Acquired brain injury

Medical quality assurance by Dr. Albrecht Nonnenmacher, MD at November 28, 2016
StartDiseasesAcquired brain injury

Acquired brain injury is a condition that results from some sort of brain injury that occurs after birth. The effects can range from mild to complete disability or a persistent vegetative state in which the individual does not respond to the world around him or her.


Definition & Facts

Acquired brain injury is defined by the World Health Organization as 'damage to the brain, which occurs after birth and is not related to a congenital or a degenerative disease.'

The brain damage may occur as a result of a traumatic brain injury, brain infection, exposure to environmental toxicants like carbon monoxide, oxygen deprivation, damage from a stroke, a brain tumor or the use of illicit drugs.

In other words, acquired brain injury can result from physical injury to brain structures, pressure on the brain from bleeding or a growing tumor, the death of brain cells from lack of oxygen, or damage from external substances such as illegal drugs.

Symptoms & Complaints

Symptoms of a brain injury vary depending on whether or not the injury is sudden, such as in cases of stroke or trauma to the brain, or whether it has progressed slowly over a number of years, which can occur in cases of long-term drug abuse. The symptoms also vary depending on the severity of the injury.

Mild injury can result in headache, fatigue, and sleep disorders. Neurological symptoms include light sensitivity or noise sensitivity, visual disturbances, and difficulties with balance.

With a moderate acquired brain injury, these symptoms are typically more severe or prolonged, and patients may also have speech problems, extremity weakness, or paralysis.

With a severe brain injury, the patient may be comatose or near-comatose.

Mood disorders can also result from an acquired brain injury, with symptoms like irritability, depression, anxiety, and mood swings. Patients may be emotionally labile – crying one minute and laughing the next – depressed and easily angered. A brain injury can affect an individual's coping skills, or cause disinhibition, which means the patient may behave in an inappropriate manner.

The individual may have difficulty with cognitive activities, find it hard to concentrate, or develop memory problems. Cognitive changes can include difficulty making decisions or using poor judgment, difficulty planning or organizing tasks, poor memory, and confusion.

People often have persistent, long-term changes in mental, physical, emotional or social functioning. Physical complaints include chronic headaches, slurred speech, visual changes, and difficulty with normal activities like walking, eating or grooming.


Trauma to the brain can be caused by penetrating or crushing head injuries, by a fracture of the skull that exposes the brain, or by a closed head injury, in which the brain is damaged but not exposed. The latter is the most common type of brain injury.

A stroke can cause brain damage either because it blocks an artery (the most common type of stroke) or because of bleeding inside the brain. Cerebral hypoxia is a lack of oxygen in the oxygen, and can result from near drowning or a heart attack.

Infections like meningitis can damage brain cells, and tumors can also damage brain cells or cause pressure inside the skull. Although surgery is often undertaken to help someone with a head injury, it can also cause brain damage, and the risks must be weighed accordingly.

Diagnosis & Tests

Mild acquired brain injury can be difficult to diagnosis because the symptoms may be subtle or based on a patient's subjective reports. In mild traumatic brain injury, diagnostic imaging studies like a magnetic resonance imaging (MRI) scan may not pick up structural damage to the brain.

That said, imaging studies can typically diagnose underlying conditions such as a stroke or a brain tumor. These conditions will typically show up on an MRI or a computed tomography (CT) scan. Carbon monoxide poisoning can be diagnosed with a blood test.

Sometimes the diagnosis must be made based on the patient's symptoms, reports of the patient's behavior from caregivers, neurological examinations, and neurological evaluations that can pinpoint brain damage.

Treatment & Therapy

The initial therapy in a brain injury varies according to the type of injury. In an open head injury, for example, the focus may initially be on stopping bleeding. However, in all cases, the primary objective is to prevent or reduce swelling in the brain, which can cause secondary damage to brain cells.

Intensive nursing care is often required. The patient's head must be kept elevated and medications may be used to prevent fluid build-up. Patients with more severe injuries may need a ventilator to breathe for them, or if paralyzed will need supportive care and physical therapy. In cases of mild traumatic brain injury, patients may be observed for signs of increased pressure inside the brain (intracranial pressure) but may not require more intensive treatment.

Once the acute phase of the injury has passed, rehabilitation is often necessary. Physical therapy, occupational therapy, and speech therapy are nearly always required to help patients regain lost functions or to compensate for physical disabilities and intellectual disabilities.

Emotional support and counseling are also often necessary. Patients with acquired brain injury are often treated in specialty units or hospitals geared specifically toward rehabilitation, and once the patient is able to go home, home care and ongoing therapy are often required.

Prevention & Prophylaxis

Basic safety precautions are often the most effective ways to prevent acquired brain injuries. For example, people should wear a helmet when cycling, skateboarding or riding a horse. Not smoking and keeping blood pressure under control greatly reduce the risk of strokes and heart attacks. Not using illegal drugs can help protect the brain.

Carbon monoxide poisoning can occur with faulty heaters or car exhaust, so correct installation and regular maintenance are important aspects of prevention. Although a tumor cannot necessarily be prevented, regular medical care can help identify early symptoms, which increases the chance of successful treatment.

One of the most important aspects of prevention is in preventing a second head injury, as people with a brain injury may be more impulsive, lack judgment or have problems with coordination or vision that increase the risk of a second injury.