Acquired Brain Injury: Overview


Acquired brain injury (ABI) occurs after the brain has developed and may be due to trauma, surgery, intracranial bleeding, tumor or ischemia. Traumatic brain injury (TBI) is one form of acquired brain injury, and is secondary to trauma. Males are twice as likely as females to have a TBI. Late adolescence, early adulthood, and those over age 65 are at highest risk of brain injury. The main causes of TBI are falls, blunt trauma and motor vehicle accidents.


ABI’s are classified as: traumatic, anoxic or hypoxic-ischemic, vascular, or other. Anoxic or hypoxic-ischemic brain injuries can be independent of trauma or as a secondary injury after a traumatic injury. Coma relates to a lack of arousibility. Vegetative state refers to having no meaningful response to the environment after one’s eyes are open. Persistent vegetative state is a vegetative state that lasts longer than 3 months (1 year if due to trauma). Locked-in syndrome is when one is awake, can communicate, aware of one’s environment, but unable to move or speak. Minimally responsive is when one is no longer comatose or vegetative, but still severely disabled, while having some inconsistent meaningful interaction with the environment.

A skull fracture is associated with risk of underlying brain injury. Non-displaced fractures heal on their own, while displaced fractures can press against brain tissue. A concussion is a transient and reversible post-traumatic alteration in mental status lasting from seconds to minutes. Symptoms include confusion, amnesia, slurred speech, headache, dizziness, nausea, vomiting, altered vision, hearing, taste, smell, fatigue, and altered emotional regulation. A contusion can impair a wide range of brain functions, depending on contusion size and location. Larger contusions may cause brain edema and increased intracranial pressure (ICP). Diffuse axonal injury (DAI) occurs when deceleration causes shear-type forces that result in generalized, widespread disruption of axonal fibers and myelin sheaths. Some DAI lesions may also result from minor head injury. Hematoma is a rupture of blood vessels with collection of blood in/around the brain. Epidural hematoma is between the skull and the dura mater. Subdural hematoma is between the dura mater and the pia mater. Subarachnoid hematoma is when blood collects beneath the arachnoid mater in the subarachnoid space. Intracerebral hematoma is bleeding directly within the brain.

Closed head trauma deficits include:

  • Cognitive: attention/concentration, memory (short and long term), problem-solving/decision making, reduced information processing speed, impulsive behavior, sequencing, conceptual formation, rigidity of response, spatial, judgment

  • Physical: ambulatory, fine motor skill, visual, speech

  • Behavioral: basic ADL’s, socially inappropriate, poor initiation, disinhibition

  • Emotional: self-control, social dependency, irritability, apathy, lack of empathy


Left hemisphere injuries affect: speech, reading, writing, conceptualization, verbal ideation, verbal memory. Right hemisphere injuries affect: non-verbal information processing, tactile and visual recognition of shapes and forms, spatial orientation, representational designs, arithmetic calculations. Complications of ABI include spasticity, seizures, contractures and impaired executive functions.

The Glasgow Coma Scale is an initial brief assessment technique for all post-traumatic states of altered consciousness. It is calculated from the sum of the highest score in each of 3 dimensions (eye opening, motor, and verbal). Scores range from 3 to 15, with 13-15 as mild, 9 to 12 as moderate, and 3 to 8 as severe.


The Rancho Los Amigos Scale of Cognitive Functioning is used to monitor an individual with ABI during rehabilitation. It is divided into 8 levels:

  1. No response

  2. Generalized response (often to pain only)

  3. Localized response (purposeful)

  4. Confused, agitated

  5. Confused, inappropriate, no-agitated

  6. Confused, appropriate

  7. Automatic, appropriate

  8. Purposeful, appropriate


Recovery from ABI usually involves an initial significant decrease in function. Over time, spontaneous recovery may occur, and usually within the first 6 months. Most gains are well established at 12 months post injury.

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