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BACKGROUND: This study compared epimysial patch electrodes with intramuscular hook electrodes using monopolar and bipolar recording configurations. The purpose was to determine which strategy transduced muscle signals with better fidelity for control of myoelectric prostheses. METHODS: One of the two electrode styles, patch (n = 4) or hook (n = 6) was applied to the left extensor digitorum longus muscle in rats. Electrodes were evaluated at the time of placement and at monthly intervals for 4 months. Evaluations consisted of evoked electromyography signals from stimulation pulses applied to the peroneal and tibial nerves in both monopolar and bipolar recording configurations. RESULTS: Compared with hook electrodes, patch electrodes recorded larger signals of interest and minimized muscle tissue injury. A bipolar electrode configuration significantly reduced signal noise when compared with a monopolar configuration. CONCLUSION: Epimysial patch electrodes outperform intramuscular hook electrodes during chronic skeletal muscle implantation.

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BACKGROUND: Originally designed for prosthetic control, regenerative peripheral nerve interfaces (RPNIs) prevent neuroma formation by providing free muscle grafts as physiological targets for peripheral nerve ingrowth. We report the first series of patients undergoing RPNI implantation for treatment of symptomatic postamputation neuromas. METHODS: A retrospective case series of all amputees undergoing RPNI implantation for treatment of symptomatic neuromas between November 2013 and June 2015 is presented. Data were obtained via chart review and phone interviews using questions derived from the Patient Reported Outcomes Measurement Information System instruments. Statistical analyses were performed using dependent sample t tests with a significance threshold of P < 0.01. RESULTS: Forty-six RPNIs were implanted into 16 amputees for neuroma relief (3 upper extremities and 14 lower extremities). Mean age was 53.5 years (6 females and 10 males). All patients participated in postoperative phone interviews at 7.5 ± 3.4 (range: 3-15) months. Patients reported a 71% reduction in neuroma pain and a 53% reduction in phantom pain. Most patients felt satisfied or highly satisfied with RPNI surgery (75%), reporting decreased (56%) or stable (44%) levels of analgesic use. Most patients would strongly recommend RPNI surgery to a friend (88%) and would do it again if given the option (94%). Complications included delayed wound healing (n = 4) and neuroma pain at a different site (n = 2). CONCLUSIONS: RPNI implantation carries a reasonable complication profile while offering a simple, effective treatment for symptomatic neuromas. Most patients report a significant reduction in neuroma and phantom pain with a high level of satisfaction. The physiological basis for preventing neuroma recurrence is an intriguing benefit to this approach.

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Brain-Machine Interfaces (BMIs) have shown great potential for generating prosthetic control signals. Translating BMIs into the clinic requires fully implantable, wireless systems; however, current solutions have high power requirements which limit their usability. Lowering this power consumption typically limits the system to a single neural modality, or signal type, and thus to a relatively small clinical market. Here, we address both of these issues by investigating the use of signal power in a single narrow frequency band as a decoding feature for extracting information from electrocorticographic (ECoG), electromyographic (EMG), and intracortical neural data. We have designed and tested the Multi-modal Implantable Neural Interface (MINI), a wireless recording system which extracts and transmits signal power in a single, configurable frequency band. In prerecorded datasets, we used the MINI to explore low frequency signal features and any resulting tradeoff between power savings and decoding performance losses. When processing intracortical data, the MINI achieved a power consumption 89.7% less than a more typical system designed to extract action potential waveforms. When processing ECoG and EMG data, the MINI achieved similar power reductions of 62.7% and 78.8%. At the same time, using the single signal feature extracted by the MINI, we were able to decode all three modalities with less than a 9% drop in accuracy relative to using high-bandwidth, modality-specific signal features. We believe this system architecture can be used to produce a viable, cost-effective, clinical BMI.

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BACKGROUND: Facebook is the leading online media platform used by plastic surgeons. This study examined Facebook use among plastic surgeons and its perceived impact. METHODS: A survey on Facebook use was distributed to two groups of plastic surgeons: 500 with professional Facebook pages and 500 without Facebook pages. Responses were stripped of identifying information and analyzed for statistical significance (p < 0.05). RESULTS: One hundred twenty-three total surveys were completed (12.3 percent response rate). No respondents with Facebook reported a negative impact on their practice, whereas 57 percent reported a very positive or positive impact. There was no correlation with perceived impact and number of "likes." Perceived advantages of Facebook included facilitation of patient feedback/communication (77 percent) and increased practice exposure (67 percent). Many surgeons (15 to 36 percent) did not follow the direct impact of Facebook on their practices. Some reported that Facebook was responsible for only one to 50 professional Web site hits and less than 5 percent of their new patient referrals in the past year. Estimated conversion-to-surgery rates were highly variable for Facebook users and nonusers. Most Facebook nonusers (67 percent) expected a "neutral" impact, expressing more concerns about unsolicited advertising (51 percent) and wasting time (47 percent). CONCLUSIONS: Plastic surgeons tend to perceive Facebook's impact on their practices as positive, but most do not track its direct effects on professional Web site hits, new referrals, or conversion-to-surgery rates. Plastic surgeons using Facebook are encouraged to monitor these parameters to determine whether its continued use is actually worthwhile.

