Peripheral Nerve Injury

Aka: Peripheral Nerve Injury, Peripheral Nerve Entrapment, Neuropraxia, Axonotmesis, Neurotmesis

1. See Also
   1. Peripheral Neuropathy
   2. Overuse Syndromes of the Hand and Wrist
2. Definition: Categories of Peripheral Nerve Injury
   1. Neuropraxia
      1. Least severe Peripheral Nerve Injury
      2. Myelin fibers surrounding the axon are injured focally
      3. Axon and connective tissue sheath remain unharmed
      4. Limited duration of injury (typically days to weeks)
   2. Axonotmesis
      1. Axon injury
      2. Recovery over months and frequently incomplete nerve regeneration with residual deficit
   3. Neurotmesis
      1. Most severe Peripheral Nerve Injury and least common of the three nerve injury types
      2. Complete axon disruption
      3. Normal regeneration of the nerve is uncommon and signficant persistent deficit is the norm
3. Pathophysiology
   1. Mechanisms of nerve injury
      1. Direct pressure
      2. Repetitive microtrauma
      3. Stretch-induced ischemia
      4. Compression-induced ischemia
   2. Degree of nerve injury factors
      1. Severity of injury mechanism
      2. Duration of exposure to compression or other mechanism
4. Causes: General
   1. Compartment Syndrome
   2. Reflex Sympathetic Dystrophy
   3. Post-herpetic Neuralgia
5. Causes: Face
   1. Trigeminal Neuralgia
6. Causes: Upper Extremity
   1. Cervical Spine and Cervicobrachial (Axilla)
      1. Cervical Disc Disease
      2. Brachial Plexus Burner
   2. Shoulder
      1. Shoulder Band Syndrome (Reflex Sympathetic Dystrophy)
      2. Quadrilateral Space Syndrome (Axillary Nerve Injury)
      3. Long Thoracic Nerve Injury
         1. Injury: Direct blow to Shoulder or chronic repetitive overhead Shoulder traction (e.g. tennis, swimming, baseball)
         2. Symptoms: Diffuse Shoulder or Neck Pain with overhead activity
         3. Exam: Forward flexion weakness at Shoulder and Scapular winging
      4. Spinal Accessory Nerve Injury
   3. Elbow and Forearm
      1. Cubital Tunnel (Ulnar Nerve)
      2. Radial Tunnel (and related Posterior Interosseus Nerve Syndrome)
   4. Wrist and Hand
      1. See Overuse Syndromes of the Hand and Wrist
      2. Carpal Tunnel Syndrome (Median Nerve)
      3. Ulnar Tunnel Syndrome (Cyclist's Palsy)
      4. Handcuff Neuropathy (Radial Nerve)
7. Causes: Lower Extremity
   1. Lumbar Spine and buttock
      1. Lumbar Disc Disease
      2. Piriformis Syndrome (Sciatica)
   2. Anterior Pelvis and thigh
      1. Ilioinguinal Nerve Compression
      2. Meralgia Paresthetica
      3. Obturator Nerve Compression
   3. Ankle and Foot
      1. Tarsal Tunnel
      2. Morton's Neuroma
8. Symptoms
   1. Burning pain
   2. Numbness
   3. Paresthesias
   4. Motor Weakness
9. References
   1. Neal (2010) Am Fam Physician 81(2): 147-55 [PubMed]