Re-emergence of hand-muscle representations in human motor cortex after hand allograft

A World Update of Progress in Lower Extremity Transplantation: What's Hot and What's Not

ABSTRACT

The field of vascularized composite allotransplantation (VCA) is the new frontier of solid organ transplantation (SOT). VCA spans life-enhancing/life-changing procedures such as upper extremity, craniofacial (including eye), laryngeal, tracheal, abdominal wall, penis, and lower extremity transplants. VCAs such as uterus transplants are life giving unlike any other SOT. Of all VCAs that have shown successful intermediate- to long-term graft survival with functional and immunologic outcomes, lower extremity VCAs have remained largely underexplored. Lower extremity transplantation (LET) can offer patients with improved function compared to the use of conventional prostheses, reducing concerns of phantom limb pain and stump complications, and offer an option for eligible amputees that either fail prosthetic rehabilitation or do not adapt to prosthetics. Nevertheless, these benefits must be carefully weighed against the risks of VCA, which are not trivial, including the adverse effects of lifelong immunosuppression, extremely challenging perioperative care, and delayed nerve regeneration. There have been 5 lower extremity transplants to date, ranging from unilateral or bilateral to quadrimembral, progressively increasing in risk that resulted in fatalities in 3 of the 5 cases, emphasizing the inherent risks. The advantages of LET over prosthetics must be carefully weighed, demanding rigorous candidate selection for optimal outcomes.

Alteration of body representation in typical and atypical motor development

Developmental coordination disorder (DCD) impacts the quality of life and ability to perform coordinated actions in 5% of school-aged children. The quality of body representations of individuals with DCD has been questioned, but never assessed. We hypothesize that children with DCD have imprecise body representations in the sensory and motor domains. Twenty neurotypical children, seventeen children with DCD (8-12 years old) and twenty neurotypical adults (25-45 years old) performed both sensory and motor body representation tasks: a limb identification and a limb movement task. We observed lower accuracy in the sensory task but not in the motor task. In both tasks, we observe a larger amplitude of errors, or synkinesis, in children with DCD than in neurotypical children. In neurotypical children, accuracy was lower than in neurotypical adults in the motor and sensory task, and the amplitude of sensory errors and synkinesis was higher than in neurotypical adults. Using a linear regression model, we showed that sensory accuracy is a good predictor of synkinesis production, and that synkinesis production is a good predictor of sensory accuracy, as can be expected by the perception-action loop. Results support the hypothesis of an imprecision of body representation in DCD. We suggest that this imprecision arises from noise in the body representation used at the level of internal models of action. Future studies may assess whether slower plasticity of body representations, initial imprecision, or both may account for this observation. At the clinical level, prevention strategies targeting body representation in early childhood are strategically important to limit such impairments. RESEARCH HIGHLIGHTS: Body representation is impaired in children with DCD and has a significant cost in terms of the accuracy of sensory identification of body parts and associated movements. Inaccuracies in the body representation measured in perception and in action (error amplitude and synkinesis) are related in both NT children and adults. In typical development, we provide evidence of a strong link between body schema and body image.

Cortical reintegration after facial allotransplantation

Neural plasticity of the brain or its ability to reorganize following injury has likely coincided with the successful clinical correction of severe deformity by facial transplantation since 2005. In this study, we present the cortical reintegration outcomes following syngeneic hemifacial vascularized composite allograft (VCA) in a small animal model. Specifically, changes in the topographic organization and unit response properties of the rodent whisker-barrel somatosensory system were assessed following hemifacial VCA. Clear differences emerged in the barrel-cortex system when comparing naïve and hemiface transplanted animals. Neurons in the somatosensory cortex of transplanted rats had decreased sensitivity albeit increased directional sensitivity compared with naïve rats and evoked responses in transplanted animals were more temporally dispersed. In addition, receptive fields were often topographically mismatched with the indication that the mismatched topography reorganized within adjacent barrel (same row-arc bias following hemifacial transplant). These results suggest subcortical changes in the thalamus and/or brainstem play a role in hemifacial transplantation cortical plasticity and demonstrate the discrete and robust data that can be derived from this clinically relevant small animal VCA model for use in optimizing postsurgical outcomes.NEW & NOTEWORTHY Robust rodent hemifacial transplant model was used to record functional changes in somatosensory cortex after transplantation. Neurons in the somatosensory cortex of face transplant recipients had decreased sensitivity to stimulation of whiskers with increased directional sensitivity vs. naive rats. Transplant recipient cortical unit response was more dispersed in temporary vs. naive rats. Despite histological similarities to naive cortices, transplant recipient cortices had a mix of topographically appropriate and inappropriate whiskered at barrel cortex relationships.

