Laser or razor? A novel experimental peripheral nerve repair technique

Local administration of glial cell line-derived neurotrophic factor improves behavioral and histological deficit of neonatal Erb's palsy in rats

OBJECTIVE

We sought to evaluate from a behavioral and histological viewpoint the effect of local administration of glial cell line-derived neurotrophic factor (GDNF) on neonatal preganglionic Erb's palsy in rats.

METHODS

The Erb's palsy model was produced by transecting the anterior and posterior roots of the left C5-C7 nerves of 7-day-old rats. The rats were divided into GDNF-treated (n = 10) and vehicle-treated groups (n = 11). After we transected the roots, contact in the proximal and distal stumps of the transected nerves was maintained, and the transected point and the entire intraspinal portion of the transected roots were enclosed by Gelfoam soaked with 10 micro g GDNF or saline. The behavioral evaluation consisted of a foot-fault test and a forepaw muscle strength test, all of which were performed from the third to the seventh weeks after the operation. Seven weeks after the operation, all rats were killed, the number of anterior horn cells was counted at C5-C7, and the differences on each side were compared.

RESULTS

In the vehicle-treated group, the foot-fault test indicated an abnormality in forelimb function on the root transection side. In the GDNF-treated group, however, significant improvement in forelimb function was observed on the basis of the foot-fault test results obtained in the third to sixth weeks after the operation. In the histological evaluation, the number of anterior horn cells from the side in which the operation took place in the vehicle-treated group was significantly less than that taken from the contralateral side at each segment. In the GDNF-treated group, however, there was no difference in any of the segments, regardless of the side from which they were taken.

CONCLUSION

Local administration of GDNF in a neonatal preganglionic Erb's palsy model resulted in significant improvement in deficits on the basis of behavioral and histological evaluations.

Glial cell line-derived neurotrophic factor enhances axonal regeneration following sciatic nerve transection in adult rats

Adult rat sciatic nerve was transected and sutured with an entubulation technique. The nerve interstump gap was filled with either collagen gel (COL) or collagen gel mixed with glial cell line-derived neurotrophic factor (COL/GDNF). Four weeks after nerve transection, horseradish peroxidase (HRP)-labelled spinal cord motoneurons and the myelinated distal stump axons were quantified. Compared with the COL group, the percentages of labeled spinal somas and axon number were significantly increased after topically applied glial cell line-derived neurotrophic factor (GDNF). The functional recovery of the transected nerve was improved in COL/GDNF group. GAP-43 expression was also significantly higher in COL/GDNF group 1 and 2 weeks after sciatic nerve axotomy vs. COL group. These data provide strong evidence that GDNF could promote axonal regeneration in adult rats, suggesting the potential use of GDNF in therapeutic approaches to peripheral nerve injury and neuropathies.

Stabilization and accurate trimming of nerve ends: practical use of fibrin glue: technical note

OBJECTIVE

Peripheral nerve transection usually results in protrusion of the endoneurial contents ("mushrooming"). Trimming of the nerve ends before repair is often necessary to achieve cut nerve end planes. In this technical report, we describe a technique for stabilization and accurate trimming of nerve ends using fibrin glue.

SURGICAL TECHNIQUE

The nerve ends of divided peripheral nerves are coated with fibrin glue and subsequently trimmed using a razor blade before repair.

RESULTS

When fibrin glue is applied, a firm layer with a rubbery consistency is formed around the nerve. This layer stabilizes the nerve ends during trimming, and a clear-cut plane of the nerve can be achieved. Moreover, the fibrin glue stabilizes the nerve ends during manipulations caused by suturing of the nerve.

CONCLUSION

The technique results in easier handling of the nerve during trimming and manipulation, minimal tissue damage to the nerve, and a clear-cut plane of the nerve.

CO2 laser repair of the facial nerve: an experimental study in the rat

The facial nerve is often injured by trauma, infection or during the course of tumour resection. Many techniques of nerve anastomosis have been described with the current standard nerve repair using the microscope and monofilament suture. The purpose of this study was to evaluate the CO2 surgical laser as a tool for facial nerve anastomosis. Following preliminary electrical measurements 36 nerves were anastomosed using either laser or conventional monofilament suture. Laser anastomosis had neither beneficial nor detrimental effects on nerve regeneration. This method of anastomosis may be advantageous when surgical access is limited. In addition this study found that the use of CO2 laser as a dissecting or vapourizing tool in proximity to intact facial nerves results in degenerative changes.

Lasers in neurosurgery

Lasers have been used in neurosurgery for the past 25 years, undergoing modifications to suit the specific needs of this medical discipline. The present report reviews the current use of lasers in neurosurgical practice and examines the pros and cons of lasers in specific neurosurgical applications. In spite of their advantages, laser use is still not widespread in neurosurgery. One reason is the continued lack of complete control over real-time laser interactions with neural tissue. A greater acceptance and use of lasers by neurosurgeons will depend upon automated control over defined specific parameters for laser applications based upon the type of tissue, the desired effect on tissue, and application to the clinical situation without loss of precision and a lot of expense. This will require the integration of newer lasers, computers, robotics, stereotaxy, and concepts of minimally invasive surgery into the routine management of neurosurgical problems.

Glia maturation factor beta stimulates axon regeneration in transected rat sciatic nerve

Rat sciatic nerves were bilaterally transected and repaired with an entubulation technique. The nerve interstump gap was filled with either collagen gel or collagen gel mixed with a putative neurotrophic factor (leupeptin, 4-aminopyridine, lipid angiogenic factor or glia maturation factor beta (GMF-beta]. Six weeks after nerve transection, the myelinated distal stump axons were quantified for each nerve. Only the nerves treated with GMF-beta had significantly more axons than the control side.