1. Introduction and Methodology

Robert Teasell MD FRCPC, Nora Cullen MD FRCPC, Shawn Marshall MD FRCPC, Shannon Janzen MSc, Mark Bayley MD FRCPC


The Evidence-Based Review of Moderate to Severe Acquired Brain Injury (ERABI) was designed to comprehensively review current practices in acquired brain injury (ABI) rehabilitation. ERABI aims to:

  1. Identify effective treatment interventions;
  2. Identify gaps in the literature deserving further research and;
  3. Serve as an accessible tool for clinicians in an effort to encourage evidence-based practice. 

ABI is an umbrella term that encompasses traumatic and non-traumatic etiologies such as cerebral concussion, brain contusions, subarachnoid hemorrhages or other ‘acquired’ problems. ABI typically involves a wide range of impairments affecting physical, neurocognitive and/or psychological functioning. A person with an ‘ABI’ might therefore refer to an individual with a traumatic brain injury (TBI) of any severity, a person with Herpes encephalitis, viral meningitis or acute hypertensive encephalopathy. As opposed to an insidious developmental process, an ‘ABI’ infers that a person, previously intact from a neurological perspective, subsequently ‘acquired’ some form of brain pathology during his or her lifespan. Common traumatic causes include motor vehicle accidents, falls, assaults, gunshot wounds, and sport injuries (Greenwald et al. 2003). Non-traumatic causes of ABI include focal brain lesions, anoxia, tumors, aneurysm, vascular malformations, and infections of the brain (Toronto Acquired Brain Injury Network 2005).

Given that ‘ABI’ is a loosely defined term, studies with an ‘ABI’ population can be equally vague in terms of the sample composition. Such studies may include any combination of persons with TBI, diffuse cerebrovascular events (i.e., subarachnoid hemorrhage) or diffuse infectious disorders (i.e., encephalitis or meningitis). Most individuals with ABI have a traumatic etiology; therefore, much of the brain injury literature is specific to TBI. 

For the purposes of this evidence-based review, we used the definition of ABI employed by the Toronto Acquired Brain Injury Network (2005). ABI is defined as damage to the brain that occurs after birth and is not related to congenital disorders, developmental disabilities, or processes that progressively damage the brain (Table 1.1). For inclusion in ERABI, the study population must have had ≥50% ABI (as defined in Table 1) or the study independently reports on a subset of participants with ABI. Further, the focus is on the efficacy of interventions for moderate to severe ABI; consequently, any studies dealing with mild forms of ABI were excluded.

Table: Defining Acquired Brain Injury

Included in ABI definition

Excluded from ABI definition

Traumatic Causes

  • Motor vehicle accidents
  • Falls
  • Assaults
  • Gunshot wounds
  • Sport Injuries

Non-traumatic Causes

  • Tumors (benign/meningioma only)
  • Anoxia
  • Subarachnoid hemorrhage (non-focal)
  • Meningitis
  • Encephalitis/encephalopathy (viral, bacterial, drug, hepatic)


  • Intracerebral hemorrhage (focal)
  • Cerebrovascular accident (i.e. stroke)
  • Vascular accidents
  • Malignant/metastatic tumors 

Congenital and Developmental Problems

  • Cerebral Palsy
  • Autism
  • Developmental delay
  • Down’s syndrome
  • Spina bifida with hydrocephalus
  • Muscular dystrophy

Progressive Processes

  • Alzheimer’s disease
  • Pick’s disease
  • Dementia
  • Amytrophic Lateral Sclerosis
  • Multiple Sclerosis
  • Parkinson’s disease
  • Huntington’s disease