Changes in Primary Somatosensory Cortex Following Allogeneic Hand Transplantation or Autogenic Hand Replantation

Former amputees who undergo allogeneic hand transplantation or autogenic hand replantation (jointly, "hand restoration") present a unique opportunity to measure the range of post-deafferentation plastic changes in the nervous system, especially primary somatosensory cortex (S1). However, few such patients exist, and previous studies compared single cases to small groups of typical adults. Here, we studied 5 individuals (n = 8 sessions: a transplant with 2 sessions, a transplant with 3 sessions, and three replants with 1 session each). We used functional magnetic resonance imaging (fMRI) to measure S1 responsiveness to controlled pneumatic tactile stimulation delivered to each patient's left and right fingertips and lower face. These data were compared with responses acquired from typical adults (n = 29) and current unilateral amputees (n = 19). During stimulation of the affected hand, patients' affected S1 (contralateral to affected hand) responded to stimulation in a manner similar both to amputees and to typical adults. The presence of contralateral responses indicated grossly typical S1 function, but responses were universally at the low end of the range of typical variability. Patients' affected S1 showed substantial individual variability in responses to stimulation of the intact hand: while all patients fell within the range of typical adults, some patient sessions (4/8) had substantial ipsilateral responses similar to those exhibited by current amputees. Unlike hand restoration patients, current amputees exhibited substantial S1 reorganization compared to typical adults, including bilateral S1 responses to stimulation of the intact hand. In all three participant groups, we assessed tactile localization by measuring individuals' ability to identify the location of touch on the palm and fingers. Curiously, while transplant patients improved their tactile sensory localization over time, this was uncorrelated with changes in S1 responses to tactile stimuli. Overall, our results provide the first description of cortical responses to well-controlled tactile stimulation after hand restoration. Our case studies indicate that hand restoration patients show S1 function within the range of both typical adults and amputees, but with low-amplitude and individual-specific responses that indicate a wide range of potential cortical neurological changes following de-afferentation and re-afferentation.

Changes in Temporal and Spatial Patterns of Intrinsic Brain Activity and Functional Connectivity in Upper-Limb Amputees: An fMRI Study

Background

Amputation in adults is a serious procedure or traumatic outcome, one that leads to a possible “remapping” of limb representations (somatotopy) in the motor and sensory cortex. The temporal and spatial extent underlying reorganization of somatotopy is unclear. The aim of this study was to better understand how local and global structural plasticity in sensory-motor cortical networks changes temporally and spatially after upper-limb amputation.

Methods

We studied 8 healthy nonamputee control subjects and 16 complete upper-limb amputees. Resting-state MRI (rs-fMRI) was used to measure local and large-scale relative differences (compared to controls) in both the amplitude of low-frequency fluctuations (ALFF) and degree of centrality (DC) at 2 months, 6 months, and 12 months after traumatic amputation.

Results

In amputees, rs-fMRI scans revealed differences in spatial patterns of ALFF and DC among brain regions over time. Significant relative increases in ALFF and DC were detected not only in the sensory and motor cortex but also in related cortical regions believed to be involved in cognition and motor planning. We observed changes in the magnitude of ALFFs in the pre- and postcentral gyrus and primary sensory cortex, as well as in the anterior cingulate, parahippocampal gyrus, and hippocampus, 2 months after the amputation. The regional distribution of increases/decreases in ALFFs and DC documented at 2-month postamputation was very different from those at 6 and 12-month postamputation.

Conclusion

Local and wide-spread changes in ALFFs in the sensorimotor cortex and cognitive-related brain regions after upper-limb amputation may imply dysfunction not only in sensory and motor function but also in areas responsible for sensorimotor integration and motor planning. These results suggest that cortical reorganization after upper extremity deafferentation is temporally and spatially more complicated than previously appreciated, affecting DC in widespread regions.

Motor potential evoked by transcranial magnetic stimulation depends on the placement protocol of recording electrodes: a pilot study

OBJECTIVE

There seems to be no consensus in the literature regarding the protocol of surface electromyography (sEMG) electrode placement for recording motor evoked potentials (MEP) in transcranial magnetic stimulation (TMS) applications. Thus, the aim of this study was to investigate the effect on the MEP amplitude bytwo different protocols for electrode placement.

