Radial nerve injuries

Radial nerve injuries

1. RADIAL NERVE INJURY AND MANAGEMENT SUSHANT S. SONARKAR

2. ANATOMY: Posterior cord,(C5-6,7,8,T1), Largest branch, Predominantly motor,

3. Course of Radial Nerve (RN) in the arm

4. Here it lies b/w brachialis and BR

5. Radial nerve (C5, 6, 7 , 8, T1 ) exiting axilla via the triangular space Brachialis (lateral part) Anconeus Triceps brachii Posterior cutaneous nerve of forearm Posterior cutaneous nerve of arm Lower lateral cutaneous nerve of arm Radial nerve in the spiral groove (posterior aspect of humeral shaft) Brachioradialis (BR) ECRL (last branch of radial nerve proper) Lateral intermuscular septum

6. BR ECRL Dorsal Radial Sensory Nerve Dorsal digital nerves Radial styloid 8 cm Course of Radial Nerve (RN) in the forearm

7. Deep terminal branch → Posterior interosseous nerve (PIN) Supinator EIP EDC and EDM ECU ECRB Superficial terminal branch Radial Nerve Proper EPL EPB APL PIN reaches the back of forearm by passing around the lateral aspect of the radius b/w the superficial and deep heads of the Supinator to supply all extensor compartment. Finally, PIN ends by supplying carpal joint sensation

8. Lower lateral cutaneous nerve of arm Posterior cutaneous nerve of arm Posterior cutaneous nerve of forearm Dorsal radial sensory nerve Gives sensibility to the dorsum of the hand over the radial two-thirds, the dorsum of the thumb, and the index, long, and half of the ring finger proximal to the distal interphalangeal joint. Cutaneous innervation from radial nerve

9. I nspection Attitude and deformity : note any typical attitude of the wrist drop Wasting of the muscles in longstanding paralysis Skin becomes dry , glossy and smooth with disapperance of cutaneous folds and subcutaneous fat Scar or wound Palpation of the nerve If there is tenderness on pressure along the course of the nerve- indicates inflammation of the nerve In the course of the nerve where complete divison of nerve is expected feeling of neuroma and glioma almost confirm the diagnosis

10. ETIOLOGY: In the Axilla, In the shoulder, In the Radial groove, B etween spiral groove and the lateral epicondyle, At the elbow, In the forearm, Other causes,

11. TYPES OF INJURY: Primary injury, Secondary Injury,

12. Functional motor deficit Inability to extend the wrist (in case of injury at level of PIN, wrist extension is weak with radial deviation since ECRL innervation is intact) Inability to extend the fingers at the MCP joints Inability to extend and radially abduct the thumb Weakness of grip strength d/t loss of mechanical advantage that wrist extension provides for grasp and power grip

13. Area of sensory loss in radial nerve injury in the axilla Unlike the median and ulnar nerves, sensory loss following radial nerve injury is not functionally disabling unless the patient develops a painful neuroma Sensory Loss Autonomous sensory zone for radial nerve → dorsum of 1 st webspace The Lateral cutaneous nerve of forearm has a significant overlap pattern with the Superficial radial sensory nerve

14. CLINICAL FEATURES: VERY HIGH RADIAL NERVE PALSY : ( in axilla) Motor paralysis : Triceps, anconeus , Brachioradialis , Supinator, Long Extensors of wrist. Sensory Paralysis: Loss of skin sensations in posterior surface of lower arm and back of forearm, Lateral three and one half fingers(dorsum)

15. HIGH RADIAL NERVE PALSY: ( R adial Groove) Motor paralysis: Brachioradialis , Supinator, Long extensors of wrist. Sensory paralysis: Back of hand, radial side of thumb, and adjoining part of thenar eminence The medial side of thumb , index , middle and lateral part of ring fingers.

16. LOW RADIAL NERVE PALSY: Motor paralysis: EDC, EDM,EDI,ECU APL,EPL,EPLB Sensory loss: No sensory loss

17. TEST FOR RADIAL NERVE INJURY: Test for brachioradialis , Test for extensors of wrist, Test for extensor digitorum , Hitch Hiker sign,

18. Diagnostic Tests: Modality tests, Functional tests, Objective test, Sweat test, Skin resistance test, Wrinkle test, Tinel’s sign, Positive axon reflex test.

19. ELECTROPHYSIOLOGICAL STUDY: Electromyography, Motor nerve conduction studies, Strength duration Curve,

20. Helpful in arriving at a diagnosis in presence of atypical presentations or equivocal clinical findings Limitations of EDT : ▪ Evaluates only large myelinated fibres → smaller axons conveying pain and temperature are not assessed ▪ Changes in unmyelinated nerve fibres, which are the first to be affected in nerve compressions, are not evaluated ▪ Performing the test before 3-6 weeks post injury can give inaccurate results ▪ Very proximal or distal nerve injuries are difficult to assess ▪ Unreliable assessment of multi-level injuries ▪ Examiner dependant

21. Nerve conduction studies ( NCS ) 2 electrodes are placed along the course of the nerve. The first electrode stimulates the nerve to fire, and the second electrode records the generated action potential

22. Electromyography (EMG)

23. Sequence of events in nerve compression ▪↑ Latency ▪↓ Nerve conduction velocity Associated Electrodiagnostic findings ▪↓ SNAP ▪↓ CMAP ▪↑ Insertional activity ▪ Fibrillation potentials and fasciculations ▪ ’Giant’ MUPs ▪ Normalization of NCV ▪ Loss of ‘giant’ MUPs

