Chronic denervation and chronic axotomy present independent barriers for axonal regeneration. Chronic denervation occurs when nerves are no longer connected to their neuronal cell bodies; chronic axotomy occurs when neurons are not connected to their targets for prolonged periods of time. The harmful effects of chronic denervation can be addressed by the side-to-side bridge surgical technique. Additionally, the negative effects of chronic axotomy can be reversed by GDNF delivery to the nerve. The experiments in this thesis were designed to evaluate nerve regeneration in a rat model of chronic injury after treatment with local GDNF delivery, side to-side bridge protection, or both. The GDNF delivery system consisted of poly(lactic-co-glycolic acid) microspheres embedded in fibrin for controlled delivery of GDNF. Overall, the side-to-side bridges technique was effective in protecting against the negative effects of chronic denervation regardless of treatment with or without GDNF. Local delivery of GDNF did not increase axonal regeneration or functional recovery.

Chronic denervation and chronic axotomy present independent barriers for axonal regeneration. Chronic denervation occurs when nerves are no longer connected to their neuronal cell bodies; chronic axotomy occurs when neurons are not connected to their targets for prolonged periods of time. The harmful effects of chronic denervation can be addressed by the side-to-side bridge surgical technique. Additionally, the negative effects of chronic axotomy can be reversed by GDNF delivery to the nerve. The experiments in this thesis were designed to evaluate nerve regeneration in a rat model of chronic injury after treatment with local GDNF delivery, side to-side bridge protection, or both. The GDNF delivery system consisted of poly(lactic-co-glycolic acid) microspheres embedded in fibrin for controlled delivery of GDNF. Overall, the side-to-side bridges technique was effective in protecting against the negative effects of chronic denervation regardless of treatment with or without GDNF. Local delivery of GDNF did not increase axonal regeneration or functional recovery.

Surgical repair alone does not lead to satisfactory recovery after nerve laceration injury, yet no adjuvant clinical treatments are available. The goal of this review is to systematically survey all adjuvant treatments after surgery investigated in rat and mouse models. Both PubMed and Embase were explored with a systematic bibliographic search algorithm. Inclusion criteria consisted of treatments applied to rats or mice after complete transection and microsurgical repair of lower-limb motor or mixed nerves. Effect size statistics enabled numerical comparison between outcomes of treated and untreated animals and ranked the best treatments. 1,553 articles were found according to our search strategies, and 22 of them corresponded to our pre-defined inclusion criteria. After data extraction and analysis, the top 3 adjuvant strategies in terms of combined average effect size were citicoline, neurotrophin-4, and nitric oxide synthesis inhibitor, with values of 5.52, 5.14 and 4.08, respectively. Definitive treatment comparison was difficult due to the lack of uniformity in outcome evaluation in the experiments performed. Animal studies, comparing treatments administered within the same experimental protocol, are needed to truly assess efficiency and to provide solid recommendations for future clinical investigation.

Surgical repair alone does not lead to satisfactory recovery after nerve laceration injury, yet no adjuvant clinical treatments are available. The goal of this review is to systematically survey all adjuvant treatments after surgery investigated in rat and mouse models. Both PubMed and Embase were explored with a systematic bibliographic search algorithm. Inclusion criteria consisted of treatments applied to rats or mice after complete transection and microsurgical repair of lower-limb motor or mixed nerves. Effect size statistics enabled numerical comparison between outcomes of treated and untreated animals and ranked the best treatments. 1,553 articles were found according to our search strategies, and 22 of them corresponded to our pre-defined inclusion criteria. After data extraction and analysis, the top 3 adjuvant strategies in terms of combined average effect size were citicoline, neurotrophin-4, and nitric oxide synthesis inhibitor, with values of 5.52, 5.14 and 4.08, respectively. Definitive treatment comparison was difficult due to the lack of uniformity in outcome evaluation in the experiments performed. Animal studies, comparing treatments administered within the same experimental protocol, are needed to truly assess efficiency and to provide solid recommendations for future clinical investigation.

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This study explores the effects of surgical reconstruction and nerve repair on sensorimotor function and quality of life (QOL) for patients with base of tongue (BOT) cancer compared to healthy, age-matched adults. Sensations were tested on the anterior two-thirds of the oral tongue for two-point discrimination, light touch, taste, temperature, form and texture on 30 patients with BOT reconstruction with radial forearm free-flap and on 30 controls. Results indicated sensation for the unaffected tongue side and affected side with lingual nerve intact was comparable to controls, with poorer sensory outcomes for nerve repair. However, lingual nerves repaired with reanastomosis provided superior results to cable-grafting and severed nerves. Patients had decreased motor function only when the hypoglossal and lingual nerves were affected. Patients' QOL responses on the UW-QOL and EORTC QLQ-H&N35 revealed involvement of lingual and hypoglossal nerves resulted in poorer QOL outcomes. QOL interviews revealed additional problematic issues in this population not identified by standardized questionnaires. / Speech-Language Pathology

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La stimulation électrique directe (SED), pour une heure, améliore la régénération de nerfs périphériques chez le rat après la réparation. Cliniquement, ceci augmenterait le temps opératoire, rehaussant les risques de complications périopératoires. Objectif: Cette étude examine si la stimulation électrique transcutanée (SETC) est aussi efficace à améliorer la régénération de nerfs périphériques que la stimulation électrique directe. Méthode: Le nerf sciatique droit de 28 souris a été axotomisé. Une réparation par microsuture est effectuée. Quatre groupes sont étudiés : (1) sham; (2) suture seulement; (3) suture et SED; (4) suture et SETC. La stimulation est appliquée pour 1 heure à 20 Hz. Les souris sont étudiées pour un total de 12 semaines. La récupération sciatique est évaluée aux semaines 0, 1, 2 et aux 2 semaines par la suite par analyse de démarche sur la poutre. Résultats: La cinématique post-récupération démontre un index fonctionnel sciatique et angle de décollement significativement améliorés pour les groupes SED et SETC aux semaines 8, 10 et 12. Conclusions: 12 semaines après l’axotomie du nerf sciatique, la récupération fonctionnelle est significativement améliorée avec la SED et la SETC. Donc, la SETC est aussi bénéfique pour la promotion de la régénération nerveuse et réinnervation musculaire fonctionnelle que la SED. / Direct electrical stimulation (DES) for one hour increases the rate of peripheral nerve regeneration in rats after nerve repair. Clinically, this would lengthen surgery time, increasing risks of perioperative complications. Purpose: This study examines whether transcutaneous electrical stimulation (TCES) is as effective at improving peripheral nerve regeneration as direct electrical stimulation. Methods: The right sciatic nerve was axotomized in 28 mice. End-to-end microsuture repair was undertaken. Four groups were studied: (1) sham; (2) suture only; (3) suture and DES; (4) suture and TCES. Stimulation was applied for 1 hour, at 20 Hz. The mice were studied for a total of 12 weeks. Hind-limb recovery was evaluated at weeks 0, 1, 2 and then every 2 weeks by walking-track analysis. Results: Post recovery kinematic showed significantly improved functional sciatic index and foot-base angles at weeks 8, 10 and 12 for both DES and TCES groups. Conclusions: 12 weeks after sciatic nerve axotomy, functional recovery was improved significantly in both DES and TCES groups. Therefore, TCES is as beneficial in promoting nerve regeneration and functional muscle reinnervation as is DES.

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