Chapter 24 Nerve Transfers
Accessory Nerve to Suprascapular Nerve (Figure 24-1)
• The distal accessory nerve can be utilized when (1) useful lead-outs from C5 or C6 are not available for neurotization of the suprascapular nerve (SCN), or (2) the surgeon wishes to use such lead-outs for other destinations in the plexus.
• The distal accessory nerve can be mobilized and sewn either end-to-end or by means of an interpositional graft to the SCN.
• Stimulation of CN XI produces muscular contraction of the trapezius and sternocleidomastoid. The SCN is dissected back into the upper trunk and is divided through viable tissue.
• The mobilized accessory nerve is divided so that it can be tunneled beneath some of the supraclavicular fat pad and sewn by 7-0 Prolene to the mobilized suprascapular nerve.
Pectoral Branches (Medial) to Musculocutaneous Nerve
• The lateral cord is traced distally to the cord’s contribution to the median nerve medially and the coracobrachialis branches and musculocutaneous nerve (MCN) laterally (see Chapter 5).
• The MCN is encircled with a Penrose drain and is usually split away from the lateral cord contribution to the median nerve more proximally. Thus a suitable entry point for anastomosis with the shorter medial pectoral branches is created so that the juxtaposition can be done gracefully and without tension.
• Medial pectoral branches, arising from the medial cord, are located by dissecting out the axillary artery. Usually the medial pectoral branches are found close to and somewhat beneath the largest pectoral arterial branches.
• The medial pectoral nerve branches reach the pectoral muscles.
• After the pectoral branches are cut close to the muscle, they are moved laterally, usually beneath the axillary artery, and sewn end-to-end with 7-0 Prolene to either a partially or a completely sectioned distal MCN.
Intercostal Nerves to Musculocutaneous Nerve
• This transfer is done to neurotize the MCN.
• The procedure provides useful biceps and brachialis function in about 40% to 50% of cases, depending on the series and the nature of the patients selected for the procedure.
• Some controversy exists over which intercostal nerves to use to maximize motor axon outflow, as well as over the level at which they should be sectioned. We prefer to use the third, fourth, fifth, and sometimes sixth intercostal nerves and usually section them at the anterior axillary line.
• The incision needs to be combined with one made to expose the plexus at the cord-to-nerve level in the axilla.
• The intercostal nerves are found under the inferior surface of their respective ribs, below the intercostal vessels, in the neurovascular plane. With upward retraction on the rib, the nerve can be identified, encircled by a Vasaloop, and then dissected away from the intercostal artery and vein.
• In women, the superficial branch of the T4 intercostal nerve can be spared and only the deep (motor or muscular) branch used. This preserves sensation on and around the nipple.
• We dissect out lengths of 4 or 5 inches, extending from the posterior axillary line.
• The intercostal nerves are sectioned anteriorly at the level of the anterior axillary line and brought back to be tunneled through axillary fat to reach the axillary level of the plexus.
• They are then sewn together directly to the MCN, which has been split away from the lateral cord contribution to the median nerve, or to the axillary nerve.
• Care must be taken not to lacerate the pleura. If this is done, it is repaired with 4-0 silk on a fine needle.
• It is sometimes useful to harvest a small piece of pectoral or intercostal muscle to be sewn in place as a stent or stamp for closure of the hole.
Descending Cervical Plexus to Upper and Middle Trunk
• Some of the most important relationships in plexus surgery are those among the C5 and C6 spinal nerves, the phrenic nerve, and the descending cervical plexus.
• The cervical plexus originates from C3 and C4. The phrenic nerve has input from C3, C4, and C5.
• The descending cervical plexus usually consists of several branches that then branch several more times to eventually innervate the strap muscles and skin of the neck
• The descending cervical plexus can be used as a transfer to plexus divisions, although motor fibers available for neurotization are limited.
• Other transfers, such as thoracodorsal to axillary, phrenic to truncal divisions, partial ulnar to musculocutaneous nerve, or contralateral C7, are used infrequently by the authors.
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