PERIPHERAL NERVE INJURIES

1. PERIPHERAL NERVE INJURIES MHD BASHAR ALBOSHI

3. Tinel sign Peripheral tingling or dysaesthesia provoked by percussing the nerve A positive Tinel sign is presumptive evidence that regenerating axonal sprouts that have not obtained complete myelinization are progressing along the endoneurial tube. @- neuropraxia(sunderland1) -------negative Tinel sign. @- axonotmesis (sunderland2,3) -------positive Tinel sign. (sunderland4-------- negative Tinel sign ) @- neurotmesis (sunderland 5) ------- negative Tinel sign.

5. The radial nerve, a continuation of the posterior cord of the brachial plexus, consists of fibers from C6, C7, and C8 and sometimes T1..

12. It is primarily a motor nerve that innervates the triceps, the supinators of the forearm, and the extensors of the wrist, fingers, and thumb.

17. This nerve is injured most often by: -fractures of the humeral shaft. • -Gunshot wounds are the second most common cause of radial nerve injury. • Other causes include lacerations of the arm and proximal forearm, • - injection injuries, - and prolonged local pressure.

18. ExaminationThe following muscles supplied by the radial nerve can be tested accurately because their bellies or tendons or both can be palpated: - the triceps brachii, - brachioradialis, - extensors carpi radialis, -extensor digitorum communis, -extensor carpi ulnaris, - abductor pollicis longus, and - extensor pollicis longus. @ Injury to this nerve results in inability to extend the elbow or supinate the forearm and in a typical wristdrop

20. Entrapment syndromes of the radial nerve @Nerve compression impaires epineural blood flow and axonal conduction --------numbness, paraethesia ,weakness -symptoms are intermittent,sometimes related to specific posture. -prolong compression------segmental demyelination(tinel sign),target muscle atrophy,nerve fibrosis. -peripheral neuropathy(diabetes,alcoholism,discogenic root compression..) +entrampment-----double-crush syndrome. MRI,US--------exlude compression by soft-tissues mass(..ganglion). -EMG,nerve conduction tests help to confirm the diagnosis, level of compression, degree of nerve damage.( conduction is slowed,EMG show abnormal wave or fibrillation in cases with severe nerve damage). - treatment: splint, corticosteroid injection ,operative decompression.

21. Entrapment syndromes of the radial nerve: -may develop when the nerve or one of its branches is compressed at some point along its course. • Two clinical patterns are encounters: 1- posterior interosseous syndrome 2- radial tunnel syndrome

22. posterior interosseous syndrome: The posterior interosseous nerve may be compressed (at proximal edge or within the substance of the supinator muscle) by: • the fibrous arcade of Frohse(thickening of the proximal edge of supinator), • - fracture-dislocations or dislocations of the elbow, • -fractures of the forearm, • -Volkmann ischemic contracture, • - neoplasms, • - enlarged bursae, • -aneurysms, • -rheumatoid synovitis of the elbow.

23. Clinical features: -pure motor disorder(weakness of metacarpophalangeal extension affects first one or two and then all the digits. -wrist extension is preserved( the nerves to extensor carpi radialis longus and brachioradialis arise proximal to the supinator) -treatment: condition does not resolve spontaneously within 3 months-----------surgical exploration is warranted--------no improvement by the end of a year and disabling---------tendon transfer.

24. radial tunnel syndrome • -entrapment of the posterior interosseous nerve cause chronic and refractory tennis elbow. • -can occur at four potentially compressive anatomical structures: - the origin of the extensor carpi radialis brevis, -adhesions about the radial head, - the radial recurrent arterial fan, -and the arcade of Frohse as the posterior • interosseous nerve enters the supinator. • - condition does not resolve-----------surgical exploration is warranted (but the patient should be warned that surgery often fails to relieve the symptoms. • @Lotem et al. found that when symptoms and signs develop only after muscular effort---------- spontaneous recovery can be anticipated. @Compression of the superficial radial nerve causes pain in the forearm and sensory impairment on the dorsum of the thumb. The nerve may be caught in scar tissue at the wrist after surgery or trauma.

25. The ulnar nerve is composed of fibers from C8 and T1 coming from the medial cord of the brachial plexus.

40. Injuries: -When it is injured in the upper arm, other nerves or the brachial artery because of their proximity also may be injured. • -In the middle of the arm the ulnar nerve is relatively protected,. • -in the distal arm and at the elbow it often is injured by dislocations of the elbow and supracondylar and condylar fractures. -The nerve is injured most commonly in the distal forearm and wrist; in these locations it may be injured by gunshot wounds, lacerations, fractures, or dislocations. - In civilian life lacerations cause most of the injuries at the wrist. .

