NEUROANATOMY/REGENERATION RELATED TO SPINAL CORD INJURY

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In adult mammals including man, severe spinal cord injury with complete disruption of nerve fiver continuity across the lesion leads to permanent loss of function below the level of the lesion. Until recently, there had been no demonstration of structural of functional recovery across a complete spinal cord lesion in an adult mammal. Using a novel spinal cord repair strategy Drs. Cheng and Olson have demonstrated that it is possible in adult rats made paraplegic by complete spinal cord transection and removal of a 5- mm-long segment of the spinal cord at the level of To, to obtain a degree of structural and functional recovery including hindlimb locomotion, weight support and sensation. The repair strategy involves five key elements: a. The use of multiple 918) fine peripheral nerve graft bridges across the lesion: b. Rerouting regenerating nerve fibers from white matter to grey matter; using precisely defined positioning of the nerve grafts: c. Stabilizing the engrafted area with a fibrin-based tissue glue: d. The use of acidic fibroblast growth factor in slow-release form: e. External stabilization of the vertebral column. Using retrograde axon-tracing methods, it was shown that nerve fibers regenerate from many centers in the brainstem and other areas. There is also regeneration of the corticospinal tract. Based on the positive results published b Dr. Cheng and Olson (Cheng, Cao & Olson: Science 273, 510-513, 1995) new experiments are now proposed. In addition to generating a further basis for interpretation of the repair strategy, several new aspects can be studied, such as whether or not there is a altered conduction across the injured area as well as aspects of specificity and topography of function of regenerated fiber tracts.