METHODS

sEMG electrodes were placed on three upper arm muscles (biceps brachii, flexor carpi radialis, and flexor pollicis brevis) of six right-handed subjects following two different protocols (1 and 2), which varied according to the interelectrode distance and location relative to the muscle. TMS pulses were applied to the hotspot of biceps brachii, while sEMGwas recorded from the two protocols and for each muscle simultaneously.

MAIN RESULTS

Greater MEP amplitudes were obtained for Protocol 1 compared to Protocol 2 (P < 0.05).

SIGNIFICANCE

Different electrode placement protocols may result in distinct MEP amplitudes, which should be taken into account when adjusting the intensity on single and repetitive TMS sessions.

Neural activation for actual and imagined movement following unilateral hand transplantation: a case study

Transplantation of a donor hand has been successful as a surgical treatment following amputation, but little is known regarding the brain mechanisms contributing to the recovery of motor function. We report functional magnetic resonance imaging (fMRI) findings for neural activation related to actual and imagined movement, for a 54-year-old male patient, who had received a donor hand transplant 50 years following amputation. Two assessments, conducted 3 months and 6 months post-operatively, demonstrate engagement of motor-control related brain regions for the transplanted hand, during both actual and imagined movement of the fingers. The intact hand exhibited a more intense and focused pattern of activation for actual movement relative to imagined movement, whereas activation for the transplanted hand was more widely distributed and did not clearly differentiate actual and imagined movement. However, the spatial overlap of actual-movement and imagined-movement voxels, for the transplanted hand, did increase over time to a level comparable to that of the intact hand. At these relatively early post-operative assessments, brain regions outside of the canonical motor-control networks appear to be supporting movement of the transplanted hand.

The functional assessment and rehabilitation programme of the UK hand and upper limb transplant service

Introduction

Hand and upper limb transplants are becoming internationally recognised as an effective treatment to improve function and quality of life in carefully selected patients. A comprehensive functional assessment and rehabilitation programme are an essential component of the multi-disciplinary assessment and treatment approach. Although there is an increasing body of published data on the surgical techniques and outcomes following hand transplant, little exists in the literature to guide the hand therapist.

Method

The pre-transplant functional assessments and rehabilitation programme provided for patients undergoing hand transplantation in the UK are described and critically analysed. The UK programme is based on that provided in Lyon, France, but adapted to suit the resources and structure of the UK National Health Service.

Results

Twelve patients have received a functional assessment as part of the multi-disciplinary hand transplant assessment process, with the loss of autonomy a key reason for patients seeking hand transplant. Six of these patients have received hand transplants, with patients more than one year post-transplant having achieved good and fair outcomes according to the Hand Transplantation Score System.

Conclusions

Although hand and upper limb transplant surgery is innovative, the therapy provided is based on the fundamental principles of good communication, accurate assessment and delivery of a bespoke rehabilitation programme; values which are common to all areas of hand therapy practice. A future study reporting the long-term outcomes of patients following hand transplant in the UK is needed to allow the effectiveness of the programme to be evaluated.

Unilateral Brachial Plexus Lesion Impairs Bilateral Touch Threshold

Unilateral brachial plexus injury (BPI) impairs sensory and motor functions of the upper limb. This study aimed to map in detail brachial plexus sensory impairment both in the injured and the uninjured upper limb. Touch sensation was measured through Semmes-Weinstein monofilaments at the autonomous regions of the brachial plexus nerves, hereafter called points of exclusive innervation (PEIs). Seventeen BPI patients (31.35 years±6.9 SD) and 14 age-matched healthy controls (27.57 years±5.8 SD) were tested bilaterally at six selected PEIs (axillary, musculocutaneous, median, radial, ulnar, and medial antebrachial cutaneous [MABC]). As expected, the comparison between the control group and the brachial plexus patients' injured limb showed a robust difference for all PEIs (p ≤ 0.001). Moreover, the comparison between the control group and the brachial plexus uninjured limb revealed a difference for the median (p = 0.0074), radial (p = 0.0185), ulnar (p = 0.0404), and MABC (p = 0.0328) PEIs. After splitting the sample into two groups with respect to the dominance of the injured limb, higher threshold values were found for the uninjured side when it occurred in the right dominant limb compared to the control group at the median (p = 0.0456), radial (p = 0.0096), and MABC (p = 0.0078) PEIs. This effect was absent for the left, non-dominant arm. To assess the effect of the severity of sensory deficits observed in the injured limb upon the alterations of the uninjured limb, a K-means clustering algorithm (k = 2) was applied resulting in two groups with less or more severe sensory impairment. The less severely affected patients presented higher thresholds at the median (p = 0.0189), radial (p = 0.0081), ulnar (p = 0.0253), and MABC (p = 0.0187) PEIs in the uninjured limb in comparison with the control group, whereas higher thresholds at the uninjured limb were found only for the median PEI (p = 0.0457) in the more severely affected group. In conclusion, an expressive reduction in touch threshold was found for the injured limb allowing a precise mapping of the impairment caused by the BPI. Crucially, BPI also led to reduced tactile threshold in specific PEIs in the uninjured upper limb. These new findings suggest a superordinate model of representational plasticity occurring bilaterally in the brain after a unilateral peripheral injury.

