MEDIAN NERVE PRESENTATION (2).pptx

Median nerve

1. MEDIAN NERVE DR. SANJAY K JUNIOR RESIDENT, DEPT. OF ORTHOPAEDICS KMCT MEDICAL COLLEGE

2. ANATOMY CARPAL TUNNEL SYNDROME ANTERIOR INTERROSEOUS NERVE SYNDROME PRONATOR SYNDROME

3. Formed by the junction of the lateral and medial cords of the brachial plexus in the axilla composed of fibers from C6, C7, C8, and T1 lateral root (C6, C7) from the lateral cord, and the medial root (C8, T1) from the medial cord

4. MOTOR In forearm- PT, PL, FDS, FCR, FDP[lateral half], FPL and PQ In hand- APB, OP, FPB[ superficial head] , 1st and 2nd lumbricals NERVE SUPPLY

5. SENSORY Palmar side- radial 3 ½ fingers and corresponding part of palm Dorsal side- terminal phalanx of radial 3 ½ fingers Autonomous zone- dorsal and palmar aspect of distal phalanx of index and middle finger

6. BRANCHES First branch of the median nerve, to pronator teres , arises 2–3 cm above the medial epicondyle. Second branch , or leash of branches, arises at the level of the tip of the medial epicondyle and innervates PL, FCR and FDS.

7. ANTERIOR INTEROSSEOUS NERVE arises proximal to the tendinous arcade of FDS Accompanied by the anterior interosseous vessels, this large branch supplies FPL, the radial half of FDP and PQ

8. The main nerve continues in the plane between the superficial and deep digital flexors, supplying two or three branches to the former. The palmar cutaneous nerve arises about 3 cm proximal to the proximal wrist crease, passes lateral to the main nerve and superficial to the flexor retinaculum to innervate the skin of the proximal palm. The median nerve passes deep to the flexor retinaculum, into the carpal tunnel, to enter the palm. The nerve to the thenar muscles arises within, or just distal to, the tunnel, usually on the lateral side of the main nerve. The palmar digital nerves are formed within the palm of the hand.

9. CAUSES OF INJURY UPPER ARM - Superficial lacerations, tight tourniqet , # humerus LOWER ARM- ligament of Struthers ELBOW- Supracondylar #, posterior elbow dislocation FOREARM- entrapment, aberrant radial artery, VIC WRIST- # distal radius, # and dislocations of carpal bones

10. CLINICAL SIGNS Oschner’s finger clasp test- pointing index Pen test- for APB Ape thumb deformity- opponens pollicis Benediction attitude Wasting of thenar eminence

11. Oshner’s finger clasp test

12. PEN TEST

13. APE THUMB DEFORMITY - CANNOT MOVE THUMB AWAY FROM REST OF FINGERS DUE TO PARALYSIS OF THENAR MUSCLES

14. Patient is asked to make a fist and the ring and little finger flex but the index and middle finger can not flex at the metacarpal-phalangeal joint or interphalangeal joint .

15. FDS - Each finger examined separately. Flexion of PIP junction is checked FPL - flexion of IP joint of thumb against resistance FDP and FPL- by Kiloh - Nevin sign

16. MEDIAN NERVE COMPRESSION NEUROPATHIES

17. CARPAL TUNNEL SYNDROME PRONATOR QUADRATUS SYNDROME ANTERIOR INTEROSSEOUS SYNDROME

18. CARPAL TUNNEL SYNDROME

19. Carpal tunnel syndrome (CTS), the term first used by Kremer in 1953, was initially described by Brain in the year 1947 and George Phalen in 1950. It refers to the compression of median nerve at the wrist while passing through the carpal tunnel.

