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|A CT of the head years after a traumatic brain injury showing an empty space where the damage occurred marked by the arrow.|
A brain injury is an injury to the brain of a living organism, and can be categorized by many properties.Primary and secondary brain injuries identify the processes involved, while focal and diffuse brain injury describe the severity and localization.
Brain injuries have far-reaching and varied consequences due to the nature of the brain as the main source of bodily control. Brain-injured people commonly experience issues with memory. This can be issues with either long or short term memories depending on the location and severity of the injury. Sometimes memory can be improved through rehabilitation, although it can be permanent. Brain injury can also affect muscle control and coordination ranging from difficulty writing to being unable to perform basic bodily functions such as swallowing or coughing. Behavioral and personality changes are also commonly observed due to changes of the brain structure in areas controlling hormones or major emotions. Headaches and pain can also occur as a result of a brain injury either directly from the damage or due to neurological conditions stemming from the injury. Due to the changes in the brain as well as the issues associated with the change in physical and mental capacity, depression and low self-esteem are common side effects that can be treated with psychological help. Antidepressants must be used with caution in brain injury people due to the potential for undesired effects because of the already altered brain chemistry.
A traumatic brain injury is an alteration of a structural, physiological, or chemical transmitter pathway as well as other brain pathology, and is caused by an external force. A post-traumatic brain injury is the alteration of the neurological function by the traumatic event. Multiple traumatic injuries can lead to chronic traumatic encephalopathy.
A concussion is the most common type of brain trauma, and can be caused by direct damage to the head, gunshot wounds, violent shaking of the head (very common in children), or force from a whiplash type injury. A concussion occurs when the brain receives trauma from an impact or a sudden momentum or movement change. The blood vessels in the brain may stretch, and cranial nerves may be damaged.
A penetrating injury occurs when a sharp object enters the brain, causing a large damage area. Penetrating injuries caused by bullets have a 91 percent mortality rate.
A coup-contrecoup injury occurs when the force impacting the head is not only strong enough to cause a contusion at the site of impact, but also able to move the brain and cause it to displace rapidly into the opposite side of the skull, causing an additional contusion.
Diffuse axonal injury is caused by shearing forces on the brain leading to lesions in the white matter tracts of the brain. These shearing forces are seen in cases where the brain had a sharp rotational acceleration, and is caused by the difference in density between white matter and grey matter.
Non-traumatic brain injuries are those caused 'from the inside' as opposed to the external factors seen in traumatic brain injuries. Generally, these are caused by disturbances in the blood flow to or in the brain, or by infections.
An anoxic brain injury occurs when the human brain receives no oxygen via the blood. Cells in the brain begin to die due to anoxia.
Hypoxic brain injury happens when the brain receives insufficient oxygen. A hypoxic brain injury, also called stagnant hypoxia, is caused by a reduction in blood flow or low blood pressure leading to a lack of blood flow to the brain.
The treatment for emergency traumatic brain injuries focuses on assuring the person has enough oxygen from the brain blood supply, and on maintaining normal blood pressure to avoid further injuries of the head or neck. The person may need surgery to remove clotted blood or repair skull fractures, for which cutting a hole in the skull may be necessary. Medicines used for traumatic injuries are diuretics, anti-seizure or coma-inducing drugs. Diuretics reduce the fluid in tissues lowering the pressure on the brain. In the first week after a traumatic brain injury, a person may have a risk of seizures, which anti-seizure drugs help prevent. Coma-inducing drugs may be used during surgery to reduce impairments and restore blood flow.