The Glasgow Outcome Scale (GOS) and Catastrophic Brain Injury in Ontario
- Apr 15
- 5 min read
For adults in Ontario, traumatic brain injury may meet the catastrophic impairment definition under paragraph 4 of section 3.1(1) of the Statutory Accident Benefits Schedule where there are positive traumatic intracranial imaging findings and the individual later meets one of the specified outcome levels on the Glasgow Outcome Scale or Extended Glasgow Outcome Scale (GOS/GOSE) at the required timepoint.
At a basic level, the test comes down to two things:
whether there is objective evidence of a traumatic brain injury, and
how the person is able to function over time
This is one of several pathways to catastrophic impairment in Ontario.
When Does a Brain Injury Meet the Catastrophic Threshold?
For adults, a brain injury may meet the catastrophic impairment definition where:
there are positive findings of traumatic intracranial pathology on imaging, and
the individual meets one of the required GOS or GOSE outcome levels at specific timepoints after the accident
For a broader explanation of how catastrophic impairment is assessed, see our page on catastrophic injury claims.
The Current Adult Traumatic Brain Injury Criterion Under Ontario’s SABS
Traumatic brain injuries are addressed in paragraph 4 of section 3.1(1) of Ontario’s Statutory Accident Benefits Schedule.
Under the regulation:
“If the insured person was 18 years of age or older at the time of the accident, a traumatic brain injury that meets the following criteria:i. The injury shows positive findings on a computerized axial tomography scan, a magnetic resonance imaging or any other medically recognized brain diagnostic technology indicating intracranial pathology that is a result of the accident, including, but not limited to, intracranial contusions or haemorrhages, diffuse axonal injury, cerebral edema, midline shift or pneumocephaly.ii. When assessed in accordance with Wilson, J., Pettigrew, L. and Teasdale, G., Structured Interviews for the Glasgow Outcome Scale and the Extended Glasgow Outcome Scale: Guidelines for Their Use, Journal of Neurotrauma, Volume 15, Number 8, 1998, the injury results in a rating of, A. Vegetative State (VS or VS*), one month or more after the accident, B. Upper Severe Disability (Upper SD or Upper SD*), or Lower Severe Disability (Lower SD or Lower SD*), six months or more after the accident, or C. Lower Moderate Disability (Lower MD or Lower MD*), one year or more after the accident.”
What This Means in Practice
In practice, there are really two parts to this test.
1. Objective Brain Injury Evidence
There must be positive imaging findings showing traumatic intracranial pathology.
That can include:
intracranial hemorrhage
diffuse axonal injury
cerebral edema
midline shift
If there are no qualifying imaging findings, this pathway usually is not available.
2. Outcome-Based Functional Assessment
The second part looks at how the person actually recovers over time. The regulation sets out three possible outcome levels:
Vegetative state at one month or more
Severe disability at six months or more
Lower moderate disability at one year or more
Of course, only extremely severe brain injuries will result in a vegetative state for longer than a month. Some individuals who sustained severe brain injuries will meet the test of a severe disability at the six month mark. However, the vast majority of claimants declared catastrophically impaired via criterion four are doing so after the one year mark by continuing to have a lower moderate disability.
What Is the Glasgow Outcome Scale?
The Glasgow Outcome Scale is used to assess overall recovery after a traumatic brain injury.
It looks at:
independence
ability to function
level of recovery
The categories include:
Good Recovery
Moderate Disability
Severe Disability
Vegetative State
Death
The Extended Glasgow Outcome Scale (GOSE) breaks these categories into more detailed levels, which is what is typically used in assessments.
How GOS and GOSE Assessments Are Performed
GOS and GOSE assessments are usually done through structured interviews designed to evaluate how a person is functioning in daily life.
In most cases in Ontario, these assessments are carried out by an occupational therapist. In some situations, the assessment could involve input from physicians, neuropsychologists, or other specialists.
The assessment is not based on a single examination. It usually involves:
detailed interviews about daily activities
questions about independence and supervision
assessment of work capacity and social functioning
review of medical and rehabilitation records
The GOSE is typically applied using a standardized interview framework, which is intended to bring consistency to how outcomes are classified. In many cases, the outcome turns on how the individual’s level of independence is described and interpreted within that framework.
The Genesis of Criterion Four
The current adult traumatic brain injury criterion came out of broader changes to Ontario’s catastrophic impairment framework.
Previously, a claimant was automatically declared catastrophically impaired if they presented with a Glasgow Coma Scale of nine or less immediately after the accident. Over time, concerns developed that the Glasgow Coma Score did not correlate well with individuals' long term disability.
What came out of that process is the test we have now, which combines:
structured, outcome-based assessment over time
The focus is now on long-term functioning and independence, rather than early presentation alone.
Time Requirements
Criterion four contains specific timepoints:
1 month
6 months
12 months
That reflects how brain injury recovery works. People often improve early on. The real issue is whether they recover to a level of independence, or plateau with ongoing limitations.
Common Areas of Dispute
In many cases, there is little dispute over whether a brain injury occurred. The dispute is over whether the individual meets the specified level of disability.
Common debates include:
whether the person is truly independent, or still requires supervision
how to interpret limitations in work capacity
whether difficulties are consistent or vary depending on context
how to classify individuals who function in some areas but struggle in others
Small differences in how these issues are assessed can determine whether the outcome falls within moderate or severe disability.
Why Many Brain Injury Cases Do Not Meet This Criterion
Not every serious brain injury meets the catastrophic impairment definition under this pathway.
This is often because:
there are no qualifying imaging findings, in most traumatic brain injury cases
the individual does not meet the required GOS or GOSE outcome level at the specified timepoint
the person is able to function independently, even with ongoing symptoms
As a result, many brain injury claims are assessed under other parts of the catastrophic impairment definition, or do not meet the threshold at all.
How These Cases Assessed
In practice, these cases are decided by looking at the full picture.
That usually includes:
imaging findings
clinical records
rehabilitation progress
functional assessments
The question is whether the person has regained meaningful independence, or whether they continue to rely on support in day-to-day life.
GOS vs Psychological Catastrophic Impairment
This pathway is different from the psychological pathway.
This test applies to physical brain injury with imaging findings
Criterion eight applies to mental or behavioural disorders
To learn more about how to be deemed catastrophic impaired pursuant to Criterion 8, read our guide on what constitutes a marked impairment of psychological function.
Real-World Context
We often see people who improve modestly in the first few months after a brain injury, but not to the point of full independent function. They may be independent in some areas, but struggle significantly in others. The question is whether that level of functioning meets the structured threshold set out in the regulation.
Timeline: When This Is Assessed
This is not decided right away. The regulation requires time to pass so that recovery can be properly assessed.
The focus is on long-term outcome, not early symptoms.
Frequently Asked Questions
Is a brain injury automatically catastrophic ?
No. The test requires both objective imaging findings and a qualifying GOS or GOSE outcome.
What role does imaging play?
It is necessary but not sufficient on its own. There must be evidence of traumatic intracranial pathology.
What outcomes qualify?
Vegetative state (after 1 month)
Severe disability (after 6 months)
Lower moderate disability (after 1 year)
Why is lower moderate disability included?
Because the regulation recognizes that long-term functional limitations may still meet the catastrophic threshold, even where some independence exists.
How is this different from marked impairment?
Criterion four applies to physical brain injury. Marked impairment applies to psychological conditions assessed across multiple domains.
