Scientific Abstract Presentations: Migraine and Peripheral Nerve Session 2 Saturday, October 11 Sat, Oct 11 2:00-3:30 p.m. CDT

Introduction

Partial denervation is a surgical approach used to relieve wrist pain in patients with various wrist pathologies. While it is generally thought to improve pain, questions exist regarding its long-term impact on patient outcomes. This study evaluates the effects of partial wrist denervation on long-term outcomes, including subjective pain scores, range of motion, and Disabilities of the Arm, Shoulder, and Hand (DASH) scores.

Methods

A retrospective review of medical records was conducted for patients who underwent partial wrist denervation at Beth Israel Deaconess Medical Center between January 2015 and January 2025. Data collected included age at surgery, demographic characteristics, and preoperative, intraoperative, and postoperative variables. Preoperative and postoperative results were compared with paired t-tests and Fisher's exact test. Significance was set at p ≤ 0.05.

Results

A total of 146 patient records were reviewed, with a mean age at surgery of 56.7 ± 13.7 years. Most patients were male (70.7%), White (71.3%), Not Hispanic or Latino (89.1%), and right-handed (88.0%). Most had no prior surgery on the affected wrist (64.8%), and nearly all underwent a concurrent procedure during denervation (98.7%). The most common indications for wrist denervation included scapholunate advanced collapse (SLAC) or scaphoid nonunion advanced collapse (SNAC) (28.8%), trauma-related injuries (21.9%), arthritis (10.3%), and synovitis (10.3%). The posterior interosseous nerve was the most frequently transected nerve (82.2%), followed by the anterior interosseous nerve (15.4%).

The mean time to follow-up was 1.2 years, with a maximum of 9.1 years. Approximately a fifth of patients (21.5%) required a subsequent reoperation and 8.9% required subsequent injections for analgesia.

Patients demonstrated a significant improvement in functional status after their respective wrist procedure and denervation, as indicated by a decrease in DASH scores from 51.8 preoperatively to 41.6 postoperatively (p = 0.007). Wrist motion was preserved with no significant differences in wrist flexion or extension. While the median postoperative pain score was 0, statistical significance was not reached. Subgroup analyses by concurrent procedure type demonstrated that DASH scores did not change significantly preoperatively and postoperatively.

Conclusion

This study uniquely assessed the long-term outcomes of partial wrist denervation with an extended follow-up period averaging more than one year post-denervation. Wrist denervation as an adjunct to traditional wrist operations such as proximal row carpectomy and partial arthrodesis appears to improve long-term functional outcomes without decreasing wrist mobility. Although pain reduction was not statistically significant, the small sample size (n = 12) for pain analysis and the low median postoperative pain score (0) may still suggest a clinical benefit. Further research with larger, prospective cohorts is warranted to better evaluate wrist denervation's role in pain relief and functional recovery.

PURPOSE: Acute compartment syndrome (ACS) and chronic exertional compartment syndrome (CECS) commonly affect the lower leg and are managed surgically by fasciotomy (1). Injury to the superficial peroneal nerve (SPN) is a complication of anterior and/or lateral compartment fascial release in as many as 8% of cases (2). Current fasciotomy techniques safeguard the SPN by avoiding the anterior intermuscular septum along which the SPN travels before it pierces the crural fascia and bifurcates at the ankle into medial (MDCN) and intermediate (IDCN) dorsal cutaneous branches (3). In ~15%, bifurcation occurs proximally (3). Post-operative nerve mapping with magnetic resonance (MR) neurography could evaluate iatrogenic injury following fasciotomy. We aimed to 1) describe SPN imaging abnormalities in symptomatic patients following fasciotomy, and 2) evaluate associations between variant nerve branching and iatrogenic nerve injury. We hypothesized increased iatrogenic nerve injuries in patients with early SPN branching.

METHODS: Patients with MR neurography performed following leg fasciotomy from January 2012 to August 2023 were included in this IRB-approved retrospective study. EMRs were reviewed for demographics, surgical details, postoperative neurological symptoms, and electrodiagnostic exams (EDX). Dedicated MR neurography at 3.0-Tesla utilized axial, fluid-sensitive, fat-suppressed sequences. A musculoskeletal radiologist (8 years' experience), blinded to operative history and symptoms, reviewed imaging for presence of normal or variant SPN anatomy, perineural scarring, nerve signal hyperintensity, nerve discontinuity, and focal enlargement to suggest neuroma.

