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Peripheral nerve injuries / palsies

Medicine > Neurosciences

Background knowledge 🧠

Definition

  • Peripheral nerve injuries refer to damage to the peripheral nerves, resulting in loss of function.
  • Palsies describe the paralysis or severe weakness of muscles due to nerve damage.

Epidemiology

  • Common in trauma, particularly in motor vehicle accidents and falls.
  • Higher incidence in males due to higher risk exposure.
  • Occupational hazards also contribute to prevalence.

Pathophysiology

  • Nerve injury can be neuropraxia (temporary block), axonotmesis (axon damage), or neurotmesis (complete severance).
  • Inflammation, ischemia, and mechanical disruption are common mechanisms.
  • Degeneration and regeneration processes affect recovery.

Aetiology/Causes/Risk factors

  • Trauma: fractures, lacerations, crush injuries.
  • Compression: carpal tunnel syndrome, thoracic outlet syndrome.
  • Inflammation: Guillain-Barré syndrome.
  • Systemic diseases: diabetes mellitus, rheumatoid arthritis.
  • Iatrogenic: surgical complications, injections.

Types

  • Brachial plexus injuries: Erb’s palsy, Klumpke’s palsy.
  • Radial nerve palsy: wrist drop.
  • Ulnar nerve palsy: claw hand.
  • Median nerve palsy: carpal tunnel syndrome, ape hand.
  • Peroneal nerve palsy: foot drop.
  • Facial nerve palsy: Bell’s palsy.

Clinical Features 🌡️

Symptoms

  • Numbness and tingling (paresthesia).
  • Muscle weakness or paralysis.
  • Pain, often described as burning or sharp.
  • Loss of sensation or altered sensation.
  • Muscle atrophy over time.
  • Difficulty with specific movements or tasks.

Signs

  • Visible muscle wasting.
  • Decreased or absent reflexes.
  • Postural deformities (e.g., wrist drop, claw hand).
  • Trophic changes (dry skin, hair loss).
  • Abnormal gait (e.g., foot drop causing high-stepping gait).
  • Positive Tinel’s sign at the site of injury.
  • Weakness in specific muscle groups innervated by the affected nerve.

Investigations 🧪

Initial tests

  • Clinical history and physical examination.
  • Electromyography (EMG) to assess muscle electrical activity.
  • Nerve conduction studies (NCS) to evaluate the speed of electrical impulses through the nerve.
  • Imaging studies like X-rays or MRI to identify structural causes.
  • Ultrasound to visualize nerve damage.

Diagnostic tests

  • MRI for detailed images of soft tissue and nerve pathways.
  • High-resolution ultrasound to assess nerve continuity and structure.
  • Blood tests to rule out metabolic causes (e.g., diabetes).
  • Lumbar puncture if inflammatory or infectious etiology is suspected.
  • Biopsy of the nerve in rare cases where diagnosis is uncertain.
  • CT scan if bony abnormalities are suspected.

Management 🥼

Management

  • Physical therapy to maintain muscle strength and prevent contractures.
  • Occupational therapy for adaptive techniques and equipment.
  • Pain management with medications (NSAIDs, anticonvulsants, antidepressants).
  • Surgical intervention for nerve repair or decompression.
  • Splinting or bracing to support affected limbs.
  • Addressing underlying causes (e.g., glycemic control in diabetes).
  • Patient education on injury prevention and management.
  • Regular follow-up to monitor recovery and adjust treatment.

Complications

  • Chronic pain and neuropathic pain.
  • Permanent muscle weakness or paralysis.
  • Joint contractures and deformities.
  • Functional impairments and disability.
  • Psychological effects such as depression and anxiety.
  • Infections from open wounds or surgical sites.

Prognosis

  • Depends on the severity and type of nerve injury.
  • Neuropraxia generally has a good prognosis with full recovery.
  • Axonotmesis may require months to years for recovery.
  • Neurotmesis often requires surgical intervention and may not fully recover.
  • Early intervention and rehabilitation improve outcomes.
  • Regular follow-up is essential to monitor progress.

Key points

  • Peripheral nerve injuries can lead to significant functional impairments.
  • Prompt diagnosis and treatment are crucial for optimal recovery.
  • Multidisciplinary approach is essential for management.
  • Regular monitoring and follow-up are necessary to prevent complications.
  • Patient education on self-care and prevention is important.

Neurosciences

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