Operative approaches to the brachial plexus

Supraclavicular brachial plexus

The patient is placed supine, occasionally placed in a modified beach chair position to facilitate a posterior approach to the shoulder or arm. A folded sheet is placed beneath the scapula. The neck is extended gently and turned to the opposite side. A bump is also placed beneath the buttock to externally rotate one leg (should a sural nerve graft be desirable). The neck, shoulder, entire limb, chest, and both legs are prepared and draped.

The supraclavicular brachial plexus can be approached through an incision paralleling the lateral border of the SCM. This approach may be combined with an incision along the clavicle by itself and one inferiorly in the deltopectoral groove for exposure of the infraclavicular brachial plexus. For cosmetic reasons, the current authors prefer displaying the supraclavicular brachial plexus through a transverse incision placed in a skin crease several fingers above the clavicle (Fig. 8). The platysma is divided, and generous subplatysmal flaps are raised, which enhance the exposure. The external jugular vein is retracted. The border of the SCM muscle is identified and its clavicular head is either retracted medially or released (and later repaired). The supraclavicular fat pad is dissected and mobilized laterally. The omohyoid muscle is either retracted, or tagged and divided for later reapproximation. Nerves of the cervical plexus may be seen during the superficial exposure, and they can be traced to C3 and C4 origins. These branches should be preserved if at all possible to prevent the potential formation of painful neuroma, if transected. If the carotid artery or internal jugular vein is identified, then the dissection is too medial.

The phenic nerve should be identified on the surface of the anterior scalene muscle and carefully mobilized proximally. The phrenic nerve runs inferiorly and medially (the only major nerve to take this course). This nerve is usually functional, and it can be stimulated intraoperatively. The phrenic nerve is traced proximally, and at the lateral edge of the anterior scalene, its C5 contribution is identified. Once C5 is identified and

Scalene Muscles Rupture

Fig. 6. Left supraclavicular exposure in this patient with an obstetric brachial plexus palsy revealed a neuroma-in-continuity (*) of the upper trunk (UT) and a rupture of the middle trunk (MT). (Both ends were tagged with sutures.) The C8, T1, and lower trunk (LT) were scarred but conducted nerve action potentials. P, phrenic nerve. (Courtesy of the Mayo Foundation, Rochester, MN; with permission.)

Fig. 6. Left supraclavicular exposure in this patient with an obstetric brachial plexus palsy revealed a neuroma-in-continuity (*) of the upper trunk (UT) and a rupture of the middle trunk (MT). (Both ends were tagged with sutures.) The C8, T1, and lower trunk (LT) were scarred but conducted nerve action potentials. P, phrenic nerve. (Courtesy of the Mayo Foundation, Rochester, MN; with permission.)

mobilized, C6 is identified caudal and dorsal to C5 (Fig. 9A). The C5 and C6 root then join to form the upper trunk. The upper trunk can be followed distally to expose the suprascapular nerve and the anterior and posterior divisions. The clavicle can be mobilized if retroclavicular exposure is necessary, and retracted downward. The suprascapular artery and vein should be ligated and the sub-clavius muscle divided.

For proximal exposure of the roots, the anterior scalene muscle is divided. This step allows

Brachial Plexus Results

Fig. 7. Because of the close anatomic relationship between the T1 root and the T1 sympathetic ganglion, avulsions of the T1 root often result in injury to the T1 sympathetic ganglion, which has outflow to the head and neck. The disruption of the T1 sympathetic outflow results in Horner's syndrome: meiosis (small pupil), enophthalmos (sinking of the eyeball), ptosis (lid droop), and anhydrosis (dry eyes) of the ipsilateral face. In the clinical example shown, the asterisk identifies the injured side. (Courtesy of the Mayo Foundation, Rochester, MN; with permission.)

Fig. 7. Because of the close anatomic relationship between the T1 root and the T1 sympathetic ganglion, avulsions of the T1 root often result in injury to the T1 sympathetic ganglion, which has outflow to the head and neck. The disruption of the T1 sympathetic outflow results in Horner's syndrome: meiosis (small pupil), enophthalmos (sinking of the eyeball), ptosis (lid droop), and anhydrosis (dry eyes) of the ipsilateral face. In the clinical example shown, the asterisk identifies the injured side. (Courtesy of the Mayo Foundation, Rochester, MN; with permission.)

Enophthalmos
Fig. 8. Planned incisions for right supraclavicular and infraclavicular exposures. C, clavicle. (Courtesy of the Mayo Foundation, Rochester, MN; with permission.)

exposure at a foraminal level. Leksell rongeurs can assist in biting away the tip of the transverse processes for more proximal exposure, if this is deemed necessary. Care must be taken to avoid injury to the vertebral artery within the foramen transversarium. Venous bleeding must also be controlled. Proximal branches to the dorsal scapular nerve (C5 ± C4) and the long thoracic (C5-C7) may be seen. Dissection on the undersur-face of C6 may expose the long thoracic nerve before it passes through the middle scalene.

