Rappels sur le nerf périphérique

AAV1.tMCK.NT-3 gene therapy improves phenotype in Sh3tc2-/- mouse model of Charcot-Marie-Tooth Type 4C

Charcot-Marie-Tooth Type 4C (CMT4C) is associated with mutations in the SH3 domain and tetratricopeptide repeats 2 (SH3TC2) gene, primarily expressed in Schwann cells (SCs). Neurotrophin-3 (NT-3) is an important autocrine factor for SC survival and differentiation, and it stimulates neurite outgrowth and myelination. In this study, scAAV1.tMCK.NT-3 was delivered intramuscularly to 4-week-old Sh3tc2-/- mice, a model for CMT4C, and treatment efficacy was assessed at 6-month post-gene delivery. Efficient transgene production was verified with the detection of NT-3 in serum from the treated cohort. NT-3 gene therapy improved functional and electrophysiological outcomes including rotarod, grip strength and nerve conduction velocity. Qualitative and quantitative histopathological studies showed that hypomyelination of peripheral nerves and denervated status of neuromuscular junctions at lumbrical muscles were also improved in the NT-3-treated mice. Morphometric analysis in mid-sciatic and tibial nerves showed treatment-induced distally prominent regenerative activity in the nerve and an increase in the estimated SC density. This indicates that SC proliferation and differentiation, including the promyelination stage, are normal in the Sh3tc2-/- mice, consistent with the previous findings that Sh3tc2 is not involved in the early stages of myelination. Moreover, in size distribution histograms, the number of myelinated axons within the 3- to 6-µm diameter range increased, suggesting that treatment resulted in continuous radial growth of regenerating axons over time. In conclusion, this study demonstrates the efficacy of AAV1.NT-3 gene therapy in the Sh3tc2-/- mouse model of CMT4C, the most common recessively inherited demyelinating CMT subtype.

Anatomy, physiology and neurobiology of the nociception: a focus on low back pain (part A)

INTRODUCTION

The treatment of Failed Back Surgery Syndrome (FBSS) remains a challenge for pain medicine due to the complexity in the interactions between [1] a residual mechanical pain after surgery and, [2] a progressive transition into chronic pain involving central nervous system plasticity and molecular reorganization. The aim of this paper is to provide a fundamental overview of the pain pathway supporting the nociceptive component of the back pain.

METHODS

Literature searches included an exhaustive review of 643 references and 74 book chapters updated by searching the major electronic databases from 1930 to August 2013.

RESULTS

Pain input is gathered by the peripheral fibre from the innervated tissue's environment and relayed by two contiguous central axons to the brain, via the spinal cord. At this level, it is possible to characterize physical pain and emotional pain. These are supported by two different pathways, encoding two dimensions of pain perception: In Neo-spino-thalamic pathway, the wide dynamic range neuron system is able to provide the information needed for mapping the "sensory-discriminative" dimension of pain. The second projection system (Paleo-spino-thalamic pathway) also involves the ventromedial thalamus but projects to the amygdala, the insula and the anterior cingulate cortex. These areas are associated with emotionality and affect.

CONCLUSION

The mechanical component of FBSS cannot be understood unless the functioning of the pain system is known. But ultimately, the highly variable nature of back pain expression among individuals would require a careful pathophysiological dissection of the potential generators of back pain to guide pain management strategies.

Comparison of ulnar nerve repair according to injury level and type

PURPOSE

The aim of the study was to evaluate the results of epiperineural suture repaired primary (clean transaction injury, massive soft-tissue associated injury) and secondary (delayed partial injury) ulnar nerve injuries according to lesion level and type.

METHODS

Forty-two patients diagnosed with ulnar nerve injury between January 2008 and January 2012 were involved in the study. Ulnar nerve lesions were classified according to the level of injury into three types: type 1--lesion located above the flexor carpi ulnaris branch; type 2--lesion located between the flexor carpi ulnaris and the flexor digitorum profundus III and IV; type 3--lesion located below the flexor digitorum profundus III and IV and no more than 10 cm distal from the elbow crease. Additionally, ulnar nerve lesions were classified according to type into three groups: group 1 (n 17)--clean transaction injury; group 2 (n 14)--massive soft-tissue associated injury; group 3 (n 11)--delayed partial clean transaction injury. In follow-up evaluations, sensory and motor recovery was analysed with the most common Highet scale modified by Dellon et al. Functional results were evaluated according to the Disability of Arm, Shoulder, and Hand (DASH) score at final follow-up.

RESULTS

There were no statistically significant differences between groups according to men/women ratio, mean age, mean follow-up period and ulnar-nerve injury level. The DASH score was significantly better in the clean transaction injury group than the other groups and significantly better for type 3 than types 1 and 2 injuries in all groups. Sensory recovery of type 1 and 3 injuries in the massive soft-tissue associated injury group was significantly worse than the other groups. The worst motor recovery was evaluated in type 1 injury and the best in type 3 injury according to injury level. According to group, motor recovery of the massive soft-tissue associated group was significantly worse than the other groups in all injury types. There were no statistically significant differences between clean transaction injury and delayed partial clean transaction injury groups in all injury types.

CONCLUSIONS

Prognostic factors that influenced motor-sensory recovery and functional results were found in interval between trauma and reconstruction, injury level (worse results from proximal to distal) and mechanism of injury (worse results from massive soft-tissue injury to clear, sharp-tissue injury).

Primary and delayed repair and nerve grafting for treatment of cut median and ulnar nerves

Traumatic cutting of peripheral nerves of median and ulnar in forearm and wrist can cause disablating sensory and motor disorders in patients' hands. We conducted the present study to compare the results of three surgical methods for repair of injured median and ulnar nerves. We studied 85 patients aged 12-59 years (average, 34 +/- 18 years) with 105 cut median and ulnar nerves at forearm and wrist presenting to Tabriz Shohada hospital from 1994 to 2003. The patients followed for 2-10 years. Sixty patients (65 nerves) underwent primary repair, 16 (25 nerves) treated with delayed method and 9 (15 nerves) received nerve graft. Success was obtained in all patients underwent primary repair. The excellent results were common in younger patients. Of 65 nerves (60 patients) repaired by primary method, 25 had excellent result. Of 16 patients 25 nerves (16 patients) underwent delayed repair, 7 was unsuccessful. Of 15 nerves (9 patients) underwent delayed repair, 5 was unsuccessful. It is concluded that the recovery following primary repair was faster than other methods. For reaching excellent results in repairing peripheral nerves, it is important to considering all rules needed for repairing cut peripheral nerves, as well as accurate evaluation and correct repair of injured surrounding soft tissue such as tendons and their synovium and injured vessels.