RESULTS: In total, 42 patients with pain (37), numbness (11) and/or paresthesias (6) were included (mean age 33 years; 21 female). Forty-eight fasciotomies (6 bilateral) were performed for CECS (27) or ACS (15) involving four-compartment (26), anterior and lateral (7), or anterior-only (6) releases. Mean time between fascial release and MRI was 20.8 months (range=1-191). EDX was available in 23 cases; in all with abnormal MRI SPN appearance, EMG/NCS was also abnormal (11). In those with normal MRI SPN appearance (12), EMG/NCS was normal and abnormal in equal proportions.

SPN had a normal appearance on MRI in 31 cases. Abnormalities included increased nerve signal intensity (4), perineural scarring (8), and/or laceration with neuroma formation (4). Early nerve branching was observed in 5 cases (10.4%), of which 3 demonstrated nerve laceration with neuroma formation of the IDCN (2) or IDCN and MDCN (1). Among the many cases with a typical branching pattern, there was one case of laceration.

CONCLUSIONS: Post-surgically, early MR neurography in patients with new sensory disturbances may identify a nerve injury amenable to surgical intervention. MR neurography may also help identify SPN branching patterns prior to fasciotomy to reduce iatrogenic insult risk.

REFERENCES: 1. Bowyer MW. Lower Extremity Fasciotomy: Indications and Technique. Curr Trauma Rep 1 2015. 2. Waterman BR, Laughlin M, Kilcoyne K et al. Surgical treatment of chronic exertional compartment syndrome of the leg: failure rates and postoperative disability in an active patient population. J Bone Joint Surg Am. 2013 Apr 3;95(7):592-6. 3. Adkison DP, Bosse MJ, Gaccione DR, Gabriel KR. Anatomical variations in the course of the superficial peroneal nerve. J bone Jt Surg Am Vol. 1991;73(1):112-114.

Introduction Occipital neuralgia is characterized by intense, often debilitating pain localized to the distribution of the greater and lesser occipital nerves. While conservative treatments remain the first-line approach, surgical decompression is frequently employed when symptoms prove refractory to medical treatment. Several salvage techniques have been described at the time of secondary occipital nerve surgery to handle the nerve, especially after neurectomy. Recent advances in peripheral nerve surgery, including Targeted Muscle Reinnervation (TMR) and Regenerative Peripheral Nerve Interface (RPNI), have demonstrated efficacy in certain contexts, yet their long-term success in occipital neuralgias has been mixed, potentially due to the intricate anatomical architecture of the occipital region. In parallel, emerging microsurgical strategies for neuroma prevention, such as centro-central neurorrhaphy (CCN), have shown promise in amputee populations by coapting severed nerve ends to prevent pathological sprouting and neuroma formation. Here we describe a technique using CCN principles to recalcitrant occipital neuralgia in patients that relapsed after primary nerve decompression.

Methods Eight patients with persistent occipital pain post-decompression (with >1yr follow-up) underwent revision surgery using a novel CCN technique. The procedure involved neurectomy of the previously decompressed occipital nerve (greater, lesser, or both) and symmetrically coapting either bilateral greater occipital nerves (where both were previously decompressed) or unilateral greater and lesser occipital nerves (where both were previously decompressed) via microsurgical neurorrhaphy. This approach aimed to minimize postop neuroma formation by providing non-physiologic end-to-end continuity without tension, an adaptation of protocols previously validated in limb amputations. Headache days, pain levels, neuroma recurrence, and overall functional outcomes were assessed pre-and postoperatively using validated scoring systems and imaging studies where indicated.

Results Six of the eight patients achieved complete pain resolution, demonstrating the potential of CCN to modulate neuropathic signaling in occipital neuralgia (mean follow-up of 5.25 months). Of the remaining two patients, one reported mild, tactile-induced discomfort at follow-up, and another experienced mild symptom recurrence consistent with incomplete proximal nerve decompression. These outcomes align with broader reports supporting neurorrhaphy and nerve-to-nerve coaptation strategies as effective deterrents to neuroma pathogenesis. These are early and limited results of our technique.

Conclusion Centro-central neurorrhaphy represents a refined microsurgical approach for occipital neuralgia, offering a viable alternative or adjunct to established methods such as TMR, RPNI, and reset neurectomy. By providing a stable conduit for axonal regrowth and mitigating neuroma formation, CCN may significantly reduce pain recurrence and improve patient quality of life. Further prospective, multicenter trials with larger cohorts and extended follow-up intervals are warranted to solidify these findings and to optimize a standardized treatment algorithm for refractory occipital neuralgia and other challenging neuropathic entities.

Purpose Screening for nerve pain in patients with headache disorders (HD) requires specialized clinical knowledge, which limits access to care. The aim of this study was to develop a 3D head model that allows for AI driven pattern recognition for nerve pain in patients with HD.

