Brain edema following an experimental missile wound to the brain.

Brain edema occurs after brain injury and may be life threatening. The occurrence and type of brain edema, its magnitude, and time course have never been ascertained following a missile wound to the brain. We therefore measured the development of brain edema in a series of cats in which a right cerebral hemisphere wound was made with a 2.0 mm, 31.7 mg steel sphere with a velocity of 240-300 m/s (0.9-1.4 J). The entire brain was surveyed for postwounding brain edema by determining the wet weight minus dry weight. Brain edema was seen to develop only in the white matter about the missile wound track in the injured cerebral hemisphere. There, brain water rose from 66 to 73%; white matter sodium also increased significantly from approximately 150 mEq/kg dry weight to 254 mEq/kg dry weight. Potassium levels remained essentially unchanged. This vasogenic edema was relatively mild, peaked at 24-48 h after wounding, and resolved spontaneously within a week without specific treatment. We infer that brain edema following an uncomplicated cerebral missile wound in the human brain is also mild, self-limited, and may resolve spontaneously without special treatment.