Explainers

Post-Traumatic Amnaesia


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 the individual losing consciousness and various other symptoms of a brain injury, they also may experience post-traumatic amnaesia, or PTA.

Recently it was Brain Injury Awareness Week. The second largest cause of brain injury in people following stroke is from accidents or trauma, and commonly called a traumatic brain injury, or TBI (Brain Injury Australia 2016). 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 (Brain Injury Australia 2016). With over 700,000 Australians suffering from brain injury, it is important to raise awareness of the causes and consequences.

What is PTA?

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, the 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 permanent memory loss, including no recollection of the accident or the events leading up to it (Acquired Brain Injury 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 twelve 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 twenty four 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 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 time, loss 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 post-traumatic amnaesia
    • Glasgow coma scale (GCS) score of more than thirteen
    • Usually negative results from any imaging or scans
    • Symptoms can include headache, dizziness, fatigue, irritability and concentration and memory disturbances
  • Moderate brain injury
    • More than twenty minutes LOC
    • PTA present
    • GCS score of nine to twelve
    • Cerebral oedema and haemorrhages
    • Symptoms of 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
    • There can be intercranial or subdural haemorrhage, tearing and/or penetration of brain tissue by a foreign object

(Mauk 2012)

As well as 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 a previous head injury
  • Alcohol and drug abuse
  • 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 therefore 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 their physical needs (Mauk 2012). Some strategies to use while the patient is experiencing PTA include:

  • Explain to the individual what you are going to be doing
  • Speak in a normal tone of voice
  • Keep comments and questions short and simple
  • Re-orientate the individual to time, person, place and situation
  • Limit the number of visitors in the room to two-three people at a time
  • Keep the room calm and quiet
  • Allow the person extra time to respond
  • Give the patient regular rest periods
  • Reassure them they are safe
  • If the patient is agitated, you may need to take extra precautions for patient and personal safety
  • Do not force them to do things
  • Repeat 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 be informed of 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 that recovery can be a slow and long process.

(For further reading see Rehabilitative Care of a Patient Following Polytrauma)

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