Materials & Methods We retrospectively identified 375 pain drawings completed by patients. Another 924 pain drawings were generated by the study team. The pain drawings were drawn onto an online 3D head model within a web application. Drawings were labeled as 'nerve pain' or 'no nerve pain' and affected nerve(s) were identified. The input features of the ML model were constructed with coordinates of the pain drawings. The feature was passed into classifiers and model performance was evaluated using 5-fold nested cross-validation, with AUROC as primary metric. Precision under 0.9 sensitivity, specificity under 0.9 sensitivity and sensitivity under 0.9 specificity were also reported.

Results The best performing model to detect nerve pain was the multilayer perception model (AUROC: 0.879 ± 0.044). When identifying specific nerve pain types, the model demonstrated high AUROC values of 0.928 (±0.025), 0.930 (±0.017), 0.884 (± 0.031), and 0.954 (± 0.025) for occipital, frontal, temporal, and trigeminal neuralgia, respectively.

Conclusion Our machine learning model demonstrated good performance in identifying nerve pain patterns in HD patients. This tool will allow for improved screening for nerve pain and may reduce the health and financial burdens on patients with HD through earlier detection by a larger pool of providers.

Introduction: Malignant peripheral nerve sheath tumors (MPNSTs) are aggressive soft tissue sarcomas that pose significant challenges in surgical management. Although neuropathic pain following soft tissue sarcoma surgery has been reported to occur in 25-30% of cases (1-4), the burden of neuropathic pain in MPNST patients – where nerve involvement is inherent to the disease process – has remained poorly characterized and likely underestimated. Therefore, This study aims to examine the anatomic distribution of MPNSTs, analyze survival rates and predictive factors for survival, and investigate the prevalence of neuropathic pain in patients who have undergone MPNST resection.

Methods: A retrospective analysis of 119 patients who underwent MPNST resection was conducted. Additionally, a cross-sectional survey was administered and completed by 39 surviving patients to assess neuropathic pain prevalence using the NRS (0-10 scale) and the s-DN4 questionnaire, and quality of life (QoL) using the EQ-5D-5L index (0-1 scale).

Results: MPNSTs most commonly occurred in the lower extremity (42.9%), followed by the upper extremity (21.0%), trunk (19.3%), head & neck (11.8%) and pelvis (5.0%). Female sex (OR: 0.25, 95% CI: 0.10-0.61) and absence of metastases (OR: 0.15, 95% CI: 0.05-0.52) were significantly associated with overall survival. Among survey respondents, 82.1% reported neuropathic pain following MPNST resection. The patients reported a mean EQ-5D-5L index score of 0.566 (±0.253) as compared to an EQ-5D-5L of 0.851 (±0.205) for the United States' general population.

Conclusions: The high prevalence of neuropathic pain following MPNST resection and its significant impact on QoL highlights the need for improved pain management strategies, and calls for a paradigm shift in the surgical approach and post-operative care pathways. Nerve-sparing and/or nerve-reconstructive techniques during or after tumor resection should be considered. Future research should focus on identifying risk factors for neuropathic pain development and evaluating the efficacy of preventive measures to improve long-term pain outcomes for surviving MPNST patients.

Martin E, Coert JH, Flucke UE, et al. A nationwide cohort study on treatment and survival in patients with malignant peripheral nerve sheath tumours. Eur J Cancer. 2020;124:77–87. https://doi.org/10.1016/J.EJCA.2019.10.014 . - DOI - PubMed Park JW, Kim HS, Yun JY, Han I. Neuropathic pain after sarcoma surgery: prevalence and predisposing factors. Medicine. 2018;97(21). https://doi.org/10.1097/MD.0000000000010852 Aslami Z V., Leland CR, Strike SA, et al. Symptomatic neuroma development following en bloc resection of skeletal and soft tissue tumors: a retrospective analysis of 331 cases. Plast Reconstr Surg. Raasveld FV, Eberlin KR. Discussion: Symptomatic neuroma development following en bloc resection of skeletal and soft tissue tumors: a retrospective analysis of 331 cases. Plast Reconstr Surg.

Purpose Neuromas are disorganized growth of nerve commonly resulting from traumatic or iatrogenic injury, with the potential to cause long-term pain and functional loss. The molecular mechanisms underlying symptomatic neuroma formation remain understudied. Proteomic profiling provides insights into processes such as wound healing, inflammation, and nerve regeneration, enabling the identification of factors that may contribute to neuroma formation. Identifying these factors informs therapeutic strategies aimed at enhancing nerve healing and reducing uncontrolled disorganized growth. In this study, we compared the proteomic profile of healthy human nerve to neuroma tissue from a patient undergoing sciatic neuroma resection to identify protein markers linked to neuroma formation and pain signaling alongside persistence. We hypothesize that the parenchymal molecular signature of neuroma tissue compared to functionally intact neural parenchyma reflects complex changes in tissue organization and cellular processes, potentially revealing novel therapeutic targets.

