Page created on October 26, 2021. Last updated on December 15, 2021 at 09:20

Summary

• Nerve injuries are classified according to severity. From least to most severe they’re neuropraxia (focal demyelination), axonotmesis (axon cut), and neurotmesis (nerve cut). Tinel sign may be positive. Radial nerve palsy causes drop hand, while ulnar nerve palsy causes claw hand. Diagnosis involves neurological examination, EMG, and ENG.
• Surgical nerve repair is indicated for neurotmesis and visibly damaged nerves. If the transection is sharp, immediate nerve repair is performed. If the transection is blunt, nerve repair should be delayed. If the nerve ends cannot be brought together without tension, a nerve graft should be used (from sural nerve).

Nerve injuries of the hand

Etiology

Nerve injuries of the hand may be primary or secondary:

• Primary
  • Trauma to nerve
  • Trauma to nearby bone/joint
• Secondary
  • Infection
  • Scar
  • Callus
  • Vascular complications

Classification

We can classify nerve injuries according to their severity. From least to most severe:

• Neuropraxia
  • Minor contusion/compression of nerve
  • Focal demyelination
  • Complete recovery expected in days or weeks
• Axonotmesis
  • Crush or stretch injury of nerve
  • Axon is cut but endoneurium and perineurium intact
  • Recovery expected in months or years
• Neurotmesis
  • Sharp, traction, or percussion injury of nerve
  • Nerve is completely cut
  • Recovery not expected without surgery

Clinical features

Typical symptoms of nerve injuries include decreased sensation and weakness or paralysis in the area and muscles supplied. Tinel sign may also be positive, which involves a tingling sensation when tapping on the nerve.

Radial nerve palsy causes a drop hand, where the hand cannot be dorsiflexed. Sensory symptoms on dorsal arm and forearm.

Ulnar nerve palsy causes a claw hand, where the 4^th and 5^th fingers are flexed but the others extended. Sensory symptoms on palmar 1/3 of the hand, including the 5^th digit and half of the 4^th digit, as well as the medial half of the dorsal hand.

Median nerve palsy causes sensory symptoms on the lateral 2/3 of the palm of the hand, including half of the 4^th digit, and digits 1 – 3. Motor symptoms depend on the level of the lesion.

Diagnosis and evaluation

Examination of nerve injuries involves physical examination of sensation and muscle strength, as well as objective tests like electromyography and nerve conduction studies (electroneurography).

Immediate and delayed nerve repair

Introduction

After traumatic nerve injury, surgical repair is often indicated. However, immediate repair is not always appropriate; in many cases, delaying the repair a few weeks or months may be better. However, nerve repair should not be delayed more than six months, as beyond that time irreversible changes occur.

Indications

Conservative treatment is indicated for:

• Nerve injuries with neurapraxia or axonotmesis

Delayed repair is indicated for:

• Nerve injuries with neurotmesis
• Open injuries with blunt transection

Immediate repair is indicated for:

• Open injuries with sharp (clean) transection

Grafts

If the gap between the nerve ends is large so that they cannot be brought together without tension, a nerve autograft or allograft should be used. Graft may be from the sural or antebrachial cutaneous nerves. If the ends can be brought together without tension graft is not necessary. However, it’s important to avoid tension on the nerve.