Outcomes of Nerve Transfers in Peroneal Nerve Palsy.

Background: The objective of this work is to: (i) evaluate the postoperative outcomes after lower extremity nerve transfer (LENT) in patients with peroneal nerve palsy, and (ii) evaluate the patient and surgical factors that best predict successful restoration of ankle dorsiflexion following nerve transfer. Methods: A retrospective cohort of prospectively collected data included all patients who underwent LENT (2010-2018). Two independent reviewers performed data collection. Primary outcome measures were: (i) clinically with British Medical Research Council (MRC) strength assessments, and (ii) electrodiagnostically with nascent motor unit potentials. Statistical analysis was performed using descriptive and nonparametric statistics. Results: Nine patients (56% male, mean age 38.3, range 18-57 years) underwent LENT surgery a mean of 4.3 months following injury (range 2.2-6.4 months). Mean follow-up was 15.6 months (range 9.1-28.2 months). Postoperatively, ankle dorsiflexion (P = .015) and ankle eversion (P = .041) increased significantly. After surgery, 44% achieved MRC 4, 33% obtained MRC 1 motor recovery, and 22% sustained MRC 0. A shorter time to surgery was associated with significantly better outcomes (P = .049). Conclusions: It appears that there is a bimodal distribution between responders and nonresponders to LENT for foot drop. Further research is required to elucidate patient and surgical factors that prognosticate success.

Contexte: Les objectifs de cette étude étaient les suivants : (i) évaluer les résultats postopératoires après un transfert de nerf dans le membre inférieur (LENT; lower extremity nerve transfer) chez des patients ayant une paralysie du nerf péronier et (ii) évaluer les facteurs propres au patient et à la chirurgie qui permettent de prédire le mieux possible le succès d'une restauration de la dorsiflexion de la cheville après le transfert nerveux. Méthodes: Une cohorte rétrospective de données collectées de façon prospective a inclus tous les patients ayant bénéficié d'un LENT de 2010 à 2018. Deux réviseurs indépendants ont réalisé la collecte des données. Les critères de jugement principaux étaient les suivants : (i) cliniques avec des évaluations de la force selon l'échelle MRC et (ii) électrodiagnostiques avec potentiels d'unités motrices naissantes. Une analyse statistique a été réalisée au moyen de statistiques descriptives et non paramétriques. Résultats: Neuf patients (hommes : 56%, âge moyen : 38,3 ans, extrêmes : 18 à 57 ans) ont subi une LENT, en moyenne 4,3 mois après une blessure (extrêmes : 2,2 à 6,4 mois). Le suivi moyen a été de 15,6 mois (extrêmes : 9,1 à 28,2 mois). En postopératoire, la dorsiflexion de la cheville (P = 015) et l'éversion de la cheville (P = 041) ont augmenté de façon significative. Après l'intervention chirurgicale, 44% des patients ont atteint un score de 4 sur l'échelle MRC, 33% ont obtenu une récupération motrice cotée à 1 et 22% ont conservé une cote MRC de 0. Un délai plus court avant la chirurgie a été associé à des résultats significativement meilleurs (P = .049). Conclusions: Il semble y avoir une répartition bimodale entre les répondeurs et les nonrépondeurs à la chirurgie de LENT pour la chute du pied. Des recherches supplémentaires sont nécessaires pour renseigner les facteurs pronostiques de succès liés au patient et à l'intervention chirurgicale.

Clinical Outcomes of Upper Extremity Nerve Transfers in Neuralgic Amyotrophy.

SUMMARY: Neuralgic amyotrophy (NA) is a disease affecting peripheral nerves. Treatment has historically been conservative, as the natural course of the disease was thought to be self-limiting. Recent work has demonstrated that as many as two-thirds of people with NA have persistent pain, fatigue, or weakness. At the authors' center, supercharged end-to-side (SETS) nerve transfers are commonly performed in patients with NA to optimize motor recovery while allowing for native axonal regrowth. The authors describe the technique and clinical outcomes of patients with NA affecting the anterior interosseous nerve (AIN) who were treated with SETS nerve transfer from extensor carpi radialis brevis to AIN. Ten patients (90% male; mean age, 51.3 ± 9.7 years) underwent extensor carpi radialis brevis-to-AIN transfer at a mean period of 6.4 ± 1.4 months after onset of symptoms. Mean postoperative follow-up duration was 14.8 ± 3.2 months. Before surgery, all patients demonstrated clinically significant weakness in the flexor pollicis longus (FPL), flexor digitorum profundus muscle to the index finger (FDP2), or both. FPL strength improved from a median Medical Research Council (MRC) grade of 1.5 to 4 ( P = 0.011) and FDP2 strength improved from a median MRC grade of 1 to 5 ( P = 0.016). A postoperative MRC grade of 4 or greater was achieved in nine of 10 (90%) FPL and 10 of 10 (100%) FDP muscles. This is the first report of SETS nerve transfer for the treatment of NA. The outcomes of this work suggest that SETS nerve transfers may be an option to optimize motor outcomes in patients with NA. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, IV.

