ULNAR NERVE INJURY

Injuries to Ulnar Nerve:
  • Mainly the type of nerve trauma depends on the mechanism of injury:
  • Neuropraxia
  • Axonotemesis
  • Neurotemesis
SITES OF NERVE INJURY:
  • The ulnar nerve is most commonly injured at the elbow, where it lies behind the medial epicondyle.The injuries at the elbow are usually associated with fractures of the medial epicondyle.
  • At the wrist, where it lies with the ulnar artery in front of the flexor retinaculum.The superficial position of the nerve at the wrist makes it vulnerable to damage from cuts and stab wounds
SIGN & SYMPTOMS: Injuries of the ulnar nerve at elbow:
Motor:

  1. The terminal phalanges of Ring & little fingers are not capable of being markedly flexed.
  2. The flexor carpi ulnaris( tightening of the tendon will be absent) and the medial half of the flexor digitorum profundus muscles( tendons to the ring and little fingers will be functionless) are paralyzed.
  3. The paralysis of the flexor carpi ulnaris can be observed by asking the patient to make a tightly clenched fist.
  4. b. Flexion of the wrist joint will result in abduction, owing to paralysis of the flexor carpi ulnaris.
  • c. The medial border of the front of the forearm will show flattening owing to the wasting of the underlying ulnaris and profundus muscles.
  1. d. The patient is unable to adduct and abduct the fingers and consequently is unable to grip a piece of paper placed between the fingers.
  2. It is impossible to adduct the thumb because the adductor pollicis muscle is paralyzed.
  3. If the patient is asked to grip a piece of paper between the thumb and the index finger, he or she does so by strongly contracting the flexor pollicis longus and flexing the terminal phalanges.
  • e. The metacarpophalangeal joints become hyperextended because of the paralysis of the lumbrical and interosseous muscles(leads to clumsiness), which normally flex these joints.
  1. f. The interphalangeal joints are flexed, owing again to the paralysis of the lumbrical and interosseous muscles, which normally extend these joints through the extensor expansion.
  2. The flexion deformity at the interphalangeal joints of the fourth and fifth fingers is obvious because the first and second lumbrical muscles of the index and middle fingers are not paralyzed.

  • In long-standing cases the hand assumes the characteristic claw deformity (main en griffe)( ulnar claw hand)(Klumpke Paralysis)
  • Wasting of the paralyzed muscles results in flattening of the hypothenar eminence and loss of the convex curve to the medial border of the hand.
  • Examination of the dorsum of the hand will show hollowing between the metacarpal bones caused by wasting of the dorsal interosseous muscles.
2. Sensory:
  • Loss of skin sensation will be observed over the anterior and posterior surfaces of the medial third of the hand and the medial one and a half fingers.
3.Vasomotor Changes
  • The skin areas involved in sensory loss are warmer and drier than normal because of the arteriolar dilatation and absence of sweating resulting from loss of sympathetic control
TARDY ULNAR NERVE PALSY:
  • Seen in malunited fracture of lateral condyle of humerus.
  • Late complication may be seen years after the injury
  • Motor loss occurs first followed by sensory changes
  • Cubitus valgus deformity leads to stretching of medial structures including ulnar nerve(# of humerus): nonunion
  • Complications associated with pediatric lateral condylar fracture include cubitus varus, cubitus valgus, fishtail deformity, and tardy ulnar nerve palsy.
  • Injury of ulnar nerve at wrist:
Motor:
  1. The small muscles of the hand will be paralyzed(Palmar interossei, Dorsal interossei, Adductor pollicis) and show wasting, except for the muscles of the thenar eminence and the first two lumbricals.
  2. The clawhand is much more obvious in wrist lesions because the flexor digitorum profundus muscle is not paralyzed, and marked flexion of the terminal phalanges occurs.
2.Sensory:
  • The main ulnar nerve and its palmar cutaneous branch are usually severed
  • The posterior cutaneous branch, which arises from the ulnar nerve trunk about 2.5 in. (6.25 cm) above the pisiform bone, is usually unaffected.
  • The sensory loss will therefore be confined to the palmar surface of the medial third of the hand and the medial one and a half fingers and to the dorsal aspects of the middle and distal phalanges of the same fingers.
  • Vasomotor and trophic changes:
  • These are the same as those described for injuries at the elbow. It is important to remember that with ulnar nerve injuries, the higher the lesion, the less obvious the clawing deformity of the hand.
NOTE:
  1. Hypothenar atrophy is seen in ulnar nerve injury.
  2. Entrapment of ulnar nerve leads to cubital tunnel syndrome.
  3. Ape thumb deformity is associated with ulnar nerve palsy.
  4. It is the most common nerve involved in Hansen's disease(leprosy)
TESTS TO DETECT ULNAR
  1. Book test (Froment sign)substituting thumb IP joint flexion for thumb adduction due to weakness of adductor pollicis muscle
  2. Card test (to test Palmar interossei) -Adduction of fingers (PAD)
  3. Egawa's test (to test Dorsal interossei)- Abduction of fingers (DAB)
  4. Positive Tinel’s sign: Exacerbation of paresthesias with light percussion over the ulnar nerve within the cubital tunnel.
TREATMENT:

  1. Surgical management & Medical 
  2. Exploration and suture of the divided nerve
  3. Anterior transposition of nerve at the elbow joint
  4. Metacarpophalengeal flexion can be improved by extensor carpi radialis longus to intrinsic tendon transferes or
  5. Looping a slip of flexor digitorum supeficialis around the opening of the flexor sheath(Zancolli procedure)
  6. Admistration of analgesics if nerve lesion is associated with fracture
  7. Index abduction can be improved by transfering extensor policis brevis or extensor indicis to interosseous insertion on the radial side of the finger.

  8. Knuckle bender splint is used in palsy of ulner nerve 
PHYSIOTHERAPY:
  • faradism
  • Ift
  • Passive movements, can be auto assisted
  • Hydrotherapy
  • Electro diagnosis
  • Tens
Exam Question

  • Ulnar nerve commonly seen involved In injuries at the elbow are usually associated with fractures of the medial epicondyle.
  • Ring & little fingers are not capable of being markedly flexed 
  • The patient is unable to adduct and abduct the fingers and consequently is unable to grip a piece of paper placed between the fingers.
  • It is impossible to adduct the thumb in ulnar nerve palsy

  • The metacarpophalangeal joints become hyperextended in ulnar nerve palsy
  • In case of lesion of ulnar nerve, paralysis of interosseous muscles occurs which leads to clumsiness
  • claw deformity is seen in long standing case of ulnar nerve palsy
  • Loss of skin sensation will be observed over the anterior and posterior surfaces of the medial third of the hand 
  • TARDY ULNAR NERVE PALSY is seen in lateral condyle # of humerus resulting in ulnar nerve injury
  • Cubitus valgus deformity and tardy ulnar nerve palsy is seen as the late complication of ulnar nerve injury
  • Hypothenar atrophy is seen in ulnar nerve injury.
  • Ape thumb deformity is associated with ulnar nerve palsy.
  • It is the most common nerve involved in Hansen's disease(leprosy)
  • Froment sign is test use to detect ulnar nerve palsy
  • Knuckle bender splint is used in palsy of ulner nerve

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