Crushing injuries to the skull; clinical and experimental observations.

Severe crushing injuries of the head are often fatal, but in those patients who survive this form of injury the absence or slight degree of concussion is usually a striking feature of the clinical picture. Even though the skull may be fractured and the cranial nerves injured, the patient often remains fully conscious. This clinical observation led one of us (W.R.R.). with Denny-Brown (1941) to investigate experimentally the mechanism ofcerebral concussion, and we found, as might be expected from clinical experience, that concussion is more readily produced by a. blow when the head is free to move and not fixed. In most cases of accidental head injury the head is subjected to a sudden change of momentum which causes the shearing stresses in the brain which have been analysed by Holbourn (1943), and so brilliantly demonstrated experimentally by Pudenz and Shelden (1946). It seems clear that the common retention of consciousness with crushing injuries of the skull is due to the absence of any sudden change of momentum with an injury of this nature. Compression of the skull beyond a certain degree will, however, cause loss of consciousness and brain damage by cerebral compression. The term compression concussion has been used 'to denote this form of. injury (Denny-Brown and Russell, 1941).