The middle trunk and C7 are found more medially and deeper to the upper trunk (Fig. 9B). The transverse cervical artery may need to be ligated. When exposing the lower trunk, C8 and T1, the subclavian artery (posterior to the scalene anterior) and subclavian vein (anterior to the scalene anterior) should be identified and mobilized (Fig. 9C, D). These neural elements embrace the first rib, so special care should be maintained during their proximal exposure to avoid injury to the pleura. The take-off of the vertebral artery should be kept in mind with dissection of the lower neural elements. The thoracic duct may be vulnerable, especially on left-sided exposures.

The spinal accessory nerve may be identified 1 cm above the point where the great auricular nerve wraps around the SCM (near the area where iatrogenic injury to it may occur during posterior triangle lymph node biopsies). The authors typically do not identify it as part of their supra-clavicular brachial plexus exposure. When they use the spinal accessory nerve as a nerve transfer, however, they prefer to identify it more distally, along the medial border of the trapezius muscle, above the clavicle. Here, the authors find that the nerve is easier to locate and closer to where they wish to transect it, deep at the inferior portion

Neuroma Plexus Brachialis

Fig. 9. Right supraclavicular exposure in an adult with schwannomatosis. The patient presented with ulnar-sided hand pain and a large neck mass, although neurologic examination was normal. MRI showed a large nerve sheath tumor involving the lower trunk (LT) and a smaller one arising from C6. (A) Initial dissection shows that the phrenic nerve (P) has been mobilized. It was used to identify C5, C6 and the upper trunk (UT). (B) C7 and the middle trunk (MT), which were displaced by the large tumor (*) have been mobilized. The smaller tumor can be seen within C6 (plus sign). (C) After proximal and distal control of neural elements has been obtained, the tumor (*) involving the LT is exposed. (D) The large tumor (*) is resected and the LT is preserved. The smaller lesion (plus sign) was then resected at a fascicular level from C6. Full neurologic function was maintained. Pathology confirmed two schwannomas (inset shows the larger resected mass). +, smaller tumor lesion; *, larger tumor lesion; EJ, external jugular vein; O, omohyoid. (Courtesy of the Mayo Foundation, Rochester, MN; with permission.)

Fig. 9. Right supraclavicular exposure in an adult with schwannomatosis. The patient presented with ulnar-sided hand pain and a large neck mass, although neurologic examination was normal. MRI showed a large nerve sheath tumor involving the lower trunk (LT) and a smaller one arising from C6. (A) Initial dissection shows that the phrenic nerve (P) has been mobilized. It was used to identify C5, C6 and the upper trunk (UT). (B) C7 and the middle trunk (MT), which were displaced by the large tumor (*) have been mobilized. The smaller tumor can be seen within C6 (plus sign). (C) After proximal and distal control of neural elements has been obtained, the tumor (*) involving the LT is exposed. (D) The large tumor (*) is resected and the LT is preserved. The smaller lesion (plus sign) was then resected at a fascicular level from C6. Full neurologic function was maintained. Pathology confirmed two schwannomas (inset shows the larger resected mass). +, smaller tumor lesion; *, larger tumor lesion; EJ, external jugular vein; O, omohyoid. (Courtesy of the Mayo Foundation, Rochester, MN; with permission.)

of the trapezius. A long segment of nerve can be harvested (ie, long enough to extend several centimeters below the clavicle). Still, proximal branches to the upper and midtrapezius are preserved.

Retroclavicular brachial plexus

Exposure to the retroclavicular brachial plexus can be facilitated by mobilization of the clavicle and by proximal and distal exposure of the brachial plexus. In select cases in which generous exposure of the divisions is necessary, the authors use a clavicular osteotomy. They contour a low-contour reconstruction plate and predrill it before osteotomizing the clavicle, because this technique improves union rates.

Infraclavicular brachial plexus

An incision is made from the clavicle down using the deltopectoral interval (deltoid and pectoralis major). A portion of the clavicular attachment of the pectoralis major and deltoid may be released to facilitate exposure. The intermuscular interval is most easily identified proxi-mally, which may be useful in revision surgery. The cephalic vein is mobilized. The authors prefer to retract it laterally. Distal exposure of the infraclavicular brachial plexus is enhanced by releasing the uppermost portion of the pectoralis major insertion. The authors typically do not release the pectoralis major insertion, but if this is necessary for broad exposure, they recommend leaving a small cuff of tendon behind and tagging it for later repair.

The deltopectoral interval is deepened. The pectoralis minor is identified arising from the coracoid and inserting on the ribs. It is tagged and divided through its tendon, although in some cases it may be retracted. The infraclavicular brachial plexus is visualized just beneath the fat pad. The lateral cord is identified first. It can be traced to the musculocutaneous nerve (although this branch may arise more distally and, on some occasions, not be seen in a standard infraclavicular approach) and the lateral cord contribution to the median nerve. The axillary artery should be mobilized and protected. Small branches may need to be ligated. The thoracoacromial trunk can be used for the arterial repair of a free-muscle transfer. The axillary vein lies more medially. The posterior cord and its terminal branches can be identified more deeply after the lateral cord, musculocutaneous nerve, and branch to the cor-acobrachialis muscles have been neurolysed and the artery sufficiently mobilized. The release of the coracobrachialis tendon may improve exposure of the axillary nerve. The medial cord can be identified medial to the axillary artery. The terminal branches of the medial cord can then be identified easily. The "M" (formed by the terminal branches of the lateral and medial cords) is then entirely visualized. The median nerve is formed just below the level of the coracoid.

