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and universal return of protective sensation (pain, thermal, who underwent hand replantation 2 h after traumatic
and gross tactile sensation) in all grafted hands. Results amputation, revealed several observations in the
in discriminative sensation and motor recovery were reorganization process. The authors observe that
[35]
more variable across these patients. A 2010 publication supplementary motor area activation is resistant to
following 49 hands transplanted between 1998 and reorganizing effects in long‑term amputation, and this is
2010 across 33 patients revealed universal recovery more prominently seen in M1. Activation patterns in M1
of protective sensation and more variable recovery of increased over 2 years following the bilateral transplantation.
discriminatory sensation and motor function in grafts In the patient undergoing hand replantation, structural
at least 1 year posttransplant. While these results differences in cortical representation were not observed,
[36]
[44]
look promising, it appears that success can be further suggesting a functional cortical reorganization instead.
optimized in the realm of motor regeneration. Magnetoencephalographic study of cortical representation
in 13 patients following limb replantation found a negative
[37]
Pomahac et al. reported 1 year postoperative functional correlation between the extent of reorganization and
outcomes of a partial face transplant of a 59‑year‑old patient‑reported pain following replantation. [45]
male following an electrical burn injury. “Meticulous
neurorrhaphy” was used to bring together the buccal, Ultimately, forming comparisons between patients, grafts,
infraorbital, and branches of facial nerves. Protective and and outcomes studies are complicated by varying degrees
discriminatory sensations returned to the entire graft by of existing transplant‑area injury in recipients, differences
6 months, and symmetrical smiling was achieved by 1 year. in the circumstances under which donor VCA tissue is
procured, and surgical protocols and challenges unique
A 2009 study compared functional recovery in a patient to each procedure. However, aggregation of outcomes
who received a dominant mid‑forearm transplantation is necessary to determine overarching trends since the
to that of four patients who underwent mid‑forearm number of patients undergoing VCA transplantation
replantations following traumatic amputation. The remains relatively low.
two procedures vary in certain regards, including
longer ischemic times in transplantation as compared A summary of recent and pertinent publications regarding
to replantation, excess allograft tissue requirements functional outcomes in VCA can be found in Table 2, and
for transplants, and the unique need for cortical regarding cortical reorganization in VCA in Table 3.
somatosensory reorganization following a transplant.
While the transplant demonstrated increased innervation FUTURE DIRECTIONS
of intrinsic hand muscles (hypothesized to be due to the
effects of tacrolimus), grip strength remained greater Nerve guidance conduits
in replantations, potentially due to muscle fibrosis and The use of nerve guidance conduits (NGCs) to appose
atrophy in the recipient’s proximal forearm stump. [38] nerve stumps protects against scar infiltration and the
Post‑VCA cortical reorganization has been studied development of neuromas, thereby enhancing the fidelity
[48]
closely, since recovery of motor and sensory function of regeneration. A NGC is a doubly open‑ended tube
requires not only peripheral nerve regeneration, but that requires separated nerve ends to be attached to
the reestablishment of cortical areas representing those either end of the structure, and the internal composition
regions. Since VCAs are often performed many years after provides a protected environment for nerve sprouts to
[49]
the loss of the limb, underlying cortical plasticity leads to extend longitudinally towards the opposing end. Early
loss of that limb’s representation in primary motor (M1) versions of NGCs only demonstrated the limited extent of
[50]
cortex and primary somatosensory (S1) cortex. Relatively repair over a few centimeters.
acute reestablishment of afferent and efferent pathways With respect to VCA, however, the benefit of NGCs has
in VCA has been shown to result in significant cortical not been studied in humans, as the gold standard remains
reorganization. [39,40] A functional magnetic resonance surgical coaptation with or without the use of nerve
imaging (fMRI) study of hand and elbow representations in allografts. This technology has primarily been used in the
M1 in the months following abilateral hand transplantation repair of peripheral nerve damage, and a review of studies
revealed a reversal of the cortical reorganization induced published through 2006 evaluating close to three hundred
by that amputation in a patient who underwent traumatic patients reported “satisfactory” results in some patients
bilateral amputation 4 years in advance. Similar results experiencing suboptimal results. At this point, NGCs are
[41]
were demonstrated with transcranial magnetic stimulation primarily limited to the repair of short lesion gaps, but
in a patient who underwent bilateral hand transplantation advances in this technology seek to increase the feasibility
[42]
3 years following traumatic amputation. fMRI evaluation and consistent success of its use. Currently, the theoretical
[51]
of S1 reorganization in a unilateral hand transplant patient benefits of using NGC over nerve allograft in VCA are
35 years following traumatic amputation demonstrated limited since donor allografts can be utilized to fill large
the significant return of cortical activity despite such a gaps without additional immunosuppression or without
prolonged absence of a limb. [43] concerns for donor‑site morbidity in the cadaveric donor.
A study comparing cortical reorganization in 2 patients, Chondroitinase
one of whom underwent bilateral hand transplantation Chondroitin sulfate proteoglycans (CSPGs) are found in
6 years following traumatic amputation, and another the extracellular matrix and are known to inhibit axonal

230 Plast Aesthet Res || Vol 2 || Issue 4 || Jul 15, 2015