Nerve Compression Syndromes

1. Nerve Compression Syndromes Gavin O’Mahony, MD

2. Objectives • To understand the cause and natural history of NCSs • To understand the diagnosis and work up of NCSs • To review operative and non-operative treatment modalities

3. Pathophysiology of Chronic Nerve Compression • Compression causes ischemic neuropathy • Continuum of neural changes depend on the force and duration of compression

4. Neural changes do not occur uniformly across the nerve • Vary depending on the distribution of compressive forces • Superficial fascicles undergo changes sooner • Result in varying patient symptoms within a single nerve distribution • Example: Early Carpal tunnel • Superficial fascicles to the long and ring fingers • More central fascicles to the thumb and radial side of • The index finger

5. Systemic Conditions and Personal Factors • Diabetes Mellitus • Hypothyroidism • Excessive alcohol use • Obesity • Tobacco use • Occupational Factors • Certain postures and positions may contribute to nerve compression • Positions of moderate flexion and extension increase pressure in the carpal tunnel • Elbow flexion increases pressure in cubital tunnel • Relationship accepted by workers compensation agencies

7. Median nerve • Carpal Tunnel Syndrome • Pronator Syndrome • Anterior Interosseous Syndrome

8. Carpal Tunnel

9. Carpal Tunnel Syndrome • Compression of the Median n. at the wrist • Most common nerve compression in UE • Paresthesia, numbness or bothin the median nerve distribution

10. Aching in the thenar eminence • Weakness of APB and OP (Palmar abduction) • Clinical diagnosisbased on a combination of • Symptoms and characteristic physical findings

11. Provocative tests • Phalen’s test

12. Durkan’s test

13. Tinel’s test

14. Electrodiagnostic studies can be useful to confirm diagnosis in equivocal cases • NCS can also stage the degree of nerve degeneration • Limitations of NCS – it evaluates only large myelinated fibers • Includes motor axons and sensory axons relaying vibration and light touch • Does not include smaller axons conveying pain or temperature sensation • Does not detect dynamic changes in blood flow that produce intermittent alterations. • Dependent on expertise of the examiner

15. Non-Operative treatment • Wrist splinting • Most prefabricated splints position the wrist in 30 degrees of extension • This increased carpal canal pressure • Wrist splints are most effective in neutral position – this makes it difficult to perform normal daily activity • Most providers recommend splinting only at night in neutral position

16. Non-Operative Treatment Corticosteroid injections – temporary relief is an excellent prognostic factor for successful carpal tunnel surgery Not indicated routinely – temporary relief with finite risk of nerve injury Nerve gliding exercises - avoidance of surgery in up to 80% of patients with mild or moderate compression Anaerobic exercise program – has been shown in one study to produce improvement in median nerve function

17. Operative treatment • Transverse carpal ligament release • Classic (standard) approach • Two-portal Endoscopic Technique • Single Portal Endoscopic Technique • Mini-open approach

18. Pronator Syndrome • Compression of the Median n. in the forearm • Between the 2 heads of the Pronator Teres • Much less common than CTS • Linked to repetitive upper extremity activity

19. Aching pain in the proximal volar forearm • Paresthesias radiating into the thumb, IF, MF and radial ½ of the RF • Similar to CTS • Palmar Cutaneous br. arises 4 cm above the wrist • Decreased sensation over the thenar eminence suggests a more proximal lesion • Provocative tests for CTS negative

20. Provocative tests • Resisted forearm pronation • Resisted elbow flexion with forearm supinated • Resisted flexion of the MF FDS • Pressure over the leading edge of the pronator teres with the forearm in maximum supination and the wrist in neutral produces paresthesias in the median sensory distribution. • NCS usually negative – useful to exclude other sites of compression

21. Treatment • Surgery usually not necessary • Activity modification, rest • NSAIDS, Corticosteroids • Conservative management effective in 50-70% • Surgery if space-occupying lesion or if several-month course of nonsurgical treatment fails. • Surgery success rate 90%

22. X-ray of the distal humerus may show a supracondylar process • Compression by anomalous ligament of Struthers

23. Anterior Interosseous Nerve Syndrome • Weakness or motor loss of: • Flexor Pollicis Longus • FDP to the IF (and occasionally the MF) • Pronator Quadratus

24. Weakness or motor loss usually occur spontaneously • Patient may describe clumsiness with fine motor skills such as writing and pinching. • AIN does not innervate the skin – no sensory loss • Pain may be present in the forearm along the course of the nerve

25. Electrodiagnostic studies are an important part of the workup • Can rule out more proximal lesions and distinguish AIN Syndrome from flexor tendon rupture • Nonsurgical treatment • Rest, splinting and observation for several months • Most improve without surgical intervention • Surgical decompression for patients who fail a several-month course of nonsurgical treatment

