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The traditional teaching that "nerve fibers are lost at the suture line" after a nerve repair was investigated by asking the question, "Can the number of nerve fibers distal to a nerve repair site be increased by increasing the number of nerve fibers proximally?" Ratios of proximal to distal nerve fibers were increased from 1:1 to 2.5:1 to 3.5:1 by suturing peroneal or posterior tibial or sciatic nerve proximally to peroneal nerve distally. At one year following the repair, distal nerve fiber numbers increased to twice normal as the ratio increased to 2.5:1, and then nerve fiber numbers plateaued. Nerve function, as judged by walking track analysis, was best in the peroneal:peroneal group (1:1 ratio), suggesting that appropriateness rather than number of proximal fibers was more critical in this nerve repair model.

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Peripheral nerves are transected in many traumatic injuries of the extremities. Satisfactory functional regeneration of such nerves often fails to occur after repair with sutures. Possible reasons for these failures include poor alignment of nerves or fascicles, intrusion of scar tissue into the nerve junction, and outgrowth of nerve tissue from the repair site. This animal study describes an experimental method of sutureless, monofascicular peripheral nerve repair using a resorbable nerve coupler in the rat model. The first version of this coupler shows approximately equal performance to suture repair. Histology and electrophysiology assessments after regeneration showed that the polyglycolic acid (PGA) tube repairs were functionally equal to monofascicular suture junctions as well as being quicker and simpler to perform. Modified coupler designs based on this and other work show greater promise. Collateral studies are using similar versions of the nerve coupler as a vehicle for the insertion of chemical and neuro-electronic factors that may enhance nerve regeneration.

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The method of stimulation electromyography and histological methods were used to study regeneration of the sciatic nerve of a rabbit after its division and joining with epineural and perineural sutures as well as by means of a vascular allograft. Successful regeneration of the nerve occurred in both types of sutures. Implantation of a vessel induced a marked inflammatory reaction in the rabbit, which aggravated the conditions for regeneration.

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Although microsurgical techniques of nerve suture are now widely practiced, the prognosis is not always satisfactory. We have therefore developed a new method using CO2 laser and fibrin film to evaluate its clinical availability by determining its adhesiveness and axonal regeneration. The sciatic nerve of Wistar rats was cleanly cut. Fibrin films that are not themselves at all adhesive were placed on the suture site and were firmly anastomosed by irradiating them with 70 mW laser energy. Measurement of the tensile strength has demonstrated that effective adhesiveness may be obtained for nerve repair. According to the postoperative quantitative evaluation of the number of myelinated fibers of larger size and the mean diameter of myelinated fibers, the laser method appears to be significantly better than the conventional suture methods. In conclusion, this laser method is useful for clinical application.

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The phenomenon of 'endoneurial bulging' from the cut end of the divided nerve fasciculus in the rat sciatic nerve has been examined with light and scanning electron microscopy and the morphological changes compared when dividing the fasciculus with either micro-scissors or a sharp razor blade.

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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.

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An experimental model of a seamless end-to-end joining of severed sciatic nerve (with gaps between the two ends 5-8 mm-wide) using an implanted arterial vessel was elaborated on random bred and inbred Wistar rats. Histological examination showed that nerve regeneration along the implanted arterial lumen was directly oriented and was not accompanied by neuroma formation which was always the case in the control. It took some nerve fibers 20 days to join the gap between the cut nerve ends. In 4 months myelination of regenerating fibers was observed in the blood vessel lumen, in 3 months the lumen was filled with bundles of myelinated fibers, and in 9 months the structure of the regenerating nerve was similar to that of the mature trunk observed in animals. The elaborated experimental model is to be employed in the studies of reparatory histogenesis in peripheral nervous tissues. The data obtained may be used in neurosurgery.

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The long-term cutaneous thermal changes and the degree of sympathetic reinnervation of the vessels after a distal sympathectomy in an experimental model are reported. Under general anesthesia, a distal sympathectomy was performed at the proximal portion of the central artery of a rabbit ear. The contralateral ear served as a control. A dual-channel digital thermometer was used to record periodic cutaneous temperatures in identical positions on the distal third of the ears. Sympathetic reinnervation was assessed with catecholamine histofluorescence in the dead animals. A mean difference in temperature of 1.2 degrees C (P less than 0.01) was recorded 12 months after surgery. All of the sympathectomized ears maintained higher temperatures than their contralateral controls. Arterial sympathetic reinnervation 3 months after surgery was sparse and inconsistent. No increased reinnervation was noted at 12 months.

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Radical surgery of pain is destined for chronic and intolerable pain, resistant to causal treatment, and rebellious to the various medicinal therapeutics. Conventional neuro surgery by selective section of nociceptive fibers is very valuable for cancerous subjects with a limited life span. On the other hand, there has been skepticism concerning the real efficiency of neuro stimulation. The advance made in the knowledge of neurophysiologic and neurochemical mechanism of pain will allow a radical transformation as substitute for this invasive type surgery.

