Diffusion Tensor Imaging: Techniques and Applications for Peripheral Nerve Injury.

ABSTRACT: Peripheral nerve injuries (PNIs) represent a complex clinical challenge, necessitating precise diagnostic approaches for optimal management. Traditional diagnostic methods often fall short in accurately assessing nerve recovery as these methods rely on the completion of nerve reinnervation, which can prolong a patient's treatment. Diffusion tensor imaging (DTI), a noninvasive magnetic resonance imaging (MRI) technique, has emerged as a promising tool in this context. DTI offers unique advantages including the ability to quantify nerve recovery and provide in vivo visualizations of neuronal architecture. Therefore, this review aims to examine and outline DTI techniques and its utility in detecting distal nerve regeneration in both preclinical and clinical settings for peripheral nerve injury.

In-Vivo MRI in Rodents: A Protocol for Optimal Animal Positioning.

ABSTRACT: Magnetic resonance imaging (MRI) is a potentially powerful novel peripheral nerve diagnosis technique. To determine its validity, in-vivo preclinical studies are necessary. However, when using a rodent model, positioning rats and achieving high-resolution images can be challenging. We present a short report that outlines an optimal protocol for positioning rats for in-vivo MRI acquisition. Female Sprague-Dawley rats with sciatic nerve injury were induced into anesthesia using 4% isoflurane in oxygen and maintained at 1.5%. Rats were placed into a plexiglass cradle in a right lateral recumbent position, and a surface coil was placed over the left leg. Respiration rate and body temperature were monitored throughout the scan. Our protocol was successful as rats were able to undergo MRI scanning safely and efficiently. There were no adverse reactions, and clear images of the left sciatic nerve were obtained. Animal positioning took 30 minutes, and 5 different acquisitions were obtained in 2 hours. The total time from anesthesia induction to recovery was under 3 hours. Given the increasing interest in MRI diagnostic techniques, we hope this report aids other researchers studying peripheral nerve injury imaging in rat models.

Challenges of Imaging the Greater Occipital Nerve Using Magnetic Resonance Imaging.

ABSTRACT: Migraine headaches are a significant global health concern, frequently managed with varying levels of success. Compression of the greater occipital nerve (GON) is hypothesized to contribute to pathology in some migraine patients, making extracranial nerve decompression surgery a potential intervention for refractory cases. However, accurate methods to image the GON along its tortuous course still need to be explored. Our group has developed magnetic resonance imaging sequences to track the GON. Yet, many challenges were met, which included navigating the GON's complex anatomy, understanding anatomical variants, and designing advanced magnetic resonance imaging sequences and coils to image the posterior scalp. Addressing these hurdles is vital to capture and understand GON pathology and guide potential interventions.

The Growth and Development of a Research Division in the Plastic Surgery Department of a Large Urban Academic Medical Center.

INTRODUCTION: Research is a critical component of academic medicine that may or may not be prioritized in centers with high clinical volumes. The benefits of research expansion go beyond notoriety and industry partnerships, expanding into resident training and preparation of the next generation of physician-scientists. Improving a division or department's research portfolio requires a commitment to reorganizing structure, personnel, resources, and a dedication to innovative funding models. To improve research productivity and quality, our group placed several initiatives into motion beginning in August 2017 that we have outlined and evaluated in the present study. Some of these initiatives included restructuring leadership, resourcing both bench and clinical outcomes research, providing initial funding directly from clinical profits and rewarding research fiscally. METHODS: Reviews of hiring records, publications, grant allocations, and interviews with key personnel were used to generate a road map of initiatives. Average impact factor was calculated by averaging journal impact factors for all publications from the department each year, excluding any publications with greater than 5 times the raw average, and creating a corrected average that more accurately represented the work. Student t tests were used to compare mean number of publications and impact factors from 2010 to 2017 to those from 2018 to 2022. RESULTS: Prior to restructuring (2010-2017), the department published an average of 9 articles annually, which increased to an average of 42 articles since that time (P < 0.01). Average impact increased from 0 in 2010 to 4.02 in 2022, with the number of publications in top 10 plastic surgery journals following a similar trajectory with 1 publication in 2010 and 31 in 2023. Following an initial $1 million investment to create an institutionally directed fund in 2018, the department leveraged its research to earn $3 million in endowments, $1.25 million in industry partnerships, $3.23 million in Department of Defense funding, and $1.65 million from a multi-institutional National Institutes of Health grant. CONCLUSION: Deliberate prioritization of research initiatives as noted above has led to remarkable growth in academic output.

