Functional assessment of misdirected axon growth after nerve repair in the rat.

Age, late repair, loss of nerve tissue, tension, and other factors are now known to influence axon regeneration and the quality of recovery after nerve repair. Many of the factors cannot be controlled by surgery. However, a few important ones depend on surgical technique, and some could be minimized, e.

Functional consequences of isolated nerve stretch: experimental long-term static loading.

The maximum longitudinal tension that can be applied to the stumps of a divided peripheral nerve during surgical repair is not precisely defined. Uncertainty about the threshold of unacceptable nerve tension may be due to the lack of studies on isolated and reproducible stretch, i.e.

Cold and post-traumatic pain: modeling of the peripheral nerve message.

Hypersensitivity to cold is a relatively frequent sequel of peripheral nerve injuries but its mechanism is not well understood. We suggested that incomplete recovery of diameter of regenerated fibers is one of the factors involved in cold intolerance after nerve damage. Conduction velocity is correlated to fiber diameter, and is slowed down by cold.

Interpreting nerve morphometry data after experimental traumatic lesions.

Morphometric data were obtained in 2 experimental conditions: crush lesions of the sciatic nerve of rats, and transection of this nerve followed by repair. Ratios were used in order to facilitate comprehension of data. Results were compared to those obtained using a method of functional assessment.

Large amounts of polylactic acid in contact with divided nerve sheaths have no adverse effects on regeneration.

The stumps of divided rat sciatic nerves were coapted by suturing the epineurium to a small rectangular device made of a sheet of polylactic acid. One month later, significant degradation of the implanted material was observed. At that time, the local condition of the nerve was excellent, and the precise location of the initial injury could not be determined by examination under the operating microscope.

Percentage of nerve injuries in which primary repair can be achieved by end-to-end approximation: review of 2,181 nerve lesions.

Primary nerve repair yields better results than secondary reconstruction but is not always possible. We reviewed a series of 2,181 fresh nerve injuries of the upper limb. One nerve only was injured in 41% of the patients; two or more in 59%.

A method for shortening of the rat spine and its neurologic consequences.

Large laboratory animals are the usual choice for complex surgical procedures on the spine and spinal cord, such as shortening of the spine. It would, however, be advantageous to be able to use a small inexpensive mammal like the rat. We describe a procedure which allows thoracic spondylectomy (T8-T9) to be performed in the rat with a satisfactory survival rate (69%).

Primary nerve repair in the upper limb. Our preferred methods: theory and practical applications.

After years of controversy, it is now generally agreed that primary nerve repair by end-to-end coaptation, whenever feasible, yields better results than secondary procedures. We reviewed the theoretic basis of current methods of repair and described our preferred techniques and indications.

Applying "cell surgery" to nerve repair: a preliminary report on the first ten human cases.

We have applied a new technique of nerve repair, based on the principles of "cell surgery", to ten nerve lesions of the upper limb. Eight lesions were recent, five to 36 hours; they were divisions of the ulnar nerve (1), median nerve (2), sensory radial nerve (1), palmar and digital nerves (4). One lesion was 15 days old (median nerve).

Experimental nerve reconnection: importance of initial repair.

We believe that the randomness of sprout regrowth is the cause of most poor experimental and clinical functional results after nerve repair. We have elaborated a technique of repair, called "nerve reconnection," aiming to minimize randomness of regrowth. This technique enhances the precision of repair by minimizing physical and chemical damage to the stumps and by ensuring stress-free stump abutment.

Functional consequences of experimental nerve lesions: effects of reinnervation blend.

In spite of a constant and irrepressible growth of sprouts from the proximal stump of peripheral nerves that have been injured, functional recovery varies greatly from one case to another. To try and understand the reasons for this variability, I have proposed a novel view of the events occurring in a regenerating nerve; based on this view, a probability model was designed that could represent all situations observed after nerve injury. This model, described elsewhere, is based on the assumptions that the guidance role of basal lamina tubes is fundamentally important and that when this guidance fails, regrowth is random.

Functional consequences of experimental nerve lesions: effects of time, location, and extent of damage.

