Experimental missile wounding of the brain.

If a missile penetrates a cerebral hemisphere and does not severely disrupt the brain or transit a vital brain structure, it is hypothesized that the indirect effect of ordinary pressure waves set up by the interaction of missile and tissue and that impinge on brain stem respiratory nuclei determines life or death. The likelihood of fatal apnea is a direct function of missile energy of deposit within the brain. With brain wounding, a reduction in CO may also occur, but missile energy required to produce a significant CO decrease is in excess of that required to produce respiratory problems. Unless the individual managed to survive a period of apnea or respiratory resuscitation occurred, the effects of apnea would overshadow any CO decreases. Although transmitted ordinary pressure waves might interfere with the reticular activating system within the brain stem and produce persistent coma, specific long-lasting neurologic defects from a missile wound usually result from direct missile damage to the cerebral cortex or cortical projections. In designing treatments for missile wounds of the brain, two distinct entities must be kept in mind: the brain stem and the cerebral cortex. To decrease the immediate mortality from brain wounding, prompt treatment has to be devised to aid dysfunctional respiratory nuclei and possibly cardiac control nuclei. To decrease long-term neurologic morbidity, drug therapy has to be instituted to help injured cerebral cortical neurons for days to weeks after wounding. Totally different strategies and drugs may be needed to treat the brain stem as opposed to the cerebral cortex.