[Outlining the limits of salvageability in severe head injury].

Severe head injury is one of the most important health, social, and economic problems in industrialized countries. The percentages of mortality and unfavourable outcomes are very similar to those reported in the last quarter of century. In order to make predictions, different "prognostic formulas or models" have been carried out. These models will be constructed on the one hand, by a group of "prognostic indicators or factors" and on the other hand, by different "prognostic scales" that are useful for measuring the final outcome of these patients. Several "statistical techniques or methods" are necessary to develop these ones.