Moderate Head Injury: An Overview

This review summarizes currently available epidemiologic, clinical, pathologic, and outcome data in patients with moderate head injury (MHI, GCS 9–12). This important subset comprises about 20% of head injuries in the United States. Affected patients usually are young, and most injuries are due to vehicular accidents. Current evidence (mortality rate and outcome) from various studies suggests an apparent dichotomy within the MHI category (9-10 vs 11-12). The fomer is more in keeping with the favorable subgroup of severe head injuries, and the latter is more appropriate to the mild head injury group. Should there be a reclassification based on this dichotomy? This is obviously important for clinical management and prognostication in these patients. The experimental evidence for a pathologic and biochemical substrate of MHI is reviewed. It is becoming increasing evident that biochemical mediators of secondary neuronal injury in MHI are at least as important as those attributed to severe head injury, but MHI may be more amenable to therapy. It may be prudent, therefore, to direct further effort to this subgroup of patients. Although additional study is required, the pattern of recovery in MHI as determined by extant neurobehavioral studies is analyzed.