Injury at the Elbow (high lesion)

Ulnar nerve injuries
Injury at the Elbow (high lesion)
➢ Causes :
➢ Fracture of the medial epicondyle (humerus)
➢ Cubital tunnel syndrome
➢ Tardy ulnar nerve palsy (valgus deformity)
➢ Motor loss ✓ Claw-hand deformity
✓ Hypothenar and interosseous wasting
✓ Loss of Abduction and adduction of the fingers (card test positive)
✓ Loss of Flexion of the metacarpophalangeal joints
✓ Loss of Adduction of the thumb (Froment sign positive)
✓ Weakness of wrist flexion (hand deviates to radial side upon flexion)
➢ Sensory loss Over the palmar and dorsal surfaces of medial third of the hand and medial 1½ fingers (little finger and the ulnar half of the ring finger)
Injury at Wrist (low lesion)
➢ Causes :
✓ Wrist laceration/slashing
✓ Guyon’s canal syndrome
➢ Motor loss
✓ Claw hand deformity (more pronounced in low injury)
✓ Hypothenar and interosseous wasting
✓ Loss of Abduction & adduction of the fingers (card test positive)
✓ Loss of Adduction of the thumb (Froment sign positive)
➢ Sensory loss ✓ Over the palmar and dorsal surfaces of medial 1½ fingers (little finger and the ulnar half of the ring finger) ✓ No sensory loss over the ulnar aspect of the dorsum of the hand (dorsal cutaneous branch is spared)
❖ Cubital tunnel syndrome
✓ pathological compression of the ulnar nerve at the cubital tunnel
✓ second most common peripheral neuropathy of the upper extremity
✓ Clinical features : numbness and tingling in the ring and little fingers.

❖ Guyon’s canal (pisohamate tunnel)
✓ Approximately 4 cm in length
✓ roof: palmar carpal ligament, palmaris brevis muscle and hypothenar connective tissue
✓ floor: transverse carpal ligament, pisohamate ligament, pisometacarpal ligament, flexor digitorum profundus tendons, and abductor digiti minimi muscle
✓ lateral wall: hook of hamate, transverse carpal ligament, flexor tendons
✓ medial wall: pisiform bone, flexor carpi ulnaris tendon, adductor digiti minimi muscle
Note : Entrapment of the ulnar nerve in the Guyon’s canal is called Guyon’s canal syndrome, causing pain, numbness, and tingling in the ring and little fingers, and motor weakness in later stages .
❖ In ulnar nerve injury Froment’s sign is positive , Froment test is to check Adductor pollicis .
❖ Ulnar paradox : High level injury- less severe claw hand