Secondary Procedures for Brachial Plexus Injuries

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CHAPTER 242 Secondary Procedures for Brachial Plexus Injuries

Huan Wang, Alexander Y. Shin, Allen T. Bishop, Robert J. Spinner

Restoring motor function after brachial plexus injury is challenging. Despite advances in the techniques of direct repair and the introduction of novel nerve transfer procedures, outcomes of treatment are far from satisfactory.

So-called secondary operations are performed in situations in which additional function can be augmented or provided by performing muscle, tendon, bone, or other soft tissue reconstruction. These procedures may be performed in patients in whom there has been a delay between development of the lesion and initial consultation, when nerve reconstruction was deemed too late to expect a reasonable functional outcome, or in those who may have undergone previous procedures such as neurorrhaphy, nerve grafting, or nerve transfer and recovery has been less than satisfactory. Unlike primary operations dealing with nerve and muscle end-organs, which are time sensitive for recovery, secondary procedures can be performed at any time after an injury, assuming that the joints are supple. Because of the magnitude of brachial plexus injury, oftentimes only a combination of nerve repair and secondary procedures is used to maximize the patient’s functional use of a paralyzed limb. A 26% rate of secondary procedures has been reported in a series of 362 brachial plexus patients.^1,²

The most common forms of secondary operations are muscle/tendon transfer, functioning free muscle transfer (FFMT), arthrodesis, tenodesis, and corrective osteotomy. The choice of secondary surgery depends on the individual patterns of paralysis. In many cases, surgical options are limited because of the extent of the brachial plexus injury and the unavailability of functioning donor tissue.

Secondary procedures may address form, function, and pain. They are undertaken to achieve the following major goals: (1) active control of the shoulder, (2) reestablishment of useful elbow flexion, (3) stabilization of the wrist, and (4) improvement in hand function.^2,³ When planning secondary operations, the fundamental question is which function the patient needs most in activities of daily living. The possibilities and potential use of secondary procedures should be discussed with the patient and realistic goals set forth. The most important factor in producing a successful result from a secondary operation is a cooperative and well-informed patient who understands the goals of the operation or operations and will work hard during rehabilitation to obtain the best result possible.

Secondary reconstructive procedures for brachial plexus injuries are usually done in a distal-to-proximal sequence. Hand and wrist operations are made more difficult by arthrodesis of the shoulder or procedures that result in a fixed elbow flexion contracture. However, because recovery of wrist and hand function occurs later than shoulder and elbow function after nerve reconstruction, it may also be reasonable to reconstruct the proximal end of the limb while waiting for further recovery in the hand. Consequently, an elbow-hand-shoulder order has been recommended by some surgeons.

Tendon Transfer

Tendon transfers for brachial plexus lesions are generally identical to the procedures performed after nonrecoverable peripheral nerve palsies.

General Principles

Other Considerations

In addition, there are special considerations for tendon transfer in patients with brachial plexus injury. Many patients complain of severe pain after brachial plexus lesions, and this pain needs to be addressed before tendon transfer. Even the best attempts to restore muscle balance in a painful limb may not succeed in reconstructing a functional limb.⁴ When choosing donor motors, reneurotized motor units should generally be excluded because regeneration is often incomplete and thus muscle strength is insufficient; furthermore, these muscles frequently do not have good independent control. Synergistic transfer may not be possible because of the limited availability of donor motors. For this reason, one transfer is sometimes designed to achieve two functions as long as they are not opposing actions. This is done by transferring the muscle across two joints and passing the motor around a pulley for strengthening.^3,⁵ It should be noted that a transferred muscle-tendon unit that crosses multiple joints will always have its maximal action on the most proximal joint.

Tendon Transfer for Shoulder Function

The shoulder is a complex joint with many muscles required for full function. Its major functions are abduction, external rotation, internal rotation, and adduction. Shoulder function also depends on the stability of the scapula with the rhomboid and serratus anterior muscles. Tendon transfers around the shoulder to achieve functional control can be futile unless multiple transfers are attempted to duplicate the normal interaction of opposing and synergistic groups of muscles.⁶ If part of the deltoid is functional, the entire muscle can be detached subperiosteally and rotated anteriorly so that the posterior functioning portion will occupy the position of the middle portion. A paralyzed deltoid can be supplemented with a latissimus dorsi transposed in a bipolar manner on top of the shoulder.^7,⁸ A more common procedure is a trapezius transfer^9,¹⁰; the trapezius, an extraplexal muscle, is spared in the majority of complete brachial plexus injuries and can be transferred (although not as effectively) after distal spinal accessory nerve transfer to the suprascapular nerve. The levator scapulae is another remaining muscle for restoration of shoulder function. Transfer of this muscle elongated with fascia lata or tendon allograft onto the supraspinatus is efficient in regaining some extent of abduction.⁸ The long head of the triceps can be brought to the acromion posteriorly and the short head or long head of the biceps anteriorly.¹¹ The external rotators can be reinforced by posterolateral transfer of the latissimus dorsi and teres major.^12,¹³ Such an extensive approach is not always possible as a result of the extent of the injury and limited functioning muscle motors.

Because the most common paralysis is that of abduction and external rotation, the following procedures are among the frequent reconstructions performed.

