Peripheral nerve injuries

1. Peripheral nerve injuries By : - Dr .Sanjeev

3. Structure of a nerve • It has an outer covering which forms a sheath around the nerve, called the epineurium. • Nerve fibers, which are axons, organize into bundles known as fascicles with each fascicle surrounded by the perineurium. • Between individual nerve fibers is an inner layer of endoneurium.

5. Peripheral nerve injury Dermotome : • is an area of skin supplied by a single spinal root Myotome : • Represents a muscle unit supplied by a single spinal root

6. Seddon's classification Neurapraxia -- temporary paralysis of a nerve caused by lack of blood flow or by pressure on the affected nerve with no loss of structural continuity. Axonotmesis – • neural tube intact, but axons are disrupted. • nerves are likely to recover. Neurotmesis – • the neural tube is severed. • Injuries are likely permanent without repair.

7. Classification of Nerve Injuries myelin axon endoneurium perineurium epineurium Degree of Injury I Neuropraxia +/- II Axonotmesis yes yes no no no III yes yes yes no no IV yes yes yes yes no V Neurotmesis yes yes yes yes yes

8. Sunderland`s classification • Grade I • Same as Seddon's neuropraxia. • Grade II • Same as Seddon's axonotmesis. • Grade III • Neurotmesis with preservation of the perineurium. • Grade IV • Neurotmesis with preservation of the epineurium. Everything else is disrupted. • Nerve grossly appear edematous. • Nerve grafting is required. • Grade V • Complete transection of the nerve trunk.

9. Typical deformities : • Wrist drop ---- radial nerve injury • Claw hand ---- ulnar nerve injury • Foot drop ---- lateral popliteal nerve injury • Ape thumb ---- median nerve injury • Winging of scapula ---- thoracodorsal nerve injury • Pointing index ---- median nerve injury

10. Simple screening tests • Ulnar nerve injury : • Loss of pain at tip of the little finger • Medial nerve injury : • Loss of pain at tip of index finger • Radial nerve injury : • Inability to extend thumb

11. Incidence of Peripheral nerve injury • Radial nerve ------ commonly injuried • Ulnar nerve ------- 30 % • Median nerve ----- 15 % • Lumbosacral plexus ---- 3 %

13. Ulnar nerve injury Causes : General causes : metabolic diseases , collagen diseases , malignancies , endogenous or exogenous toxins , chemical or mechanical trauma , etc. Local causes : Causes in the axilla : • Crutch pressure • Aneurysm of the axillary vessels Causes in the arm : • # shaft of humerus • Gunshot and penetrating injuries

14. Cont .. Causes at the elbow : • Compression by the accessory muscles • # lateral epicondyle of humerus • Repeated occupational strains • Recurrent subluxation of the nerve • Compression by the osteophytes as in rheumatoid and osteoarthritis Causes in the forearm : • # both bones forearm • Incised wounds , gunshot wounds and penetrating injuries of the forearm

15. Cont .. Causes at the wrist : • Compression by osteophytes • # hook of the hamate • Compression by ganglion • Wrist injuries Causes in the hand: • Blunt trauma • Penetrating injuries • Ulnar nerve injuries gives rise to claw hand deformity

16. Claw hand deformity • It is a deformity with hyperextension of the MCP joints and flexion of the IP joints of the fingers ( loss of flexon at MCP and extension at IP joints )

17. Clinical features • Loss of sensation along the ulnar nerve distribution and • Wasting of the hypothenar muscles , intrinsic muscles of the hand leading to hollow intermetacarpal spaces on the dorsum of the hand

18. .

