When an external force damages the head - the result is head trauma, and if there’s temporary or permanent brain dysfunction, we call it a traumatic brain injury, or TBI. This external force could be a blunt impact, like a baseball bat, a penetrating injury, like a gunshot wound, a blast wave, like an explosion, or an accelerating-decelerating force, like in a motor vehicle crash. The most common causes of TBIs are falls and motor vehicle crashes, and high-risk groups include the elderly and individuals using alcohol and illicit drugs. When TBIs occur in children, non-accidental trauma, or child abuse, should always be considered.
TBIs can cause primary injuries which are a direct result of the external force. These include skull injuries like fractures; blood vessel injuries like an epidural or subdural hematoma, or a subarachnoid or intracerebral hemorrhage; and brain parenchymal injuries like brain contusions and diffuse axonal injury. Sometimes, primary injuries can lead to secondary injuries - like cerebral herniation, seizures, and increased intracranial pressure.
When an individual has a suspected head trauma, the initial evaluation starts with the primary survey, during which the “ABCDEs” are assessed. “A” is for airway, and individuals with a traumatic brain injury may not be able to protect their airway, leading to aspiration and hypoxia, which can worsens the brain injury. These individuals may require endotracheal intubation and mechanical ventilation. “B” is for breathing, and if there’s increased intracranial pressure, it can lead to an irregular breathing pattern - which is part of the Cushing triad. “C” is for circulation, and hypertension and bradycardia are the two remaining features in the Cushing’s triad. There may also be hypotension, which can reduce brain perfusion.