Brain Injury Severity: PTA and GCS Explained

Brain injury severity: PTA and GCS explained

Somewhere in a hospital file is a number that will shape the next forty years of a person’s life, and almost no family knows to ask for it.

Two numbers, in fact. The Glasgow Coma Scale score recorded when the person arrived, and the duration of post-traumatic amnesia. Together they classify the severity of a traumatic brain injury — and in Australia, that classification does more than predict recovery. It determines eligibility for the state lifetime care schemes, which fund support at a level the NDIS frequently does not.

The NSW Lifetime Care and Support Scheme, for instance, uses post-traumatic amnesia lasting more than one week as its brain injury threshold. A person with six days of PTA and a person with eight days have very different financial futures.

This guide explains what the measures are, how they are used, and what to ask for.

The Glasgow Coma Scale

The GCS is the standard measure of conscious level, used worldwide since the 1970s. It scores three things and adds them together:

Eye opening (1–4): spontaneously, to speech, to pain, or not at all.

Verbal response (1–5): oriented conversation, confused conversation, inappropriate words, incomprehensible sounds, or none.

Motor response (1–6): obeys commands, localises pain, withdraws from pain, abnormal flexion, extension, or none.

The total runs from 3 — no response at all on any scale, which is the lowest possible score rather than zero — to 15, fully alert and oriented.

The GCS is quick, reliable between different assessors, and genuinely useful in the first hours. It also has real limitations that are worth knowing, because families sometimes attach more weight to it than it can bear.

It is a snapshot. A GCS taken at the roadside, in the ambulance, at the emergency department door and after two hours of resuscitation can be four different numbers. The one recorded in the notes may be any of them. It is also distorted by alcohol, drugs, sedation and intubation — a person who has been sedated and ventilated cannot produce a verbal score at all, so the GCS becomes uninterpretable. And it says nothing about where the damage is: a brainstem injury and a frontal injury can produce identical scores and entirely different lives.

Post-traumatic amnesia

PTA is the more useful measure for predicting long-term outcome, and it is the one families least often understand.

Post-traumatic amnesia is the period after a traumatic brain injury during which a person is not laying down continuous day-to-day memory. They are awake. They may be talking, walking, eating, apparently holding conversations. But they are not forming memories, they are disoriented, and their behaviour is frequently disinhibited.

PTA ends when the person becomes consistently oriented and begins forming continuous memories again. The clinical description, from the NSW Agency for Clinical Innovation, is a stage of recovery in which orientation, day-to-day memory and behaviour are impaired, lasting anywhere from minutes to many months.

What families actually see

This is the part worth preparing for, because it is distressing and it is almost always misread.

During PTA, people commonly:

• Ask the same question repeatedly, having no recollection of asking it
• Are confused and disoriented about where they are and what has happened
• Are distressed, agitated or frightened
• Swear, lash out, or behave in a sexually disinhibited way that is entirely out of character
• Fail to recognise familiar people, including close family
• Have no awareness of their injuries
• Wander, sleep at the wrong times, and tire extremely quickly
• Cannot tolerate light or noise
• Are unusually passive, or unusually and indiscriminately friendly

Not all of these appear in any one person, and a single one can indicate PTA.

Two things to hold on to. This is a phase, not an outcome. Families who watch a relative swear at them, hit a nurse and fail to recognise their own children routinely conclude that this is who the person now is. In the great majority of cases it is not. And the person will not remember any of it, which means there is no point in reasoning, arguing or being embarrassed on their behalf. The distress during PTA belongs almost entirely to the people watching.

What helps during PTA: one visitor at a time, a quiet dark room, short visits, consistent staff, a calm low-stimulus environment, no quizzing, and no attempt to orient someone repeatedly who cannot retain the information. Follow the ward’s guidance, which will be deliberately restrictive about visitors for exactly this reason.

The Westmead PTA Scale

PTA duration is measured rather than guessed, and the instrument used across Australia was developed at Westmead Hospital in Sydney.

The Westmead PTA Scale is used for moderate to very severe TBI. It asks a short set of orientation questions and requires the person to recall three pictures, administered daily. PTA is considered to have ended when the person scores perfectly — full orientation plus recall of all three pictures — on consecutive administrations.

The Abbreviated Westmead PTA Scale (A-WPTAS) is used in emergency departments for mild TBI, over a much shorter window.

If your relative is in a brain injury unit, the Westmead Scale is almost certainly being administered. Ask for the date PTA was assessed as having ended, and ask for it in writing, because that date is the one the compensation schemes care about.

The severity categories

Combining the two measures, Australian clinical practice uses roughly these bands:

Different sources draw the GCS boundaries slightly differently — some place mild at 12–15 and moderate at 9–11 — and the ACI notes that these cut-offs reflect Australasian clinical practice, with newer research suggesting different values and no clear consensus yet. Classification needs clinical judgment rather than arithmetic.

Coma duration tracks alongside both. Coma of seconds to minutes generally means PTA of hours to days and recovery plateauing over weeks. Coma of hours to days means PTA of days to weeks and recovery over months. Coma lasting weeks means PTA lasting months and recovery over months to years.

What severity predicts, and what it doesn’t

It predicts, broadly: how long recovery will take, and how much impairment is likely to remain once the rate of change slows. PTA of more than a week generally means ongoing cognitive problems should be expected.

It does not predict which problems a person will have. That depends on where the damage is. Two people with four weeks of PTA can have entirely different profiles — one with severe memory impairment and intact behaviour, one the reverse.

