Penetrating Bihemispheric Traumatic Brain Injury: A Collective Review of Gunshot Wounds to the Head

BACKGROUND: Head injuries that cross midline structures of the brain are bihemispheric. Other terms have been used to describe such injuries, but bihemispheric is the most accurate and should be standard nomenclature. Bihemispheric head injuries are associated with greater mortality and morbidity than other penetrating traumatic brain injuries (TBIs). Currently, there is a tendency to manage severe gunshot wounds (GSWs) to the head nonoperatively, despite reports of improved outcome in military patients treated aggressively. Thus, controversy exists in the management of civilian TBI. METHODS: PubMed was searched for query terms, and PRISMA guidelines were used. Studies were selected by relevance and inclusion of data regarding etiology, diagnosis, and management of bihemispheric TBI. Case reports, studies not in English, and records lacking information on mechanism or bihemispheric injuries were excluded. RESULTS: Thirteen studies were included and most contained level IV evidence. The mean mortality rate of all head GSWs was 62% in adults and 32% in children. Bihemispheric GSWs had greater mortality rates of 82% in adults and 60% in children. There was a larger proportion of self-inflicted injury in studies with greater rates of bihemispheric injuries. CONCLUSIONS: Bihemispheric injuries have greater mortality rates than other penetrating TBI. Violation of midline brain structures such as the diencephalon and mesencephalon, increased rate of self-inflicted wounds, and lack of a standard management algorithm may increase the lethality of these injuries. Although bihemispheric injuries historically have been considered non-salvageable, an aggressive surgical approach has been shown to improve outcomes, particularly in the military population.