Plexo Braquial Transfer of the Nerve to the Brachioradialis Muscle to the Anterior Interosseous Nerve for Treatment for Lower Brachial Plexus Lesions: Case Report

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AUTHORS:  Antonio García-López, MD, Pablo Sebastian, MD, Francisco Martinez, PhD, David Perea, MD

In lower lesions of the brachial plexus (C8–T1) there is good function of the shoulder, elbow, and wrist, although that of the hand is impaired. Reconstruction of finger flexion is generally obtained by tendon transfer. We present a case report involving transfer of the motor nerve branch of the brachioradialis muscle to the anterior interosseous nerve to restore finger flexion in acute lower brachial plexus lesion. (J Hand Surg 2011;36A:394397. Copyright © 2011 by the American Society for Surgery of the Hand. All rights reserved.)

Key words Brachial plexus, nerve injury, nerve transfer, neurotization, paralysis.

ISOLATED LESIONS OF the lower 2 roots (C8–D1) of the brachial plexus, known as Dejerine-Klumpke, are uncommon lesions and account for 3% of the supraclavicular lesions of the brachial plexus.1 The usual mechanism is traction of the abducted arm, caus­ing tearing of the lower roots. This leads to a functional motor loss that is essentially equivalent to a high me­dian and ulnar nerve paralysis and sensory loss in the territory of the ulnar nerve.

In adults, attempts to restore flexion of the fingers by nerve repair at the plexus level have always been un­successful. Therefore, tendon transfers, tenodesis, and trapeziometacarpal arthrodesis have been done to ob­tain partly effective “automatic” thumb opposition, sim­ilar to that of a tetraplegic hand.2 When no muscle was available, the alternative was transfer of a functional, free gracilis muscle.3,4 Recently, selective nerve trans­fer to the posterior groups of the median nerve of the arm have been performed, using the phrenic nerve in complete lesions5,6 and using the brachialis branch of the musculocutaneous nerve7 with satisfactory results.

From the Upper Limb Unit, Orthopaedic Department, Hospital General Universitario de Alicante,Spain.

Received for publication August 19, 2010; accepted in revised form November 19, 2010.

No benefits in any form have been received or will be received related directly or indirectly to the subject of this article.

Corresponding author: Antonio García-López, MD, Hospital General Universitario de Alicante, Orthopaedic Department, C/ Madre Teresa de Calcuta, 4 B4 E2 4I, Alicante 03016, Spain; e-mail: garcialopez1@hotmail.com.

0363-5023/11/36A03-0003$36.00/0 doi:10.1016/j.jhsa.2010.11.030

The posterior fascicular group (PFG) of the brachial median nerve is composed mainly of the branches to the anterior interosseous nerve and to the palmaris longus, as well as some fine branches to the proximal part of the flexor digitorum superficialis or flexor digitorum pro­fundus.

In an attempt to obtain the maximum number of axons for transference and maximum synergistic effect, and to be as near as possible to the muscles affected, we propose a new technique that involves transferring the brachioradialis muscle branch (BRMB) directly to the anterior interosseous antebrachii nerve (AIN). We pres­ent a detailed description of this technique.

CASE REPORT

A 52-year-old man had injured his left arm in a motor­cycle accident. He was seen by us as an outpatient 4 months after the accident, complaining that he could not move his hand, although there was no problem with movement of his shoulder, elbow, or wrist.

Tinel’s sign was negative for paresthesias in the supraclavicular area. Sensory function was good in the 3 radial digits, but there was anesthesia of the ring and little fingers. There was no Horner’s syndrome and no neuropathic pain. The shoulder, biceps brachii, and triceps had a normal muscle power of M5. The remain­der of motor function was as follows: pronator teres (PT), M5; supinator, M5; brachioradialis, M5; extensor carpi radialis longus and brevis, M4; extensor carpi ulnaris, M5; flexor carpi radialis, M4; and flexor carpi ulnaris, M1. There was neither extension/flexion, ab­duction, or opposition of the thumb (M0). Extension of the index through small fingers was M3. Finger flexion was absent. There was paralysis of the intrinsic muscles of the hand. Magnetic resonance imaging showed left side meningoceles at C8 and T1 levels. Electrophysi­ologic studies were consistent with preganglionic le­sions of the brachial plexus of the roots of C8 and T1. No motor unit potentials were seen in the muscles innervated by the C8 and T1 nerve roots. Nerve con­duction studies showed the presence of sensory action potentials in the C8–T1 territory.

Surgical treatment was performed 5 months after the initial injury. The dissections were carried out under general anesthesia without pharmacologic paralysis, with a pneumatic tourniquet and 4X magnifications. We used a zigzag incision, anterior to the elbow.

