Penetrating brain injury
In the past 20 years, there has been an increase in the incidence of head injuries caused by gunshot wounds. Penetrating brain injury is a traumatic brain injury caused by high-velocity projectiles or low-velocity sharp objects. A wound in which the projectile breaches the cranium but does not exit is referred as a penetrating wound, and an injury in which the projectile passes entirely through the head, leaving both entrance and exit wounds, is referred to as a perforating wound. A large number of these patients who survive their initial wounding will nevertheless expire shortly after admission to the hospital. Until the introduction of aseptic surgery in the last quarter of the nineteenth century, penetrating missile injuries of the brain were almost universally fatal. We have learned a great deal about gunshot wounds and their management from military experience gained during times of war, when a large number of firearm-related casualties are treated in a short period of time. Newly designed protective body armor has reduced the incidence of penetrating brain injuries significantly. Many of the victims in the vicinity of a cased explosive or an improvised explosive device will incur injuries by fragments. Blast injury is a common mechanism of traumatic brain injury among soldiers serving in war zone. Each war has had different lessons to teach. World War I for example, proved the efficacy of vigorous surgical intervention. During World War II, the importance of initial dural repair and antibiotic medication was first, debated, then acknowledged, and finally, universally accepted. The incidence of blast-induced traumatic brain injury has increased substantially in recent military conflicts. Blast-induced neurotrauma is the term given to describe an injury to the brain that occurs after exposure to a blast. Resent conflict has exposed military personnel to sophisticated explosive devices generating blast overpressure that results in secondary cellular and molecular insults to the brain parenchyma akin to diffuse brain injury. In soldiers with varying amounts of body armor, the pattern is quite different. What had previously been fatal penetrating brain injuries now become treatable brain injuries as a consequence of secondary damping of energy by the helmet. Traumatic brain injury is not prevented by a protective helmet. High- and low-frequency blast waves disrupt the blood-brain barrier and produce massive brain swelling in a very short time, thereby necessitating urgent decompressive craniectomy, and when low in energy, such blast waves may result in cytoskeletal and diffuse axonal injury that leads to neurodegeneration. Penetrating traumatic brain injury is typically identified and treated immediately mild traumatic brain injury may be missed, particularly in the presence of other more obvious injuries. In recent years there has been an apparent paradigm shift of scientific interest in long-term effects of mild traumatic brain injury and its contribution to posttraumatic stress disorder. The introduction of Guidelines for the Management of Penetrating Brain Injury has revolutionized the medical and surgical management of penetrating brain injury during the last decade. There has been a paradigm shift toward a less aggressive debridement of deep seated fragments and a more aggressive antibiotics prophylaxis in an effort to improve outcomes.
