Radial Nerve - Post test


1. In planning a tendon transfer for radial nerve palsy, a wrist flexor (amplitude 33 mm) is chosen to motor the finger extensors (amplitude 50 mm). In order to obtain full finger extension from the transfer, the effective amplitude of the donor wrist flexor tendon can be increased by: 

A. Following the vector of the original muscle
B. Synergism of the wrist extensors with the finger extensors 
C. Using the donor tendon to motor both the EPL and the EDC tendons. 
D. Selecting a donor muscle possessing strength equal to or greater than recipient 
E. Converting the donor muscle from monoarticular to multiarticular 

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Discussion: The true amplitude of a tendon cannot be increased. The effective amplitude can be augmented by converting a muscle from monarticular to a multiarticular. This allows the tenodesis effect to augment the effective amplitude of the transferred wrist flexor. Full finger extension is made possible by active wrist flexion. 

References: 
1. Brand PW, Beach RB, Thompson DE: Relative tension and potential excursion of muscles in the forearm and hand. J Hand Surg 6:209-219, 1981. 
2. Green DP: Radial nerve palsy. In Green DP, Hotchkiss RN, Pedersen WC (eds): Green’s Operative Hand Surgery, 4th ed. Philadelphia: Churchill Livingstone, 1999, pp. 1481-1496.

2. Compression of the superficial branch of the radial nerve in the distal forearm (Wartenberg syndrome) most commonly occurs between which structures? 

A. Extensor carpi radialis longus and extensor carpi radialis brevis 
B. Extensor carpi radialis longus and brachioradialis 
C. Brachioradialis and flexor carpi radialis 
D. Abductor pollicis longus and extensor pollicis brevis 
E. Abductor pollicis longus and extensor pollicis longus 

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Discussion: The superficial branch of the radial nerve courses along the radial forearm deep to the brachioradialis muscle. The nerve pierces the superficial forearm fascia near the junction of the middle and distal thirds of the forearm between brachioradialis and the extensor carpi radialis longus. It can be entrapped by either the margin of the brachioradialis or extensor carpi radialis longus or in the fascia between these two tendons. 

References: 
1. Dellon AL, Mackinnon SE: Radial sensory nerve entrapment in the forearm. J Hand Surg 11A:119-205, 1986. 

3. A 34 year-old man has persistent radial nerve deficit 6 weeks following a closed nondisplaced humeral shaft fracture that is nearly healed with splinting. The patient has no clinical or electromyographic sign of nerve recovery. Which of the following is the most appropriate treatment? 

A. Nerve grafting 
B. Neurolysis 
C. Tendon transfers 
D. Nerve transfers 
E. Observation 

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Discussion: 85-95% of radial nerve injuries with closed humerus fractures have been reported to spontaneously recover. Based on this premise, most surgeons favor expectant management of these injuries. Even if there is no evidence of recovery at 6 weeks post-injury, observation for an additional 6-18 weeks is recommended. If there is no clinical recovery within that period, then repeat EMG can be performed. If no recovery is evident at 6 months, exploration is considered. If the nerve is in continuity at the time of exploration, nerve action potentials can be useful in helping determine the need for neurolysis, repair or excision and grafting. 

References: 
1. Pollock FH, Drake D, Bovill EG, Day L, Trafton PG: Treatment of radial neuropathy associated with fractures of the humerus. J Bone Joint Surg Am 1981;63:239-243. 
2. Mohler LR, Hanel DP: Closed Fractures Complicated by Peripheral Nerve Injury. JAAOS 2006; 14: 32-37. 

4. A 45 year-old patient presents with the radiograph shown in Figure 1 and a chief complaint of weakness after sustaining a non-dominant humeral shaft fracture. He states that he has not felt the back of his hand, extended his fingers, or extended his wrist since his initial injury 2 years ago. On exam, he has extrinsic atrophy and no radial nerve function distal to the triceps. What surgical plan is most appropriate to offer him? 