Preoperative visualization of the greater occipital nerve with magnetic resonance imaging in candidates for occipital nerve decompression for headaches.

Occipital nerve decompression is effective in reducing headache symptoms in select patients with migraine and occipital neuralgia. Eligibility for surgery relies on subjective symptoms and responses to nerve blocks and Onabotulinum toxin A (Botox) injections. No validated objective method exists for detecting occipital headache pathologies. The purpose of the study is to explore the potential of high-resolution Magnetic Resolution Imaging (MRI) in identifying greater occipital nerve (GON) pathologies in chronic headache patients. The MRI protocol included three sequences targeting fat-suppressed fluid-sensitive T2-weighted signals. Visualization of the GON involved generating 2-D image slices with sequential rotation to track the nerve course. Twelve patients underwent pre-surgical MRI assessment. MRI identified four main pathologies that were validated against intra-operative examination: GON entanglement by the occipital artery, increased nerve thickness and hyperintensity suggesting inflammation compared to the non-symptomatic contralateral side, early GON branching with rejoining at a distal point, and a connection between the GON and the lesser occipital nerve. MRI possesses the ability to visualize the GON and identify suspected trigger points associated with headache symptoms. This case series highlights MRI's potential to provide objective evidence of nerve pathology. Further research is warranted to establish MRI as a gold standard for diagnosing extracranial contributors in headaches.

Timing of Autologous Tissue Breast Reconstruction Does Not Affect Free Flap Failure.

ABSTRACT: This study aimed to determine whether there is a difference in free flap failure based on the decision to undergo immediate versus delayed autologous tissue breast reconstruction after mastectomy. The National Surgical Quality Improvement Program database was queried for breast free flap procedures performed between 2015 and 2020. This study demonstrates that the decision to undergo immediate versus delayed autologous tissue breast reconstruction does not have a significant association with free flap failure. This remains true regardless of whether patients undergo unilateral mastectomy with reconstruction or whether patients choose to also undergo contralateral prophylactic mastectomy with reconstruction.

Amputated Digit Replantations: Critical Digit Ischemia Timing, Temperature, and Other Predictors of Survival.

INTRODUCTION: A common consideration for replantation success is the ischemia time following injury and the preservation temperature. A classic principle within the hand surgery community describes 12 hours of warm ischemia and 24 hours of cold ischemia as the upper limits for digit replantation; however, these limits are largely anecdotal and based on older studies. We aimed to compare survival data from the large body of literature to aid surgeons and all those involved in the replantation process in hopes of optimizing success rates. METHODS: The PubMed database was queried on April 4th, 2023, for articles that included data on digit replantation survival in terms of temperature of preservation and ischemia time. All primary outcomes were analyzed with the Mantel-Haenszel method within a random effects model. Secondary outcomes were pooled and analyzed using the chi-square statistic. Statistical analysis and forest plot generation were completed with RevMan 5.4 software with odds ratios calculated within a 95% confidence interval. RESULTS: Our meta-analysis identified that digits preserved in cold ischemia for over 12 hours had significantly higher odds of replantation success than the amputated digits replanted with 0-12 hours of warm ischemia time ( P ≤ 0.05). The odds of survival in the early (0-6 hours) replantation group were around 40% greater than the later (6-12 hours) replantation group ( P ≤ 0.05). Secondary outcomes that were associated with higher survival rates included a clean-cut amputation, increased venous and arterial anastomosis, a repair that did not require a vein graft, and replants performed in nonsmokers ( P ≤ 0.05). DISCUSSION: Overall, these findings suggest that when predicting digit replantation success, time is of the essence when the digit has yet to be preserved in a cold environment. This benefit, however, is almost completely diminished when the amputated digit is appropriately maintained in a cold environment soon after injury. In conclusion, our results suggest that there is potential for broadening the ischemia time limits for digit replant survival outlined in the literature, particularly for digits that have been stored correctly in cold ischemia.

Polyethylene Glycol-Mediated Axonal Fusion Promotes Early Sensory Recovery After Digital Nerve Injury: A Randomized Clinical Trial.

