The contrecoup phenomenon. Reappraisal of a classic problem.

We describe briefly and comment upon the salient strengths and limitations of the major published theories that purport to explain the mechanism of contrecoup cerebrocortical contusions. Through the application of mechanical principles, we then present a modification, clarification, and expansion of selected aspects of several theories. Our final formulation emphasizes the injurious potential of nonuniform compressive stress and the relationship between brain lag and rotationally induced injury. The resulting theory remains faithful to the laws of physics while explaining the location and distribution of cerebrocortical contusions opposite the site of a moving head impact.