The radial nerve was explored as it entered the in­terstitial canal between the biceps brachii and brachio­radialis muscles. In the superior portion of the canal we identified and stimulated the BRMB. As in 33% of the Caucasian population, the motor branch from radial nerve to the biceps brachii was not present8,9 in this patient. Distally, we found the following radial nerve branches: the extensor carpi radialis longus muscle branch and extensor carpi radialis brevis muscle branch, for the supinator, the posterior interosseous nerve and its superficial sensory branch (Fig. 1).

The median nerve was identified in the depths of the internal bicipital canal, along with the vascular bundle. Dissection of the median nerve extended proximally to the junction of the lower and middle thirds of the arm and distally between the 2 heads of the PT muscle, as far as the starting point of the AIN and its entrance into the arch of origin of flexor digitorum superficialis mus­cle. The AIN originates in the dorsoradial aspect of the median nerve and gives off branches to innervate the flexor pollicis longus (FPL), flexor digitorum profundus (FDP)—particularly to the index, middle, and occasion­ally ring fingers—and further distally, the pronator cuadratus. After the origin of the anterior interosseous nerve, we observed the origin of the muscle branch to the flexor digitorum superficialis. More proximally, from the anterior part of the median nerve, the muscle branches for the PT and the flexor carpi radialis were seen, and in this patient, an absence of the palmaris longus muscle and nerve was observed (Fig. 2). Intra­operative electrostimulation is useful in locating these nerves.

Figure 1

FIGURE 1: Identification of the radial nerve at the bottom of the external bicipital canal. Distal on the top. In the left part, the cutaneous antebrachii lateralis nerve and the basilic vein, displaced laterally with a retractor, can be seen. The radial nerve is shown pulled to the right with a rubber band before dividing into its superficial and deep branches. Likewise, the extensor carpi radialis longus muscle branch is shown with a black arrow and the BRMB with a white arrow, which is the one to be used for transference.

The AIN was mobilized proximally by interfascicu-lar dissection and can easily reach the distal third of the upper arm in the posterior part of the median nerve, 1 cm proximal to the origin of the BRMB (Fig. 3). We cut the fascicle of the median nerve corresponding to the AIN with a 1.5 mm neurotome. With the 1.5 mm neurotome, we also cut the BRMB near its entry into the muscle and transferred it to the AIN. Nerve coap­tation without tension was obtained with 9-0 epineural sutures and Tissucol (Baxter AG, Viena, Austria) using a microscope (Fig. 4). During the postoperative period, the arm was immobilized with the elbow in flexion­supination for 6 weeks to prevent muscle contraction or flexion/extension of the elbow, which could cause a suture dehiscence.

At the 3-month follow-up visit, the limb had recov­ered to the preoperative status, with no functional deficit of flexion of the elbow or of supination, following transference of the BRMB. At 5 months after surgery, the patient began to recover flexion of his fingers, and after a year, there was flexion of M3 for the FPL, M2 for the FDP of index and middle fingers, and M1 for the FDP of the ring and small fingers.

TRANSFER OF THE NERVE TO THE BR MUSCLE TO THE AIN

Figure 2 Figure 3
FIGURE 2: An intraoperative photograph of dissection of the median nerve. Distal on the top. To the right there is the PT muscle branch, marked with a black arrow. The AIN is marked with a white arrow. The origin of the flexor digitorum superficialis muscle branch (no marker) can then be seen crossing the AIN toward the flexor digitorum superficialis muscle. FIGURE 3: Proximal interfascicular intraneural dissection of AIN, labeled with a black arrow.

DISCUSSION

In lesions of the lower brachial plexus that involve the last 2 roots (C8, T1), some of the functions of the median nerve are affected. Sensory function is main­tained, and involvement is mainly of the motor function of the PFG and the medial fascicular group of the median nerve, with preservation of the function of the anterior fascicular group (AFG). The AFG is mainly motor, and it innervates the PT and flexor carpi radialis muscles, which still function in lesions of the inferior trunk. The medial fascicular group carries all the sen­sory fibres to the hand and retains this function, but it also contains some motor fascicles of flexor digitorum superficialis and the motor fibers to the hand in which the muscles are paralyzed. The PFG is also mainly motor and carries fibers of the AIN, which innervate the

FDP of the thumb, index, and middle fingers, FPL, and pronator cuadratus.5 The priority in paralysis of the lower 2 roots is to recover flexion of the digits so that the PFG should serve as the recipient for nerve transfer.

The brachioradialis is an accessory muscle for flex­ion of the elbow and an accessory supinator when the arm is maximally pronated. Because it does not play an important part in flexing the elbow, its denervation does not cause functional impairment of this movement.

Figure 4

FIGURE4: Intraoperative photograph showing the coaptation of the BRMB transferred to the AIN. The completed nerve repair rests on the rubber background.