Clinical Application of Mathematical Long Bone Ratios to Calculate Appropriate Donor Limb Lengths in Bilateral Upper Limb Transplantation

Background: Limited methods exist to aid in deciding the appropriate donor limb lengths in bilateral upper limb amputees qualifying for vascularized composite allotransplantation. We hypothesized mathematical equations could be created using long bone length ratios, and applied to radiographs, to approximate the patient's limb length prior to amputation. Methods: A data set of 30 skeletons' unilateral upper limb long bones measured using osteometric board and calipers was used. Anatomic segment ratios were calculated based on humerus length after multivariate linear regression analysis. For clinical application testing, 5 cadavers' upper limbs were radiographed. Radiographic bone lengths were then measured along the long axis of each long bone. These measured radiographic lengths were then compared with the predicted bone lengths, generated from the skeleton data set ratios, for each cadaver. Results: The chi-square goodness-of-fit test showed excellent fit (P < .01) between the predicted and radiographically measured lengths for the 5 cadavers, and interobserver measurements showed no statistical difference. Depending on the cadaver, percent error in total limb length predicted to measure ranged from 0.9% to 2.7%. The variables to multiply an individual humerus length to calculate a given anatomic segment thus proved to be effective. Conclusions: If a bilateral upper limb amputee has 1 intact humerus, ratios to the humerus length can be reliably applied to calculate the preamputation limb length based on the patient's radiographic humerus length. These formulas are indicated for finding the appropriate limb lengths, and smaller anatomic segments, for donor-recipient matching in upper limb transplantation.

Psychological and psychiatric aspects of face transplantation: Lessons learned from the long-term follow-up of six patients

Since 2005, at least 38 face transplantations have been performed worldwide. Available recommendations on psychological management are based on isolated cases or small case series, either not focused on mental health or with a short follow-up. We propose herein a clinical commentary on psychological and psychiatric outcomes from the follow-up of a prospective single-center cohort of six patients over a period of 3.5 to 9 years. Seven patients received a face transplant between January 2007 and April 2011: two patients with neurofibromatosis, four with self-inflicted ballistic trauma, one with self-immolation. One patient died at 63 days of cerebral sequelae from cardiac arrest in the setting of bacterial infection. The six other patients were routinely evaluated with unstructured psychological interviews up to May 2016 and with the Short Form 36-item health survey and the Mini-International Neuropsychiatric Interview at one year and at the end of the follow-up. Clinically meaningful observations were the following: a history of mental disorders before disfigurement was associated with poor physical and mental outcomes, including poor adherence and one suicide; untreated depression was associated with poor adherence; acceptance of the new face occurred rapidly and without significant distress in all of the patients; fear of transplant rejection was present to some degree in all of the patients and did not substantially differ from other transplantation settings; media exposure may be disturbing but may also have had positive psychological effects on some of the patients. Mental health issues related to chronic rejection and re-transplantation remain to be explored.

Lower limb amputees undergo long-distance plasticity in sensorimotor functional connectivity

Amputation in adults is associated with an extensive remapping of cortical topography in primary and secondary sensorimotor areas. Here, we used tactile residual limb stimulation and 3T functional magnetic resonance imaging in humans to investigate functional connectivity changes in the sensorimotor network of patients with long-term lower limb traumatic amputations with phantom sensation, but without pain. We found a pronounced reduction of inter-hemispheric functional connectivity between homologous sensorimotor cortical regions in amputees, including the primary (S1) and secondary (S2) somatosensory areas, and primary (M1) and secondary (M2) motor areas. We additionally observed an intra-hemispheric increased functional connectivity between primary and secondary somatosensory regions, and between the primary and premotor areas, contralateral to amputation. These functional connectivity changes in specialized small-scale sensory-motor networks improve our understanding of the functional impact of lower limb amputation in the brain. Our findings in a selective group of patients with phantom limb sensations, but without pain suggest that disinhibition of neural inputs following traumatic limb amputation disrupts sensorimotor topology, unbalancing functional brain network organization. These findings step up the description of brain plasticity related with phantom sensations by showing that pain is not critical for sensorimotor network changes after peripheral injury.