Methods With IRB approval, intraoperative samples of a terminal sciatic nerve neuroma alongside physiologic proximal sciatic nerve resected in preparation for targeted muscle reinnervation, were obtained. Tissue was placed in 4% paraformaldehyde, further dissected to isolate degraded neural components, and then prepared for mass spectrometry. Raw mass spectrometry data were analyzed using Xcaliber and Proteome Discoverer for peptide identification and quantification. Missing values were imputed using Multiple Imputation by Chained Equations (MICE), followed by variance stabilization normalization. Differentially expressed peptides were identified based on a variance-stabilized difference greater than two, corresponding to a four-fold or greater difference between neuroma and non-neuroma tissue. To explore protein functional groups, protein-protein interaction networks were constructed using STRINGdb, and enriched biological pathways within clusters were analyzed using Gene Ontology (GO) analysis.

Results We identified distinct molecular signatures that differentiate neuroma parenchymal tissue from functionally intact neural parenchyma, highlighting key processes involved in neuroma formation and persistence. Specifically, we observed: (1) altered extracellular matrix organization, characterized by upregulation of COL1A1 and COL1A2; (2) disrupted cytoskeletal dynamics, marked by changes in protein polymerization, with downregulation of CNTNAP1 and upregulation of MAP4; (3) dysregulated RNA processing and translation, characterized by upregulation of EIF3L and downregulation of PRPF8; (4) alterations in inflammatory response pathways, marked by downregulation of ORM1 and upregulation of SERPINA3; and (5) metabolic shifts, particularly in fatty acid and purine metabolism, characterized by the downregulation of AOC3.

Conclusion Sustained immune activation, dysregulated extracellular matrix and cytoskeletal organization, and metabolic reprogramming may underpin neuroma formation and symptomatic activity. Additional collection of neuroma tissue and healthy neurologic tissue is needed to continue assessing protein and genetic level alterations. Future work will further explore these pathways as therapeutic targets for inhibiting neuroma formation and permitting decline in symptomatic activity.

Introduction: Targeted Muscle Reinnervation (TMR) offers a promising surgical approach to prevent and treat neuropathic pain but has primarily been utilized in amputees (1-4). This study aims to describe indications and outcomes for TMR in non-amputees. Methods: Non-amputee patients who underwent TMR for neuropathic pain at a tertiary center (2019-2024) were identified. Demographics, comorbidity, and surgical characteristics were collected through chart review. Patient satisfaction (Patient Global Impression of Change, PGIC) and quality of life (EQ-5D-5L) were assessed through a cross-sectional survey. Results: Seventy-six TMR operations were performed in 74 patients (median age 54.5 (IQR: 42.0-65.0) years, 47.3% female). Thirty-four patients (44.7%) previously underwent other peripheral nerve surgery in the same nerve distribution prior to TMR surgery. Most TMR surgeries were performed in the lower extremity (n=52, 68.4%), followed by the trunk (n=15, 19.8%), upper extremity (n=6, 7.9%), and head/neck (n=3, 3.9%). Six patients (7.9%) underwent revision surgery to the nerve treated with TMR. Of 45 survey respondents (60.8%, mean follow-up 2.0±1.2 years), improvement (PGIC) was reported for 82.4% of lower extremity (n=28), 88.9% of trunk (n=8), and 50.0% of upper extremity (n=2) cases. Overall, 78.7% reported improvement (25.5% very much improved, 34.0% much improved, 19.2% minimally improved). Mean EQ-5D-5L indices were 0.828 (±0.082), 0.794 (±0.056), and 0.763 (±0.024) for lower extremity, trunk, and upper extremity respectively, comparable to the US general population (0.851±0.205). Longitudinal studies are warranted to better understand long-term efficacy.

Chappell AG, Yang CS, Dumanian GA. Surgical Treatment of Abdominal Wall Neuromas. Plast Reconstr Surg Glob Open. 2021;9(5):e3585. doi:10.1097/GOX.0000000000003585 Fracol ME, Dumanian GA, Janes LE, Bai J, Ko JH. Management of Sural Nerve Neuromas with Targeted Muscle Reinnervation. Plast Reconstr Surg Glob Open. 2020;8(1):E2545. doi:10.1097/GOX.0000000000002545 Remy K, Raasveld F V., Saqr H, et al. The neuroma map: A systematic review of the anatomic distribution, etiologies, and surgical treatment of painful traumatic neuromas. Surgery. Published online 2024. doi:10.1016/J.SURG.2024.05.037 O'Brien AL, Kraft CT, Valerio IL, Rendon JL, Spitz JA, Skoracki RJ. Targeted Muscle Reinnervation following Breast Surgery: A Novel Technique. Plast Reconstr Surg Glob Open. 2020;8(4):e2782. doi:10.1097/GOX.0000000000002782

Purpose: Complex Regional Pain Syndrome (CRPS) poses significant diagnostic challenges due to its varied clinical presentation. (1-5) This study aims to examine the diagnostic trajectory of patients labeled with CRPS, focusing on referral patterns, application of the Budapest criteria, and diagnostic accuracy.

