Brain injury

Brain injury, also known as brain damage or neurotrauma, is the destruction or degeneration of brain cells. It may result from external trauma, such as accidents or falls, or from internal factors, such as strokes, infections, or metabolic disorders.

Traumatic brain injury (TBI), the most common type of brain injury, is typically caused by external physical trauma to the head. Acquired brain injuries occur after birth, in contrast to congenital brain injuries that patients are born with.

In addition, brain injuries can be classified by timing: primary injuries occur at the moment of trauma, while secondary injuries develop afterward due to physiological responses. They can also be categorized by location: focal injuries affect specific areas, whereas diffuse injuries involve widespread brain regions.

The symptoms and complications of brain injuries vary greatly depending on the area(s) of the brain injured, the individual case, the cause of the injury and whether the person receives treatment. People may suffer from headaches, vomit or lose consciousness (potentially falling into a coma or a similar disorder of consciousness) after a brain injury. Long-term cognitive impairment, disturbances in language and motor skills, emotional dysfunction and changes in personality are common.

Treatments for brain injuries include preventing further injuries, medication, physical therapy, psychotherapy, occupational therapy and surgery. Because of neuroplasticity, the brain can partially recover function by forming new neural connections to compensate for damaged areas. Patients may regain adaptive skills such as movement and speech, especially if they undergo therapy and practice.

Focal brain injuries affect only a single area of the brain; they result from direct force to the head and manifest as haemorrhages, contusions, and subdural and epidural haematomas. Diffuse brain injuries cause widespread damage to all or many areas, and are caused by diffuse axonal injuries, hypoxia, ischaemia and vascular injuries. If both are severe, focal brain injuries are deadlier than diffuse ones; severe focal injuries have a mortality rate of 40% whereas severe diffuse injuries have a mortality rate of 25%. Although, diffuse brain injuries more often result in long-term neurological and cognitive deficits.

Primary brain injuries, most of which are traumatic brain injuries, occur directly because of mechanical forces that deform the brain. Secondary brain injuries result from conditions, such as hypoxia, ischaemia, oedema, hydrocephalus and intracranial hypertension, that may or may not be the aftereffects of primary brain injuries.

Symptoms of brain injuries vary based on the severity of the injury, the area of the brain injured, and how much of the brain was affected. The three categories used for classifying the severity of brain injuries are mild, moderate and severe.