Grasping objects by former amputees: The visuo-motor control of allografted hands

PURPOSE

Hand allograft has recently emerged as a therapeutic option for upper limb amputees. Functional neuroimaging studies have progressively revealed sensorimotor cortices plasticity following both amputation and transplantation. The purpose of our study was to assess and characterize the functional recovery of the visuo-motor control of prehension in bilateral hand transplanted patients.

METHODS

Using kinematics recordings, we characterized the performance of prehension with or without visual feed-back for object of different position and size, in five bilateral hand allograft recipients and age-matched control subjects. Both hands were assessed, separately.

RESULTS

Despite an overall slower execution, allografted patients succeeded in grasping for more than 90% of the trials. They exhibited a preserved hand grip scaling according to object size, and preserved prehension performances when tested without visual feedback. These findings highlight the allograft recipients' abilities to produce an effective motor program, and a good proprioceptive-dependent online control. Nevertheless, the maximum grip aperture was reduced and delayed, the coupling between Transport and Grasp components was altered, and the final phase of the movement was lengthened.

CONCLUSION

Hand allotransplantation can offer recipients a good recovery of the visuo-motor control of prehension, with slight impairments likely attributable to peripheral neuro-orthopedic limitations.

Technology and vascularized composite allotransplantation (VCA)-lessons learned from the first bilateral pediatric hand transplant

The reconstructive principle of replacing "like with like" is best met with vascularized composite allotransplantation in which the components of an existing defect are "matched" to the greatest extent possible in a single stage restoration. Hand transplantation is a labor-intensive and time-intensive process and can be conceptualized into distinct phases that include (1) patient selection and preoperative preparation, (2) technical execution of the procedure, and (3) postoperative rehabilitation and follow-up. The advent of technological innovations, such as 3D printing technology, novel implant technology, as well as innovative imaging technology, such as functional magnetic resonance imaging have the potential of favorably affecting all phases of this process, thus contributing to improved outcomes. The use of these technologies in the world's first case of bilateral hand transplantation in a pediatric patient is discussed.

Primary Motor Cortex Representation of Handgrip Muscles in Patients with Leprosy

BACKGROUND

Leprosy is an endemic infectious disease caused by Mycobacterium leprae that predominantly attacks the skin and peripheral nerves, leading to progressive impairment of motor, sensory and autonomic function. Little is known about how this peripheral neuropathy affects corticospinal excitability of handgrip muscles. Our purpose was to explore the motor cortex organization after progressive peripheral nerve injury and upper-limb dysfunction induced by leprosy using noninvasive transcranial magnetic stimulation (TMS).

METHODS

In a cross-sectional study design, we mapped bilaterally in the primary motor cortex (M1) the representations of the hand flexor digitorum superficialis (FDS), as well as of the intrinsic hand muscles abductor pollicis brevis (APB), first dorsal interosseous (FDI) and abductor digiti minimi (ADM). All participants underwent clinical assessment, handgrip dynamometry and motor and sensory nerve conduction exams 30 days before mapping. Wilcoxon signed rank and Mann-Whitney tests were performed with an alpha-value of p<0.05.

FINDINGS

Dynamometry performance of the patients' most affected hand (MAH), was worse than that of the less affected hand (LAH) and of healthy controls participants (p = 0.031), confirming handgrip impairment. Motor threshold (MT) of the FDS muscle was higher in both hemispheres in patients as compared to controls, and lower in the hemisphere contralateral to the MAH when compared to that of the LAH. Moreover, motor evoked potential (MEP) amplitudes collected in the FDS of the MAH were higher in comparison to those of controls. Strikingly, MEPs in the intrinsic hand muscle FDI had lower amplitudes in the hemisphere contralateral to MAH as compared to those of the LAH and the control group. Taken together, these results are suggestive of a more robust representation of an extrinsic hand flexor and impaired intrinsic hand muscle function in the hemisphere contralateral to the MAH due to leprosy.

CONCLUSION

Decreased sensory-motor function induced by leprosy affects handgrip muscle representation in M1.

Outcomes after bilateral hand allotransplantation: a risk/benefit ratio analysis

BACKGROUND

The clinic era of composite tissue allotransplantation was inaugurated by hand allotransplantation in 1998, giving rise to many controversies and scepticism because of the lifelong immunosuppression, the unclear risk-benefit ratio, and the uncertain long-term functional results of the procedure. The aim of this study was to evaluate the outcomes and the risk/benefit balance in bilateral hand allotransplantation.

