Overview
Traumatic brain injury (TBI) is sudden damage to the brain caused by a blow or jolt to the head. Common causes include car or motorcycle crashes, falls, sports injuries, and assaults. Injuries can range from mild concussions to severe permanent brain damage. While treatment for mild TBI may include rest and medication, severe TBI may require intensive care and life-saving surgery. Those who survive a brain injury can face lasting effects in their physical and mental abilities as well as emotions and personality. Most people who suffer moderate to severe TBI will need rehabilitation to recover and relearn skills.
What is a traumatic brain injury?
TBI is an injury to the brain caused by a blow or jolt to the head from blunt or penetrating trauma. The injury that occurs at the moment of impact is known as the primary injury. Primary injuries can involve a specific lobe of the brain or can involve the entire brain. Sometimes the skull may be fractured, but not always. During the impact of an accident, the brain crashes back and forth inside the skull causing bruising, bleeding, and tearing of nerve fibers (Fig. 1). Immediately after the accident the person may be confused, not remember what happened, have blurry vision and dizziness, or lose consciousness. At first the person may appear fine, but their condition can decline rapidly. After the initial impact occurs, the brain undergoes a delayed trauma – it swells – pushing itself against the skull and reducing the flow of oxygen-rich blood. This is called secondary injury, which is often more damaging than the primary injury.
TBI
Figure 1. During impact to the head, the soft brain crashes back and forth against the inside of the hard skull causing bruising, bleeding, and shearing of the brain.
Traumatic brain injuries are classified according to the severity and mechanism of injury
Mild: person is awake eyes open. Symptoms can include confusion, disorientation, memory loss, headache, and brief loss of consciousness.
Moderate: person is lethargic eyes open to stimulation. Loss of consciousness lasting 20 minutes to 6 hours. Some brain swelling or bleeding causing sleepiness, but still arousable.
Severe: person is unconscious eyes do not open, even with stimulation. Loss of consciousness lasting more than 6 hours.
Types of traumatic brain injuries
Concussion is a mild head injury that can cause a brief loss of consciousness and usually does not cause permanent brain injury.
Contusion is a bruise to a specific area of the brain caused by an impact to the head also called coup or contrecoup injuries. In coup injuries, the brain is injured directly under the area of impact, while in contrecoup injuries it is injured on the side opposite the impact.
Diffuse axonal injury (DAI) is a shearing and stretching of the nerve cells at the cellular level. It occurs when the brain quickly moves back and forth inside the skull, tearing and damaging the nerve axons. Axons connect one nerve cell to another throughout the brain, like telephone wires. Widespread axonal injury disrupts the brain''s normal transmission of information and can result in substantial changes in a person''s wakefulness.
Traumatic Subarachnoid Hemorrhage (tSAH) is bleeding into the space that surrounds the brain. This space is normally filled with cerebrospinal fluid (CSF), which acts as a floating cushion to protect the brain. Traumatic SAH occurs when small arteries tear during the initial injury. The blood spreads over the surface of the brain causing widespread effects.
Hematoma is a blood clot that forms when a blood vessel ruptures. Blood that escapes the normal bloodstream starts to thicken and clot. Clotting is the body''s natural way to stop the bleeding. A hematoma may be small or it may grow large and compress the brain. Symptoms vary depending on the location of the clot. A clot that forms between the skull and the dura lining of the brain is called an epidural hematoma. A clot that forms between the brain and the dura is called a subdural hematoma. A clot that forms deep within the brain tissue itself is called an intracerebral hematoma. Over time the body reabsorbs the clot. Sometimes surgery is performed to remove large clots.
Although described as individual injuries, a person who has suffered a TBI is more likely to have a combination of injuries, each of which may have a different level of severity. This makes answering questions like “what part of the brain is hurt?” difficult, as more than one area is usually involved.
Secondary brain injury occurs as a result of the body''s inflammatory response to the primary injury. Extra fluid and nutrients accumulate in an attempt to heal the injury. In other areas of the body, this is a good and expected result that helps the body heal. However, brain inflammation can be dangerous because the rigid skull limits the space available for the extra fluid and nutrients. Brain swelling increases pressure within the head, which causes injury to parts of the brain that were not initially injured. The swelling happens gradually and can occur up to 5 days after the injury.
What are the symptoms?
Depending on the type and location of the injury, the person''s symptoms may include
Loss of consciousness
Confusion and disorientation
Memory loss / amnesia
Fatigue
Headaches
Visual problems
Poor attention / concentration
Sleep disturbances
Dizziness / loss of balance
Irritability / emotional disturbances
Feelings of depression
Seizures
Vomiting
Diffuse injuries (such as a concussion or diffuse axonal injury) will typically cause an overall decreased level of consciousness. Whereas, focal injuries (such as an ICH or a contusion) will have symptoms based on the brain area affected
Every patient is unique and some injuries can involve more than one area or a partial section, making it difficult to predict which specific symptoms the patient will experience.
