Caused by an impact to the head that damages the brain, traumatic brain injuries affect 1.7 million people each year, according to the Centers for Disease Control and Prevention (CDC). Even if the impact does not fracture the skull, the patient can still have a brain injury. After the initial injury occurs, a patient can develop a hematoma, a condition in which blood collects in an area of the brain. Patients can also have brain injuries caused by diseases that damage the brain.
Diffuse Axonal Injury
This type of brain injury results from the brain moving back and forth in the skull. Automobile accidents, sports-related accidents, violence, falls, and child abuse such as shaken baby syndrome are common causes. With a diffuse axonal injury, patients have tearing of the nerve fibers in the brain. Since this brain injury causes stretching of some blood vessels, patients can have a hemorrhage, or bleeding in the brain. The Merck Manual Professional Edition states that patients with diffuse axonal injuries lose consciousness for more than six hours. The Neurology Channel adds that the frontal lobe and temporal lobe are susceptible to diffuse axonal injuries. The frontal lobe is located near the forehead, while the temporal lobe is behind the frontal lobe, near the ears. Symptoms of a diffuse axonal injury include problems with attention, memory and organization.
Contusions
Caused by either an open head injury or a closed head injury, a contusion results in bruising of the brain. With an open head injury in which an object penetrates the skull, brain tissue can tear. The bruising can result in swelling and bleeding in the brain, which damages the brain. The Neurology Channel notes that contusions occur more often in the temporal and frontal lobes. The Merck Manual Professional Edition adds that the contusion can become larger a few hours or days after the injury occurs. Symptoms of a contusion include memory problems, impaired vision and abnormal sensations.
Hypoxic-Ischemic Injury
Patients who have hypoxic-ischemic injuries have brain swelling, which reduces the flow of oxygen and glucose in the brain. Disrupting this flow of nutrients causes problems for the brain. For example, without enough oxygen, brain cells die. The Neurology Channel notes that if a patient has another injury that limits his oxygen supply, his hypoxic-ischemic injury becomes worse. Symptoms of a hypoxic-ischemic injury include problems with memory.
Anoxic Brain Injury
When the brain does not get enough oxygen, brain cells can die, resulting in a brain injury. Patients can have anoxic brain injuries when they have an accident that affects their oxygen supply, such as a near drowning experience, according to the Better Health Channel, a service of the Victorian government. A stroke can also result in an anoxic brain injury. An abnormality with a blood vessel in the brain, either a burst blood vessel or a blocked blood vessel, causes the stroke and prevents the blood from flowing properly in the brain. Since the blood carries oxygen to the brain, an affected blood flow interferes with the oxygen supply, resulting in brain damage.
Hematomas
When a patient has a head injury, she can develop a hematoma. The collection of blood puts pressure on the brain, resulting in injuries to the brain. The Merck Manual Professional Edition states that one of three types of hematoma can occur: subdural hematoma, epidural hematoma, or intracerebral hematoma. With a subdural hematoma, the blood collects between the outer and middle layers of the brain. An epidural hematoma forms between the outer layer of the brain and the skull. With an intracranial hematoma, the blood accumulates within the brain.
Other Types of Brain Injuries
Diseases that affect the brain can result in brain injuries. For example, disorders that cause a loss of brain cells, like Parkinson's disease, Alzheimer's disease and multiple sclerosis, can cause brain injuries, according to the Better Health Channel. Other diseases that can result in brain injuries include AIDS and cancer. Excessive use of alcohol and drugs, such as cocaine, can injure the brain. For example, brain injuries from alcohol use can result in severe memory problems, impairing the patient's ability to learn and recall memories, according to the National Institute of Alcohol Abuse and Alcoholism.
