• Clinical science

Peripheral nerve injuries


Peripheral nerve injuries include a variety of conditions in which one or more peripheral nerves are damaged, leading to neurological deficits distal to the level of the lesion. Possible causes include systemic diseases (e.g., diabetes, autoimmune disease) and localized damage (e.g., trauma, compression, tumors). Peripheral nerve injuries may occur as isolated neurological conditions or, more commonly, in association with soft tissue, vascular, and/or skeletal damage. Patients with peripheral nerve injury may present with sensory deficits, loss of motor function, or a combination of both. Diagnosis is based on clinical evaluation, imaging techniques (x-ray, CT/MRI), and electrodiagnostic examination (e.g., nerve conduction study, EMG). Observation and conservative treatment (e.g., activity modification, splinting, electrical stimulation) are indicated in most closed injuries, which have a high rate of spontaneous recovery. Patients with open injuries or long disease courses may require surgical treatment. Recovery from peripheral nerve injury is often incomplete and patients may experience chronic pain.

Types of nerve damage

Classification of peripheral nerve injury is useful for determining the prognosis and choosing a treatment strategy.

  • Neuropraxia
    • Compression injury; causing temporary disruption of nerve conduction
    • The whole nerve remains structurally intact.
    • Good prognosis with complete recovery of nerve function
  • Axonotmesis
    • The axon is damaged but the perineurium and epineurium remain intact.
    • Leads to central chromatolysis
      • Definition: the reaction of a neuronal cell body in response to an axonal injury
      • Characteristics:
        • Swelling of the neuronal body
        • Dispersion of the Nissl bodies
        • Displacement of the nucleus to the periphery
      • Function: These changes reflect an increase in protein synthesis in an effort to restore the integrity of the damaged axon.
    • Results in Wallerian degeneration
      • Definition: an active neuronal degeneration process in response to axonal injury
      • Characteristics
      • Function
        • To clear axonal debris and prevent scarring
        • Facilitate targeted reinnervation and functional recovery of tissues previously innervated by that axon before injury
    • Good chance of at least partial recovery
  • Neurotmesis
    • Complete nerve transection
    • Connective sheath damage
    • The chances of recovery are very poor without surgical repair.
  • Traumatic neuroma: benign, painful nodular thickening caused by nerve regeneration at the site of different forms of nerve injury


Nerve injuries in the upper body

Brachial plexus injuries

Erb palsy

Klumpke palsy

Peripheral nerve injuries in the upper extremity

Injured nerve Nerve roots Common causes Motor deficits Sensory deficits
Axillary nerve injury
  • C5–C6
Musculocutaneous nerve injury
  • C5–C7
  • Trauma
  • Upper trunk compression (e.g., Erb palsy)
Median nerve injury
  • C5–T1
  • Palmar aspect of thumb, index and middle fingers, lateral ring finger
Radial nerve injury
  • C5–T1
  • Dorsal aspect of thumb, index, and middle fingers, lateral ring finger

Ulnar nerve injury

  • C7–T1

Peripheral nerve injuries in the cervicothoracic region

Injured nerve

Innervated muscles

Common causes

Motor deficits

Suprascapular nerve injury

Thoracodorsal nerve injury

Long thoracic nerve injury

  • Axillary surgery (e.g., lymph node dissection during mastectomy)
  • Stab wounds
  • Carrying a heavy backpack for a long time

Dorsal scapular nerve injury

  • Isolated injury is uncommon; usually accompanies injury to the scalene muscles

Phrenic nerve injury

  • Diaphragm
  • Elevation of the diaphragm on the side of the phrenic nerve lesion → ↓ pulmonary and cardiac function

"C3, 4, 5 keeps the diaphragm alive"


Nerve injuries in the lower body

Injured nerve

Nerve roots

Common causes

Motor deficits

Sensory deficits
Superior gluteal nerve injury
  • L4–S1
  • Iatrogenic injury due to intramuscular injections in the superomedial region
  • None
Inferior gluteal nerve injury
  • L5–S2
  • None

Femoral nerve injury

  • L2–L4
  • Direct injury (trauma)
  • Prolonged pressure on the nerve: psoas hematoma, aortic or iliac aneurysms or tumors
  • Iatrogenic: pelvic, abdominal, or spinal surgery; femoral line placement
Lateral femoral cutaneous nerve injury (meralgia paresthetica)
  • L2–L3
  • Compression at the level of the inguinal ligament, caused by:
    • Increased intra-abdominal pressure (e.g., pregnancy, obesity, ascites)
    • External compression (e.g., tight belts, pants, or compression dressings)
    • Local compression (e.g., tumors, hematomas)
  • None
Obturator nerve injury
  • Paralysis of hip adductors
Sciatic nerve injury
  • Lower leg and foot
Tibial nerve injury
  • Paralysis of foot flexors → inability to walk on the toes or balls of the feet; inability to invert foot
Common peroneal nerve injury
  • L4–S2
  • Fracture of the fibular head
  • Compression: tight casts, sitting cross-legged, Lithotomy position during surgery
Sural nerve lesion
  • None
  • Posterolateral side of the lower leg, the lateral border of the foot, and a small area under the heel

TIPPED = tibial nerve injury versus peroneal nerve injury: TIP = Tibial → damaged foot Inversion, Plantarflexion; PED = Peroneal → damaged foot, Eversion, Dorsiflexion



The diagnosis of peripheral nerve injuries is based on a thorough clinical history, neurological examination, and, in some cases, diagnostic tests (e.g., x-ray if fracture is suspected).

  • Imaging
    • Plain x-ray: detection of compression or transection due to dislocated bone or fracture segments
    • CT/MRI: evaluation of causes like nerve tumors, avulsions, and focal soft tissue pathologies
  • Electrodiagnostic studies


Nerve repair

Conservative treatment

  • Observation and expectant management in closed injuries of the nerve, which have a high rate of spontaneous recovery
  • Activity modification (e.g., avoid sports or activities that increase likelihood of further nerve injury)
  • Splinting: prevents stiffness and contractures of joints; supports residual nerve functionality and reinnervation
  • Electrical stimulation: supports the regeneration of the proximal axons and reinnervation of the denervated muscles after surgical nerve repair
  • Drug therapy: treatment of chronic neuropathic pain following peripheral nerve injury (e.g., gabapentin); used in combination with surgical treatment to enhance remyelination and motor regeneration (e.g., lithium)
  • Analgesia: infiltration with local anesthetics

Surgical repair

  • Indications
    • Open, non-contaminated, sharp injuries; concomitant vascular injuries → immediate surgical exploration and repair
    • Open, contaminated injuries; postreduction palsy → early surgical exploration and repair (within 3 weeks)
    • Patients without clinical or electromyographic signs of spontaneous recovery → delayed surgical exploration and repair (within 3 months)
  • Procedures
    • Nerve repair (neurorrhaphy): reconstruction of nerve continuity
    • Tendon transfer: A tendon from a sufficiently powerful muscle is redirected towards another tendon in order to restore its motion and function.
    • Nerve transfer: An intact healthy nerve is redirected towards a denervated nerve in order to restore the innervation of its target organ.


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last updated 09/12/2020
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