Learn how to calculate the length of post-traumatic amnesia (PTA) using the Westmead PTA Scale.
The duration of PTA is calculated from the date of the traumatic brain injury. It is not calculated from the day when PTA testing first started. If the patient experienced coma, it will include this period.
The end date for PTA calculation is the first of 3 consecutive days of scores of 12 out of 12. It is not the last day that the PTA test was administered.
When PTA duration is difficult to determine
The patient scores perfect scores from the first day of testing, i.e. 7, 12, 12, 12
In this case, it is not possible to accurately identify the duration of PTA based on the Westmead PTA Scale. However, you know the patient’s duration of PTA does not exceed the number of days from injury to the first of the 3 consecutive scores of 12 out of 12. Other clinical observations may allow an estimation of the duration of PTA.
The patient emerged from PTA but subsequently deteriorates
The initial PTA duration, as determined by relevant testing at the time, should be recorded in the medical notes. Use clinical judgement to establish whether a new TBI has occurred (requiring PTA testing to restart) or the presentation is due to a non-TBI health condition.
Extended period of interrupted testing, after which the patient is no longer in PTA
In this case, it is not possible to accurately identify the duration of PTA based on the Westmead PTA Scale. However, you know the patient’s duration of PTA is longer than when testing stopped, but shorter than when testing restarted.
Recording results in the medical record
It is crucial that the results of PTA testing, and the accurate period of PTA, is recorded in the patient’s medical record.
Hospitals and medical systems will have different requirements and methods regarding medical records. This is particularly true with the move to electronic medical records, where different systems will have a range of features, requirements and auto-population capabilities.
Recommended information to be recorded:
- Each day, record the date and the patient’s Westmead PTA Scale score.
- Make very clear the first, second and third days of achieving consecutive 12 out of 12 scores. End with confirmation that the first of these 3 dates constitutes the date the patient is considered to have emerged from PTA on the Westmead PTA Scale.
- A clear statement regarding the length of PTA.
- Make a referral to the medical team, a brain injury rehabilitation team or a neuropsychologist to confirm PTA status and decisions regarding next steps for management.