Ulnar Nerve Disorders

• Ulnar nerve can be damaged by dislocation or fracture dislocation of the elbow and can be compressed by those who habitually lean on their elbows.
• May be associated with medial epicondylitis (golfer's elbow)
• Nerve can become entrapped in the cubital tunnel during heavy manual work or following a previous poorly healed supracondylar fracture of the humerus or due to osteophytic encroachment in osteoarthritis.
• Nerve can be damaged at wrist either by compression by ganglia or by repeated trauma at work.

• Ulnar nerve entrapment is the second most frequent entrapment neuropathy in the upper extremity. The elbow is the most common area for entrapment¹.
• The wrist is the second most common area of entrapment.
• Entrapment of the ulnar nerve may occur at more than one level¹.

Lesions at the elbow

• Total paralysis of the nerve, including those branches of the nerve serving the flexor digitorum profundus and flexor carpi ulnaris muscles, shows wasting along medial side of forearm.
• Also, weakness of flexion of fourth and fifth fingers.
• If proximal portions of these fingers are held steady, patient is unable to flex terminal phalanges.
• With hand flexed to the ulnar side against resistance can not palpate tendon of flexor carpi ulnaris.
• With paralysis of hypothenar muscles abduction of fifth finger is impossible.
• Paralysis of interossei and medial two lumbricals causes 'claw hand' deformity mainly seen in ulnar fingers.
• There may be wasting of hypothenar muscles, interossei and medial part of thenar eminence. Also weakness in movement of fingers and abduction to the extended thumb against the palm.
• There is sensory loss of the dorsal and palmar aspects of the medial side of the hand together with the medial one and a half fingers.
• Ulnar nerve often palpably enlarged in ulnar groove and for a short distance in the proximal direction in cubital tunnel syndrome.

Lesions at wrist

• Cutaneous sensation of hand and fingers often spared.
• If lesion just proximal to the wrist, causes impaired sensation on palmar aspects of hands and fingers and muscle weakness.
• Positive Tinel's sign on percussion over ulnar nerve at wrist¹
• Positive Phalen's test with paresthesias in ring & small fingers¹.

• Cervical intervertebral disc disease
• Brachial plexus abnormalities, thoracic outlet syndrome, Pancoast tumour
• Elbow abnormalities, epicondylitis
• Infections, tumours, diabetes mellitus, hypothyroidism, rheumatoid diseases, and alcoholism
• Wrist fractures
• Ulnar artery aneurysms or thrombosis at the wrist

• Blood tests may be appropriate to rule out various disorders, e.g. anaemia, diabetes mellitus, hypothyroidism and rheumatoid arthritis.
• X-rays:
  • Neck if cervical disc disease is suspected and to rule out cervical ribs.
  • X-rays of chest: if Pancoast tumor or tuberculosis is suspected.
  • X-rays of elbow and wrist are essential to rule out possible associated bone or joint abnormalities, or alternate diagnoses.
  • Ultrasound of cubital tunnel².
  • Electromyography tests and nerve conduction studies: to confirm the area of entrapment.

Conservative treatment

• Is most successful when paraesthesias are transient and caused by malposition of the elbow or blunt trauma.
• Patient education: resting on elbows at work, using elbows to lift the body from bed, and resting elbows on car windows while driving all are causes of paraesthesia that can be corrected without surgical treatment.
• Anterior elbow extension splinting
• Correction of ergonomics at work or with home computer may be all that is required.
• Non-steroidal anti-inflammatory medications also are useful adjuncts to relieve nerve irritation.

Surgery

• Indications for surgery include:
  • No improvement in presenting symptoms after 6-12 weeks of conservative treatment
  • Progressive palsy or paralysis
  • Clinical evidence of a long-standing lesion (eg, muscle wasting, clawing of the fourth and fifth digits)
• Elbow lesions due to repeated compression - surgical transposition of nerve. Decompression in cubital tunnel syndrome³.
• Wrist lesions - exploration of ganglia.

• With early appropriate decompression, the result should be a return to normal function. Return to normal function is almost immediate.
• With transposition of the nerve following decompression, post-operative immobilization, and rehabilitation, return to normal function may take 3-6 months.
• In chronic palsy (greater than 3-4 months duration) associated with pain, muscle weakness, and/or atrophy, surgical outcome is less certain. Duration of entrapment and severity of numbness and muscle weakness are important factors in prognosis. Improvement may be limited or may not occur following decompression and transposition but further progression can be halted with proper decompression.