The purpose of this experiment was to investigate the part played by each of the four fundamental components of a nerve in functional recovery from injury. In order to single out the role of cellular elements (the neurites), tissular elements (the Schwann cells), structural elements (the basal lamina tubes), and the blood-nerve barrier, various crush lesions were made on sciatic nerves of rats and functional recovery was studied. I examined the effects of the location and number of damaged sites and of the time elapsed between successive injuries.

Local autoimmune reaction and behavioral abnormalities after repeated nerve injury: an experimental study.

Sciatic nerves of rats were submitted to single and repeated injuries. The animals' gait was used to study motor function; autophagia was used to study sensory effects. An association with local post-traumatic autoimmune reaction was sought, after histochemical studies of the nerves.

How to correctly match 175,000 neurites: two postulates for a quick solution.

I propose two postulates that allow precise matching of an indefinite number of neurites when repairing a transected nerve. The first one, based on the principle of de Saint-Venant, indicates how to keep nerve fibers in proper longitudinal alignment, by diverting stress to an appropriate distance from the tip of the stumps. The second postulate, based on the symmetrical mechanical resistance of the stumps, indicates how to restore correct transversal alignment of the fibers, by circularizing the severed nerve extremities.

Is it possible to predict the outcome of peripheral nerve injuries? A probability model based on prospects for regenerating neurites.

The long term functional consequences of peripheral nerve injuries are notoriously unpredictable. We hypothesized that considering the individual regrowth of the elementary components of a nerve (the neurites) rather than the global regeneration of the organ could lead to a better understanding of the mechanisms of nerve repair. Our basic assumptions were that regrowth was random and regrowth of any individual neurite could be defined in terms of its influence on recovery; this influence could be either valid, neutral or invalid.

Is vigor of regeneration a key factor in recovery from peripheral nerve injuries?

The nerve-growth-promoting effects of the tricyclic antidepressant, imipramine, were tested on the sympathetic ganglion of chickens and on the sciatic nerve of rats. A powerful neuronotrophic action was observed in vitro, but the utilization of the drug in vivo did not modify the functional recovery from a crush lesion.

An anatomical landmark for procedures on rat thoracic spinal cord.

A vein is described that allows easy identification of the fifth thoracic vertebra of the rat. Leading from the dorsal hibernating gland to the azygos vein, the vessel was present in each of 135 rats.

Posttraumatic autoimmune reaction in peripheral nerve: effect of a single injury.

This study was conducted to show that local autoimmune reactions could be observed in rat sciatic nerve after a single injury. Furthermore, we attempted to correlate the intensity of the immunological reaction with the severity of nerve damage, with the type of surgical treatment and with the degree of functional recovery. Through the use of direct immunofluorescence techniques, we found that the severity of the initial damage was associated with the intensity of the local immunological response assessed 2.

Posttraumatic autoimmune reaction in peripheral nerve: effect of two successive injuries at different locations.

We studied the influence of previous nerve damage on the evolution of recovery that follows a second nerve injury. Recovery from nerve injury was assessed by analyzing rats' foot prints during a 74-day period. In addition, at the end of this period, the surgically treated sciatic nerves were immunohistochemically stained for the presence of immunoglobulins, an indicator of an autoimmune reaction.

Posttraumatic autoimmune reaction in peripheral nerve: effect of two successive injuries at the same site.

We studied local autoimmune reactions in rat sciatic nerve after two successive injuries at the same site. The behavioral consequences of these injuries were also examined. We found that repetitive injuries had a moderately adverse effect on function and were accompanied by local autoimmune reactions.

Promoting functional plasticity in the damaged nervous system.

Damage to the central and peripheral nervous system often produces lasting functional deficits. A major focus of neuroscience research has been to enhance functional restitution of the damaged nervous system and thereby produce recovery of behavioral or physiological processes. Promising procedures include surgical, physical, and chemical manipulations to reduce scar formation and minimize the disruption of support elements, administration of growth-stimulating substances, tissue grafts to bridge gaps in fiber pathways, and embryonic brain tissue grafts to provide new cells with the potential to generate fiber systems.