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Trigeminal evoked potentials were recorded before and 6 weeks after a percutaneous retrogasserian glycerol rhizotomy was performed in 22 patients with tic douloureux. The latency of the trigeminal evoked potential (TEP) N20 peak and the sensory threshold to electrical stimulation of the maxillary gum were measured in each patient. The N20 latency differences between normal and affected sides for each patient were reduced after glycerol injection. Sensory thresholds were significantly different between the normal and the affected sides both before and after rhizotomy. These results were interpreted to indicate that glycerol more specifically affects the damaged myelinated axons implicated in the pathogenesis of trigeminal neuralgia. Of the 22 patients, 82% were either pain-free or significantly improved after operation. Postoperative normal N20 latencies were associated with pain relief in most cases. Our preliminary experience suggests that recurrent pain is more likely to develop in those patients whose postoperative TEP remains abnormal, especially if the abnormality cannot be ascribed to a prior surgical deafferentiation procedure. In addition to providing insight into the mechanism of pain relief, TEP measurements may help to predict the likelihood of long term relief after percutaneous retrogasserian glycerol rhizotomy.

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The results of stereotactic thalamotomy in the treatment of 32 patients with Parkinson's disease are described. The outcome is compared with reports from the literature and with the author's former results with patients not treated with levodopa preoperatively. Especially, ipsilateral tremor aggravation is caused more frequently. Also the quite disappointing results of bilateral thalamotomy are briefly mentioned. The location of the lesion and its possible relation to the side-effects are discussed. On the basis of the outcome described, the indication for the operation seems to be a tremor, not necessarily unilateral, which is resistant to all medications available for Parkinson's disease. Such medication is given for a period of some months after the pros and cons have been thoroughly discussed with the candidate.

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Present techniques of nerve repair by suture are based on an anatomical approach. The severed layers of connective tissue are reapproximated. Another approach to nerve repair is to separate the specific cellular components of the peripheral nerve that contribute to fibrous healing and nerve regeneration. The perineurium normally separates the extrafascicular epineurium of mesodermal origin from the intrafascicular endoneurium of ectodermal origin. A cellular approach to nerve repair would use a tube around the fascicle as an artificial perineurium to separate fibrous healing from axonal regeneration until the perineurium reestablishes its continuity. Fascicular tubulization with polyglycolic acid tubes was studied in 25 rats. The polyglycolic acid tube is resorbed after the perineurium has reestablished its continuity. The repairs by fascicular tubulization demonstrated improved organization of the repair site compared to suture repairs. The diameter histograms of the regenerated myelinated axons were similar in repairs by tube and suture techniques. The total regenerated cross-sectional area of the myelinated axons was similar in the repairs by fascicular tubulization to repairs by fascicular suture.

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The partially denervated human fingertip was used as a model to correlate results of a detailed evaluation of sensibility with the presence of reinnervated sensory corpuscles identified by light and electron microscopy. In each of the three patients studied, the histologically identified reinnervated mechanoreceptors were appropriate to provide the neurophysiologic basis for the observed results of clinically tested sensibility.

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The formation of neuromuscular junctions in free heterotopic muscle transplants in the rat has been studied quantitatively and compared with the reinnervation of the muscle in situ. The AChE-containing area and the nerve terminal were stained in the same longitudinal section and the length of end-plate, the average number of nerve terminal branch points within the end-plate and the terminal innervation ratio (TIR) were determined. In denervated muscles we noticed early disappearance of nerves whereas the AChE-stained end-plates were visible after eight weeks. The reinnervation of the muscle in situ and after transplantation showed considerable similarities. Early during reinnervation the number of AChE positive areas increased and many of them were innervated by more than one axon. Terminal axons were also seen innervating more than one end-plate situated on the same or on different muscle fibres. Later the number of end-plates decreased and they were innervated by only one axon. The end-plate length reached normal value in the reinnervated muscle in situ but remained smaller in the transplanted muscle. In all reinnervated muscles ultraterminal sprouting was found as indicated by an increased number of nerve terminal branch points within the end-plate area. The TIR was increased in all reinnervated muscles due to terminal and ultraterminal sprouting of the axon. No significant difference in reinnervation was noted between normal and predenervated transplants. The reinnervation of transplanted muscles obviously has similarities not only with the reinnervation of normal muscles but also with the development of muscular innervation during early postnatal growth. In spite of the plasticity of the peripheral nerve the transplanted muscles underwent considerable atrophy which may have been enhanced by the unphysiological placement of the muscles in the abdomen. However, this experimental model made it possible to study reinnervation of muscle fibres only originating from the graft.

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Fascicular and group fascicular repairs have limited application. Standard epineurial repair is suggested for most severed peripheral nerves. However, fascicular and group fascicular repairs are beneficial and even preferred in certain types of nerve injuries. To apply these methods effectively, the surgeon must understand the internal anatomy of the individual peripheral nerve, possess the proper microsurgical equipment and suture material, and be skilled in the microsurgical technique.

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Embryonic cerebral cortex was transplanted over the cerebellum of one- to two-day-old rats. In mature rats, clusters of granule cells that failed to migrate into the internal granule cell layer were now found within the graft tissue. Immunocytochemical staining of astrocytic glial cells in the cortical transplants revealed that glial processes were distributed in an unusual polarized orientation in those regions that contained host granule cells. Other areas of the graft exhibited glia cells with processes that projected radially from their cell body, thus resembling fibrous astrocytes. Fibrous astrocytes in transplants, however, were more heavily stained than similar glial cells in the intact cerebral cortex of the host, indicating a quantitative difference in the glia fibrillary acidic protein. Acetylcholinesterase-positive fibers were observed between the clusters of granule cells in the cortical grafts. Such fibers traversed the molecular layer and, since they could be traced from the white matter of the host cerebellum, they were presumed to be mossy fibers. It is concluded that migration of external granule cells in the cerebellum can altered by placing embryonic cerebral cortex next to the developing cerebellum. Granule cells that have migrated into the grafted cerebral cortical tissue nevertheless receive afferent fibres.

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