19. Levels of the lesion High: above the level of elbow , entire nerve function is lost Low : Below the elbow at the junction of the middle and lower third of forearm : Spared : - function of FDP and FUC Lost : • Motor : HTM ,Its , Lum ,PB • Sensory : dorsal aspect of hand and one and half fingers

20. Cont .. Proximal to Guyon`s canal : • Spared : FDP , FCU and dorsal sensation • Lost : same as above + loss of volar sensation

21. Cont .. Distal to Guyon`s canal : - • Spared : FDP , FCU , HTM , PB, dorsal and volar sensation • Lost : interossei and lumbricals • FCU – flexor carpi ulnaris • FDP – flexor digitorum profundus • HTM – hypothenar muscles • PB – palmaris brevis • Lum – lumbricals • Its - interossei

22. Clinical tests : • Froment's sign. When the patient attempts to pinch with the thumb and index finger, the long flexor of the thumb is used to substitute for the thumb adductor, resulting in flexion of the thumb at the interphalangeal joint. • This characteristic appearance is present in this patient's left hand, caused by an ulnar nerve lesion at the elbow

23. Card test • Inability to hold a card or paper in between fingers due to loss of adduction by the palmar interossei Pen test • Unable to touch the pen due to the loss of action of abductor pollicic brevis

24. Egawa test ( median nerve injury ) • With palm flat on the table the patient is asked to move the middle finger sideways( test for the dorsal interossei of middle finger ) • In total clawing median nerve is also injuried Pointing index or oschner`s clasp test : • When both the hands are clapsed together , index and middle fingers , fail to flex due to the loss of action of long finger flexors of the index and middle fingers which are supplied by the median nerve .

25. Treatment of ulnar nerve injury • Unless there is a lot of muscle wasting, (nonsurgical treatment ) Prevention • Avoid frequent use of the arm with the elbow bent • If you use a computer frequently, make sure that your chair is not too low. Do not rest the elbow on the armrest. • Avoid putting pressure on the inside of the arm (do not drive with the arm resting on the open window ). • Keep the elbow straight at night when you are sleeping (done by wrapping a towel around the straight elbow, wearing an elbow pad backwards, or using a special brace ) Loosely wrapping a towel around the arm with tape can help you to remember not to bend the elbow during the night

26. Nonsurgical Treatment • If symptoms have only just started, • Anti – inflammatory drugs, ibuprofen,( to reduce swelling around the nerve ). • Steroid (cortisone) injections around the ulnar nerve are not generally used because there is a risk of damage to the nerve. • Exercises ( prevents arm and wrist from stiffness ). With your arm forward and the elbow straight, curl the wrist and fingers toward the body, then extend them away from you and then bend the elbow With the arm to the side, curl the wrist and fingers toward the shoulder and then turn the palm up and then stretch the neck to the other side.

27. Surgical Treatment • If the nerve is very compressed; or if there is muscle wasting Surgery : • Around the elbow and the wrist or both • More commonly, the nerve is moved from its place behind the elbow to a new place in front of the elbow. This is called an anterior transposition of the ulnar nerve. The nerve can be moved : - • under the skin and fat (subcutaneous transposition), • within the muscle (intermuscular transposition) or • under the muscle (submuscular transposition).

28. . For anterior transposition of the ulnar nerve, an incision along the inside of the elbow is used. Nerve moved from behind the elbow to in front of it and will make sure that it is not compressed by any other structures.

29. . Entrapment of the ulnar nerve at Guyon's canal. If ulnar nerve is compressed at the wrist, make an incision and free the nerve where it is compressed.

30. Ulnar paradox • The higher the lesion of the median and ulnar nerve injury , the less prominent is the deformity and vice versa, because in higher lesions the long finger flexors are paralysed . • The loss of finger flexion makes the deformity look less obvius

34. Radial nerve injury Causes : - General causes : metabolic diseases , collagen diseases , malignancies , endogenous or exogenous toxins , chemical or mechanical trauma , etc. Local causes : - In the axilla : • Aneurysm of the axillary vessels • Crutch palsy In the shoulder: • Proximal humeral # • Shoulder dislocation

35. Cont.. In the spiral groove ( 5 `s ) • Shaft # • Saturday night # • Syringe palsy • `S ` march`s tourniquet palsy Between spiral groove and lateral epicondyle : • # shaft humerus • Supracondylar # humerus • Lateral epicondyle # of humerus • Penetrating and gunshot injuries • Cubitus valgus deformity