METHODS

The study included 5 cases of bilateral hand allotransplantation performed in a single center, with a follow-up ranging from 3 to 13 years. The recipients (4 men, 1 woman) were young. The level of amputation was distal in all cases except for 2 patients amputated at the midforearm level. All the recipients initially received the same immunosuppressive treatment that included tacrolimus, mycophenolate mofetil, prednisone, and, for induction, antithymocyte globulins.

RESULTS

Patient and graft survival was 100%. All recipients showed adequate sensorimotor recovery (protective and tactile sensitivity and partial recovery of intrinsic muscles), they were able to perform the majority of activities of daily living, and had a normal social life. Most complications occurred in the first posttransplant year and were successfully managed. All recipients experienced at least 1 episode of acute rejection, which was easily reversed by increasing oral steroid dose or by intravenous steroids, except for patient 3, who presented 6 episodes of acute rejection, the latest 2 treated with Campath-1H.

CONCLUSIONS

Although bilateral hand transplantation may be a satisfactory treatment option for amputees, a careful selection of candidates and a rigorous evaluation of recipients after transplantation are imperative.

Facial transplantation: the first 9 years

Since the first facial transplantation in 2005, 28 have been done worldwide with encouraging immunological, functional, psychological, and aesthetic outcomes. Unlike solid organ transplantation, which is potentially life-saving, facial transplantation is life-changing. This difference has generated ethical concerns about the exposure of otherwise young and healthy individuals to the sequelae of lifelong, high-dose, multidrug immunosuppression. Nevertheless, advances in immunomodulatory and immunosuppressive protocols, microsurgical techniques, and computer-aided surgical planning have enabled broader clinical application of this procedure to patients. Although episodes of acute skin rejection continue to pose a serious threat to face transplant recipients, all cases have been controlled with conventional immunosuppressive regimens, and no cases of chronic rejection have been reported.

Degraded EEG decoding of wrist movements in absence of kinaesthetic feedback

A major assumption of brain–machine interface research is that patients with disconnected neural pathways can still volitionally recall precise motor commands that could be decoded for naturalistic prosthetic control. However, the disconnected condition of these patients also blocks kinaesthetic feedback from the periphery, which has been shown to regulate centrally generated output responsible for accurate motor control. Here, we tested how well motor commands are generated in the absence of kinaesthetic feedback by decoding hand movements from human scalp electroencephalography in three conditions: unimpaired movement, imagined movement, and movement attempted during temporary disconnection of peripheral afferent and efferent nerves by ischemic nerve block. Our results suggest that the recall of cortical motor commands is impoverished in the absence of kinaesthetic feedback, challenging the possibility of precise naturalistic cortical prosthetic control. Hum Brain Mapp 36:643–654, 2015. © 2014 The Authors. Human Brain Mapping Published by Wiley Periodicals, Inc.

[Hand allograft transplantation: what are the implications?]

The first hand allograft transplantation was performed in 1998 by a French surgeons team and has opened the era of functional allotransfers. In France, the authorized preliminary study included five patients who sustained traumatic amputation of both hands. All patients had bilateral hand allograft transplantation. Long-term results (follow-up ranging from 3 to 12 years) undoubtedly show a useful daily function, a good psychological acceptance and a physiological integration. Despite several obstacles as the need of immunosuppressive therapy for life, hand allograft transplantation is worthy of interest in some outstanding situations.

Cortical motor activity and reorganization following upper-limb amputation and subsequent targeted reinnervation

Previous studies have postulated that the amount of brain reorganization following peripheral injuries may be correlated with negative symptoms or consequences. However, it is unknown whether restoring effective limb function may then be associated with further changes in the expression of this reorganization. Recently, targeted reinnervation (TR), a surgical technique that restores a direct neural connection from amputated sensorimotor nerves to new peripheral targets such as muscle, has been successfully applied to upper-limb amputees. It has been shown to be effective in restoring both peripheral motor and sensory functions via the reinnervated nerves as soon as a few months after the surgery. However, it was unclear whether TR could also restore normal cortical motor representations for control of the missing limb. To answer this question, we used high-density electroencephalography (EEG) to localize cortical activity related to cued motor tasks generated by the intact and missing limb. Using a case study of 3 upper-limb amputees, 2 of whom went through pre and post-TR experiments, we present unique quantitative evidence for the re-mapping of motor representations for the missing limb closer to their original locations following TR. This provides evidence that an effective restoration of peripheral function from TR can be linked to the return of more normal cortical expression for the missing limb. Therefore, cortical mapping may be used as a potential guide for monitoring rehabilitation following peripheral injuries.

