Many people have had the unfortunate experience of a head injury at some point in their lifetime. It could be a simple bump of the head while stepping out of a car, falling and hitting one’s head on the pavement, or a severe impact on the skull during a car accident. When any such trauma causes an injury to the brain, it is called a Traumatic Brain Injury or TBI. A patient with a traumatic brain injury may be referred to a neurologist or neurosurgeon for further evaluation.
Mild types of brain injury cause minor symptoms that resolve within a few weeks. Moderate to severe head injuries, whether from blunt or penetrating traumas, can be associated with long-term effects and changes to the quality of one’s life.
The brain, our body’s control center, is housed within the bones of the skull. A membrane called the dura mater covers the surface of the brain as a type of skin layer. It also extends to enclose the spinal cord. Cerebral spinal fluid (CSF) fills the narrow space between the brain and skull bones to cushion and protect the brain during our everyday activities.
There are also pockets of this fluid, or ventricles, in the central areas of the brain. Blood vessels lie along the brain’s surface, and within the brain tissue itself. Any disruption of these blood vessels or layers of protection can cause disability.
When a significant head injury occurs, the impact force overcomes the cushioning effect of the cerebral spinal fluid. This causes the brain to literally hit against the inside of the skull. A mild impact results in only brain tissue bruising, but more significant impacts can rupture blood vessels, break the dura, or cause leakage of cerebral spinal fluid.
Any increased fluid within the skull cavity exerts pressure on the brain, causing pain and neurological impairment. In addition, brain cell injury sets off a cascade of biochemical reactions that causes swelling and damage to the tissue itself. Some common causes of traumatic brain injury include:
Mild
Moderate
Severe
A headache is the most common symptom of a traumatic brain injury. Whether or not there is a loss of consciousness at the time of injury is an important factor in determining the severity of the injury. Mild TBIs may be associated with nausea, dizziness, mood changes, and difficulty with focus, memory, and sleep.
Symptoms of a mild head injury usually self-resolve within a few weeks. In contrast, however, moderate to severe TBIs typically involve a period of altered consciousness which can range from a few minutes to hours. In these cases, the headache is quite severe and unbearable.
Seizure and other neurological symptoms such as somnolence, weakness or numbness, agitation and confusion are common. Physical signs such as external head bruising or deformity, bleeding from the ears, or dilated pupils may also be present.
When a head injury occurs, it may be necessary to contact emergency services. Once in the emergency room, a detailed physical examination is performed, including a complete neurological check of reflexes, sensation, muscle strength, and mental status.
In most cases, a head CT scan is done to identify skull fractures and bleeding on or around the brain. Further information may be obtained via an MRI or cerebral blood flow scan. All of these modalities are helpful in determining the best treatment plan.
Most mild brain injuries can be managed with rest, over-the-counter pain relievers, and a reduction in tasks that require prolonged concentration. Rest includes more sleep time which helps the brain to heal. Screened devices such as cell phones, computers, and tablets tend to exacerbate symptoms, so their use should be limited during recovery. Avoidance of situations or activities that could result in a second head injury is important to prevent a delay in recovery.
For more severe brain trauma, a variety of treatment modalities are used to both treat the injury and limit the risk of further brain damage. During the first few days after an injury, keeping the head elevated reduces pressure on the injured brain caused by bleeding or displaced cerebrospinal fluid.
If mechanical ventilation is necessary, a brief period of hyperventilation can reduce blood flow to the brain, and lower intracranial pressure. Because seizures are common, anti-epileptic medications may be administered prophylactically. Where this is a concern for post-injury pressure within the skull, an intracranial pressure monitor is surgically placed.
In severe cases, a medically induced coma may be necessary. This allows brain swelling to gradually resolve while minimizing as much damage as possible. In pediatric cases, this same effect is achieved by medical hypothermia techniques.
If imaging studies indicate a significant amount of intracranial bleeding, surgical intervention may be necessary. While there are a variety of techniques used depending on the location of the bleeding, surgery basically involves penetration of the skull and evacuation of the blood.
If the bleeding is between bone and the dura mater, or an epidural hematoma, a portion of the skull is opened to relieve the pressure on the brain, and to remove the blood. For bleeding under the dura, a subdural hematoma, minimally invasive techniques may be used.
The outcome of traumatic brain injuries depends on the severity of the injury and any complications that have occurred. Mild TBIs usually have a very benign course. After two to four weeks, most individuals fully recover and have no residual symptoms. If headaches or other symptoms do persist, continued monitoring and pain management by a neurologist may be warranted.
Once the acute symptoms of moderate and severe TBIs have been treated, there are often long-term sequelae that require ongoing care. Intermittent headaches and dizziness may persist. If any cranial nerves were damaged at the time of injury, there may be a resultant loss of taste or smell, impaired vision, or hearing problems.
Executive brain functioning may sometimes be impaired as a result of a brain injury, causing difficulty with the skills needed for employment and everyday tasks. Social interactions may be more difficult under certain circumstances. Physical rehabilitation, social skills re-training and psychotherapy can all be helpful with recovery.