Factors Influencing Mortality in Head Injury

Abstract

It has long been recognized that the most important factors in a given case of head trauma are the location and severity of the brain injury. A great deal of attention has consequently been paid to that phase of the problem, and, while much remains to be elucidated and there is a great deal of confusion in the literature in the usage of such terms as concussion and contusion, we do have much important clinical and experimental information on brain injury. As has been pointed out elsewhere (Voris, Verbrugghen and Kearns), however, an estimate of the degree and extent of the injury to the brain at the time the patient first comes under observation is often difficult if not impossible. A simple clinical classification that may be applied at this time has been suggested. This classification groups the patients as follows: (a) moribund; (b) gravely injured; (c) mildly injured; (d) complicated cases. Any cases in the first three groups, even in group a, may fall into the fourth group of complicated cases because of associated injuries, old age, or pre-existing disease or debilitation. Thus in actual experience it early becomes apparent that there are many other factors influencing mortality besides the primary ones of the location and severity of the brain injury. Of these various factors, probably the most important is the age of the patient. During the four-year period, 1939–1942, inclusive, 2,714 cases of head injury were cared for on the author's neurosurgical service at the Cook County Hospital. There were 298 deaths in this group, a gross mortality rate of 11 per cent. Table I gives the distribution of these cases by decades with the mortality rate for each decade. This shows the great importance of the age of the patient in determining his chances for recovery. The older patient with a head injury is, of course, subject to many complications that a younger person is less liable to suffer from. These include hypostatic pneumonia, cardiovascular-renal complications, and late cerebral vascular changes. Then, too, the elderly patient who is admitted to a charity hospital is often debilitated and ill-nourished. Still another factor seems to be of great importance, namely, the impairment of the circulation of the brain in many elderly persons, with consequent poorer reparative response to injury. Reference to Table I shows there was a considerable group (300 cases) of severely injured derelicts in whom the exact age was never ascertained. As might be anticipated, this group showed the highest mortality of all, almost three times that for the entire series. Fracture of the skull has, especially in the past, received undue emphasis in cases of head injury. One writer (Mock) has gone so far as to use the presence or absence of fracture of the skull as a so-called “yardstick” for evaluation of the seriousness of head injury and has confined his statistical analyses to proved cases of skull fracture.