[Functional magnetic resonance imaging. What are the benefits expected in hand surgery?]

Functional MRI (fMRI) allowed considerable advances upon understanding of cerebral functioning. Cortical plasticity, which allows the voluntary command of a restored function by a transferred muscle remains to be investigated in its intimacy. The authors present here the round table held at the 48th annual meeting of the French Society for Surgery of the Hand on December 22nd, 2012. It tries to review the analysis of the phenomenon observed during multiple tendinous transfers for restoration of proximal radial nerve palsy. Were successively approached: 1) Methods of acquisition and analysis of the signals (C. D-M.); 2) Movement reorganization (O.M.); 3) Motor plasticity after hand allograft (A. S.); 4) The potential interest of the fMRI in hand rehabilitation (F. D.); 5) The analysis of cerebral plasticity in general (H. B.). A rather philosophical conclusion opens other fields to f MRI (A.M.).

Increase in flexor but not extensor corticospinal motor outputs following ischemic nerve block

Human motor cortex is capable of rapid and long-lasting reorganization, evident globally, as shifts in body part representations, and at the level of individual muscles as changes in corticospinal excitability. Representational shifts provide an overview of how various body parts reorganize relative to each other but do not tell us whether all muscles in a given body part reorganize in the same manner and to the same extent. Transcranial magnetic stimulation (TMS) provides information about individual muscles and can therefore inform us about the uniformity of plastic changes within a body part. We used TMS to investigate changes in corticospinal excitability of forearm flexors and extensors after inflation of a tourniquet around the wrist. Motor evoked potential (MEP) amplitudes and input/output (I/O) curves were obtained from wrist flexors and extensors simultaneously before and during block. TMS was delivered to the optimal site for eliciting MEPs in flexors in experiment 1, extensors in experiment 2, and both flexors and extensors in experiment 3. In all experiments flexor MEP amplitude increased during block while extensor MEP amplitude showed no systematic change, and the slope of flexor but not extensor I/O curves increased. Flexor H-reflex amplitude normalized to maximal M wave showed negligible changes during block, suggesting that the increase in corticospinal excitability in the flexors cannot be completely explained by increased excitability at the spinal cord level. These findings show that forearm flexors and extensors differ in their potential for plastic changes, highlight the importance of investigating how experimentally induced plasticity affects anatomically close, but functionally distinct, muscle groups, and suggest that rehabilitation interventions aiming to alter cortical organization should consider the differential sensitivity of various muscle groups to plasticity processes.

Functional expansion of sensorimotor representation and structural reorganization of callosal connections in lower limb amputees

Previous studies have indicated that amputation or deafferentation of a limb induces functional changes in sensory (S1) and motor (M1) cortices, related to phantom limb pain. However, the extent of cortical reorganization after lower limb amputation in patients with nonpainful phantom phenomena remains uncertain. In this study, we combined functional magnetic resonance (fMRI) and diffusion tensor imaging (DTI) to investigate the existence and extent of cortical and callosal plasticity in these subjects. Nine "painless" patients with lower limb amputation and nine control subjects (sex- and age-matched) underwent a 3-T MRI protocol, including fMRI with somatosensory stimulation. In amputees, we observed an expansion of activation maps of the stump in S1 and M1 of the deafferented hemisphere, spreading to neighboring regions that represent the trunk and upper limbs. We also observed that tactile stimulation of the intact foot in amputees induced a greater activation of ipsilateral S1, when compared with controls. These results demonstrate a functional remapping of S1 in lower limb amputees. However, in contrast to previous studies, these neuroplastic changes do not appear to be dependent on phantom pain but do also occur in those who reported only the presence of phantom sensation without pain. In addition, our findings indicate that amputation of a limb also induces changes in the cortical representation of the intact limb. Finally, DTI analysis showed structural changes in the corpus callosum of amputees, compatible with the hypothesis that phantom sensations may depend on inhibitory release in the sensorimotor cortex.