26. Operative treatment • Decompression of the median nerve in the forearm is the same for pronator syndrome and compression of the AIN • All potential compressive sites are released

27. Ulnar Nerve • Cubital Tunnel Syndrome • Guyon’s Canal

28. Cubital Tunnel Syndrome • Second most common compression syndrome • Also a clinical diagnosis • Electrodiagnostic testing frequently negative – good for staging • Numbness in the ring and small finger • Aching in the medial aspect of the elbow and forearm

30. Tinel’s sign positive at or proximal to Cubital Tunnel • Elbow flexion test • Elbow flexion combined with digital pressure

31. Clawing of the small and ring fingers

32. Fromentsign

33. Wartenberg sign

34. Interosseous wasting

35. Non-Operative treatment • Avoid positioning that combines elbow flexion with pressure over the ulnar nerve • Driving, phoning, during sleep • Nerve gliding exercises • Static night splinting in extension • Rigid splints often ineffective due to discomfort and noncompliance • 24 hour use of soft elbow pads to protect the ulnar nerve from direct compression

36. Mild Cuts can often be managed successfully with 2-4 months of non-operative treatment • If this is unsuccessful or if severe on presentation surgery is usually required • In Situ Decompression • Anterior Subcutaneous transposition • Anterior Subfascial/Submuscular transposition • Medial epicondylectomy • Outcomes tend to be less predictable than for Carpal tunnel • 75% with unilateral decompression report improvement • 68% with bilateral decompression report improvement

37. Compression of Guyon’s Canal

38. Nerve can be compressed: • Proximal to it’s bifurcation - motor and sensory deficits • Along the course of the deep motor branch – motor deficits only • Along superficial sensory branch – sensory deficits only

39. Often caused by space occupying lesion in the canal • Ganglions, thrombosis, pseudoaneurysms • Hamate hook nonunion • Anomalous muscles • Pre op imaging studies and electrodiagnostic studies are helpful • Non-operative treatment is recommended with acute cases of localized closed trauma • Wrist splint in neutral

40. Radial Nerve • SRN compression • PIN Syndrome • Radial Tunnel Syndrome

41. Posterior Interosseous Nerve Syndrome • Muscles innervated by PIN are affected: • ECRB, Supinator, ECU, EDC, EDQ, EIP, APL, EPL, EPB • May occur after trauma or may have insidious onset

42. Present with dropped fingers and thumb • Even with complete PIN palsy function of the ECRL (wrist extension) is preserved • Partial lesions are more common • MRI may reveal a mass causing the compression – Lipoma, ganglia • Nerve conduction studies can be useful – EMG detects motor dysfunction • Therapeutic approach identical to RTS – same nerve affected

43. Radial Tunnel Syndrome • Symptoms of pain and weakness after activities of forceful elbow extension and forearm pronation • Pain typically localizes to the lateral aspect of the forearm • Weakness is often secondary to the pain • May occur simultaneously with lateral epicondylitis • The tendinous origin of the ECRB can be involved in both conditions

44. Radial tunnel begins anterior to the radiocapitellar joint • Approximately 5cm in length • Formed laterally by the ECRL and BR • Medially by the biceps tendon and brachialis • Posteriorly by the radiocapitellar joint capsule • The BR passes over the nerve in a lateral to anterior direction to form the roof • Ends at the arcade of Frohse

45. Clinical diagnosis • Most patients have normal NCS • Few objective tests to confirm the presence of RTS • Pain relief after administration of Lidocaine/corticosteroid adjacent to the PIN at the level of the proximal radius is useful in diagnosis

46. Treatment • Nonsurgical management of both PIN syndrome and RTS is recommended initially • Rest, activity modification, splinting, stretching, anti-inflammatories • Nerve gliding exercises may be useful • In patients with concomitant lateral epicondylitis, tennis elbow straps are not recommended because of the increased pressure on the radial nerve • Surgical decompression after trial of non-operative management

47. Controversy • Generally described as a nerve compression and entrapment syndrome • Dispute over etiology • Prominent focal tenderness • Normal neurologic function • No confirmatory electrodiagnostic evidence • Symptoms do not occur in the distribution of the affected nerve

48. Superficial Radial Nerve Compressionaka Wartenberg’s Syndrome • Paresthesia, pain or numbness in the radial sensory nerve distribution

49. Symptoms are reproduced by forearm pronation and ulnar wrist deviation • Tinel sign over the radial sensory nerve at the point where it exits the deep fascia in the forearm • Nerve conduction studies rarely useful

50. Treatment • Modify activities to maintain a more supinated position wherever possible • Avoidance of excessive pronosupination • Local corticosteroid injection at the entrapment site between tendons of BR and ECRB are often successful. • Splinting not usually recommended • SRN decompression if non-operative treatment unsuccessful