Some additional factors that shape outcome:

Diffuse axonal injury — widespread shearing of nerve fibres, typical of high-speed deceleration — recovers more slowly than focal contusions.

Hypoxic injury on top of trauma makes recovery less complete.

Needing neurosurgery does not by itself mean a worse outcome, which surprises families.

Age, pre-injury function, education, substance use and social support all affect the trajectory, and the last of those is the one most amenable to influence.

Why this matters for money

Here is the part that makes severity classification worth understanding rather than merely interesting.

NSW Lifetime Care and Support Scheme. The brain injury criterion is a motor accident injury with post-traumatic amnesia lasting more than one week, plus a functional score requirement — for people over 8, a score of 5 or less on any item of the Functional Independence Measure as a result of the injury. Where PTA cannot be assessed, such as in children under 8 or penetrating injuries, the alternative is coma for over an hour from a very significant head impact, or a significant abnormality on brain imaging.

Queensland’s NIISQ covers serious personal injury from a motor vehicle accident in Queensland, regardless of fault, with its own severity criteria.

Victoria’s TAC, and workers compensation schemes in each state, have their own thresholds for catastrophic injury.

So: PTA duration is not a clinical curiosity. For someone injured in a motor vehicle accident, it is the number that may decide whether their care is funded by a lifetime scheme or by the NDIS — and the lifetime schemes are generally more generous, are not subject to the NDIS price limits, and cover treatment as well as support.

The practical consequences:

Get the PTA duration documented. Ask the treating team for the Westmead PTA Scale result and the date PTA ended, in writing. Do this while the person is an inpatient, because reconstructing it later is difficult and sometimes impossible.

Get the GCS, the imaging report and the discharge summary. Request copies of the medical records rather than relying on them being available later.

Note the time limits. A NSW Lifetime Care interim application must be made within three years of the accident, and the scheme can only extend that with a full and satisfactory explanation for the delay.

Do not accept an informal severity label. “He had a nasty bang on the head” is not a classification. If the file says moderate and the PTA was eleven days, that discrepancy is worth raising, because it may be the difference between two funding systems.

We go through the schemes in detail in compensation schemes and brain injury.

Severity measures for non-traumatic injury

Everything above applies to traumatic brain injury. For the non-traumatic causes, GCS and PTA are less useful or not applicable, and different measures get used — which matters because the compensation scheme criteria are built around traumatic injury and leave other causes relying on the NDIS.

Hypoxic and anoxic injury — cardiac arrest, drowning, overdose, strangulation. Severity relates to how long the brain was without adequate oxygen and how quickly circulation was restored. The usual markers are the duration of the arrest, the time to return of spontaneous circulation, whether therapeutic hypothermia was used, and findings on MRI and EEG. These injuries are typically diffuse, so the profile tends to involve memory, attention and coordination together rather than one focal deficit, and recovery is often less complete than a focal injury of comparable apparent severity.

Disorders of consciousness are classified separately, and the distinctions are clinically and ethically important: coma, where there is no arousal and no awareness; the vegetative state or unresponsive wakefulness syndrome, where sleep-wake cycles return without evidence of awareness; and the minimally conscious state, where there is inconsistent but reproducible evidence of awareness. Measures such as the Coma Recovery Scale–Revised are used to distinguish them, and misdiagnosis rates in this area have historically been high — which is an argument for specialist assessment rather than a bedside judgment.

Infection and tumour are assessed on the imaging, the clinical course and subsequent neuropsychological profile rather than on any single severity score.

Alcohol-related brain injury has no acute severity measure at all, because there is no single event to measure — one reason it is so badly under-recognised. See alcohol-related brain injury.

For all of these, the neuropsychological assessment becomes the primary document rather than the acute severity score, because it describes what is actually impaired. That is also the document the NDIS needs.

A caution about mild injury

Mild TBI — GCS 13 to 15, PTA under 24 hours — is by far the most common category, and it carries a specific trap.

Most people with a mild TBI recover fully within days to weeks. A minority do not, and they are poorly served, because their injury is officially mild and their symptoms are real: persisting headache, fatigue, poor concentration, memory lapses, irritability, light and noise sensitivity, dizziness, and low mood.

Those people are frequently told there is nothing wrong, because imaging is normal and the injury was classified as mild. “Mild” describes the acute injury, not the consequences. Someone whose life has been disrupted for eight months by a mild TBI deserves assessment and management rather than reassurance.

Two things that genuinely help: early, graded return to activity rather than prolonged rest, and a neuropsychological assessment where symptoms persist beyond about three months. And if the person has had repeated mild injuries — contact sport, assaults, domestic violence — that cumulative history belongs in the record, because the risks of repeated concussion are taken far more seriously now than they were.

What severity does not decide

Two things worth saying before the questions, because families fix on the severity label and draw conclusions it cannot support.

It does not decide how much support someone needs. Support need is driven by the pattern of impairment, not its overall magnitude. A person with very severe injury, dense physical disability and intact cognition and behaviour may be straightforward to support: they know what they need and can direct it. A person classified moderate, who walks and talks normally but has no insight, poor impulse control and no capacity to organise a day, may need far more — and will be far harder to fund, because none of it shows.

It does not decide what the person is capable of. Outcome correlates with severity across a population and predicts an individual poorly. Pre-injury function, education, age, substance use, mental health, the intensity of rehabilitation and the quality of the support around someone all move the result, and the last two are the ones anybody can influence.

The useful way to hold the severity label: it tells you roughly how long to expect recovery to take and how much impairment may remain, it determines which funding door you may be able to open, and it tells you almost nothing about who this person will be in five years.