41. Postoperative ulnar nerve palsy: - may result from either direct pressure on the ulnar nerve at the elbow or prolonged flexion of the elbow during surgery. - The ulnar nerve is especially vulnerable to compression when the forearm is allowed to rest in pronation.

42. Examination-Interrupting the ulnar nerve proximal to the elbow is followed by paralysis of: • - the flexor carpi ulnaris, • -the flexor profundus to the little and ring fingers, • -the lumbricals of the same fingers, • - all of the interossei, • - the adductor of the thumb, • - and all of the short muscles of the little finger. @Occasionally when a nerve is completely divided at this level, the intrinsic muscles of the hand function normally because of anomalous innervation of these muscles by the median nerve. (Martin- Gruber anastomosis)..

43. Complete division of the ulnar nerve at the wrist usually causes paralysis of all ulnar-innervated intrinsic muscles unless an anatomical variation connects the median and ulnar nerves in the palm (Riche-Cannieu anastomosis). - Usually when the nerve is divided at the wrist, only the opponens pollicis, the lateral or superficial head of the flexor pollicis brevis, and the lateral two lumbricals remain functional

44. @In practice only three muscles tested accurately: -the flexor carpi ulnaris, - the abductor digiti quinti, and - the first dorsal interosseus -The bellies or tendons (or both) of these muscles may be easily palpated or seen

45. @Atrophy of the muscles supplied by the ulnar nerve and clawing of the little and ring fingers usually are confirmatory evidence of paralysis of the muscles supplied by this nerve. @ However, if the nerve has been injured proximal to the elbow, clawing of these two fingers may be absent because the flexor digitorum profundus to the ring and little fingers also is denervated. @The sensory examination usually is straightforward, although anatomical variations may cause confusing sensory findings. One need examine only the middle and distal phalanges of the little finger, which make up the autonomous zone of the ulnar nerve .

46. cubital tunnel syndrome compression neuropathy of the ulnar nerve about the elbow with no antecedent trauma. - As the ulnar nerve enters the cubital tunnel it is first bordered by the medial epicondyle anteriorly, then by the elbow joint laterally, and finally by the two heads of the flexor carpi ulnaris medially. -In other areas the nerve may be compressed by ligaments, neoplasms, rheumatoid synovitis, aneurysms, vascular thromboses, or anomalous muscles.

47. @In patients suspected of having cubital tunnel syndrome: • -a positive percussion test( tinel,s sign) over the ulnar nerve at the level of the medial epicondyle • - and a positive elbow flexion test are strongly suggestive of a significant compressive neuropathy. • -negative test does not exclude the diagnosis. -in late cases there may be weakness of grip,slight clawing, intrinsic muscle wasting and diminished sensibility in ulnar nerve territory,weakness of abductor digiti minimi . • - Nerve conduction ----- slowing velocities across the elbow, although normal velocities may be maintained during early involvement. Electromyography ------ fibrillations in the ulnar innervated intrinsic muscles. -Conservative treatment for this syndrome should be attempted such as modification of posture and splintage of elbow in mid-extension at night, before surgical treatment&

49. The surgical treatment of cubital tunnel syndrome :& -includes simple decompression, • medial epicondylectomy, • -and anterior transposition of the ulnar nerve either into a subcutaneous, intramuscular, or submuscular bed @For a moderate degree ----excellent results ----with the submuscular technique.

50. Compression in Guyon,s canal:Ulnar nerve can be compressed as it passes through Guyon,s canal at ulnar border of the wrist. The exact level of compression determines whether symptoms are motor or sensory or both. Compression affects the deep branch of the nerve that supplies most of the intrinsic muscles. -A space-occupying lesion such as a ganglion from the triquentrohamate joint is the most common cause to compression in this area. - True or false aneurysm of the ulnar artery, thrombosis of the ulnar artery, or fracture of the hamate with hemorrhage may be the cause of pressure on the ulnar nerve. @-Preservation of sensation in the dorsal branch of the ulnar nerve suggest entrapment at the wrist rather than in the elbow. • further investigation should be considered: • MRI--------------- diagnosis a ganglion • CT----------------- = carpal fracture Doppler studies----- = ulnar artery aneurysm -Treatment consists of removal of any ganglion or other cause of compression.