Specific cord damage at the atlas level as a pathogenic mechanism in cerebral concussion.

Significant changes in the neurons of some of the brain stem nuclei were found following experimentally induced brain concussion (Windle, Groat, and Fox, (5), Windle, Groat, and Magoun, (fi)). A chromatolysis was found in the neurons of the reticular formation of the medulla oblongata, in the lateral vestibular nucleus (Deiter's nucleus), the red nucleus, the nucleus of the spinal trigeminal tract, and certain other nuclei. The motor nuclei of the cranial nerves remained unchanged. The number of damaged cells in the affected nuclei was in relation to the severity of the trauma. A reduction of the cell population of the affected nuclei was found in longer follow-ups (7, 2). The present report describes the neuropathology of cats in which an abrupt stretch of the cervical vertebral column was produced by dropping the anaesthetized cats with the heads fixed in a restraining collar (Hollister, Jolly, and Horne (3)). This experimental technique resulted in the same type of cell degeneration in the brain stem as described by Windle et al. in animals which had received a blow to the skull, or true head injury. In addition and in contradiction to prior studies, a specific fiber damage was resolved confined to the first segments of the spinal cord. The thick fibers were specifically affected. The damage was localized and required a special investigation of the cervical cord; it was apparently produced by the intimate cord-bone relationship at the atlas level. Fiber damage and chromatolysis in the axons were related phenomena. In controls, exactly the same type of injury was found also in cats which had received true head injuries by a blow on the head.