Management of Brachial Plexus Injuries


Fig. 7.1
A 26-year-old male patient who presented 2 months after a bullet-penetrating injury to his right brachial plexus. Physical examination and EMG showed a total lesion of the right axillary and accessory nerves, partial lesion of the right musculocutaneous, suprascapular, right lateral, and posterior cords (ac). Four weeks after, the EMG showed the same lesions without any improvement and a surgical exploration was planned. It showed the presence of an organized fibrotic hematoma compressing the different structures of the brachial plexus which was totally removed releasing the compressed nerves (d). Six months postop, the patient recovered a near-normal function of the different paralyzed muscles (e, f)

The staples of acute and subacute care for the brachial plexus patient are therefore wound care, evaluation of vascular and bony injuries and their treatments, and wherever possible appropriate splinting and physical activity to maintain muscle mass and pliability of joints and prevent contractures. Studies have shown brachial plexus-injured patients who undergo preoperative physiotherapy to have superior postoperative results to those who do not.

Management in the Chronic Phase

Brachial plexus injuries that show no or inadequate improvement by 10–12 weeks of conservative treatment warrant surgical exploration and repair. Physical examination and EMG findings must be carefully documented and readily available intraoperatively for reference if needed.

The patient is placed under general anesthesia and in the supine position , with the upper extremity prepped and abducted. It is prudent to also prep and drape bilateral lower extremities in case sural nerves grafting is required. The anesthesiology team should be informed of the need for only minimal muscle relaxation at induction and no further muscle-relaxant dosing due to the need to use a nerve stimulator intraoperatively. Loupe and/or microscope magnification is usually used to adequately visualize structures and meticulously perform nerve repairs.

The skin incision depends on the entry point of the bullet. If this point is above the clavicle, the skin incision is made in the shape of an “L” or “J” along the lateral border of the sternocleidomastoid muscle and continued below the clavicle. If the entry point is below the clavicle, the skin incision extends from the infraclavicular region to the deltopectoral crease. When the nerve lesion is located on the supra or infraclavicle regions, the clavicle should not be osteotomized [2]. By pulling it up with shoulder mobilization, the different cords of the brachial plexus passing behind the clavicle can be easily dissected, exposed, and released from any compression [4].

When the brachial plexus exposure is expected to be difficult or the neural lesions are predicted to be behind the clavicle , a total approach is recommended with an “S”-shaped incision extending from the lateral border of the sternocleidomastoid muscle to the upper arm infra-axillary region. The clavicle may need to be osteotomized and the major and minor pectoral muscle tendons may need to be transected and retracted for exposure. This approach will allow the entire exposure of the brachial plexus from top to bottom. Before performing the osteotomy, an anatomic shaped plate is presented to the superior surface of the clavicle and the screw holes drilled and prepared . This will facilitate the clavicle fixation later on.

Dissection should start by freeing the median nerve in the axilla , progressing upwards to reach the lateral and medial cords, each of which gives one of the two branches forming the median nerve. Lateral to the median nerve, the other branch of the lateral cord is easily identified as the musculocutaneous nerve, and on its medial side, the ulnar nerve is identified corresponding to the second branch of the medial cord. The posterior cord is found by locating the radial nerve and continuing upwards behind the axillary artery. The axillary nerve should be found on the lateral aspect of the posterior cord.

In continuing the dissection of the cords upwards, the trunks are identified. Dissection and repair of the nerves in the trunk region are always technically difficult and require precise anatomical knowledge and extreme caution. Finally, the roots are also dissected and identified if necessary. In this way the entire brachial plexus along with the vascular elements is dissected and exposed from bottom to top.

Injuries to the brachial plexus elements are visualized intraoperatively as either neuroma formation or areas of nerves that are fibrosed and pale. These may result from thermal injury to the nerves, traction, or compressing hematomas overlying the nerves in the aftermath of the original injury. In the case of nerve continuity but areas of fibrosis or neuroma formation in continuity, dissection of the fibrosed tissues or neuroma from the nerve tissue is warranted. When this is completed, nerve function is tested using the intraoperative nerve stimulator; if this is found to show good distal muscle function, no further repair is indicated.

In the case of more severe injury not adequately treated with neurolysis, and also in the case of complete nerve transection and neuroma formation at the nerve ends, the nonviable portion of the affected nerves needs to be excised and its function repaired or replaced. The simplest form of repair is primary nerve repair where debrided nerve ends are repaired in an end-to-end fashion using nylon sutures taken in the epineurium. To be effective, nerve repair must be completely tension-free and unfortunately conditions for this kind of repair are rarely found in the war-injures brachial plexus.

Where primary suturing of nerves is impossible due to inadequate nerve length and subsequent tension, nerves can be repaired using interposing nerve grafts [1]. Nerve grafts are usually harvested from the sural nerve in the lateral leg; each sural nerve can reach up to 45 cm depending on the height of the patient [1]. The nerve grafts are then used to bridge the gap in the brachial plexus nerve. Notably, the grafts need to be reversed so as to minimize random nerve sprouting. Due to the smaller caliber of the sural nerve and other nerve donors when compared to the brachial plexus nerves, multiple graft “cables” are used to bridge the defect of the larger nerve. Nerve grafts do well in well-vascularized beds and in lengths of up to 10 cm [5]. Poor outcomes are seen in heavily fibrosed beds and with longer cables. It must be noted that nerve recovery proceeds at 1 mm per day [5] in young patients and may be slower in adults; and it may take up to 2 years for recovery to reach the end-organ, paradoxically, motor end plates in muscles disintegrated within 12–18 months of denervation [6] (Fig. 7.2).
Nov 17, 2017 | Posted by in MUSCULOSKELETAL MEDICINE | Comments Off on Management of Brachial Plexus Injuries
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