Methods: Patients were eligible if they were evaluated for CRPS at a peripheral nerve clinic within a tertiary care center (2020-2024). Patient data (medical and surgical history) was obtained through chart review. Three clinicians (two plastic surgeons, one pain medicine specialist) retrospectively assessed the validity of CRPS diagnoses using the Budapest criteria. Inter-rater reliability (IRR) for CRPS presence and type was calculated using Cohen's kappa (κ).

Results: Of the 53 patients (median time-to-referral: 3.9 years(IQR:2.2–6.6)), the Budapest criteria had been assessed in 26% of patients before referral. In 33% of CRPS-type-I labeled patients, an inciting nerve injury was identified. Following retrospective assessment, 42% were determined to have CRPS by all raters, 26% were determined not to have CRPS, and 32% showed inconsistent agreement. IRR for CRPS diagnosis and type ranged from minimal to moderate (κ=0.32-0.72).

Conclusion: Our findings highlight variability in the application of the Budapest criteria for CRPS diagnosis, as well as inconsistencies in its retrospective application. Potentially treatable peripheral nerve injuries should be addressed prior to CRPS diagnosis. These findings may help improve early diagnostic assessment in patients with chronic pain.

Shim H, Rose J, Halle S, Shekane P. Complex regional pain syndrome: a narrative review for the practising clinician. BJA: British Journal of Anaesthesia. 2019;123(2):e424. Classification of Chronic Pain, Second Edition (Revised) - International Association for the Study of Pain (IASP). Accessed August 22, 2024. https://www.iasp-pain.org/publications/free-ebooks/classification-of-chronic-pain-second-edition-revised/ Bruehl S. Complex regional pain syndrome. BMJ. 2015;351. Terkelsen AJ, Birklein F. Complex Regional Pain Syndrome or Limb Pain: A Plea for a Critical Approach. J Pain Res. 2022;15:1915. Harden RN, Bruehl S, Perez RSGM, et al. Validation of proposed diagnostic criteria (the "Budapest Criteria") for Complex Regional Pain Syndrome. Pain. 2010;150(2):268.

Introduction: Neuropathic pain, weakness, or numbness can complicate total knee arthroplasty (TKA) and may be resistant to non-surgical treatments (1-5). This study evaluates surgical peripheral nerve management after TKA and a treatment algorithm is proposed. Methods: Patients who underwent peripheral nerve surgery for neuropathic symptoms following TKA between 2012-2024 (≥3-month follow-up) were included. Data on demographics, comorbidities, and treatment were collected, and a cross-sectional survey assessed satisfaction (Patient Global Impression of Change, PGIC) and quality of life (EuroQol-5-Dimension-5-Level, EQ-5D-5L). Results: Twenty-seven lower extremities treated in 26 patients were included (median age-at-surgery 67(IQR: 58-71.8) years). Surgical indications included neuropathic pain (n=24/27, 89%), foot drop (n=1/27, 4%) or both (n=2/27, 7%). Median time between TKA and nerve surgery was 2.5(IQR: 1.0-5.9) years. Procedures included saphenous or infrapatellar branch neurectomy with adjunctive nerve management (48%, n=13), decompression (41%, n=11), and combinations (11%, n=3). Twenty-one patients (78%) completed the survey (median follow-up 2.1(IQR: 1.4-4.3 years). Improvement (PGIC) was reported in 20/21(95%) patients, the mean EQ-5D-5L index was 0.854(±0.102) (US general population: 0.851(±0.205)). Discussion: Surgery appears beneficial for patients with neuropathic pain, numbness, or weakness post-TKA. We recommend common peroneal nerve decompression for lateral knee pain and/or foot drop, active saphenous nerve management (targeted muscle reinnervation or regenerative peripheral nerve interface) for medial knee pain, and combinations for both. These findings may aid in patient counseling, expectation management, and surgical management.

