By concussion is meant the modification occurring in the spinal cord after a trauma has acted externally on the vertebrae without any direct lesion of the spinal tissue. Schmaus made the first experimental study of medullary concussion, by which he was able to establish the anatomic picture corresponding to indirect trauma of the spinal cord. Recently, during and after the World War, spinal concussion has been accurately investigated, and many papers have been published on this subject.
From the anatomic point of view, according to Rossi,1 medullary concussion in man may be followed by: (a) intramedullary cavities; (b) the so-called primary traumatic necrosis of the nervous parenchyma; (c) large areas of medullary destruction; (d) hematomyelia.
Besides the action of a material agent, concussion may be the result of the so-called wind of explosion of French authors (Guillain2 and Barré) in the first zone of action, or "zone of