

  • Analgesia: NSAIDs for pain relief.
  • Neuropathic pain management: amitriptyline, gabapentin if needed.
  • Lead chelation therapy: if lead poisoning is identified.

3. Surgical Intervention:

  • Nerve decompression: if entrapment is the cause.
  • Radial nerve repair: in cases of traumatic nerve laceration.
  • Tendon transfer: for chronic, irreversible cases.

4. Long-Term Monitoring and Rehabilitation:

  • Regular physiotherapy to maintain mobility.
  • Follow-up for nerve recovery in cases of compression neuropathy.
NeurologymypanotesWrist Drop