Singh JA, Yu S, Chen L, Cleveland JD. Rates of Total Joint Replacement in the United States: Future Projections to 2020-2040 Using the National Inpatient Sample. J Rheumatol. Sep 2019;46(9):1134-1140. doi:10.3899/jrheum.170990 Bertram W, Howells N, White SP, et al. Prevalence and patterns of neuropathic pain in people with chronic post-surgical pain after total knee arthroplasty. Bone Joint J. Jun 1 2024;106-b(6):582-588. doi:10.1302/0301-620x.106b6.Bjj-2023-0889.R1 Hasegawa M, Tone S, Naito Y, Wakabayashi H, Sudo A. Prevalence of Persistent Pain after Total Knee Arthroplasty and the Impact of Neuropathic Pain. J Knee Surg. Oct 2019;32(10):1020-1023. doi:10.1055/s-0038-1675415 Wylde V, Hewlett S, Learmonth ID, Dieppe P. Persistent pain after joint replacement: Prevalence, sensory qualities, and postoperative determinants. PAIN. 2011;152(3):566-572. doi:10.1016/j.pain.2010.11.023 Carender CN, Bedard NA, An Q, Brown TS. Common Peroneal Nerve Injury and Recovery after Total Knee Arthroplasty: A Systematic Review. Arthroplasty Today. 2020/12/01/ 2020;6(4):662-667. doi:https://doi.org/10.1016/j.artd.2020.07.017

Background Surgical decompression of the greater occipital nerve (GON) has become a recognized treatment for occipital migraines. Emerging research suggests that vascular compression, particularly by the occipital artery (OA), plays a significant role in migraine pathophysiology. This study compares the outcomes of two surgical approaches: endoscopic-assisted extensive GON decompression with complete OA resection or ligation versus conventional open GON decompression with only proximal OA ligation with the goal to determine the most effective technique to achieve long-term migraine relief.

Methods A retrospective review was conducted on 159 patients who underwent either endoscopic-assisted GON decompression involving either complete OA resection or proximal and distal OA ligation (n = 139) or open GON decompression (n = 20). Primary outcomes included changes in migraine headache index (MHI) as well as migraine intensity, frequency, and duration. Cox regression analysis was performed to assess the probability of achieving at least a 90% reduction in migraine frequency and MHI over 35 months.

Results Both endoscopic-assisted and open GON decompression led to significant postoperative improvements in MHI, migraine intensity, duration, and frequency (p < 0.01 for all measures). However, patients in the endoscopic-assisted group experienced greater reductions in MHI (-182.11 vs. -152.85, p = 0.17), migraine frequency (-20.90 vs. -15.45, p = 0.08), and migraine intensity (-5.44 vs. -3.00, p < 0.001) compared to the open decompression group. Additionally, significantly higher rates of complete migraine resolution were observed in the endoscopic group (69.8% vs. 45.0%, p = 0.04). Cox regression analysis further demonstrated that patients with endoscopic release had a significantly higher probability of sustaining a 90% reduction in migraine frequency and MHI 35 months after surgery.

Conclusions Endoscopic-assisted GON decompression with proximal and distal OA resection or ligation is more effective than conventional open GON decompression to achieve occipital migraine resolution and maintain long-term migraine relief. These findings support the critical role of vascular compression in occipital migraine pathogenesis and highlight endoscopic-assisted decompression as the preferred surgical approach.

Background: Brachial plexus neuropathy is a potential complication following cervical spinal surgery. Some propose nerve transfers to treat subsequent deficits. Since nerve transfers work best within one year after injury, the decision to proceed with surgery must be made relatively quickly after onset of the palsy. As recovery has occurred up to 41 months after cervical surgery, surgical management within one year of injury may result in over-treatment. We therefore asked: 1) What is the probability of recovery of brachial plexus neuropathy after cervical spinal surgery, accounting for time since injury? 2) What factors are independently associated with recovery for brachial plexus neuropathy? Methods: We performed a systematic review and meta-analysis of individual patient data according to PRISMA guidelines. We included articles reporting on time to recovery (MRC 3 or greater) from patients with brachial plexus neuropathy after cervical spinal surgery. Articles that did not report MRC-scores were excluded. After screening 4308 titles/abstract and 346 full texts, we included 18 studies for analysis. In total, 85 C5 palsies were included with a mean age of 63 (SD 12) years. Mean follow-up was 22 (SD 28) months. Bayesian analysis begins with a prior probability and updates it with new data to obtain a posterior probability. We used survival-analysis to estimate the prior probability of recovery at 24 months. By incorporating cumulative recovery rates over time, Bayesian analysis allowed us to derive posterior probabilities of recovery at different timepoints. Results: Survival analysis showed that 88% (95% CI 80 to 95%) of palsies recovered within 24 months, with 50% of patients recovering within 7 months. Bayesian analysis revealed that if a patient had not yet recovered, the probability of recovery by 24 months remained above 50% until 16 months. Beyond this point, the probability declined to 39% at 18 months, 34% at 19 months and 24% at 20 months. Multivariable Cox proportional hazards analysis found that cervical spondylotic radiculo-myelopathy as the indication for spinal surgery was associated with an increased recovery (HR 2.0, 95% CI 1.2 to 3.4, p=0.013) compared to ossification of the posterior longitudinal ligament. An initial MRC score of 2 was also associated with improved recovery (HR 2.0, 95% CI 1.2 to 3.5, p=0.013) compared to a score of 0 or 1. Posterior decompression as spinal surgery was associated with a reduced recovery (HR 0.53, 95% CI 0.28 to 1.0, p=0.047) compared to anterior cervical discectomy or corpectomy and fusion. Conclusion: Natural recovery for BP palsy is common with most palsies resolving by two years. At 7 months, about 1/2 of the patients will still recover, resulting in a number needed to harm of 2 if one decides to perform nerve transfers at this time. Surgeons and patients have to decide if this risk of harm is acceptable to them. Awaiting recovery for 2 years and performing tendon transfers at this time seems to result in the lowest amount of overtreatment and unnecessary iatrogenic harm.