24. presence of motor weakness suggests a more proximal site of compression Also seen in patients who use forearms in pronated position for extended periods → in pronation, the tendons of BR and ECRL approximate and may compress the nerve ▪ In WS, pain is exacerbated by pronation, while in DQT pain is elicited with changes in thumb and wrist position ▪ DQT - normal sensation in the dorso-radial hand ▪ DQT - pain on percussion over the 1 st extensor compartment Electrodiagnostic testing is of limited value in Wartenberg’s syndrome

25. The radial tunnel is a 5 cm space bounded by: ▪ Dorsally : capsule of the radiocapitellar joint ▪ Volarly : the BR ▪ Laterally : the ECRL and ECRB muscles ▪ Medially : the biceps tendon and brachialis muscles Within radial tunnel, there are 5 potential sites of compression: ▪ fibrous bands to the radiocapitellar joint between the brachialis and BR ▪ the recurrent radial vessels ( leash of Henry ) ▪ the proximal edge of the ECRB ▪ the proximal edge of the Supinator ( arcade of Fröhse ) ▪ the distal edge of the Supinator BR Supinator arcade of Fröhse ECRL PIN

26. Radial Tunnel Syndrome is a clinical diagnosis

27. Management: In nerve root avulsion injuries: non operative, early neurotization , Open injuries, Closed injuries,

28. SURGICAL TECHNIQUES Techniques of neurorrhaphy : -partial neurorrhaphy - epineural neurorrhaphy - perineural neurorrhaphy - epiperineural neurorrhaphy - interfasicular nerve grafting

29. MANAGEMENT Nerve grafting: Types of graft -Trunk graft -Cable graft -Pedicle nerve graft -Inter fascicular nerve graft -Pre vascularized nerve graft Source of graft - Sural nerve is probably the best source of graft in majority of cases -Medial and lateral cutaneous nerve at the wrist is an ideal donor graft for fascicular nerve after for digital nerve - Superifical radial nerve is an excellent source of graft generally used in case of radial nerve injuries -Dorsal branch of ulnar nerve can also be used as a graft.

30. RECONSTRUCTIVE PROCEDURES Tendon transfers Arthodesis Tendon transfers work to correct: instability imbalance lack of co-ordination restore function by redistributing remaining muscular forces

31. TENDON TRANSFER Robert jones described 2 sets of tendon transfers 1916: PT - ECRL and ECRB FCU - EDC III,IV,V FCR - EDCII,EIP and EPL 1921: PT - ECRL and ECRB FCU - EDC III,IV,V FCR - EDCII,EIP , EPL,APL ,EPB Current standard tendon transfer protocol BRANDT PT - ECRB FCR - EDC PL - EPL

32. INTERNAL SPLINT Burkhalter proposed early transfer of PT-ECRB to restore wrist extension as an adjunct to nerve repair. It restores the power grip quickly and effectively since wrist extension is restored Advantages are: It works as a substitute during nerve regrowth and largely eliminates an external splint Subsequently the transfer aids the newly innervated and week wrist extensor It continues to act as a substitute in case nerve regeneration is poor or absent

33. TENDON TRANSFER BOYE’S tendon transfer PT -ECRL and ECRB FCR - EPB and APL FDS middle –EDC FDS ring - EPL and EI POST OP CARE: immobilization for 6 weeks usually maintained for 4 weeks followed by a spring loaded extension splint for the wrist and finger. during the cast immobilization the MCP joints held in 40degee of reflection wrist should be fully extended with thumb in abduction and extension ip joints of fingers in comfortable flexion

34. NON-OPERATIVE TREATMENT SPLINTS wrist drop can be treated successfully by splints Bark halter has observed that grip strength may be increased by 3 to 5 times by simply stabilizing the wrist with splints Many types of splints have been described Each patient individual need should be dictate the type of splinting used s plints are used for patients who are debilitated and who reject surgery. Cock up splint)

35. OPPENHEIMER SPLINT It is a dynamic splint used for radial nerve palsy it consists of one palmar bar over the prox.phalanx,one distal forearm cuff dorsally and proimal cuff volarly . Provides global extension of wrist and fingers Limitation of this splint:restriction of grasp due to palmar bar. Proximal migration of splint cause friction blisters around the wrist

36. RECOVERY Factors influencing the prognosis for recovery -age -level of injury -delay between the time of injury and repair -gap between nerve ends -Condition of the nerve -type of nerve -

37. Level of injury: The more proximal the injury, the more incomplete the overall return of motor and sensory function, especially in the more distal structures. Delay between the time of injury and repair -Delay of neurorrhaphy affects motor recovery more profoundly than sensory recovery -satisfactory reinnervation of muscle can occur after denervation upto 12 months . - irreversible changes develop in the muscles after 24 months -with respect to sensory recovery ,nerve can be repaired even after 2 yrs for satisfactory recovery. However results are best if done earlier.

38. Gap between nerve ends The methods for closing the gap are nerve mobilization nerve transposition, positioning of the extremity , nerve grafts, bone shortening. Condition of the nerve: A clear cut sharp nerve injury has got better prognosis following primary repair than crushed or avulsed nerve injuries which needs secondary repair Type of nerves: pure motor ,pure sensory nerves recover better than mixed nerves because the consequence of mismatching are not so great in pure motor or sensory nerves.