Transfer of the Trapezius

A “U”-shaped skin incision begins above the clavicle over the trapezius insertion, traverses the lateral aspect of the clavicle, and crosses around the acromion and along the spine of the scapula. The upper part of the trapezius is dissected from the clavicle and scapular spine to 2 cm from the vertebral border of the scapula. Its attachment at the acromion can be addressed either by preserving the attachment with a bone segment from the acromion or by completely detaching and prolonging it with a tendon graft. The neurovascular bundle of the spinal accessory nerve is protected and mobilized to facilitate transposition of the trapezius muscle. A vertical incision is made along the mid-deltoid. The deltoid is detached from the acromion and split along its fiber orientation to expose the proximal end of the humerus. If a bone segment of the acromion is used, the humeral shaft is roughened with an osteotome to facilitate growth of bone to the detached acromion-tendon unit. If the trapezius is prolonged with a tendon graft, holes are drilled in the humerus and the tendon graft is woven into the humerus. With the arm abducted 90 degrees, the acromion bone segment with the attached trapezius muscle is brought to the proximal end of the humerus as close to the tuberosity as possible and fixed with cortical lag screws. Similarly, if the trapezius is prolonged with a tendon, the arm is abducted and the tendon graft inserted underneath the acromion, placed through the drill holes, tensioned appropriately, and sewn back to itself. The deltoid is sutured over the new trapezius insertion and the wound closed in layers. Postoperatively, the shoulder is immobilized with a spica bandage in 90 degrees of abduction for 6 weeks to allow union of bone between the humerus and the acromion segment. The arm should be supported with a series of abduction splints and gradually lowered to adduction to prevent overstretching of the trapezius while muscle-strengthening exercises begin (Fig. 242-1).

FIGURE 242-1 Illustration demonstrating transfer of the trapezius muscle for shoulder abduction and stability. A, The trapezius is taken off the clavicle, acromion, and spine of the scapula. B, A tendon graft (typically fascia lata) is woven through the distal end of the trapezius tendon. Holes are drilled in the humerus at the level of the deltoid insertion, and the tendon is inserted underneath the acromion, placed through the drill holes (C), and sewn to itself after being tensioned with the humerus abducted 90 degrees (D).

(With permission, Mayo Foundation.)

The outcome of this transfer varies in different cases. Generally, better recovery of abduction is seen in shoulders with additional tendon transfers or shoulders with some remnant muscle function. In a series of 6 patients who underwent trapezius transfer after brachial plexus injuries, shoulder abduction improved from an average of 13 degrees to 76 degrees, whereas flexion increased from 18 to 78 degrees.¹⁰ Abolishment of shoulder subluxation plus improvement in abduction from a preoperative average of 3.5 degrees to a postoperative average of 45.4 degrees was seen in another series of 27 patients.⁹ Even when functional recovery is not adequate, the trapezius transfer is strong enough to keep the shoulder stable and correct subluxation of the glenohumeral joint, which allows some active abduction.

Latissimus Dorsi and Teres Major Transfer

Combined latissimus dorsi and teres major transfer for external rotation of the shoulder is carried out for the treatment of sequelae of obstetric brachial plexus palsy.^12,¹⁴^–¹⁶ This procedure increases the range of external rotation and abduction and provides considerable improvement in shoulder function. Theoretically, the transfer is equally effective in children and adults, provided that the latissimus has full strength. In brachial plexus injury in adults, however, this is not seen frequently. Poor results were observed after latissimus dorsi and teres major transfer in adult patients.¹⁷ Surgical techniques for this procedure are described elsewhere.¹⁸

Tendon Transfer for Elbow Function

Elbow flexion is fundamental for spatial placement of the hand and requires M4 power to be useful. Most surgeons would agree that elbow flexion should be the first priority on the reconstructive ladder. When there is no elbow flexion or only weak flexion, consideration of flexorplasty is imperative—provided that other appropriate innervated muscles are available. The goal of flexorplasty is active elbow flexion beyond 90 degrees against resistance.

There are various flexorplasty procedures.^19,²⁰ Selection of motors depends on the type and extent of the plexus injury, the degree of nerve recovery, and the muscles available. The latissimus dorsi is the most powerful, followed by pectoralis major. If these muscles are not available, the Steindler procedure can provide good flexion but is not as strong and in our experience not as consistent; it also leaves the patient with an elbow flexion contracture. Triceps transfer can reliably restore elbow flexion when the triceps is strong. It is especially advantageous in patients with biceps/triceps co-contraction.²¹^–²³ However, it is not suitable for patients who need triceps function to use assistive devices such as crutches. Transfer of the long head of the triceps has been reported to achieve MRC grade 4− and 85 degrees of elbow flexion with preserved elbow extension at reduced muscle strength²⁴; we have no experience using this transfer technique with a portion of the triceps. Other options include sternocleidomastoid transfer. The muscle is extended with a fascial graft and woven into the biceps tendon. The procedure can produce appropriate elbow flexion but causes an unsightly prominence at the lateral aspect of the neck, a cosmetic appearance that is not acceptable to most patients.²⁵

Steindler’s Procedure

The original transfer of the flexor-pronator mass from the medial epicondyle of the humerus proximally to enhance elbow flexion was described by Steindler in 1918.²⁶ The pronator, flexor carpi radialis, palmaris longus, flexor carpi ulnaris, and flexor digitorum superficialis are detached from the medial epicondyle, advanced 5 to 7 cm proximally, and sutured to the medial intermuscular septum. To reduce pronation and flexion contracture side effects (i.e., the Steindler effect), modifications have been adopted.²⁷^–²⁹ The flexor-pronator mass is detached along with a bone segment from the medial epicondyle. The muscles are mobilized, while protecting both the median and ulnar nerves, to enable proximal translocation of the muscle pedicle and bone up to 4 cm above the elbow and then attached to the anterior cortex of the humerus. However, this transfer results in just minor improvement in elbow flexion strength. Therefore, the Steindler flexorplasty technique should be used mainly as an augmentative procedure when the elbow flexors have retained some strength or exhibit partial recovery.