Introduction 50 million Americans suffer from migraines, causing individual morbidity and national economic burdens (1). Medications and chemodenervation have controversial treatment efficacy, while surgical decompression has cost-effective, long-term results (2,3). Despite being pioneered by plastic surgeons, migraine surgery is only offered by 18% of board-certified plastic surgeons, though 60% are interested in performing them (4). Furthermore, these procedures are not required in residency training. This novel survey examines the current state of migraine surgery education during residency.

Methods Program directors from US integrated and independent plastic surgery residency programs were surveyed via email. Demographics and responses were collected anonymously through REDCap. Descriptive statistics were computed for all study variables. Comparisons were analyzed using Fisher's Exact test. P-values <0.05 were considered statistically significant.

Results The survey was sent to 97 of 102 plastic surgery residency program directors (five emails were unconfirmed) and yielded a 31% response rate. 47% of respondents are from the Midwest; however, all geographic areas across various population sizes are represented. 53% of programs have 12 or fewer residents; 40% have 10 or fewer faculty.

Over 90% of respondents state plastic surgeons should perform migraine surgeries, and 70% believe this should be taught during residency. However, only 38% of institutions surveyed have plastic surgeons who offer migraine surgery and 90% of residents at these programs perform 10 or fewer cases annually. The lack of trained surgeons was the most cited reason for not providing these procedures. 66% of programs have educational time for migraine surgery, which is significantly more common in smaller compared to larger programs (88% vs 40% p=0.0256). Chemodenervation exposure occurs at 48% of institutions. Overall, 50% of respondents report their residents are completely unprepared/unprepared to address surgery-related migraine concerns.

Conclusions Migraines affect millions of people, yet there is inadequate training in plastic surgery residency in surgical management, despite the efficacy and cost-effectiveness. Program directors feel migraine surgery training is important and while didactics are frequently provided, less than 40% of programs have surgical exposure and there are minimal case numbers for those that do. Thus, half of program directors report their residents are unprepared to surgically manage migraines. This survey demonstrates the current state of migraine education in plastic surgery residencies and indicates further training is needed to ensure plastic surgeons can effectively meet patients' treatment needs. Future studies can elucidate other treatment barriers and explore educational initiatives to increase residency training.

References 1. Bonafede M, Sapra S, Shah N, Tepper S, Cappell K, Desai P. Direct and Indirect Healthcare Resource Utilization and Costs Among Migraine Patients in the United States. Headache. 2018;58(5):700-714. doi:10.1111/head.13275 2. Blumenfeld AM, Kaur G, Mahajan A, et al. Effectiveness and Safety of Chronic Migraine Preventive Treatments: A Systematic Literature Review. Pain Ther. 2023;12(1):251-274. doi:10.1007/s40122-022-00452-3 3. ElHawary H, Gorgy A, Janis JE. Migraine Surgery: Two Decades of Innovation. Plast Reconstr Surg. 2021;148(5):858e-860e. doi:10.1097/PRS.0000000000008467 4. Kung TA, Pannucci CJ, Chamberlain JL, Cederna PS. Migraine Surgery Practice Patterns and Attitudes. Plast Reconstr Surg. 2012; 129 (3): 623-628. doi: 10.1097/PRS.0b013e3182412a24

Purpose: Peripheral nerve injuries continue to be challenging to accurately diagnose and manage. Many peripheral nerve surgeons evaluate these lesions with electromyography and magnetic resonance imaging, but with these modalities of imaging, early detection and delineation between fully denervation versus partially denervation injuries are still challenging. We recently identified glutamate carboxypeptidase II (GCPII) expression as a novel biomarker for muscle denervation and demonstrated that a commercially available and FDA approved imaging agent, 18F-DCFPyl could detect changes in muscle GCPII expression. In this study, we sought to investigate muscle GCPII expression uptake in complete and partial nerve injuries.

