Lesions of radial nerves

LESIONS OF RADIAL NERVE:

TYPES OF RADIAL NERVE LESIONS
Above spiral Groove B/w spiral groove & lateral
Epicondyle
Below the elbow
(low radial nerve palsy)
Post. Interosseous Nerve Palsy
Total Palsy Elbow Extension spared Elbow & wrist extension spared Elbow, wrist I.P Joint
extension & sensation spared
CLINICAL FEATURES OF LESION
  • Injection palsy(Tetracycline injection)
  • Sensory loss over area supplied by posterior cutaneous nerve of forearm.
  • Wrist, thumb and finger extension is lost.
  • Crutch Palsy -involvement of triceps:- fracture dislocation of humerus & Wrist drop- fracture of Shaft of humerus(commnest in middle 3rd shaft#)( association with Holstein-Lewis type distal third fracture)
  • Saturday night palsy - Acute compression injury in spiral groove. The triceps is usually spared but the weakness conspicuous in the wrist and finger extensors, brachioradialis and supinator.Injury to radial nerve in lower part of spiral groove results in Anconeus muscle paralysis.
  • Long head of triceps is supplied by radial nerve before entering the radial groove. Medial head of triceps is supplied by the radial nerve before entering and while in the spiral groove. Lateral head of triceps is innervated by the radial nerve while in the groove. So if lesion occurs in radial groove long head of triceps are spared & thus it leaves extensions at elbow joint intact.
  • Inability to extend the metacarpophalangeal joints, owing to paralysis of the extensor digitorum communis muscle.
  • Muscles paralyses in radial nerve injury are brachioradialis, extensor carpi radialis longus and brevis, extensor digitorum and extensor pollicis longus but no triceps(Nerve supply to the triceps is proximal to the mid shaft level) are spared.
  • Low radial nerve palsy occurs when the radial nerve is injured at the level of elbow, so that the muscles supplied by the radial nerve in the distal arm (Brachioradialis and Extensor Carpi radialis longus ) are not affected. The muscles affected are finger extensors, extensor carpi radialis brevis & sensation on dorsum of hand.
  • Radial nerve injury cause anaesthesia over anatomical snuff box
  • In radial nerve injury only weakens (affects) abduction & extension movements of thumb and spares flexion, adduction & opposition
  • Radial sensory nerve entrapment (Wartenberg's disease):
  • Entrapment of superficial radial nerve as it emerges from beneath the edge of the brachioradialis tendon 6 cm proximal to the radial styloid.
  • Frequently associated with previous trauma.
  • The symptoms are pain and paraesthesia over the radial aspect of the dorsum of the wrist and hand.
  • Clinical features depend upon the site of lesion.
1) If lesion is high
  • Wrist drop, thumb drop and finger drop.
  • Inability to extend elbow, wrist, thumb & fingers (MP joint)
  • Patient can extend interphalangeal joints due to action of lumbricals and interossei.
  • Sensory loss over posterior surface of arm & forearm and lower lateral half of forearm.
2) If lesion is low
  • a) Type I
  • Wrist drop, thumb drop and finger drop.
  • Elbow extension is preserved.
  • Sensory loss over the dorsum of first web space.
b) Type II
  • Thumb drop and finger drop
  • Elbow and wrist extension is preserved
  • Sensory loss over the dorsum of first web space.
MANAGEMENT:
  • Cock-up splint is used for radial nerve palsy (extensors of wrist and metacarpophalangeal joints paralyzed)
Exam Question
  • Injection palsy(Tetracycline injection)
  • Injury to radial nerve in lower part of spiral groove results in Anconeus muscle paralysis.
  • If lesion occurs in radial groove long head of triceps are spared & thus it leaves extensions at elbow joint intact.
  • Radial nerve palsy produces an inability to extend the metacarpophalangeal joints, owing to paralysis of the extensor digitorum communis muscle. In radial nerve injury triceps(Nerve supply to the triceps is proximal to the mid shaft level) are spared.
  • Low radial nerve palsy occurs when the radial nerve is injured at the level of elbow, so that the muscles supplied by the radial nerve in the distal arm (Brachioradialis and Extensor Carpi radialis longus ) are not affected. The muscles affected are finger extensors, extensor carpi radialis brevis & sensation on dorsum of hand. Radial nerve injury cause anaesthesia over anatomical snuff box
  • Radial nerve injury only weakens (affects) abduction & extension movements of thumb and spares flexion, adduction & opposition
  • Cock-up splint is used for radial nerve palsy (extensors of wrist and metacarpophalangeal joints paralyzed)
  • In radial nerve injury Below the elbow low radial nerve palsy occurs.
  • Wrist drop- fracture is seen in radial nerve injury.
  • radial nerve injury is most common incase of # of middle 3rd of shaft of humerus.
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