Head Injuries

Traumatic brain injuries (TBIs) are the leading cause of mortality and morbidity in patients younger than 40 years, affecting 1.7 million people every year in the USA. They are responsible for one-third of all injury-related deaths, whereas patients who survive may develop severe debilitating long-term sequelae. They consist of a wide spectrum of diseases, defined as a whole as an “alteration in brain function, or other evidence of brain pathology, caused by an external force.” The causes may vary depending on patient’s age: abuse traumas are most commonly observed in infants, while traumatic and sports-related injuries are seen in toddlers and children. Motor vehicle accidents involve most commonly young adults, whereas the elderly population is more prone to accidental falls. TBIs are clinically divided into minor, mild, moderate, and severe traumas by using the Glasgow Coma Scale (GCS), the most commonly used grading scale to evaluate the entity of head injuries within the first 48 h, which aims to provide a uniform approach to the clinical assessment of patients involved in acute head traumas. GCS is the sum of three components which are eye opening, motor response, and verbal response; a minor trauma has a GCS = 15; mild, GCS > 13; moderate, GCS 9–12; and severe, GCS < 8. An additional TBI clinical classification is provided by the Brain Injury Interdisciplinary Special Interest Group of the American Congress of Rehabilitation Medicine, based on the loss of consciousness, loss of memory for events occurred immediately before or after trauma, changes in mental status, and focal neurologic deficits. According to this classification, a mild trauma is defined as a physiologically disruption of brain functions, evaluated by the presence of one of the previous described criteria; additional findings are no abnormalities on computed tomography (CT) scan, GCS > 12, no surgical lesions, and length of hospital recovery less than 48 h. Moderate trauma is defined as a GCS of 9–12, hospital recovery of at least 48 h, surgical intracranial lesions, and positive CT scan findings. Severe traumas are evident at the moment of clinical presentation. Chronologically, TBIs are divided into primary (injuries occurring at the time of impact) and secondary lesions (lesions occurring after the initial injury, i.e., cerebral herniation, swelling, ischemia, infection, hydrocephalus), resulting from complication of physiological response to injury. Secondary injuries are potentially preventable by stabilizing the patient, by monitoring vital parameters, and, in some cases, by performing decompressive hemicraniectomy. Other classifications are based on the mechanism of injury (open or blunt trauma) and on the location, dividing them into intra-axial lesions (cortical contusions, diffuse axonal injury, intracerebral hematoma) and extra-axial lesions (subdural, epidural, subarachnoid, and intraventricular hematomas). Given these data, it is easy to understand the significative role of imaging in this clinical setting, since its goals are to identify treatable lesions, assist to prevent secondary damage, and provide prognostic information. In this chapter we aim to review the most commonly encountered and severe brain injuries and their complications