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Despite modern technological advances, the most widely available prostheses provide little functional recovery beyond basic grasping. Although sophisticated upper extremity prostheses are available, optimal prosthetic interfaces which give patients high-fidelity control of these artificial limbs are limited. We have developed a novel Regenerative Peripheral Nerve Interface (RPNI), which consists of a unit of free muscle that has been neurotized by a transected peripheral nerve. In conjunction with a biocompatible electrode on the muscle surface, the RPNI facilitates signal transduction from a residual peripheral nerve to a neuroprosthetic limb. The purpose of this study was to explore signal quality and reliability in an RPNI following an extended period of implantation. Following a 14-month maturation period, electromyographic signal generation was evaluated via electrical stimulation of the innervating nerve. The long-term RPNI was viable and healthy, as demonstrated by evoked compound muscle action potentials as well as histological tissue analysis. Signals exceeding 4 mV were successfully acquired and amplitudes were consistent across multiple repetitions of applied stimuli. There were no evident signs of muscle denervation, significant scar tissue, or muscle necrosis. This study provides further evidence that after a maturation period exceeding 1 year, reliable and consistent signals can still be acquired from an RPNI.

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High-fidelity signal acquisition is critical for the fundamental control of a neuroprosthesis. Our group has developed a bio-artificial interface consisting of a muscle graft neurotized by a severed nerve in a rat hind limb model. This regenerative peripheral nerve interface (RPNI) permits nerve signal transmission, amplification, and detection via in situ electromyography (EMG). Our study examined the magnitude of signal interference from simultaneously contracting muscles adjacent to our muscle of interest. In eighteen F344 rats, the extensor digitorum longus (EDL) muscle was used to fabricate simulated RPNI constructs of various sizes in which the neurovascular pedicle was preserved, obviating the need for reinnervation or revascularization. After 3 weeks of recovery, in situ EMG testing was performed using electrical stimulation of the common peroneal nerve. A recording needle was placed in the EDL muscle with a reference/ground electrode in the contralateral toe webspace, comprising a monopolar recording configuration. The superficial peroneal nerve was transected to further isolate stimulation of the anterior compartment. Recordings from the EDL were performed before and after excision of the tibialis anterior (TA) and extensor hallucis longus (EHL) muscles. After TA/EHL excision, EDL compound muscle action potential (CMAP) peak-to-peak amplitudes were significantly lower by an average of 7.4±5.6(SD) mV, or 32±18%, (paired t(17)=-5.7, p<;0.0001). A significant positive linear correlation was seen between CMAP amplitude and EDL mass both before TA/EHL excision (r=0.68, n=18, p<;0.01) and after TA/EHL excision (r=0.79, n=18, p<;0.0001). EDL mass did not correlate with differences in CMAP amplitude or area caused by TA/EHL excision. Monopolar needle EMG recordings from the EDL muscle are significantly, but predictively, contaminated by concomitant muscular contractions in the anterior compartment of the rat hind limb. Further investigation of strategies to reduce this signal interference, including electrode choice or configuration, use of bioelectrical insulators, and filtering methods, is warranted to promote high-fidelity signal acquisition for prosthetic control.

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BACKGROUND: Prolonged healing times and hypertrophic scarring of the donor site for split-thickness-skin grafts thicker than 0.3 mm are common problems that continue to challenge plastic surgeons in the clinic. As such, a human tissue-engineered epidermal membrane was constructed to promote wound healing and reduce scar hypertrophy. METHODS: An artificial allogenic epidermis was created in vitro using human keratinocytes and chitosan-gelatin membrane. Split-thickness skin graft donor sites were divided into three treatment groups: those covered with the combined keratinocyte/chitosan-gelatin membrane, those covered with chitosan-gelatin membrane only (control group), and those covered with traditional petroleum jelly gauze (blank group). The degree of wound healing was assessed at various time points after the operation by gross observation, hematoxylin and eosin staining, immunohistochemistry, and an assay of type I collagen using the picrosirius polarization method. Reverse-transcriptase polymerase chain reaction detection of the Y chromosome was also performed to distinguish between sexes. RESULTS: Over a 6-month observation period, treatment with the human tissue-engineered epidermal membrane (keratinocyte/chitosan-gelatin) appeared to decrease donor-site healing time (48 wounds in 24 cases). Average healing time was 8.1 +/- 1.3 days for the keratinocyte/chitosan-gelatin group, 16.4 +/- 1.7 days for the chitosan-gelatin group, and 22.9 +/- 4.2 days for the blank group. The artificial epidermis survived well and maintained a normal structure. Furthermore, hypertrophic scar formation was less severe for these wounds. CONCLUSIONS: Keratinocyte/chitosan-gelatin membranes can be constructed in vitro and survive temporarily in vivo. They can be used to promote wound healing and reduce the severity of hypertrophic scarring of skin graft donor sites.

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OBJECTIVE: Functional deactivation of the posteromedial cortex (PMC) seems to be a physiologic process underlying normal memory. The authors examined whether older subjects with subsyndromal depressive symptoms show impaired PMC deactivation. DESIGN: Subjects underwent 4T functional magnetic resonance imaging scan while performing a novel and familiar face-name associative encoding task. The Beck-II Depression Inventory (BDI) was used to self-rate depression symptoms. A novel-minus-familiar encoding contrast was built into a simple regression model showing brain activation magnitudes that covaried with BDI score. A region-of-interest mask was applied to isolate the PMC and other midline structures of the default-mode network. SETTING: The study was conducted at a university-based medical center. PARTICIPANTS: Participants included 62 nondemented subjects aged 55-85, with and without mild memory deficits. BDI scores ranged from 0 to 17. RESULTS: Analysis revealed a distinct PMC cluster confined to the dorsal posterior cingulate cortex (BA 31) whose activity correlated significantly with BDI score. A multiple regression model further showed that BDI score, as well as a history of depression and current use of antidepressants, had a significant effect on cluster variance, while age, education, gender, and mini-mental state exam scores did not. CONCLUSIONS: Our findings raise the hypothesis that subsyndromal depressive symptoms in late life may impair physiological PMC deactivation in the dorsal posterior cingulate cortex. A prospective study of a full spectrum of depressed patients may be warranted.

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