A. External neurolysis of the radial nerve and collagen conduit treatment 
B. Radial nerve grafting at the level of the fracture 
C. FCR and palmaris nerve branches to posterior interosseous nerve transfer 
D. FCU to ECRB, FDS IV to EDC, and abductor digiti minimi opponens tendon transfers 
E. Pronator teres to ECRB, FCR to EDC, and palmaris longus to EPL tendon transfers 

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Discussion: Patients with long-standing nerve injury (two years from injury) are better served by tendon transfers for radial nerve palsy than nerve repair, as motor-end plate damage tends to occur 9-12 months after the injury. This patient already has atrophy of his nondominant forearm and would be well served with tendon transfers to restore hand position for activities of daily living. Pronator teres to ECRB, FCR to EDC, and palmaris longus to EPL tendon transfers accomplish acceptable hand position for activities of daily living. If intervention is performed prior to nine months after injury, Mackinnon’s group has recently described nerve transfers from selected expendable branches of the median or ulnar nerve to the posterior interosseous nerve and ECRB or ECRL for restoration of long extensor function. 

References: 
1. Bishop J, Ring D. Management of radial nerve palsy associated with humeral shaft fracture: a decision analysis model. J Hand Surg 2009;34A:991-6. 
2. Bumbasirevic´ M, Lesic´ A, Bumbasirevic´ V, Cobeljic´ G, Milosevic´ I, Atkinson HD. The management of humeral shaft fractures with associated radial nerve palsy: a review of 117 cases. Arch Orthop Trauma Surg 2010;4:519-22. 
3. Mackinnon SE, Roque B, Tung TH. Median to radial nerve transfer for treatment of radial nerve palsy. Case report. J Neurosurg 2007;107:666-71. 
4. Lowe JB 3rd, Tung TR, Mackinnon SE. New surgical option for radial nerve paralysis. Plast Reconstr Surg 2002;110:836-43. 

5. When performing tendon transfers for complete radial nerve palsy, in the absence of a palmaris longus, which procedure is the most appropriate?

A. Extensor pollicis longus tenodesis 
B. Flexor capri ulnaris to extensor pollicis longus 
C. Brachioradialis to extensor pollicis longus 
D. Flexor digitorum superficialis to extensor pollicis longus 
E. Interphalangeal arthrodesis 

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Discussion: In the absence of palmaris longus, several alternatives have been described. Incorporating EPL into the FCU to EDC transfer greatly diminishes the abduction component of the transfer’s effect on the thumb. The brachioradialis would not be functional with radial nerve palsy, but is a reasonable transfer if the palsy was isolated to the posterior interosseous nerve. Extensor pollicis longus tenodesis may be possible, but is not as effective as a FDS III or IV transfer. 

References: 
1. Bevin AG. Early tendon transfer for radial nerve transection. Hand 1976;8:134-136. 
2. Goldner JL, Kelley JM. Radial nerve injuries. South Med J 1958;51:873-883. 
3. Tsuge K, Adachi N. Tendon transfer for extensor palsy of forearm. Hiroshima J Med Sci 1969;18:219-232. 

6. A 38 year-old factory worker sustained a laceration from a piece of sheet metal resulting in numbness in the following distribution image. This most likely represents a laceration of which nerve:  

A. Ulnar 
B. Lateral Antebrachial Cutaneous 
C. Medial Antebrachial Cutaneous 
D. Superficial Radial 
E. Posterior Interosseous  

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Discussion: The area of numbness closely corresponds to the superficial sensory branch of the radial nerve. This nerve emerges from beneath the brachioradialis approximately 9 cm proximal to the radial styloid. The cutaneous innervation of the lateral antebrachial cutaneous nerve is more proximal.  

References: 
1. Netter FH. Atlas of Human Anatomy, Summit, NJ: CIBA-GEIGY,  1991: 151. 
2. Green D. In: Green DP, Hotchkiss RN, Pederson WC, Wolfe SW, eds. Green’s Operative Hand Surgery. 5th ed. Philadelphia: Churchill Livingstone/Elsevier, 2005:1033-141.