Outcomes with respect to disabilities of the upper limb after hand allograft transplantation: a systematic review

The aim of this work is to compare disabilities of the upper limb before and after hand allograft transplantation (HAT), and to describe the side effects of immunosuppressive (IS) agents given to recipients of hand allografts. Clinical cases of HAT published between 1999 and 2011 in English, French, or German were reviewed systematically, with emphasis on comparing disabilities of the arm, shoulder and hand (DASH) scores before and after transplantation. Duration of ischemia, extent of amputation, and time since amputation were evaluated for their effect on intrinsic musculature function. Infectious, metabolic, and oncological complications because of IS therapy were recorded. Twenty-eight patients were reported in 56 clinical manuscripts. Among these patients, disabilities of the upper limb dropped by a mean of 27.6 (±19.04) points on the DASH score after HAT (P = 0.005). Lower DASH scores (P = 0.036) were recorded after secondary surgery on hand allografts. The presence of intrinsic muscle function was observed in 57% of the recipients. Duration of ischemia, extent of transplantation, and time since amputation were not associated statistically with the return of intrinsic musculature function. Three grafts were lost to follow-up because of noncompliance with immunosuppression, rejection, and arterial thrombosis, respectively. Fifty-two complications caused by IS agents were reported, and they were successfully managed medically or surgically. HAT recipients showed notable functional gains, but most complications resulted from the IS protocols.

The current state of hand transplantation

Hand transplantation is the most common form of modern composite tissue allotransplantation. Successful application of this technology requires a multidisciplinary approach incorporating not only skilled hand surgeons, transplant surgeons, and transplant immunologists, but also hand therapists, psychiatrists, medical specialists, anesthesiologists, and others. Functional outcomes can be life changing for properly selected candidates. Hand transplantation is becoming more common, with more centers offering this relatively new reconstructive modality. Its success depends on proper patient selection, a technically successful operation, postoperative rehabilitation, and an immunotherapy protocol that prevents rejection but has minimal or acceptable morbidity.

World experience after more than a decade of clinical hand transplantation: update on the French program

The first hand transplantation was realized in Lyon and the results achieved in this case showed the feasibility of the surgical technique, the efficacy of the immunosuppressive protocol, the limited adverse effects and the importance of a patient's compliance and rehabilitation to ensure graft viability and functional recovery. Based on these findings and the positive results achieved in other single hand transplants realized around the world the authors performed also the first double hand transplantation, then followed by other four cases. The recipients received the same immunosuppressive treatment including tacrolimus, prednisone, mycophenolate mofetil and antithymocyte globulins for induction, nevertheless they showed some episodes of acute rejection episodes which reversed after a prompt treatment. All the bilateral hand grafted patients showed a relevant sensorimotor recovery particularly of sensibility and activity of intrinsic muscles. They were able to perform the majority of daily activities and to lead a normal social life. On the basis of the authors' experience the results achieved in hand allotransplantation are very encouraging as major adverse effects due to surgery and immunosuppressive regimen did not occur and patients' quality of life improved considerably.

Achievements and challenges in composite tissue allotransplantation

Overall, more than 60 hand/forearm/arm transplantations and 16 face transplantations have been performed in the past 12 years. In the European experience summarized here, three grafts have been lost in response to a vascular thrombosis (n = 1), rejection and incompliance with immunosuppression (n = 1) and death (n = 1). The overall functional and esthetic outcome is very satisfactory, but serious side effects and complications related to immunosuppression are challenges hindering progress in this field. The high levels of immunosuppression, skin rejection, nerve regeneration, donor legislation and the acceptance level need to be addressed to promote growth of this promising new field in transplantation and reconstructive surgery.

A device for the relief of phantom limb pain and rehabilitation in stroke

PURPOSE

To determine if simple, robust spectacle mounted devices are feasible for the replacement of the mirror boxes currently used in the rehabilitation of patients suffering from phantom limb pain, complex regional pain syndrome and stroke.

METHODS

Four devices, using three different optical systems were produced: plane mirror, astronomical telescope using cylindrical lenses and two reflecting prism systems.

RESULT

The illusory effect of the devices was similar to that of the mirror box.

CONCLUSIONS

Any of the systems would be suitable to replace the mirror box, but the reflecting prism system is the easiest to set up.

Dynamic reorganization of referred sensations by movements of phantom limbs

After amputation of an arm the sensory map of the body changes radically, causing the sensory input from face to 'invade' the original hand area in the brain. As a result, touching the face of the amputee evokes tactile sensations on the phantom. These sensory referrals from the face to phantom hand occur in a stable, topographically organized manner. We now find that volitional movements of the phantom cause striking, systematic shifts in the map along the direction of movement. We conclude that the reorganization of maps is based partly on reversible inhibition of ordinarily silent synapses, not entirely on new anatomical connections. This finding further highlights the dynamic nature of the brain on remarkably short-time scales.