Helmets are one of the earliest and most enduring methods of personal protection in human civilization. Although primarily developed for combat purposes in ancient times, modern helmets have become highly diversified to sports, recreation, and transportation. History and the scientific literature exhibit that helmets continue to be the primary and most effective prevention method against traumatic brain injury (TBI), which presents high mortality and morbidity rates in the US. The neurosurgical and neurotrauma literature on helmets and TBI indicate that helmets provide effectual protection against moderate to severe head trauma resulting in severe disability or death. However, there is a dearth of scientific data on helmet efficacy against concussion in both civilian and military aspects. The objective of this literature review was to explore the historical evolution of helmets, consider the effectiveness of helmets in protecting against severe intracranial injuries, and examine recent evidence on helmet efficacy against concussion. It was also the goal of this report to emphasize the need for more research on helmet efficacy with improved experimental design and quantitative standardization of assessments for concussion and TBI, and to promote expanded involvement of neurosurgery in studying the quantitative diagnostics of concussion and TBI. Recent evidence summarized by this literature review suggests that helmeted patients do not have better relative clinical outcome and protection against concussion than unhelmeted patients.
Keywords: ACH = Advanced Combat Helmet; ACRM = American Congress of Rehabilitation Medicine; CTE = chronic traumatic encephalopathy; DAI = diffuse axonal injury; GCS = Glasgow Coma Scale; ICH = intracranial hemorrhage; ICP = intracranial pressure; ImPACT = Immediate Post-Concussion Assessment and Cognitive Testing; LOC = loss of consciousness; LOS = length of stay; RSC = referee stop contest; SAH = subarachnoid hemorrhage; SCAT3 = Sport Concussion Assessment Tool, 3rd edition; SDH = subdural hematoma; SRC = sports-related concussion; T-tau = total tau; concussion; helmet efficacy; mTBI = mild traumatic brain injury; review; traumatic brain injury.