Abstract
Survivors of severe brain injury may remain in a decreased state of conscious awareness for an extended period of time. Clinical scales are used to describe levels of consciousness but rely on behavioural responses, precipitating misdiagnosis. We have previously utilized event-related potentials (ERPs) to circumvent reliance on behavioural responses. However, practical implementation barriers limit the clinical utility of ERP assessment at point-of-care (POC). To address this challenge, we developed the Halifax Consciousness Scanner (HCS)—a rapid, semi-automated electroencephalography system. The current study evaluated: (i) HCS feasibility in sub-acute, POC settings nationwide; (ii) ERP P300 responses in patients with acquired brain injury versus healthy controls; and (iii) correlations within and between clinical measures and P300 latencies. We assessed 28 patients with severe, chronic impairments from brain injuries and contrasted the results with healthy control data (n = 100). Correlational analyses examined relationships between P300 latencies and the commonly used clinical scales. P300 latencies were significantly delayed in patients compared to healthy controls (P < 0.05). Clinical assessment scores were significantly inter-correlated and correlated significantly with P300 latencies (P < 0.05). In sub-acute and chronic care settings, the HCS provided a physiological measure of neurocognitive processing at POC for patients with severe acquired brain injury, including those with disorders of consciousness.
Highlights
After serious neurological injury, patients may die, remain in coma or awaken as evidenced by eye opening
In sub-acute and chronic care settings, the Halifax Consciousness Scanner (HCS) provided a physiological measure of neurocognitive processing at POC for patients with severe acquired brain injury, including those with disorders of consciousness
It was hypothesized that: (i) patient P300 latencies would be delayed relative to healthy control normative data; (ii) that the Glasgow Coma Scale (GCS), Coma Recovery Scale-R (CRS-R) and Functional Independence Measure (FIM) (Keith et al 1987) clinical scales would be significantly inter-correlated; and (iii) patient P300 latencies would be significantly correlated with the above clinical scales, demonstrating an important relationship with functional impairment
Summary
Patients may die, remain in coma or awaken as evidenced by eye opening. Medical complications and the related interventions often impede accurate evaluation of consciousness (Giacino et al 2013). Given these confounds, assessing a patient’s level of consciousness (LOC) too early may misinform clinical decision-making at the top of the critical care cascade. Many patients may truly be incapable of functional information processing but in some cases, consciousness gradually recovers. This cognitive recovery can happen with or without the development of motor capacities and behavioural output. In view of this and the fact that subtle changes can go unnoticed in busy long-term care settings, Giacino et al (2014) stress the importance of an integrated system of care that responds to the needs of patients as they evolve
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