Post Traumatic Amnesia (PTA)
Post Traumatic Amnesia (PTA) is a stage of recovery following a traumatic brain injury. On emerging from a loss of consciousness, the patients orientation and memory for ongoing events is poor. PTA can last for hours, days or weeks depending upon the severity of the brain injury. PTA has been shown to be the best predictor of cognitive-behavioural-social dysfunction.
PTA Score | Severity |
1-4 hours | Mild brain injury |
<= 1 day | Moderate brain injury |
2-7 days | Severe brain injury |
1-4 weeks | Very severe brain injury |
1-6 months | Extremely Severe Brain Injury |
> 6 months | Chronic amnesia state |
Table 1: Scale used by the NSW Brain Injury Rehabilitation Program (BIRP) to assess the severity of brain injury for the purpose of admission.
There are various tools used to measure PTA. In Australia, the most widely used screening tool is the Westmead PTA Scale, developed by Shores et al and published in 1986. The Westmead PTA Scale consists of 7 orientation questions and 5 memory items designed to objectively measure the period of PTA. The Westmead PTA Scale is a standardised and prospective measure of PTA. A person is said to be out of PTA if they can achieve a perfect score on the Westmead PTA Scale for 3 consecutive days. More information is available on the Westmead PTA Scale website.
A modified version of the Westmead PTA Scale was developed by Ponnsford et al in Melbourne and published in 2004 to test the PTA status in mild head injured patients in the Emergency Department. The modified scale tests 10 items every hour. Testing is ceased after 3 consecutive hours of achieving a score of 10/10. This tool assists clinicians in rapidly identifying those patients who may require admission or outpatient follow-up despite a GCS of 15 and a normal CT scan and also the appropriate timing of dicharge of patients from the Emergency Department. This modified Westmead PTA Scale is currently being trialled in various Emergency Departments in Sydney showing early promising results.
Information Sheets for patients on PTA and other head injury related topics are available on the NSW Brain Injury Rehabilitation Program website.
References:
Shores EA., Marosszeky JE., Sandanam J., Batchelor J. Preliminary validation of a clinical scale for measuring the duration of post-traumatic amnesia. Medical Journal of Australia. 144(11):569-72, 1986 May 26.
Ponsford J., Willmott C., Rothwell A., Kelly AM., Nelms R., Ng KT. Use of the Westmead PTA Scale to Monitor Recovery of Memory after Mild Head Injury. Brain Injury. 18(6): 603-614, June 2004.