492ST & 462ST

C HAPTER 18 Emerging Techniques for Nerve Repair: Nerve Transfers and Nerve Guidance Tubes Rajiv Midha, M.D., M.Sc., F.R.C.S.C. P eripheral nerve injury is a serious health concern for
society, affecting 2.8% of trauma patients, many of whom acquire life-long disability. 52 For example, approximately 360,000 people in the United States experience upper extrem-
ity paralytic syndromes yearly, resulting in 8,648,000 and
4,916,000 restricted activity days and bed/disability days,
respectively. 23 Because peripheral neurons spontaneously sprout new axons after injury, patients with milder severity
nerve injuries improve spontaneously, but many patients have
more severe injuries that have a poor natural history to
recover. 16 Most severe injuries are associated with nerve injury gaps or lengthy scar within the nerve that prevents
regenerating axons from effectively innervating the distal
nerve stump. 44 These are managed with a nerve repair of the divided nerve or, for the usual scenario of gaps longer than 1
cm or scar segments that need to be resected, placement of
interposed nerve grafts. 47 The nerve grafts provide a pathway for regenerating axons from the proximal nerve stump to
innervate the distal one. 45 However, recovery after nerve graft repair is limited by incomplete and non-specic regen-
eration and variable clinical results. 27,43 Based on sound and solid experimental literature over the past half century, peripheral nerve surgeons in the past
three decades have been increasingly using alternative tech-
niques to interposed nerve autografts in an attempt to improve
outcomes. For lengthy nerve injuries, or for those very
proximal ones in which the spinal nerve root has been or are
likely avulsed from the spinal cord, the use of nerve transfers
has emerged. 35 For short injury gaps, surgeons are using nerve guidance tubes in place of nerve grafts to perform the
repair. 6 This chapter reviews the rationale, principles, and theoretical advantages that these state-of-the-art techniques
offer to the surgeon and their patient. Readers are encouraged
to read other literature and reviews on each of these topics,
which are provided in the references cited at the end of this
chapter, for more detailed information as appropriate. NERVE TRANSFERS Nerve transfers, also referred to as neurotization, involve the repair of a distal denervated nerve element using
a proximal foreign nerve as the donor of neurons and their
axons, which will reinnervate the distal targets. The concept
is to sacrice the function of a (lesser valued) donor muscle
to revive function in the recipient nerve and muscle that will
undergo reinnervation. 50 Since their rst report by Tuttle 64 in 1913 and popularization by Narakas 49 three decades ago, nerve transfers have been used increasingly for the repair of
brachial plexus injuries, especially in cases in which the
proximal motor source of the denervated element is absent
because of avulsion from the spinal cord. 43 Increasingly advocated are the use of transfers in situations in which the
proximal motor source is available, but the regeneration
distance is so long that the outcome would be poor. A nerve
transfer into the denervated distal nerve stump close to the
motor end-organ would then restore function, which would
not be possible otherwise. 51 The use of nerve transfers has, therefore, been a major advance in the eld of brachial plexus
nerve reconstructive surgery, with many different ingenious
transfers associated with improving results, as reported and
reviewed recently. 8,21,42,57,62 The anatomic and physiological principles that underlie nerve transfers are relatively straightforward. Because motor
recovery has been the main goal, the choice of a donor nerve
element that has a reasonable aliquot of motor bers is
required. 50 The loss of the muscle denervated by transferring the donor nerve must not represent loss of important or
critical function. 31 Obviously, the value of the neuromuscular element to be reinnervated must greatly exceed the utility of
the sacriced one. An excellent compromise is achieved if
some function of the donor muscle can be retained, by using
only a portion of the nerve as the donor, exemplied by the
use of only the distal terminal branch of accessory (trans-
ferred to suprascapular nerve), thereby sparing proximal
branches to trapezius muscle. 43 There are several important principles to adopt in order to maximize outcome in nerve transfers, the rst of which is
to reinnevate the recipient nerve as close to the target muscle
as possible. 51 An outstanding example of the latter is the Copyright

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