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What is an ABI?

An acquired brain injury is an injury to the brain that has occurred after birth and is not hereditary, congenital or degenerative. The injury commonly results in a change in neuronal activity, which affects the physical integrity, the metabolic activity, or the functional ability of the cell. The term does not refer to brain injuries induced by birth trauma.

  • Read inspiring stories from ABI survivors, their carers & healthcare professionals. Click here.


  • Causes of Acquired Brain Injury

    • Road traffic accidents
    • Stroke
    • Trip/fall
    • Assault
    • Aneurysm
    • Viral infection ( e.g. encephalitis, meningitis)
    • Brain haemorrhage
    • Concussion
    • Tumour
    • Seizures
    • Anoxia /Lack of Oxygen to the brain (e.g. drowning)

    An ABI may result in mild, moderate or severe impairments in one or more of the following areas:

    Any of these impairments can affect a person’s ability to control their own lives and live independently.  They can also cause major stress in peer and family relationships as well as in educational and employment settings 

    • Sensory and Motor functions – e.g. seeing, hearing, movement, balancing, sitting, walking
    • Cognition - e.g. attention (concentration) memory, reasoning, concrete and abstract thinking 
    • Communication – e.g. voice, speech, comprehension and expression of spoken and written language, pragmatics and non-verbal communication 
    • Psychosocial and Executive Skills – e.g. social skills, planning, initiating, censoring, monitoring and managing appropriate behaviours, controlling emotions and behaviours 

    Understanding Brain Injury

    For a person living with an ABI and family members.

    An ABI can occur for many reasons. The leading cause of ABI is traumatic brain injury (TBI). A blow to the head can occur in a motor vehicle accident, a fall, when the skull is struck by a blunt or heavy object, or in other ways. In most cases, there are no lasting symptoms or ill effects from an injury to the head. This is because the brain is surrounded by shock absorbing liquid and protected by the skull. Often, these are enough to protect the brain from any damage.

    However when the force of impact is more severe, it can cause the skull to break or fracture. When the skull fractures, this absorbs some of the force of the blow and protects the brain. This is the same way that a crash helmet works. When the head is hit, the brain may be shaken around inside the skull. This can sometimes cause the brain to be bruised if it hits the inside of the skull hard enough. Like a black and blue mark on an arm or leg, this will recover with time. If there are many bruises on the brain, there will be some swelling that can take a while longer to return to normal.

    The brain is made of thousands of long, thin nerve fibres. Some of these nerves can stretch or tear if a blow to the head is severe enough. Although these nerves cannot be seen without a microscope, they can recover. Like any other part of the body, the brain has blood vessels in it. If a brain injury is very serious, some of these blood vessels can tear and bleed. This happens soon after the injury. The bleeding often stops itself and the blood vessels heal like any cut.

    Bruises, swelling, injured nerves and broken blood vessels are the causes of symptoms after a brain injury. Doctors examine for any signs of injury to the brain and prescribe treatment if needed. Most people who suffer a brain injury recover completely in time because the damage is minor and heals. Other causes of ABI, which often result in a more serious brain injury, are tumours, blood clots, strokes, seizures, toxic exposures, infection, metabolic disorders and anoxia.

    What is a Coma?

    When we hear the word “coma” many of us think of a person in a state of complete unawareness. In reality, coma simply means unconsciousness, of which there are varying levels. The injured person may be in a deeply unconscious state where no amount of stimulation will elicit a response. However, in other cases a person who is in a coma may move, make noises or respond to stimulation.

    The process of recovery from a coma is gradual. The injured person will typically emerge rather than suddenly wake-up from this state, becoming progressively responsive to their environment and eventually regaining full consciousness. While a person is in a coma, individual members of the medical team may conduct a number of assessments. The Glasgow Coma Scale (GCS) is universally used upon admission to determine the depth of the coma, and periodically thereafter to determine a more accurate duration of coma.

    The Scale has 3 categories: 1) Eye Opening; 2) Best Motor Response; and 3) Verbal Response. Each of these categories is scored from 1 to 15. The lower the total score on admission, the more severe the injury is assumed to be. The length of time a person remains in a state of coma is considered a reliable indication of the extent of damage that remains causing long-term difficulties.

    What is Post-Traumatic Amnesia?

    Post-traumatic amnesia (PTA) is the period of time following a brain injury when the person appears conscious and awake, but is confused and does not have continuous memory for ongoing events. The person forgets what happened minutes, hours or days before. The person may also be disoriented about simple things such as person, time and place.

    PTA is assessed in a variety of ways by professionals. During PTA there may be isolated “islands” of memory, when the person appears to be oriented and retaining information, but these are not continuous. The duration of PTA provides information on the severity of the brain injury and, in combination with other measures, is used to estimate prognosis. Longer durations of PTA are associated with poorer outcomes and may be linked to the likelihood of emotional and behavioural problems after brain injur

    Loss of consciousness and Brain Injury

    One way to tell if a brain injury is serious is the amount of time you were unconscious afterwards. If you weren’t knocked out at all, or if you were unconscious for less than 30 minutes, then the injury was most likely mild in nature. Although you may have some symptoms, there was probably little injury to the brain and complete recovery is expected. Most people who have a brain injury fall into this category. The longer you were unconscious, the longer recovery usually takes. If you were knocked out for more than 15 minutes but less than a day, the injuries were most likely moderate. Returning to normal will probably take a while.

    Persons with ABI who are unconscious for more than 6 hours have suffered a severe injury. Although many persons with ABI make a good recovery even after a severe head trauma, symptoms can often last for some time. Treatment at a rehabilitation hospital is usually recommended and can help recovery.

    Table: Severity of injury According to PTA and LOC


    PTA (Post- Traumatic Amnesia)

    LOC (Loss of Consciousness)

    Very Mild

    Less than 5 minutes



    5 minutes to 60 minutes

    Less than 30 minutes


    1 hour to 24 hours

    30 minutes to 24 hours


    1 day to 7 days

    More than 24 hours

    Very Severe

    More than 7 days


    Systems of Care

    The Slinky Model of Rehabilitation Service Delivery 

    Neurological recovery following an acquired brain injury occurs over an extended period of many months or years. Fundamental to the provision of rehabilitation services is the appreciation that different people need different input at different stages in their recovery. 

    The ‘Slinky’ Model (as presented by the British Society of Rehabilitation Medicine, 2003), taking its name from the slinky toy, emphasises that, although patients may need to access different services as they progress from acute care to recovery, their transition between services should be smoothed by excellent communication and sharing of information

    between services so that they progress through the stages in a seamless continuum of care. There should be considerable debate about whether services should be based in the hospital or in the community.

    The reality is that in Ireland, many aspects of this ideal model remain unimplemented and care pathways can be fragmented. Following on from the slinky model of rehabilitation service delivery, below are examples of different service patients/clients may need to access the continuum of care.

    Certified Brain Injury Specialist Programme

    We at, Acquired Brain Injury Ireland, entered into a formal agreement with ACBIS to undertake the development of an Irish edition of the CBIS Training Programme. This is the first ACBIS programme to be developed in Europe. Click here to download more information.


    Individual Rehabilitation Plan - Click here for more information

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