Accioli10 described a technique of nerve transfer of the epitrochlear branch or AFG of the median nerve by direct coaptation with the branch to the brachialis mus­cle.10 However, this technique is useful only in cases involving C7, C8, and T1 roots in which wrist flexion is impaired. More function is established in the hand by restoring flexion of the digits because the goal is to re-establish digital pinch. In some cases in which Ac­cioli’s technique was used, good results were reported in PT muscle function but weakness in FPL muscle activity.11 Gu7 suggested a more functional transfer of the branch to the brachialis muscle for the median nerve.7 After a careful anatomical study, he located in the internal aspect of the arm the nonfunctioning fasci­cles of the flexors of the fingers in the posterior quarter of the median nerve, by dissecting between fascicles and logically giving priority to the neurotization of PFG rather than AFG. Although neurophysiological studies using sensory evoked potential help locate the PFG, the limitation that one does not observe anatomical conti­nuity of the neurotized fascicles with the AIN leaves room for error in the transference. However, Gu’s re­sults were slightly worse than those from our case (M2 for FPL and FDP of index and middle fingers). Nerve transfer of the AIN can be performed more distal than the techniques previously proposed, and therefore, closer to the target muscles, which facilitates rapid reinnervation and better recovery. The site of AIN is more distal, and an intraneural proximal extension is done of the PFG of the median nerve to obtain direct neurorrhaphy with the BRMB. Therefore, it is not sub­ject to location errors, and intraoperative sensory evoked potential studies are unnecessary. The proce­dure, as shown by our clinical experience, is done using a single incision on the anterior aspect of the elbow, is simple, is technically possible to reproduce, and permits recovery of flexion of the first 3 radial digits. The results are obviously more moderate than the nerve transfers that have been made in isolated lesions of the median nerve. This is due to antagonistic mus­cles completely retaining their function.12

This technique is indicated for recovery of flexion of the thumb and fingers in recent lower brachial plexus lesions (C8–T1) without reducing flexor function of the wrist or elbow. This technique could also be applicable in the flexor phase of group 3 to 7 quadriplegia.

REFERENCES

1. Midha R. Epidemiology of brachial plexus injuries in a multitrauma population. Neurosurg 1997;40:1182–1189.

2. Gohritz A, Fridén J, Herold C, Aust M, Spies M, Vogt PM. Tendon transposition to restore muscle function in the hand [in German]. Unfallchirurg 2007;110:759–76.

3. Manktelow RT, Mckee NH. Free muscle transplantation to provide active finger flexion. J Hand Surg 1978;3:416 –421.

4. Doi K, Sakai K, Kuwata N, Ihara K, Kawai S. Reconstruction of finger and elbow function after complete avulsion of the brachial plexus. J Hand Surg 1991;16A:796 –803.

5. Zhao X, Lao J, Hung L-K, Zhang G-M, Zhang L-Y, Gu Y-D. Selective neurotization of the median nerve in the arm to treat brachial plexus palsy. An anatomic study and case report. J Bone Joint Surg 2004;86A:736–742.

6. Zhao X, Lao J, Hung LK, Zhang GM, Zhang LY, Gu YD. Selective neurotization of the median nerve in the arm to treat brachial plexus palsy. J Bone Joint Surg 2005;87A Suppl 1, Part 1:122–135.

7. Gu Y-D, Wang H, Zhang LY, Zhang GM, Zhao X, Chen L. Transfer of brachialis branch of musculocutaneous nerve for finger flexion: anatomic study and case report. Microsurgery 2004;24:358–362.

8. Blackburn SC, Wood CP, Evans DJ, Watt DJ. Radial nerve contri­bution to brachialis in the UK Caucasian population: position is predictable based on surface landmarks. Clin Anat 2007;20:64 –67.

9. Frazer EA, Hobson M, McDonald SW. The distribution of the radial and musculocutaneous nerves in the brachialis muscle. Clin Anat 2007;20:785–789.

10. Accioli De Vasconcellos ZA, Mira JC. Contribution a l’étude des neurotisations intra-et extra-plexuelles du plexus brachial et de ses branches terminales. Étude chez le Rat et chez l’Homme. [Contri­bution to intra and extra brachial plexus and terminal branches neurotisations. Animal and human study]. Thèse. Université de Paris 05, Paris. 1999.

11. Palazzi S, Palazzi JL, Caceres J-P. Neurotization with the brachialis muscle motor nerve. Microsurgery 2006;26:330–333.

12. Hsiao EC, Fox IK, Tung TH, Mackinnon SE. Motor nerve transfers to restore extrinsic median nerve function: case report. Hand 2009; 4:92–97. Epub 2008 Sep 19.

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