7. A 35 year-old laborer presents 15 months after ORIF of an open distal humerus fracture with no return of radial nerve function. At the index surgery, the nerve was described in the operative report as “hemorrhagic, and stretched but intact”. Recent EMG demonstrates no polyphasic waveforms in the brachioradialis. The most appropriate treatment at this time is: 

A. Continued observation and repeat EMG in 6 months 
B. Humeral osteotomy with anterior radial nerve transposition 
C. Double fasicular nerve transfer 
D. Tendon transfers 
E. Contralateral C7 nerve transfer 

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Discussion: Radial nerve palsy is associated with 6-12% of humeral fractures. The nerve is most at risk at the posterior mid shaft humerus (where the nerve lies in contact with the humerus) and at the distal lateral humerus (where it pierces the lateral intermuscular septum). Although spontaneous resolution is the rule, the fact that the nerve was significantly damaged and there has been no recovery clinically or electrically portends a poor chance of any recovery. Continued observation will likely lead to similar findings upon reexamination. Although nerve exploration and grafting can be considered, the likelihood for satisfactory outcomes at this point is speculative. Anterior transposition of the radial nerve through the fracture site at the time of initial ORIF could have been considered, but not indicated at this stage. Double fascicular and contralateral C7 nerve transfers are indicated in brachial plexus reconstruction. Other nerve transfers have been described in managing radial nerve injuries. Appropriate tendon transfers to restore function are indicated at this time. 

References: 
1. Carlan D, Pratt J, Patterson JM, et al. The radial nerve in the brachium: an anatomic study in human cadavers. J Hand Surg Am. 2007; 32(8):1177-1182. 
2. DeFranco MJ, Lawton JN. Radial nerve injuries associated with humeral fractures. J Hand Surg Am. 2006; 31(4):655-633. 
3. Green DP, Ingari JV; Radiol nerve palsy in Wolf SW , Hotchkiss RN, Pederson WC, Kozin SH: Green’s Operative Hand Surgery. 6th Edition. 
4. Shao YC, Harwood P, Grotz MRW, et al. Radial nerve palsy associated with fractures of the shaft of the humerus: a systematic review. J Bone Joint Surg Br. 2005; 87(12):1647- 1652. 

8. What is the indication for demonstrated tendon transfer in Figure 1? 

A. Posterior interosseous nerve (PIN) injury at the supinator 
B. Median nerve injury at the antecubital level 
C. Ulnar nerve injury at the cubital tunnel 
D. Lower trunk brachial plexus injury 
E. Radial nerve injury at the midhumeral level

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Discussion: The demonstrated procedure is the Brand version of tendon transfers used in a radial nerve palsy, resultant from radial nerve injury below the triceps innervation and above the brachioradialis innervation. At this level (midhumeral), functional losses include wrist extension and finger/thumb extension, which are restored using the transfers shown (PT to ECRB, FCR to EDC, and PL to EPL). In a PIN injury, wrist extension is maintained through the intact ECRL and ECRB muscles, so PT to ECRB transfer is not indicated. Median nerve, ulnar nerve, and lower trunk brachial plexus injury do not result in deficits that involve the combined restoration of wrist extension and finger/thumb extension. 

References: 
1. Stefanovic M, Sharpe F: Chapter 67: Tendon Transfer for Radial Nerve Palsy. In: Weiss APC, Goldfarb CA, Hentz VR, Raven RB, Slutsky DJ, Steinmann SP, eds. Textbook of Hand & Upper Extremity Surgery. The American Society for Surgery of the Hand. 2013. 
2. JG Seiler, MJ Desai, and SH Payne. Tendon Transfers for Radial, Median, and Ulnar Nerve Palsy. J Am Acad Orthop Surg. 2013; 21:675-684. 3. Brand PW: Clinical mechanics of the hand. St. Louis, MO, CV Mosby. 1985; 127-165.