BACKGROUND: Peripheral nerve repair is limited by Wallerian degeneration coupled with the slow and inconsistent rates of nerve regrowth. In more proximal injuries, delayed nerve regeneration can cause debilitating muscle atrophy. Topical application of polyethylene glycol (PEG) during neurorrhaphy facilitates the fusion of severed axonal membranes, immediately restoring action potentials across the coaptation site. In preclinical animal models, PEG-fusion resulted in remarkable early functional recovery. METHODS: This is the first randomized clinical trial comparing functional outcomes between PEG-fusion and standard neurorrhaphy. Participants with digital nerve transections were followed up at 2 weeks, 1 month, and 3 months postoperatively. The primary outcome was assessed using the Medical Research Council Classification (MRCC) rating for sensory recovery at each timepoint. Semmes-Weinstein monofilaments and static two-point discrimination determined MRCC ratings. Postoperative quality of life was measured using the Michigan Hand Questionnaire (MHQ). RESULTS: Forty-eight transected digital nerves (25 control, 23 PEG) across twenty-two patients were analyzed. PEG-fused nerves demonstrated significantly higher MRCC scores at 2 weeks (OR 16.95, 95% CI: 1.79 - 160.38, p = 0.008) and 1 month (OR 13.40, 95% CI: 1.64 - 109.77, p = 0.009). Participants in the PEG cohort also had significantly higher average MHQ scores at 2 weeks (Hodge's g 1.28, 95% CI: 0.23 - 2.30, p = 0.0163) and 1 month (Hodge's g 1.02, 95% CI: 0.04 - 1.99, p = 0.049). No participants had adverse events related to the study drug. CONCLUSION: PEG-fusion promotes early sensory recovery and improved patient well-being following peripheral nerve repair of digital nerves.

Patient Characteristics and Spending Among Individuals Undergoing Ambulatory Panniculectomy and Abdominoplasty in the US from 2016 to 2019.

BACKGROUND: Abdominal contouring surgery can provide both functional and cosmetic benefits to patients with abdominal soft tissue laxity. Although these procedures have been studied in the inpatient setting, few studies describe abdominal contouring surgery in the ambulatory setting. OBJECTIVE: The purpose of this analysis was to investigate patterns in patient demographics between functional panniculectomy and cosmetic abdominoplasty using national data from the last four years. METHODS: Using the Nationwide Ambulatory Surgery Sample, we analyzed outpatient abdominal contouring procedures between 2016 and 2019. Encounters with a CPT 15830 were included. Procedures with ICD Z41.1 or CPT 15847 modifiers were defined as cases of cosmetic abdominoplasty. RESULTS: A weighted estimate of 95,289 encounters were included, with 66,531 (69.8%) functional panniculectomy and 28,758 (30.2%) cosmetic abdominoplasty procedures. Among patients with a history of bariatric surgery (23.8%; 95% CI, 22.3-25.4%), there was a 28.5% (4,866 in 2016 vs 6,254 in 2019) increase in panniculectomy and abdominoplasty. Compared with individuals who underwent cosmetic abdominoplasty, individuals who underwent functional panniculectomy were more racially diverse, had more comorbidities, and were more likely to be from low-income backgrounds. CONCLUSIONS: Rates of abdominal contouring surgery in the ambulatory setting have increased in recent years especially among individuals with previous bariatric surgery. There are important demographic and clinical differences between patients who underwent functional panniculectomy and cosmetic abdominoplasty including primary payer, comorbidities, and racial identity. LEVEL OF EVIDENCE III: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Reduced Access to Acute Hand Care and Potential Role of Telemedicine in Tennessee During the COVID Pandemic.

INTRODUCTION: Previous studies have identified that there is limited, although expanding, access to acute hand care in Tennessee. Because of the rapid changes that occurred in health delivery and access during the coronavirus disease pandemic, we reassessed access to acute hand care, with particular interest in the utilization of telemedicine to assess if this increased access. METHOD: We surveyed Tennessee hospitals listed by the Tennessee Hospital Association on their management of hand trauma and availability of telemedicine programs. Census data including population demographics such as race, age, income, and county size were merged with the survey data. Descriptive analysis was performed comparing the 2021 cohort with the historic 2018 cohort and between counties that had hand care versus counties that had no hand care. RESULT: Survey response rate was 71.4% (n = 80 of 112). Telemedicine was used in 80% of the hospitals for other specialties but was not used for hand care. Overall, counties that offered hand trauma care reduced from 60% to 26% from 2018 to 2021 ( P < 0.001). This change was associated with a significant reduction of acute hand care among counties that were classified micropolitan (from 56.3% to 6.7%, P < 0.01). Percentage of hand specialists on staff and 24/7 specialists availability remained low and were similar to the availability in 2018. CONCLUSIONS: There was a decrease of acute hand care access in Tennessee during the coronavirus disease pandemic despite widespread utilization of telemedicine for other specialty consults. Expansion of telemedicine in acute hand care, targeted to micropolitan areas, may help to reduce variability in access to care.