What are the causes?
Common causes include falls, car or motorcycle crashes, vehicular accidents involving pedestrians, athletics, and assaults with or without a weapon.
Who is affected?
Approximately 1.5 to 2 million adults and children suffer a traumatic brain injury (TBI) each year in the United States. Most people who experience a head injury, about 1.1 million, will have a mild injury that does not require an admission to the hospital. Another 235,000 individuals will be hospitalized with a moderate to severe head injury, and approximately 50,000 will die.
How is a diagnosis made?
When a person is brought to the emergency room with a head injury, doctors will learn as much as possible about his or her symptoms and how the injury occurred. The person''s condition is assessed quickly to determine the extent of injury.
Computed Tomography (CT) is a noninvasive X-ray that provides detailed images of anatomical structures within the brain. A CT scan of the head is taken at the time of injury to quickly identify fractures, bleeding in the brain, blood clots (hematomas) and the extent of injury (Fig. 3). CT scans are used throughout recovery to evaluate the evolution of the injury and to help guide decision-making about the patient''s care.
Magnetic Resonance Imaging (MRI) is a noninvasive test that uses a magnetic field and radiofrequency waves to give a detailed view of the soft tissues of the brain. A dye (contrast agent) may be injected into the patient''s bloodstream. MRI can detect subtle changes in the brain that cannot be seen on a CT scan.
Magnetic Resonance Spectroscopy (MRS) gives information about the metabolism of the brain. The numbers generated from this scan provide a general prognosis about the patient''s ability to recover from the injury.
What treatments are available?
Mild TBI usually requires rest and medication to relieve headache. Moderate to severe TBI require intensive care in a hospital. Bleeding and swelling in the brain can become an emergency that requires surgery. However, there are times when a patient does not require surgery and can be safely monitored by nurses and physicians in the neuroscience intensive care unit (NSICU).
The goals of treatment are to resuscitate and support the critically ill patient, minimize secondary brain injury and complications, and facilitate the patient''s transition to a recovery environment. Despite significant research, doctors only have measures to control brain swelling, but do not have a way to eliminate swelling from occurring.
Neurocritical care
Neurocritical care is the intensive care of patients who have suffered a life-threatening brain injury. Many patients with severe TBI are comatose or paralyzed they also may have suffered injuries in other parts of the body. Their care is overseen by a neurointensivist, a specialty-trained physician who coordinates the patient''s complex neurological and medical care. Patients are monitored and awakened every hour for nursing assessments of their mental status or brain function.
Seeing a patient who has suffered a severe TBI can be shocking. It is possible that your loved one''s appearance will be ed because of facial injury and equipment that is used for monitoring. Numerous tubes, lines, and equipment may be used to closely monitor his or her heart rate, blood pressure, and other critical body functions. (Fig. 4)
ICP monitor
Intracranial pressure (ICP) monitor. A catheter is placed through a small hole in the skull and positioned inside the ventricle (fluid-filled area deep within the brain) to measure pressure inside the head (Fig. 5). The ICP monitor allows the NSICU team to intervene quickly if the pressure becomes too high. Typical intracranial pressure is less than 20 mmHg. However, there are times when a higher number is safe and acceptable.
Brain oxygen monitor (Licox). A catheter is placed through a small hole in the skull and positioned within the brain tissue. The Licox measures the oxygen level and temperature within the brain. Adjustments in the amount of oxygen given to the patient are often made to maximize the brain''s oxygen level. A cerebral blood flow monitor, called a Hemedex, is a newer monitor that is placed with the Licox and helps the NSICU team evaluate blood flow through the brain.
Ventilator. Some patients may require a ventilator, a machine that helps them breathe. The ventilator is connected to the patient by the endotracheal tube, or ET tube. The tube is placed into the patient''s mouth and down into the trachea, or windpipe. The tube allows the machine to push air into and out of the lungs, thereby helping the patient breathe.
Feeding tube. When patients are on a ventilator or have a decreased level of alertness, they may not be able to eat or get sufficient nutrition to meet their needs. A nasal-gastric feeding tube may be ed through the patient''s nose and passed down the throat into the stomach. It delivers liquid nutrition as well as any medication that is required.
Seizures and EEG monitoring. A seizure is an abnormal electrical discharge from the brain. Approximately 24% of patients who suffer a TBI will have a seizure that is undetected unless they are monitored by an electroencephalogram (EEG). Seizures that are not visible to the human eye are referred to as non-convulsive seizures. Because these seizures are serious, all patients with a severe TBI are monitored with continuous EEG for 24 to 72 hours after injury.
Medication
Sedation and pain. After a head injury it may be necessary to keep the patient sedated with medications. These medications can be turned off quickly in order to awaken the patient and check their mental status. Because patients often have other injuries, pain medication is given to keep them comfortable.
Controlling intracranial pressure. Hypertonic saline is a medication used to control pressure within the brain. It works by drawing the extra wat
