Accelerating axonal regeneration to shorten the delay of reinnervation and improve functional recovery after a peripheral nerve lesion is a clinical demand and an experimental challenge. We developed a resorbable nerve conduit (NC) for controlled release of glial cell line-derived neurotrophic factor (GDNF) with the aim of assessing motor functional recovery according to the release kinetics of this factor in a short gap model. Different types of resorbable NCs were manufactured from a collagen tube and multiple coating layers of poly(lactide-coglycolide), varying in poly(lactide-coglycolide) type and coating thickness to afford three distinct release kinetics of the neurotrophic factor. GDNF release was quantified in vitro. End-to-end suture and GDNF-free NC served as controls. Thirty-five Wistar rats underwent surgery. Motor recovery was followed from 1 to 12 weeks after surgery by video gait analysis. Morphometrical data were obtained at mid-tube level and distal to the NC. NCs were completely resorbed within 3 months with minimal inflammation. GDNF induced a threefold overgrowth of fibers at mid-tube level. However, the number of fibers was similar in the distal segment of all groups. The speed of recovery was inversely proportional to the number of fibers at the NC level but the level of recovery was similar for all groups at 3 months. The resorbable conduits proved their ability to modulate axonal regrowth through controlled release of GDNF. In relation to the dose delivered, GDNF strikingly multiplied the number of myelinated fibers within the NC but this increase was not positively correlated with the return of motor function in this model.

OBJECTIVE Chronic neuropathic pain after peripheral nerve injury is a major clinical problem. Its management is difficult, and therapeutic approaches vary and include oral medication, neurostimulation, and surgery. The aim of this study was to assess the adequacy of surgical nerve revision in a large series of patients with long-term follow-up. METHODS The authors reviewed the charts of 231 patients (335 nerve injuries) who experienced neuropathic pain after peripheral nerve injury and underwent surgery for nerve revision at the authors' institution between 1997 and 2012. The following parameters were recorded for each patient: history, location, duration, and severity of the pain and details of nerve revision surgery. In addition, patients were invited to participate in a follow-up consultation and were asked to score their pain at that time. Current medications and examination findings were also documented. RESULTS Elective surgery was the source of nerve injury for 55.4% of the patients. The lower extremity was the most commonly involved anatomical region (54.3%), followed by the lower abdomen (16.4%) and the thoracic region (13%). The mean time between the onset of injury and revision surgery was 48 months. On average, 1.3 injured nerves per patient were explored, and surgery was performed 1.2 times per patient. Each nerve underwent revision 1.1 times on average. Neuromas-in-continuity and scar-tethered nerves were observed in 205 nerves (61%) and terminal neuromas were observed in 130 nerves (39%). The authors performed 186 (56%) neurolyses and 149 (44%) neuroma resections and translocations. The mean follow-up of the 127 (55%) patients who agreed to come back for a consultation was 68 months. These patients indicated an average pain decrease of 4 points in the visual analog scale (VAS) score. Pain relief greater than a 2-point decrease on the VAS, a criterion for a successful treatment according to the European Federation of Neurological Societies guidelines, was encountered in 80% of patients. Pain relief did not vary in a statistically significant way with regard to surgical technique, age and sex of the patient, affected nerve, or time between trauma and surgery. Before surgery, 76% of the patients were on a regimen of paracetamol and/or NSAIDs and 44% received opiates, while after nerve revision only 37% still required simple analgesia and 14% needed opiates. CONCLUSIONS Bearing in mind that medication achieves satisfying pain relief in only 30%-40% of patients with neuropathic pain, surgery must be considered as an effective alternative therapy. No objective criteria were shown to be factors of poor prognosis. Systematic preoperative clinical mapping of the injured nerves and diagnostic nerve blocks could improve the primary success rate of the surgery.

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Background: Ulnar nerve compression at the elbow level is the second-most common entrapment neuropathy. The aim of this study was to use shear-wave elastography for the quantification of ulnar nerve elasticity in patients after ulnar nerve decompression with anterior transposition and in the contralateral non-operative side. Method: Eleven patients with confirmed diagnosis and ulnar nerve decompression with anterior transposition were included and examinations were performed on an AixplorerTM ultrasound system (Supersonic Imagine, Aix-en-Provence, France). Results: We observed significant differences at 0-degree (p < 0.001), 45-degree (p < 0.05), 90-degree (p < 0.01) and 120-degree (p < 0.001) elbow flexion in the shear elastic modulus of the ulnar nerve in the operative and non-operative sides. There were no statistically significant differences between the elasticity values of the ulnar nerve after transposition at 0-degree elbow flexion and in the non-operative side at 120-degree elbow flexion (p = 0.39), or in the ulnar nerve after transposition at 120-degree elbow flexion and in the non-operative side at 0-degree elbow flexion (p = 0.09). Conclusion: Shear-wave elastography has the potential to be used postoperatively as a method for assessing nerve tension noninvasively by the estimation of mechanical properties, such as the shear elastic modulus.