Model-based parcellation of diffusion MRI of injured spinal cord predicts hand use impairment and recovery in squirrel monkeys.

A mathematical model-based parcellation of magnetic resonance diffusion tensor images (DTI) has been developed to quantify progressive changes in three types of tissues - grey (GM), white matter (WM), and damaged spinal cord tissue, along with behavioral assessments over a 6 month period following targeted spinal cord injuries (SCI) in monkeys. Sigmoid Gompertz function based fittings of DTI metrics provide early indicators that correlate with, and predict, recovery of hand grasping behavior. Our three tissue pool model provided unbiased, data-driven segmentation of spinal cord images and identified DTI metrics that can serve as reliable biomarkers of severity of spinal cord injuries and predictors of behavioral outcomes.

Systematic Review and Meta-Analysis of Global Neuroma Incidence in Upper Extremity Amputees.

BACKGROUND: Neuromas substantially decrease a patient's quality of life and obstruct the use of prosthetics. This systematic review and meta-analysis aimed to determine the global incidence of neuroma formation in upper extremity amputees. METHODS: A literature search was performed using 3 databases: Web of Science, MEDLINE, and Cochrane. Inclusion criteria for the systematic review were those studies investigating only upper extremity amputees and reported postamputation neuroma. A random-effects, inverse-variance analysis was conducted to determine the pooled proportion of neuromas within the upper extremity amputation population. Critical appraisal using the JBI Checklist for Studies Reporting Prevalence Data of each individual article were performed for the systematic review. RESULTS: Eleven studies met the inclusion criteria collating a total of 1931 patients across 8 countries. More than three-fourth of patients are young men (77%; age range, 19-54 years) and had an amputation due to trauma. The random-effects analysis found the pooled combined proportion of neuromas to be 13% (95% confidence interval, 8%-18%). The treatment of neuroma is highly variable, with some patients receiving no treatment. CONCLUSIONS: The pooled proportion of neuroma incidence in the 1931 patients was 13%. With the known global prevalence of upper extremity amputees, this translates to nearly 3 million amputees suffering from a neuroma globally. Increasing training in preventative surgical methods could contribute to lowering this incidence and improving the outcomes of this patient population.

Effect of a Perioperative Educational Video in Patients Undergoing Mohs Reconstruction: A Randomized Clinical Trial.

BACKGROUND: Skin cancer is the most common type of cancer in the United States, and most are treated with Mohs micrographic surgery (MMS) by fellowship-trained dermatologic surgeons. Complex reconstruction in cosmetically and functionally sensitive areas often requires a plastic surgery consult. The uncertainty regarding reconstructive options and cosmetic appearance is difficult emotionally and cognitively for patients. OBJECTIVES: To improve patient understanding about MMS reconstruction with plastic surgeons, we investigated the utility of a multimedia presentation during perioperative education. METHODS: A randomized clinical trial was conducted at a hospital-affiliated outpatient MMS clinic and surgery center in the United States. Patients in the intervention arm were given a tablet or Web site link to watch a multimedia presentation about reconstruction after MMS. All patients were given a questionnaire about their understanding of MMS reconstruction and satisfaction with the reconstructive care they received. RESULTS: A total of 46 patients were recruited for the study and completed the questionnaire. Of these patients, 22 were randomized to the test intervention arm, and the remaining 24 were in the control group. Among participants in the test intervention arm, feedback regarding the platform was positive with more than 90% of patients reporting that the video was engaging, useful, and easy to understand. Patient understanding and satisfaction scores in the test intervention arm ranked higher across all domains than those of the control group. CONCLUSIONS: This randomized clinical trial showed increases in patient understanding and satisfaction among patients undergoing MMS reconstruction with the implementation of a perioperative educational video.

Delayed Versus Immediate Breast Reconstruction in the Ambulatory Surgery Setting: A Cross-Sectional Analysis of the Nationwide Ambulatory Surgery Sample.