20. Herbert Galloway was the first to perform the carpal tunnel release (CTR) Phalen was the first to use steroid injections for the treatment of CTS, even before the complete understanding of the pathogenesis of the disease

21. Carpal Tunnel Anatomy and Pathoanatomy and Pathophysiology Dorsally – CARPAL BONES forming an arch Volar aspect - Transverse carpal ligament (TCL). Medially - pisiform and the hook of the hamate laterally - tubercle of the scaphoid and the trapezium’s crest. The depth of the tunnel : 10 mm to 13 mm. The TCL is a tough fibrous band which acts as a tie beam which converts the concave surface of the carpus into an osseofibrous tunnel

22. Ten structures from the volar forearm pass through the carpal tunnel •• Eight flexor tendons to the fingers •• Flexor pollicis longus •• The median nerve.

23. The median nerve is the most superficial of the structures it is closely applied to the posterior surface of the TCL . At the distal edge of the TCL the median nerve gives 6 terminal branches, two common digital nerves, Three proper digital nerves and the recurrent motor branch.

24. Normal pressure within the carpal tunnel measures 2.5 mm Hg. An external compression of 20–30 mm Hg reduces the venule flow in the epineurium and the nerve gets edematous , A pressure of greater than 30 mm Hg diminishes the nerve conduction

25. DIAGNOSIS based on history and clinical examination. Most common symptom is “nocturnal acroparesthesia ,” - painful tingling and numbness in the thumb and one of the radial digits, which may even disturb sleep Daytime paresthesias may also occur with activities which involve extremes of wrist flexion. Certain activities or position of the hands that may trigger paresthesias in daytime are such as pray position, the act of sewing, holding the phone or a book while reading

26. The most sensitive test for detecting early CTS is the Semmes-Weinstein monofilament test and probably vibrometry . These threshold tests reflect both sensory changes and decreases in sensory nerve function quite reliably and early

27. Bilateral CTS is common; however, the symptoms may be more marked in one hand In chronic cases grip strength and pinch may diminish. There may be symptoms of autonomic dysfunction like finger blanching, Raynaud’s phenomenon, subjective swelling of fingers, etc. Thenar atrophy is a late sign often in neglected cases over a long duration of disease and patients often report less pain by this time!

28. TINELS SIGN An electric shock like or tingling sensation is felt in the distribution of median nerve after a firm but gentle tap on the median nerve at the TCL region. Not been described for CTS as it is mainly a sign of regenerating sensory nerves after injury and should not be present for an on going damaging process.

29. Phalen’s wrist hyperflexion test Paresthesia in the median nerve distribution on flexion of the wrist for 60 seconds

30. DURKANS TEST Durkan’s direct median nerve compression at TCL for 30 seconds (variously described as 15–120 seconds) causing parasthesia Performing Durkan’s after Phalens might increase its sensitivity.

31. Reverse Phalen’s test has also been found positive and useful but in moderate to advanced compression predominantly

32. Scratch collapse test or Hierarchical Scratch collapse test: New provocative clinical test of nerve compression. The use of ethyl chloride allows for a Hierarchical test which can even reveal additional sites of compression.

33. DIAGNOSTIC STUDIES Electrodiagnostic Testing The goals of an electrodiagnostic examination are basically for : •• Localization of lesion •• Evidence of reinnervation or of ongoing axonal loss •• Type of fibers involved : motor, sensory fibers , or both •• Define the extent of injury to neural tissue (axon loss, demyelination) •• Defining degree of axonal loss, the continuity of axon.

34. IMAGING Radiographs in standard anteroposterior and lateral projections are commonly ordered carpal tunnel view are also sometimes ordered but are helpful only to identify and study cause of CTS due to: •• Trauma •• Arthritis •• Degenerative cases may show calcification at the carpal region in carpal tunnel view.

35. Magnetic resonance imaging (MRI) and ultrasonography defining the pathology and also provides measurements of the canal size. Flattening of the nerve at the level of hook of hamate is a usual finding.

36. Differential Diagnosis •• Cervical spondylosis •• Rheumatoid arthritis •• Neural tumors •• Brachial plexopathy .

37. TREATMENT •• Nonsurgical measures •• Steroid injections •• Surgical CTR including endoscopic methods.

38. Nonsurgical Measures Splinting , Activity Modification and Oral Medications About 80% patients respond to wrist immobilization in night and intermittently during day within days. Particularly helpful in patients with positive Phalen’s test or a positive fist test. It keeps the lumbricals out of the tunnel.