The infraclavicular brachial plexus dissection is usually fairly easy under routine situations where the injury has occurred in the supraclavicular region. When the infraclavicular brachial plexus is scarred either from injury or previous surgery (eg, vascular repair), however, dissection may be difficult.

Medial exposure of nerve branches in proximal arm

Several terminal branches can be identified quickly by a separate short longitudinal incision in the proximal medial arm. This step may be useful, especially when performing nerve transfers (eg, the Oberlin transfer) [10,11]. Alternatively, extension of the deltopectoral incision into the proximal arm may be performed. The medial antebrachial cutaneous nerve, median nerve (the largest neural structure in this exposure is found deep to the brachial artery), and ulnar nerve can be identified within several centimeters of each other. The musculocutaneous nerve can be found between the biceps and coracobrachialis muscles. Its branches to the biceps, brachialis, and lateral antebrachial cutaneous nerve can then be isolated [12].

Posterior approaches

Posterior subscapular approach

The posterior subscapular approach, popularized by Dr. David Kline, is especially useful when very proximal exposure is needed, especially for C7

through T1 [13,14]. It may be particularly helpful for select cases, such as revision cases (eg, after supraclavicular approach for thoracic outlet surgery) or tumors involving lower plexal elements.

The patient is placed prone with rolls beneath the chest and transversely under the shoulders. The patient is placed in a reverse Trendelenberg position. The arm on the affected side must be permitted to move freely so as not to limit scapular mobilization. A lazy-S-shaped parascap-ular incision is made between the medial edge of the scapula and the thoracic spinous processes and is extended to the midneck region. The trapezius is divided. The rhomboids and, at times, the levator scapulae, are divided and tagged, and the serratus posterior is sectioned. A thoracotomy retractor is placed between the scapula and para-spinous muscles. The ribs are exposed. The scalenes are detached from the first rib insertion. The first rib is removed near the costovertebral junction. The neural elements and subclavian vessels are identified. Care must be taken to avoid injury to the spinal accessory, long thoracic, and dorsal scapular nerves (the phrenic nerve lies anteriorly). Very proximal exposure can be obtained by performing foraminotomies and even partial laminectomies, as appropriate. This approach also allows good exposure to divisions.

Meticulous attention must be placed to anatomic closure. The surgeon must check for potential pneumothorax and treat appropriately with a chest tube. Tagging sutures (Vicryl-0) should reapproximate muscular layers anatomically.

Posterior approach to the suprascapular nerve

The suprascapular nerve can be exposed posteriorly when the site of the lesion is at the suprascapular notch region. This exposure can be obtained when the patient is in a semilateral position, when performed as part of an anterior brachial plexus (or suprascapular nerve) exposure, or prone, when it is used for an entrapment lesion. A 6- to 8-cm incision is made 1 cm superior to the scapular spine. The posterior incision is made centered at the level of the coracoid process, which can be palpated anteriorly. The trapezius muscle may be split in line with its fibers or it may be taken down from the scapular spine. A fat pad is seen. The atrophied supraspinatus muscle is reflected inferiorly. The suprascapular nerve passes obliquely through the transverse scapular ligament. The ligament is released. The operative

Superior Transverse Scapular Ligament

Fig. 10. (A) Posterior approach for a triceps branch to axillary nerve transfer, with the triceps branch to the long head identified and the axillary nerve identified. (B). A close-up view shows the triceps branch to the long head already divided distally and flipped proximally. (Courtesy of the Mayo Foundation, Rochester, MN; with permission.)

Fig. 10. (A) Posterior approach for a triceps branch to axillary nerve transfer, with the triceps branch to the long head identified and the axillary nerve identified. (B). A close-up view shows the triceps branch to the long head already divided distally and flipped proximally. (Courtesy of the Mayo Foundation, Rochester, MN; with permission.)

microscope may be helpful, as much for the lighting as the magnification.

Posterior approach to the axillary and radial nerves

Posterior exposure of the axillary and radial nerves may be helpful when adequate distal exposure of these nerves cannot be obtained anteriorly. The authors also have found this exposure especially useful when performing a nerve transfer suturing a triceps branch to the axillary nerve. When this approach is being considered, they place a bump under the patient so that they may obtain a more lateral approach.

A longitudinal incision is made along the posterior surface of the proximal arm that extends to the lateral edge of the scapula. The deltoid is retracted anteriorly. The interval between the long and lateral heads of the triceps is developed. The superior lateral brachial cutaneous nerve can be helpful if seen in the superficial dissection and if traced deep to the main axillary nerve. The axillary nerve and its branches (and the posterior humeral circumflex artery) can be identified as the nerve emerges from the quadrangular space, superior to the teres major. The radial nerve and its branches (and the profunda brachii artery) can be seen inferior to the teres major [15,16] (Fig. 10).

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  • gaudenzia
    How to find the brachial plexus origin?
    8 years ago

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