BACKGROUND: Breast reconstruction remains an important part of a patient's journey after the diagnosis of breast carcinoma and treatment with mastectomy. Although inpatient immediate breast reconstruction has been described, there is a paucity information about whether similar procedures are performed in the ambulatory setting. OBJECTIVE: The authors sought to investigate rates and patterns for delayed and immediate breast reconstruction in the ambulatory surgery setting using nationally representative data from 2016 to 2019. METHODS: Using the Nationwide Ambulatory Surgery Sample database, we identified patients with an International Statistical Classification of Disease and Related Health Problems, Tenth Revision, procedure code for breast reconstruction. Demographic and clinical characteristics were recorded for each encounter of breast reconstruction, and linear regression and logistic regression were used to assess for trends and disparities. RESULTS: National weighted estimates for ambulatory breast reconstruction increased by 15.6% from 89 237 in 2016 to 103 134 in 2019, resulting in 377 109 procedures during the study period. Inflation-adjusted total charges for ambulatory breast reconstruction were $14 billion between 2016 and 2019, or 1.7% of overall charges for ambulatory surgery. Immediate reconstruction was performed in 34.7% (95% CI, 33.4%-36.1%) of cases and increased by 46.9% from 26 930 in 2016 to 39 559 in 2019. Racial disparities were observed in access, comorbidities, and spending. CONCLUSIONS: Our findings indicate a moderate increase in ambulatory breast reconstruction with a substantial growth in the performance of immediate breast reconstruction in the ambulatory setting.

Implantable, Bioresorbable Radio Frequency Resonant Circuits for Magnetic Resonance Imaging.

Magnetic resonance imaging (MRI) is widely used in clinical care and medical research. The signal-to-noise ratio (SNR) in the measurement affects parameters that determine the diagnostic value of the image, such as the spatial resolution, contrast, and scan time. Surgically implanted radiofrequency coils can increase SNR of subsequent MRI studies of adjacent tissues. The resulting benefits in SNR are, however, balanced by significant risks associated with surgically removing these coils or with leaving them in place permanently. As an alternative, here the authors report classes of implantable inductor-capacitor circuits made entirely of bioresorbable organic and inorganic materials. Engineering choices for the designs of an inductor and a capacitor provide the ability to select the resonant frequency of the devices to meet MRI specifications (e.g., 200 MHz at 4.7 T MRI). Such devices enhance the SNR and improve the associated imaging capabilities. These simple, small bioelectronic systems function over clinically relevant time frames (up to 1 month) at physiological conditions and then disappear completely by natural mechanisms of bioresorption, thereby eliminating the need for surgical extraction. Imaging demonstrations in a nerve phantom and a human cadaver suggest that this technology has broad potential for post-surgical monitoring/evaluation of recovery processes.

Longitudinal traumatic peripheral nerve injury recovery: quantitative description, classification and prediction.

Aim: Repair of peripheral nerves is recommended following transection. Systematic evaluation of longitudinal recovery in injury models is needed to improve patient management. Gompertz function provided straightforward interpretation and prediction of recovery outcomes. Materials & methods: Behavioural sciatic function index, measured 3 days post injury, and weekly for 12 weeks following full nerve transection and repair (n = 6) as well as crush injuries (n = 6). Results: Gompertz parametrization provided early classification between types of traumatic peripheral nerve injuries following surgical repair. Results distinguished injury nerves (A: p < 0.01; Ti: p < 0.05; Ic: p < 0.05 and outcome: p < 0.01). Early prognostication of outcomes (crush: 5.5 ± 0.3 and cut/repair: 8 ± 1 weeks) preceded current methods. Conclusion: Our findings identify injury type, state of recovery and early prognostication of outcome.

Infrared neural stimulation markedly enhances nerve functionality assessment during nerve monitoring.

In surgical procedures where the risk of accidental nerve damage is prevalent, surgeons commonly use electrical stimulation (ES) during intraoperative nerve monitoring (IONM) to assess a nerve's functional integrity. ES, however, is subject to off-target stimulation and stimulation artifacts disguising the true functionality of the specific target and complicating interpretation. Lacking a stimulation artifact and having a higher degree of spatial specificity, infrared neural stimulation (INS) has the potential to improve upon clinical ES for IONM. Here, we present a direct comparison between clinical ES and INS for IONM performance in an in vivo rat model. The sensitivity of INS surpasses that of ES in detecting partial forms of damage while maintaining a comparable specificity and sensitivity to more complete forms. Without loss in performance, INS is readily compatible with existing clinical nerve monitoring systems. These findings underscore the clinical potential of INS to improve IONM and surgical outcomes.