Elevated Body Mass Index Negatively Impacts Recovery of Shoulder Abduction Strength in Triceps Motor Branch to Axillary Nerve Transfers.

BACKGROUND: The purpose of this work was to evaluate the clinical outcomes of triceps motor branch to axillary nerve transfers and to identify prognostic factors which may influence these outcomes. METHODS: A retrospective cohort included all patients who underwent a triceps motor branch to axillary nerve transfer (2010-2019) with at least 12 months of follow-up. The primary outcome measure was shoulder abduction strength assessed with British Medical Research Council (MRC) grade. RESULTS: Ten patients were included with a mean follow-up of 19.1 (SD 5.9) months. Compared with preoperative MRC shoulder abduction strength (0.2 SD 0.4), patients significantly improved postoperatively (2.8 SD 1.6; P = .005). Increased body mass index (BMI) was significantly associated with worse postoperative MRC (P = .014). CONCLUSION: Triceps motor branch to axillary nerve transfer is a beneficial procedure for restoring shoulder function in patients presenting with either isolated axillary nerve or brachial plexus pathology. Patients with elevated BMI may not have as robust strength recovery and should be counseled carefully regarding prognosis.

Impact of Body Mass Index and Comorbidities on Outcomes in Upper Extremity Nerve Transfers.

BACKGROUND: There is a paucity of research investigating the impact of patient comorbidities, such as obesity and smoking, on nerve transfer outcomes. The objective of this retrospective cohort study was to evaluate the impact of body mass index (BMI) and comorbidities on the clinical outcomes of upper extremity nerve transfers. METHODS: A retrospective cohort study was executed. Patients were eligible for inclusion if they had an upper extremity nerve transfer with a minimum of 12-months follow-up. Data was collected regarding demographics, comorbidities, injury etiology, nerve transfer, as well as preoperative and postoperative clinical assessments. The primary outcome measure was strength of the recipient nerve innervated musculature. Statistical analysis used the Mann-Whitney U test, Wilcoxon signed-rank test, and Spearman's rho. RESULTS: Thirty-eight patients undergoing 43 nerve transfers were eligible for inclusion. Patients had a mean age of 48.8 years and a mean BMI of 27.4 kg/m2 (range:19.7-39.0). Injuries involved the brachial plexus (32%) or its terminal branches (68%) with the most common etiologies including trauma (50%) and compression (26%). Anterior interosseous nerve to ulnar motor nerve (35%) was the most common transfer performed. With a mean follow-up of 20.1 months, increased BMI (p = 0.036) and smoking (p = 0.021) were associated with worse postoperative strength. CONCLUSION: This retrospective cohort study demonstrated that increased BMI and smoking may be associated with worse outcomes in upper extremity nerve transfers-review of the literature yields ambiguity in both regards. To facilitate appropriate patient selection and guide expectations regarding prognosis, further experimental and clinical work is warranted.

Evaluation of Intrinsic Hand Musculature Reinnervation following Supercharge End-to-Side Anterior Interosseous-to-Ulnar Motor Nerve Transfer.

Supercharge end-to-side anterior interosseous-to-ulnar motor nerve transfer is commonly performed in the authors' institution to augment intrinsic hand function. Following observations of recovery patterns, the authors hypothesized that despite its more distal innervation, the first dorsal interosseous muscle recovers to a greater extent than the abductor digiti minimi muscle. The objective of this work was to evaluate the clinical and electrodiagnostic pattern of reinnervation of intrinsic hand musculature following supercharge end-to-side anterior interosseous-to-ulnar motor nerve transfer. A retrospective cohort of prospectively collected data included all patients who underwent a supercharge end-to-side anterior interosseous-to-ulnar motor nerve transfer. Two independent reviewers performed data collection. Reinnervation was assessed with two primary outcome measures: (1) clinically, with serial Medical Research Council strength assessments; and (2) electrodiagnostically, with serial motor amplitude measurements. Statistical analysis was performed using nonparametric statistics. Seventeen patients (65 percent male; mean age, 56.9 ± 13.3 years) were included with a mean follow-up of 16.7 ± 8.5 months. Preoperatively, all patients demonstrated clinically significant weakness and electrodiagnostic evidence of denervation. Postoperatively, strength and motor amplitude increased significantly for both the first dorsal interosseous muscle (p = 0.002 and p = 0.016) and the abductor digiti minimi muscle (p = 0.044 and p = 0.015). Despite comparable preoperative strength (p = 0.098), postoperatively, the first dorsal interosseous muscle achieved significantly greater strength when compared to the abductor digiti minimi muscle (p = 0.023). Following supercharge end-to-side anterior interosseous-to-ulnar motor nerve transfer, recovery of intrinsic muscle function differs between the abductor digiti minimi and the first dorsal interosseous muscles, with better recovery observed in the more distally innervated first dorsal interosseous muscle. Further work to elucidate the underlying physiologic and anatomical basis for this discrepancy is indicated. CLINICAL QUESTION/LEVEL OF EVIDENCE:: Therapeutic, IV.

