Karolinska institutet 200-year anniversary. Symposium on traumatic injuries in the nervous system: injuries to the spinal cord and peripheral nervous system - injuries and repair, pain problems, lesions to brachial plexus.

The Karolinska Institutet 200-year anniversary symposium on injuries to the spinal cord and peripheral nervous system gathered expertise in the spinal cord, spinal nerve, and peripheral nerve injury field spanning from molecular prerequisites for nerve regeneration to clinical methods in nerve repair and rehabilitation. The topics presented at the meeting covered findings on adult neural stem cells that when transplanted to the hypoglossal nucleus in the rat could integrate with its host and promote neuron survival. Studies on vascularization after intraspinal replantation of ventral nerve roots and microarray studies in ventral root replantation as a tool for mapping of biological patterns typical for neuronal regeneration were discussed. Different immune molecules in neurons and glia and their very specific roles in synapse plasticity after injury were presented. Novel strategies in repair of injured peripheral nerves with ethyl-cyanoacrylate adhesive showed functional recovery comparable to that of conventional epineural sutures. Various aspects on surgical techniques which are available to improve function of the limb, once the nerve regeneration after brachial plexus lesions and repair has reached its limit were presented. Moreover, neurogenic pain after amputation and its treatment with mirror therapy were shown to be followed by dramatic decrease in phantom limb pain. Finally clinical experiences on surgical techniques to repair avulsed spinal nerve root and the motoric as well as sensoric regain of function were presented.

Selectivity in the reinnervation of the lateral gastrocnemius muscle after nerve repair with ethyl cyanoacrylate in the rat.

There is a need for complementary surgical techniques that enable rapid and reliable primary repair of transected nerves. Previous studies after peripheral nerve transection and repair with synthetic adhesives have demonstrated regeneration to an extent comparable to that of conventional techniques. The aim of this study was to compare two different repair techniques on the selectivity of muscle reinnervation after repair and completed regeneration. We used the cholera toxin B technique of retrograde axonal tracing to evaluate the morphology, the number, and the three-dimensional location of α-motoneurons innervating the lateral gastrocnemius muscle and compared the results after repair with either ethyl cyanoacrylate (ECA) or epineural sutures of the transected parent sciatic nerve. In addition, we recorded the wet weight of the muscle. Six months after transection and repair of the sciatic nerve, the redistribution of the motoneuron pool was markedly disorganized, the motoneurons had apparently increased in number, and they were scattered throughout a larger volume of the spinal cord gray matter with a decrease in the synaptic coverage compared to controls. A reduction in muscle weight was observed as well. No difference in morphometric variables or muscle weight between the two repair methods could be detected. We conclude that the selectivity of motor reinnervation following sciatic nerve transection and subsequent repair with ECA is comparable to that following conventional micro suturing.

Local tissue reactions after nerve repair with ethyl-cyanoacrylate compared with epineural sutures.

Anastomosis of a nerve with cyanoacrylate following a lesion has previously been shown to indicate morphological and functional recovery to an extent comparable to that of conventional epineural sutures. In this study we examined the local tissue reactions after transection and repair of rat sciatic nerve, and compared sutures with a synthetic ethyl-cyanoacrylate adhesive. Many ED-1-immunoreactive macrophages were found accumulating on either side of the repair site whereas neurofilament labelling was less pronounced distal to the repair site seven days after reparation with cyanoacrylate compared with sutures. After six months, when reinnervation was completed, the difference in ED-1-immunoreactivity was still present but to a less extent. These results indicate that ethyl-cyanoacrylate seems to induce an increased inflammatory reaction, which may lead to accelerated Wallerian degeneration, and could therefore have benefits over conventional sutures for reconstruction of peripheral nerves.

Long-term results of peripheral nerve repair: a comparison of nerve anastomosis with ethyl-cyanoacrylate and epineural sutures.

The morphological and functional recovery after repair of lesions to the sciatic nerve was studied in adult rats. We compared conventional microsuturing with a synthetic ethyl-cyanoacrylate adhesive. Six months after a unilateral lesion and subsequent repair the tibial branch to the lateral gastrocnemius muscle and the caudal sural cutaneous nerve were examined with electrophysiological measurements of motor and sensory conduction velocity, motor nerve action potentials, and quantitative histological examinations. There was functional reinnervation of motor and sensory nerves in both groups, as shown by equivalent recovery of motor and sensory conduction velocities, and motor nerve action potentials. Histological examination showed no significant difference in the mean diameter, fibre density or the number of regenerated myelinated motor and sensory axons distal to the repair site between the two groups. We conclude that anastomosis of the nerve with ethyl-cyanoacrylate adhesive supports morphological and functional recovery comparable to that of conventional epineural sutures after a unilateral lesion of the sciatic nerve in adult rats.