An acquired brain injury (ABI) is an injury to the brain which occurs after someone is born. Acquired brain injuries are thus not genetic or congenital in nature. This term also usually excludes brain injuries which are the result of neurological disorders. For example, damage to the brain caused by Alzheimer's is not considered an acquired brain injury, while damage incurred as a result of a car accident would be.
There are a number of potential causes of an acquired brain injury. One common source of damage to the brain is a traumatic brain injury (TBI) which is caused by head trauma. These types of injuries can be closed or penetrating in nature. In a closed TBI, the skull is struck, but not broken, and the brain is slammed around inside the head. In an open or penetrating brain injury, something breaks the skull and penetrates the brain.
Nontraumatic brain injuries are another source of acquired brain injury. These can include the results of oxygen deprivation, drug overdose, poisoning, or stroke, among other things. In both traumatic and nontraumatic brain injuries, the brain is damaged on a cellular level. The effects of the injury vary depending on where the damage is located and on the patient's individual circumstances. Brains can be very different between individual people and as a result identical damage in different people may not cause the same effects.
In some cases, an acquired brain injury results in minimal change for the patient, especially after recovery. In other instances, it can interfere with cognitive functions on a variety of levels. People may lose the ability to speak, may not be able to exercise muscular control, can develop emotional instability, and can have trouble performing a variety of tasks. For someone with an acquired brain injury, there is also a risk of reinjury. For example, someone with a stroke which impaired walking ability could fall and incur physical trauma to the skull, reinjuring the brain.
Treatment for an acquired brain injury must be individualized. The patient is evaluated by a neurologist who tries to determine the location and extent of the damage. With this information, the most appropriate treatment can be provided. Patients are often encouraged to work with a therapeutic professional to redevelop basic skills which have been lost as a result of the injury and to see if it is possible to remap brain functions to compensate for areas of the brain which are no longer capable of functioning.