Methods: 30 female Lewis rats ages 6-8 weeks old were selected for posterior spinal exposure with/or without selective transection of spinal roots (L4, L5, L6) that contribute to the right sciatic nerve. The groups were designated as spinal exposure of right L4, L5, L6 spinal roots without root transection Sham group (n=6, selective L4 root transection group (n=8), selective L4, L5 root transection group (n=8), L4, L5, L6 roots transection group (n=8). Surgery was performed using microsurgical technique via posterior midline, right paraspinal approach to expose L4, L5, L6 vertebrae, and the lumbosacral junction, along with their corresponding spinal roots. Based on the groups, selective spinal root transection was performed. The main outcome was to identify the amount of GCPII upregulation based on the amount of sciatic nerve denervation at the 12-week timepoint. Ex-Vivo biodistribution was performed at 12 weeks after surgery by first injecting the rats intravenously with 18F-DCFPyL 1 hour prior to the sacrifice and harvest. At sacrifice, the follow tissues were harvested: blood, right kidney, bilateral gastrocnemius muscles, bilateral tibialis anterior muscles, bilateral extensor digitorum longus muscles. The blood and kidney were used to normalize the level of 18F-DCFPyL uptake, which was computed using an automated gamma counter and expressed in percent injection dose per gram (%ID/g). Statistical analysis was performed with one-way ANOVA and Tukey post-hoc test.

Results: 12 weeks after selective spinal root transection, complete denervation (L4, L5, L6 transection) resulted in greater uptake of 18F-DCFPyL in the right gastrocnemius when compared with the sham (p= 0.01) and the L4, L5 root transection (p= 0.018) and greater uptake in extensor digitorum longus muscles when compared with the sham (p= 0.03) and selective L4 root transection (0.005). These findings are pending histological correlation.

Conclusion: GCPII overexpression and corresponding 18F-DCFPyL uptake on PET imaging may serve as a promising radiotracer for evaluating and monitoring the degree of nerve injury. 18F-DCFPyL uptake was elevated in fully denervated rodent muscles compared to partially denervated and naïve muscles. Pending biodistribution studies at shorter timepoints as well as histological evaluation of neuromuscular junction percent innervation will reveal whether 18F-DCFPyL uptake is increased in acute partial prior to collateral reinnervation at later timepoints.

Purpose: Proponents of scar release around the nerve, or end-to-side nerve transfers for idiopathic brachial neuropathy (Parsonage-Turner syndrome) justify the iatrogenic harm from surgery by a suspected low natural recovery rate. However, the natural recovery rate is variably defined, therefore we asked: what is the reported rate of recovery after developing idiopathic brachial neuropathy?

Methods: We searched PubMed, Embase and Cochrane Library for studies reporting on recovery in patients with idiopathic brachial neuropathy. We excluded case reports with less than 4 patients, studies on a single suspected etiology (not idiopathic), and studies with people treated with injections or surgery. We screened 2147 titles and abstracts and analyzed 126 full texts. We included 55 studies with a total of 1599 patients. Majority of studies were case-series (47%) and retrospective cohort studies (45%). Men represented 72% [987 of 1364] of the patients and the mean age was 42 ±SD 8.1 years. Neuropathy was unilateral in 72% [1065 of 1332] and sensory deficits were reported in 47% [415 of 892]. Mean follow-up duration was 37 ± 28 months. 91% of studies [51 of 55] reported poorly defined outcome measures (e.g. 'improved', 'partial or good recovery', 'mild residual weakness') and 45% [25 of 55] somewhat better-defined outcome measures (e.g. MRC, electromyography [EMG], grip strength, FEV1).

Results: MRC-scores were reported in 11 studies. Recovery to MRC 5 is seen in 42% of patients (95% confidence interval [CI] 23 to 63%) and to MRC 4 or 5 in 80% (95% CI 59 to 95%). Follow-up electrodiagnostic studies were reported in 7 studies. Electromyography (EMG) returned to normal in 66% of patients (95% CI 47% to 83%). Complete recovery was reported in 23 articles with synonyms like 'complete recovery', 'recovered', 'normal', 'full recovery'. This poorly defined 'complete recovery' was seen in 59% (95% CI 44 to 73%).

Conclusion: The natural recovery rate after idiopathic brachial neuropathy is substantial, with about two-thirds recovering completely, and 4 out of 5 recovering more than anti-gravity strength. It remains to be determined if any intervention alters the recovery of this neuropathy, but if it does, it will likely be accompanied by a notable number needed to treat, and a low number needed to harm due to the relatively high rate of natural recovery.