Post-Traumatic Amnaesia


Published: 27 August 2016

When an accident occurs and there is an impact to an individual’s head, their brain tissue can be damaged, resulting in a brain injury (Mauk 2012).

Primary injuries to the brain include cerebral contusions, lacerations and diffuse axonal injury, which can then be followed by secondary injuries such as cerebral oedema, hypotension, hypoxia and electrolyte imbalances (Chua et al. 2007; Mauk 2012).

At the time of the injury - in addition to losing consciousness and experiencing various other symptoms of brain injury - the individual might also experience post-traumatic amnesia (PTA).

After stroke, the second largest causes of brain injury are accidents and trauma. Brain injuries caused by trauma are known as a traumatic brain injuries (TBIs) (Brain Injury Australia 2020). Nearly half of all TBIs are caused by falls, one in three are from a motor vehicle accident, and one in six are from an assault (AIHW 2008). With over 700,000 Australians suffering from brain injury, it is important to raise awareness of the causes and consequences (Brain Injury Australia 2020).

What is Post-traumatic Amnaesia?

PTA is defined as "the period of time in which the brain is unable to lay down continuous day-to-day memories" (Khan et al. 2003). During this time, a individual with the TBI may be disorientated and unable to connect memories or events. For example, they may engage in conversation but then forget they have spoken to someone, or they may have breakfast and then forget they have eaten. There may also be long-term memory loss, including no recollection of the accident itself (MSKTC 2016).

PTA Assessment

In Australia, the most common way to assess PTA is by using the Westmead PTA Scale (Khan et al. 2003). The Westmead Scale was developed in the 1980’s to fill a gap in the assessment tools used to determine the presence of PTA in patients (Shores et al. 1986). It is a brief bedside tool that consists of 12 questions posed to the patient to assess their orientation to person, place and time, as well as their ability to consistently retain new information from one day to the next. It is completed every day until the patient achieves a perfect score for three consecutive days. When this occurs, they are deemed out of PTA.

Post-Traumatic Amnaesia

PTA and Classification of Brain Injury

PTA duration can be a predictor of outcomes in patients with a TBI. A PTA duration of over 24 hours can be indicative of a severe TBI, and a PTA of more than four weeks can often be a sign of a very severe brain injury (Chua et al. 2007). The duration of PTA can predict the presence of any chronic cognitive deficits, the development of psychiatric disorders,and the ability of the individual to return to work (Chua et al. 2007). It is a long recovery for someone who has experienced a TBI. Generally, if an individual has PTA for over three weeks, they can expect to still have cognitive deficits a year after their injury first occurred (Chua et al. 2007).

The severity of a TBI ranges from concussion through to someone who is in a persistent vegetative state. There are three classifications of brain injury, which depend on the length of timeloss of consciousness (LOC), the length of PTA and the mechanism of the injury. These are:

Mild Brain Injury

  • Less than twenty minutes LOC or no LOC at all;
  • Mild PTA;
  • Glasgow coma scale (GCS) score of more than 13;
  • Usually negative results from any imaging or scans and;
  • Symptoms including headache, dizziness, fatigue, irritability and concentration and memory disturbances.

Moderate brain injury

  • More than twenty minutes LOC;
  • PTA present;
  • GCS score of 9 to 12;
  • Cerebral oedema and hemorrhages; and
  • Symptoms including disturbed balance and co-ordination, agitation, seizures and speech disturbances.

Severe brain injury

  • LOC of more than six hours;
  • Prolonged PTA;
  • GCS of less than eight; and
  • There can be intercranial or subdural haemorrhage, tearing and/or penetration of brain tissue by a foreign object.

(Mauk 2012)

As well as the length of time in PTA being a predictor of outcomes, certain pre-existing factors have also been found to be linked to worse outcomes following a TBI, including:

  • A history of previous head injury;
  • Alcohol and drug abuse; and
  • Lower socio-economic and educational status.

(Chua et al. 2007)

Nursing the Patient in PTA

Every patient with a TBI who experiences PTA will be different, so different strategies will need to be implemented for different individuals. When a patient is experiencing PTA, it is important for the nurse to ensure they provide a safe environment and respond to the patient's physical needs (Mauk 2012). Some strategies to use while the patient is experiencing PTA include:

  • Explaining to the individual what you are going to be doing;
  • Speaking in a normal tone of voice;
  • Keeping comments and questions short and simple;
  • Re-orientating the individual to time, person, place and situation;
  • Limiting the number of visitors in the room to two to three people at a time;
  • Keeping the room calm and quiet;
  • Allowing the person extra time to respond;
  • Giving the patient regular rest periods;
  • Reassuring them they are safe;
  • Taking extra precautions for patient and personal safety if the patient is agitated;
  • Refraining from forcing the patient to do things; and
  • Repeating things as needed - do not expect the patient will remember what you told them.

(Mauk 2012)

The patient's family must also be included in their care and informed about treatment plans. This can be a very distressing time for family members and loved ones, therefore, it is important they are kept informed of what their loved one is going through and understand that recovery can be a slow and long process.

Additional Resources