Rationale and objective: Traumatic brain injury (TBI) is one of the leading causes of death and invalidity in young people, making it a large problem for the public health. Patients with TBI admitted to the intensive care unit (ICU) are often sedated and ventilated, which makes clinical evaluation unreliable. In addition, after the initial event, various processes may result in secondary brain injury. Secondary brain damage is detrimental but could (possibly) be prevented, though only in a very short time window. Therefore early detection of clinical deterioration and early prognostication are needed. Early prognosis could also help in determining the further treatment and in informing the family about the prospects of the patient. TBI is very heterogenic in both cause and pathology making it hard to find prognostic parameters present in all patients. During this study the use of continuous electroencephalogram (cEEG) in early prognostication and early detection of deterioration and/or improvement of clinical status in patients with moderate or severe TBI is investigated. For clinical application, quantitative analysis is necessary to reduce time-consuming visual analysis of cEEG measurements and to allow evaluation by non-trained personnel.

Methods: Within 12 hours after admission to the intensive care unit (ICU) cEEG measurements were started in 21 patients with TBI. From these cEEG measurements quantitative EEG (qEEG) were calculated. The qEEG features determined were; power, relative powers, amplitude, alpha delta ratio (ADR), power ratio index (PRI), center of gravity (COG), brain symmetry index (BSI), spectral edge frequency (SEF) and infra slow activity (ISA). These features and intracranial pressure (ICP), the Glasgow coma score (GCS), the FOUR-score and admission data including age and gender were correlated with outcome. Outcome was defined as poor for non-survivors and good for survivors.

Results: The median amplitude of the first 24 hours was significantly different between non-survivors and survivors (p<0.05). A threshold of 10µV had a sensitivity of 18% and a specificity of 100% for predicting poor outcome, a threshold of 18µV had a sensitivity of 70% and a specificity of 82% for predicting good outcome. ICP measures were negatively correlated with power but did not discriminate between poor and good outcome.

Conclusions: We showed that measuring cEEG in TBI patient within 12 hours after the occurrence of the trauma is feasible. The median of the amplitude over 24 hours was significantly different between survivors and non-survivors. Median amplitudes lower than 10µV were only found in non-survivors. Mean values for other qEEG features did not differ between non-survivors and survivors but trends within patients did give information about clinical deterioration of a patient. Single features should be combined in order to be more predictive.

Keywords: Traumatic brain injury (TBI), continuous electroencephalography (cEEG), quantitative electroencephalography (qEEG), intracranial pressure (ICP)

Wednesday 4 February 2015, 16:30 - 17:30 h

Building Carré - room CR 3.718