39. Anti-inflammatory medications like nonsteroidal antiinflammatory drugs (NSAIDs) and supplementation with pyridoxine (B6) and methylcobalamin may have a beneficial role. Oral steroids and diuretics are prescribed to lower the interstitial fluid pressure

40. LOCAL CORTICOSTEROID INJECTIONS The benefits and effectiveness of local steroids is controversial, little information is available at present regarding the dosage, site of injection and number of repetitions. Recurrence of symptoms after local corticosteroid injection : 8–100%. Some investigators have even found the benefit of injection to be similar to NSAIDs and splinting. Up to 3 months local injection with a steroid is better than oral steroids.

41. Surgical Release Various methods of CTR include: •• Open release •• Limited open method •• Endoscopic methods

42. OPEN RELEASE Most common used method for carpal tunnel decompression. Commonly involves deep dissection releasing palmar fascia and carpal ligament longitudinally. The proximal point for starting the incision is determined by flexing the fourth finger towards the distal wrist crease. The cutaneous incision line is ulnarly located with respect to the thenar crease and is located 2 mm ulnarly to the fourth ray It is important to keep the superficial and the deep dissection lateral so as to prevent injury to motor branch and palmar cutaneous nerve of median nerve

43. Limited open carpal tunnel release: Modified instruments, light source, availability of magnification have led to development of this technique. A “palm-only” less than 2 cm mini-incision is used to release the transverse carpal ligament.

44. Endoscopic Technique In an attempt to reduce the complications of open release like scar tenderness and prolonged healing time endoscopic procedures were developed. Both single and dual portals have been described. In single portal technique a portal placed midway between flexor carpi ulnaris (FCU) and flexor carpi radialis (FCR). With wrist extended and endoscopic blade assembly aligned to ring finger distal edge of ligament is identified and sectioned from distal to proximal in controlled fashion.

45. Contraindications of endoscopic procedures include: Proliferative synovitis Stiffness of wrist joint Space occupying lesions in the tunnel that obliterate the view of canal

46. COMPLICATIONS Motor and/or palmar cutaneous branch injuries Hypertrophic scar formation and scar tenderness Pillar pain Injury to superficial palmar arch (more with endoscopic release) Tendon adhesions Infection Incomplete CTR Wound hematoma Reflex sympathetic dystrophy Weak grip strength Finger stiffness Laceration of ulnar artery (more with endoscopic release) Recurrence 7–20% Transient paresthesias (more with endoscopic release) .

47. ANTERIOR INTEROSSEOUS NERVE (AIN) COMPRESSIVE NEUROPATHY (ANTERIOR INTEROSSEOUS NERVE SYNDROME)

48. The anterior interosseous nerve may be injured in fractures and lacerations or may be compressed or entrapped by any of the following: the tendinous origins of the flexor digitorum sublimis , pronator teres , palmaris profundus and flexor carpi radialis brevis , accessory muscle slips and tendons from the flexor digitorum sublimis to the flexor pollicis longus An accessory head of the flexor pollicis longus ( Gantzer muscle), an aberrant radial artery thrombosis of the ulnar collateral vessels enlargement of the bicipital bursa Volkmann ischemic contracture

49. ETIOLOGY Various causes can be attributed to the compression of AIN: Spontaneous compression Anatomic variations Trauma—supracondylar fractures (usually traction injury) Infections Iatrogenic cause— venipuncture , catheterization, etc. in cubital fossa. Compartment syndrome Volkmann ischemic contracture (VIC).

50. CLINICAL PRESENTATION –– Motor deficits only: Patient with complete AIN palsy loses motor function of all the 3 muscles supplied by AIN : FPL, FDP of index and middle fingers, PQ The patient is unable to flex the interphalangeal (IP) joint of the thumb and the distal interphalangeal (DIP) joint of the index and middle fingers. A typical pinch attitude occurs where patient is unable to make a ring by bringing together the tips of thumb and index finger and rather it transforms into a “Peacock’s eye”.

