CEREBRAL INJURY BY BLUNT MECHANICAL TRAUMA: SPECIAL REFERENCE TO THE EFFECTS OF REPEATED IMPACTS OF MINIMAL INTENSITY; OBSERVATIONS ON EXPERIMENTAL ANIMALS

PURPOSE OF INVESTIGATION  It has been suggested by several investigators that the effects of cerebral trauma may be cumulative. As far back as 1874 Koch and Filene¹ had shown that animals could be killed by repeated small blows on the head without showing any evidence of structural damage to the brain. Later Martland² recognized a peculiar condition occurring among prize fighters, which he named "punch drunk" and which he attributed to the repeated head punishments they had suffered while in the ring. Then Shaller, Tamaki and Newman³ showed the apparent increase in vulnerability of the cerebral vessels induced by the application of repeated blows. More recently Denny-Brown and Russell⁴ demonstrated that paralysis of respiration of increasing duration and rise of blood pressure occurred with successive blows and that concussion could be obtained readily by repetition of moderately severe blows.In apparent contrast to these observations are