Post traumatic amnesia in children: sequence of recovery and prediction of outcome

Abstract

Traumatic brain injury (TBI) is a major cause of death and disability in childhood. Nevertheless, research in this area has predominately been among adults. This adult research has shown that early indicators of TBI severity are predictive of functional outcomes and critical to informing acute and ongoing rehabilitative care. The most commonly used indicators of TBI severity include depth and length of coma and duration of post-traumatic amnesia (PTA). Coma is measured in the moments immediately following the trauma. PTA refers to the period following emergence from coma where a person remains disoriented and amnesic for new events. PTA is typically assessed using a formal measure that involves serial testing from day to day where the patient is required to answer questions pertaining to their person, their current location and the time of day/month/year (referred to as the orientation subscale) and then questions relating to either immediate or delayed recall of facts and information they were provided with the day before (the memory subscale). Initially, testing of PTA is used to monitor patients’ cognitive recovery and guides inpatient rehabilitation. Several adult studies have shown that disorientation is generally resolved before amnesia. In contrast, to our knowledge, no published child studies have examined natural sequence of skills recovery during PTA. This is important, as differences in the level of brain maturity and skills mastery at the time of injury, and the timing of skills acquisition in normal development may influence natural sequence of skills recovery in children relative to adults. Moreover, very few studies have examined predictive validity of PTA duration for functional outcomes in children, with only one published study reporting on predictive validity of the most commonly used PTA scale in Australia and United Kingdom – the Westmead PTA Scale (WPTAS), which is the focus of this thesis. Chapter 1 provides a general introduction to traumatic brain injury, the types of ongoing impairments encountered and their relationship to injury severity indices. In Chapter 2, children’s natural sequence of skill recovery during PTA is examined in a cohort of 50 children aged 8 to 15 years consecutively admitted to Sydney Children’s Hospital with moderate to severe TBI (paper now published in Child Neuropsychology). Assessment of PTA was conducted with the WPTAS. Orientation to time took significantly longer to recover than orientation to person and place, but not memory. This sequence of recovery is similar to the sequence in which they are originally acquired in normal development, with orientation to time and memory emerging later than orientation to person and place in normal development. In Chapter 3, the existing literature on relations between PTA and functional outcomes is explored in a detailed, systematic review (now published in Developmental Medicine and Child Neurology). The review revealed ten papers, which showed that duration of PTA predicts short- and long-term functional outcomes (in intelligence, memory, emotional/behavioural functioning, self-care, mobility and global functioning) in children. Of the ten papers, only three compared PTA with other indices of TBI severity, with PTA the stronger predictor of functional outcome in more than 70% of case. The review also showed only one study to have directly examined the relationship between duration of PTA measured by the WPTAS and functional outcomes in school aged children, with the study restricted to prediction of global functional outcomes at discharge. Finally, Chapter 4 contains a study that examined the validity of the WPTAS for prediction of functional outcomes in a cohort of 55 consecutively admitted children aged 8 to 15 years consecutively admitted to Sydney Children’s Hospital with moderate to severe TBI whose PTA was measured by the WPTAS. Longer duration of PTA was strongly related to global and some specific (mobility, mood/behaviour, and cognition/memory/concentration) at the first outpatient follow up. Like in adults, PTA was also found to be a more reliable predictor of cognitive outcomes in children than GCS. In summary, in our studies we were (to our knowledge) the first to demonstrate the natural sequence of skill recovery during PTA and examine the re-acquisition of disrupted abilities during PTA using a developmental framework. In addition, our study showed the duration of PTA measured by the WPTAS is a good predictor of early functional outcomes in school-aged children.