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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_612_Библиотеки_им_академика_М_И_Перельмана
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FIGURE 9.11. A -C. Nerve cap reconstruction of
symptomatic neuromas of digital nerves to the thumb after
prior thumb amputation at outside institution.
Regenerative Peripheral Nerve Interface
Regenerative peripheral nerve interface (RPNI) was initially
described to increase control of myoelectric prosthetics. The
technique involves implantation of the proximal nerve end fascicles
into an autologous free skeletal muscle graft
29,30
(Figure 9.12). This
muscle graft possesses denervated muscle and motor end plates
that permit reinnervation if the graft successfully revascularizes.
29
RPNIs have been shown to facilitate reinnervation of the implanted
skeletal muscle graft, formation of new neuromuscular junctions, and
decreased symptomatic neuroma formation.30 RPNI has shown
promising early outcomes in treatment of painful neuromas.
31
Disadvantages of this active nerve treatment technique include
increased dissection, ischemia-induced fibrosis, and resorption of
muscle graft that may inhibit the nerve from regenerating into and
reinnervating the reimplanted muscle graft. Recently, vascularized
denervated muscle targets (VDMTs) have been investigated to avoid
ischemia-related issues of the free skeletal muscle grafts. The VDMT
technique is similar to RPNI but utilizes a skeletal muscle graft raised
on an intact, vascular pedicle with subsequent implantation of the
proximal nerve end.
32
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FIGURE 9.12. Median neuroma after previous mid-
forearm injury treated at outside institution with
implantation into muscle (A). Excision of neuroma to
healthy fascicles and preparation of free skeletal muscle
graft (B). Completed regenerative peripheral nerve
interface with implantation of proximal nerve end into free
skeletal muscle graft (C) .
Targeted Muscle Reinnervation
Targeted muscle reinnervation (TMR) was originally designed to
augment function of myoelectric prothesis for upper extremity
amputees.33 The proximal end of the injured nerve is coapted to a
nearby “target” motor nerve that can be transected to freshly
denervate a specific portion of muscle and its associated motor end
plates (ie, in essence a nerve transfer technique) (Figure 9.13). The
proximal nerve end then regrows through the target motor nerve,
and this regenerating nerve reinnervates the specific denervated
target muscle that acts as the distal end organ for the proximal
nerve. Although originally meant to allow for more specific prosthetic
control, this technique has been shown in basic science, and
retrospective and prospective, as well as randomized clinical studies,
to decrease phantom and residual limb pain and neuropathic pain
and as an active treatment strategy for symptomatic neuromas.
34,35
This technique has been applied in both upper and lower extremities
as well as throughout other anatomic areas (Figure 9.14 and Video
9.1). Purported disadvantages include increased dissection,
denervation of otherwise unaffected muscle, and size mismatch of
nerve coaptation between the larger injured nerve and smaller motor
nerve. Recently, a combined technique of TMR with a vascularized
RPNI has been reported with promising results; this addresses size
mismatch and axonal escape of the TMR technique36 (Figures 9.15
and 9.16).
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FIGURE 9.13. Clinical photograph of targeted muscle
reinnervation demonstrating the size mismatch of the
donor (larger) and recipient motor nerve (smaller).
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FIGURE 9.14. Ring finger ray amputation performed with
dissection of radial and ulnar digital nerves (A). TMR of
the ulnar digital nerve performed to a motor branch of the
dorsal interosseous muscle (B) .
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FIGURE 9.15. A clinical example of the TMR with vRPNI
technique. A. Immediate TMR nerve coaptation illustrating
the size mismatch of the larger proximal mixed nerve and
smaller distal motor target nerve within surrounding target
muscle. Clinical intraoperative example. B. Illustrated
rending of TMR concept for the clinical example provided
in (A). (Reprinted with permission from Valerio I, Schulz
SA, West J, et al. Targeted muscle reinnervation combined
with a vascularized pedicled regenerative peripheral nerve
interface. Plast Reconstr Surg Glob Open.
2020;8(3):e2689.)
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FIGURE 9.16 Clinical example of the TMR with vRPNI
technique. A. The transferred nerve coaptation is seen
wrapped with a surrounding vascularized but freshly
denervated muscle cuff (vRPNI) to completely cover the
prior performed nerve coaptation illustrated in Figure 9.12.
Clinical intraoperative example. B and C. Illustrated
rending of TMR vRPNI concept for the clinical example
provided in (A). (Reprinted with permission from Valerio I,
Schulz SA, West J, et al. Targeted muscle reinnervation
combined with a vascularized pedicled regenerative
peripheral nerve interface. Plast Reconstr Surg Glob
Open. 2020;8(3):e2689.)
SYMPTOMATIC NEUROMA PREVENTION
There has been an ongoing paradigm shift in the management of
peripheral nerve injuries with regards to neuroma prevention.
Clinicians have started to employ the previously discussed
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techniques at the time of nerve injury with the goal of neuroma
prevention, specifically in patients undergoing major limb
amputation, where a high incidence of symptomatic neuromas and
phantom limb pain that decrease quality of life and functional
outcomes exists. Prospective studies utilizing RPNI and TMR for
reconstruction of severed nerves at time of amputation have shown
promising results with decreased neuroma pain and phantom limb
pain.37-39 Currently, the techniques have not been compared headto-head and the decision on whether to apply TMR or RPNI in a
certain patient is largely based on surgeon preference.
CONCLUSION
Multiple surgical techniques are available for management of painful
neuromas; however, no singular treatment has been shown to be
superior to the others.40 Treatment algorithms are largely based on
surgeon preference and presence/absence of distal nerve end.8 In
terms of neuroma prevention, both TMR and RPNI performed at the
time of amputation or injury have shown promising results.
Management of neuroma pain is an evolving area of research, and
clinical practice with new techniques, materials, and treatment
algorithms is being investigated.
QUESTIONS
1. A 30-year-old female chef presents with numbness of the
radial aspect of her left index finger after a kitchen accident
about 1 year prior. She has a transverse scar in her palm
around the level of the index finger A1 pulley and Tinel sign
just proximal to the scar. She was taken to the operating room
where a neuroma excision and allograft reconstruction was
performed. Allograft nerve reconstruction is an example of
which type of surgical neuroma management?
a. Ablative
b. Active
c. Passive
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d. Prevention
2. A 24-year-old construction worker presents with a painful
fingertip after suffering amputation of his left middle finger with
failed replantation and subsequent revision amputation
3 years ago. He has shooting pain at the tip of his residual
stump when grasping objects and dysesthesias when wearing
his work gloves. Upon surgical exploration digital neuromas
are discovered. Neuromas occur from which process?
a. Wallerian degeneration
b. Disorganized axonal regrowth
c. Pain centralization
d. Reinnervation of denervated muscle
3. A 42-year-old male veteran and right lower extremity below
knee amputee presents to clinic with pain at his residual
stump. He also endorses significant phantom limb pain that
prevents him from using his prosthesis. What surgical
treatment has been shown in randomized clinical trials to
decrease neuroma pain and phantom limb pain compared
with passive/ablative surgical techniques?
a. Targeted muscle reinnervation (TMR)
b. Regenerative peripheral muscle interfaces (RPNIs)
c. Agonist-antagonist myoneural interface (AMI)
d. Reset neurectomy
ANSWERS AND EXPLANATIONS
1. Answer: b. This patient had neuroma excision and allograft
reconstruction performed of the radial digital nerve of the index
finger. Allograft reconstruction of the nerve defect is an active or
reconstructive surgical technique that addresses the neuroma
and the potential axonal regrowth, giving the nerve “somewhere
to go and something to do.” Ablative and passive describe
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