36. Cont … At the elbow : • Posterior dislocation of elbow • # head of radius • Monteggia # Causes in the forearm : • # both bones of forearm • Penetrating and gunshot injuries

37. Levels of lesion High above spiral groove---- total palsy Low : Type 1 (Between the spiral groove and the lateral epicondyle ) : - Spared : - elbow extensor Lost : - • Motor : wrist extensor , thumb extensor , finger extensor • Sensory : dorsum of first web space

38. Cont .. Low • Type 2 ( below the elbow ) : Spared : • Elbow extensor • Wrist extensor Lost : • Motor : thumb extensor , finger extensor • Sensory : • First web space

39. Clinical features Depend upon the site of the injury: - Lesions in or above the axilla : • Paralysis and wasting of all the muscles innervated. • Clinically, this is manifest as: • weakness of forearm extension and flexion - triceps and brachioradialis • wrist drop and finger drop - paralysis of the extensors of the wrist and digits • weakness of the long thumb abductor and extensor muscles

40. Cont .. • Sensory loss on the dorsum of hand and forearm appropriate to the cutaneous distribution • Lesions around the humerus • spare brachioradialis and • extensor carpi radialis longus. • Posterior interosseous palsy (due to a dislocation or fracture of the elbow ). • weakness of finger extension, and of thumb extension and abduction. • little or no wrist drop, and usually, no sensory loss.

41. Fig : - Wrist drop • .

42. Tests • Muscles supplied by the radial nerve and how to test each: • C7,8: triceps - ask patient to extend elbow against resistance. • C5,6: brachioradialis - ask patient to flex elbow with forearm half way between pronation and supination. • C6,7: extensor carpi radialis longus - ask patient to extend wrist to radial side with fingers extended. • C5,6: supinator - with arm by side, ask patient to resist hand pronation. • C7,8: extensor digitorum - ask patient to keep fingers extended at MCP joint. • C7,8: extensor carpi ulnaris - ask patient to extend wrist to ulnar side. • C7,8: abductor pollicis longus - ask patient to abduct thumb at 90° to palm. • C7,8: extensor pollicis brevis - ask patient to extend thumb at MCP joint. • C7,8: extensor pollicis longus - ask patient to resist thumb flexion at IP joint.

43. Sensation: • The cutaneous branches of the radial nerve supply the dorsal aspect of the forearm from below the elbow down over the lateral part of the hand to include the thumb to the interphalangeal joint and the fingers to the distal interphalangeal joint.

44. Exams and Tests An examination of the arm, hand, and wrist identify radial nerve dysfunction. • Decreased ability to extend the arm at the elbow • Decreased ability to rotate the arm outward (supination) • Difficulty lifting the wrist or fingers (extensor muscle weakness) • Muscle loss (atrophy) in the forearm • Weakness of the wrist and finger • Wrist or finger drop Tests for nerve dysfunction : • EMG • MRI of the head, neck, and shoulder • Nerve biopsy • Nerve conduction tests

45. Treatment Closed fracture CONTROL OF SYMPTOMS • Analgesics ( to control pain neuralgia) • Phenytoin, carbamazepine, or tricyclic antidepressants (amitriptyline) to reduce stabbing pain • Steroids (prednisone) to reduce swelling Other treatments include: • Braces, splints, • Physical therapy to help maintain muscle strength • Occupational therapy, or job counseling • Surgery : - • Failure of conservative by 12 to 18 months

46. Surgery ( open # ) Clean wound : Primary repair , splint , physiotherapy Contaminated wound : Delayed primary repair and secondary repair Late cases : • Tendon transfers • Arthrodesis

47. Splints

48. Complications • Mild to severe deformity of the hand • Partial or complete loss of feeling in the hand • Partial or complete loss of wrist or hand movement • Recurrent injury to the hand

49. Sciatic nerve injury • Thickest nerve in the body • Leprosy is the commonest cause • High stepping gait is the characterisic • Conservative treatment is indicated up to one year