51. On physical examination there is specifically: Patient is unable to make the OK sign which tests for weakness of FDP and FPL . There may be weakness of grip and pinch, specifically thumb, index and middle finger flexion.

52. TREATMENT Nonoperative treatment - commonly effective for acute onset lesions Empirically observation, rest and splinting in supination help if no organic lesion for compression is identified. Systemic disorders should be corrected (diabetes mellitus, alcoholism and hypothyroidism). Additional vitamins like pyridoxine 100 mg for a few weeks (6–8 weeks) may be given

53. OPERATIVE The cause of compression should be relieved Surgical decompression done by a long incision beginning 5 cm proximal to elbow near the supracondylar spur to medially along the biceps tendon in forearm and further 5 cm into forearm. –– Cutaneous nerves should be preserved –– Nerve should be isolated from the brachial vessels and released from compressive lesions –– Excise the supracondylar spur and fibrous bands (ligament of struthers , pronator band, lacertus fibrosus , etc.) –– Preserve the branches to Pronator Teres –– Interfascicular neurolysis may be necessary in some long-standing cases

54. PRONATOR SYNDROME

55. It is a compression of median nerve between the two heads of pronator muscle at the level of elbow joint Common in women usually seen in 5 th decade. The syndrome in males seen in weightlifters and body builders with well-developed forearm muscles.

56. Anatomy and Pathoanatomy The potential sites of entrapment include: •• Fibrous bands between ulnar and humeral heads of PT where the median nerve passes—most common cause of compression. •• Thickened or tight bicipital aponeurosis ( lacertus fibrosus ): Lacertus fibrosus syndrome is acute pronator syndrome after venipuncture or exercise •• Supracondylar process: Present in 1% of population

57. •• Flexor digitorum superficialis (FDS) aponeurotic arch •• Honeymoon paralysis: This is a transient compression of median nerve at elbow due to prolonged compression on forearm. •• Other uncommon causes of compression include: Compression due to casting (iatrogenic), hypertrophic PT, or its high origin especially the humeral head, anomalous insertion of the coracobrachialis muscle

58. CLINICAL PRESENTATION •• Symptoms: Insidious onset of aching pain in the volar aspect of the proximal forearm and the distal arm. Pain increased by exertion, excessive use of extremity and forceful pronation. Paresthesias and hypoesthesias similar to CTS is present but the difference being that it is more severe with pronation and supination rather than wrist flexion sensory loss over the distribution of palmar cutaneous branch of median nerve.

59. •• Physical examination: –– Tenderness on the median nerve in the proximal forearm –– Weakness of the muscles supplied by median nerve –– Provocative tests are specific for different sites of entrapment: ◊ Positive Tinel’s sign in the proximal anterior forearm that is usually present only after 4–5 months of compression ◊ Resisted elbow flexion with forearm in supination (compression at bicipital aponeurosis ) ◊ Direct pressure over proximal pronator muscle increases paresthesias ◊ Resisted forearm pronation with elbow flexed and gradually extended (compression at two heads of PT)

60. Diagnostic Studies •• Radiographs: It may reveal supracondylar process •• Electromyogram and NCV: To exclude other sites of nerve entrapment.

61. TREATMENT Nonoperative Effective in 50% of patients. comprises rest, splinting and NSAIDs for 3–6 months but effect may be seen up to a year or later. Patients experiencing progressive symptoms and those with trouble are not good candidates. Operative treatment involves surgical decompression of median nerve Typically the decompression of nerve is done simultaneously at all the possible compression sites. Effective in 90% patients.

62. REFERENCES Campbell's Operative Orthopaedics – 14 th Edition Rockwood and Greens fractures in adults 10 th edition Essential Orthopedics Principles & Practice by Manish Kumar Varshney gray's anatomy the anatomical basis of clinical practice 42 nd edition Apley and Solomon’s system of orthopaedics and trauma 10 th edition

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