Evaluation of the Scratch Collapse Test for Carpal and Cubital Tunnel Syndrome-A Prospective, Blinded Study.

PURPOSE: To clarify the sensitivity, specificity, and interrater reliability of the scratch collapse test for carpal tunnel syndrome (CTS) and cubital tunnel syndrome, using blinded observers in a general patient population. METHODS: Ninety-two subjects were recruited from all patients referred for electrodiagnostic studies for upper extremity symptoms that were thought to be related to an entrapment mononeuropathy. The scratch collapse test was performed twice on each patient, once by the resident and once by a nerve conduction technician. Both observers were blinded to all aspects of the patient's presentation. Sensitivity and specificity for the scratch collapse test were calculated twice, once using electrodiagnostic testing results and a second time using a validated clinical tool (the CTS-6) as the reference standard. The interrater reliability was also calculated. RESULTS: Using electrodiagnostic criteria as a reference standard, the scratch collapse test had a sensitivity of 7% and a specificity of 78% for CTS. Using clinical criteria as a reference standard, the test had a sensitivity of 15% and a specificity of 87%. For cubital tunnel syndrome, the sensitivity was 10% and the specificity was 90%. For the resident/technician 1, kappa was -0.025 (worse than chance alone). For the resident/technician 2, kappa was 0.211 (fair strength of agreement). CONCLUSIONS: The sensitivity of the scratch collapse test for CTS and cubital tunnel syndrome was lower than that found in other studies, regardless of whether a clinical or an electrodiagnostic reference standard was used. The specificity was high. Overall interrater agreement was lower than previously reported. These results call into question the sensitivity and interrater reliability of the scratch collapse test for CTS and cubital tunnel syndrome. TYPE OF STUDY/LEVEL OF EVIDENCE: Diagnostic II.

Reinnervation of Extrinsic Finger Flexors and Brachioradialis 22 and 36 Months Following Traumatic Pan-Brachial Plexopathy: A Case Report.

A 25-year-old man sustained a right-sided brachial plexus injury from a high-velocity motocross accident. Physical examination and electromyography were consistent with a pan-brachial plexopathy with no evidence of axonal continuity. The patient underwent a spinal accessory to suprascapular nerve transfer and an intercostal to musculocutaneous nerve transfer with interpositional sural nerve grafts. He recovered MRC 4/5 elbow flexion and MRC 2/5 shoulder abduction and external rotation. Twenty-two months post-injury the patient displayed a flicker of flexion of his flexor pollicis longus and flexor digitorum profundus to his index finger - he went on to recover a functional pinch. Thirty-six months post-injury the patient displayed a flicker of contraction in brachioradialis with motor unit potentials on electromyography. This case demonstrates that some patients may have capacity for functional recovery after prolonged denervation and highlights the potential impact of anatomical anomalies in the assessment and treatment of peripheral nerve injuries.

Clinical Outcomes of Nerve Transfers in Peroneal Nerve Palsy: A Systematic Review and Meta-Analysis.

BACKGROUND: Given the unsatisfactory outcomes with traditional treatments, there is growing interest in nerve transfers to reestablish ankle dorsiflexion in peroneal nerve palsy. The objective of this work was to perform a systematic review and meta-analysis of the primary literature to assess the effectiveness of nerve transfer surgery in restoring ankle dorsiflexion in patients with peroneal nerve palsy. METHODS: Methodology was registered with PROSPERO, and PRISMA guidelines were followed. MEDLINE, EMBASE, and the Cochrane Library were systematically searched. English studies investigating outcomes of nerve transfers in peroneal nerve palsy were included. Two reviewers completed screening and extraction. Methodological quality was evaluated with Newcastle-Ottawa Scale. RESULTS: Literature search identified 108 unique articles. Following screening, 14 full-text articles were reviewed. Four retrospective case series met inclusion criteria for meta-analysis. Overall, 41 patients underwent nerve transfer for peroneal nerve palsy. The mean age of the patients was 36.1 years, mean time to surgery was 6.3 months, and the mean follow-up period was 19.0 months. Donor nerve was either tibial (n = 36) or superficial peroneal branches/fascicles (n = 5). Recipient nerve was either deep peroneal (n = 24) or tibialis anterior branch (n = 17). Postoperative ankle dorsiflexion strength demonstrated a bimodal distribution with a mean Medical Research Council of 2.1. There were no significant differences in dorsiflexion strength between injury sites (p = 0.491), injury mechanisms (p = 0.125), donor (p = 0.066), or recipient nerves (p = 0.496). There were no significant correlations between dorsiflexion strength and patient age (p = 0.094) or time to surgery (p = 0.493). CONCLUSIONS: There is variability in dorsiflexion strength following nerve transfer in peroneal nerve palsy, whereby there appear to be responders and non-responders. Further studies are needed to better define appropriate patient selection and the role of nerve transfers in the management of peroneal nerve palsy.