Bedside quantitative electroencephalography improves assessment of consciousness in comatose subarachnoid hemorrhage patients

Abstract

Objective Accurate behavioral assessments of consciousness carry tremendous significance in guiding management, but are extremely challenging in acutely brain-injured patients. We evaluated whether EEG and multimodality monitoring parameters may facilitate assessment of consciousness in patients with subarachnoid hemorrhage. Methods A retrospective analysis was performed of 83 consecutively treated adults with subarachnoid hemorrhage. All patients were initially comatose and had invasive brain monitoring placed. Behavioral assessments were performed during daily interruption of sedation and categorized into three groups based on their best examination as (1) comatose, (2) arousable (eye opening or attending towards a stimulus), and (3) aware (command following). EEG features included spectral power and complexity measures. Comparisons were made using bootstrapping methods and partial least squares regression. Results We identified 389 artifact-free EEG clips following behavioral assessments. Increasing central gamma, posterior alpha, and diffuse theta-delta oscillations differentiated patients that were arousable from those in coma. Command following was characterized by a further increase in central gamma and posterior alpha, as well as an increase in alpha permutation entropy. These EEG features together with basic neurological examinations (e.g., pupillary light reflex) contributed heavily to a linear model predicting behavioral state while brain physiology measures (e.g., brain oxygenation), structural injury, and clinical course added less. Interpretation EEG measures of behavioral states provide distinctive signatures that complement behavioral assessments of patients with subarachnoid hemorrhage shortly after the injury. Our data support the hypothesis that impaired connectivity of cortex with both central thalamus and basal forebrain underlies decreasing levels of consciousness.

Acute EEG spectra characteristics predict thalamic atrophy after severe TBI

“…Because of its low cost and ease of use at the bedside, continuous electroencephalography (EEG) has become widely performed to measure electrical brain activity and to monitor neurological status of patients with severe brain injury 1. Nonetheless, the exact relationship tying spontaneous electroencephalographic activity recorded acutely after traumatic brain injury (TBI), the unfolding of secondary brain damage processes in the subacute and chronic settings,2 3 and functional outcome remains poorly understood.…”

“…Nonetheless, the exact relationship tying spontaneous electroencephalographic activity recorded acutely after traumatic brain injury (TBI), the unfolding of secondary brain damage processes in the subacute and chronic settings,2 3 and functional outcome remains poorly understood. The present study begins bridging this gap, adopting a multimodal approach combining EEG spectral analysis,1 magnetic resonance (MR)-based measures of brain pathology2 3 and clinical outcome at 6 months. Specifically, we perform three analyses: (1) we assess the relationship between acute EEG spectral features and 6-month outcome; (2) we assess the relationship between acute EEG spectral features and subcortical atrophy over the first 6 months postinjury; and (3) we bring together EEG, MRI and other covariate variables in a multimodal analysis predicting 6-month outcome.…”

Deep structural brain lesions associated with consciousness impairment early after haemorrhagic stroke

“…This study has several limitations. First, assessment of consciousness relied on a previously described, standardized neurological assessment [17] instead of a scale specifically developed for the assessment of consciousness such as the Coma Recovery Scale Revised (CRS-R) [34]. However, the CRS-R has some limitations in the ICU setting as it was primarily developed for patients in the subacute and chronic rehabilitation setting.…”

“…We assessed level of consciousness daily from ICU admission to 30 days post-injury or hospital discharge, whichever was sooner. As described previously [17], behavioural assessments of consciousness were performed during morning rounds. These consisted of protocolized, hierarchical assessments categorizing consciousness into three levels of behavioural states: (1) “comatose” (no response to stimulation), (2) “arousable” (opening eyes and/or attending to stimulation), or (3) “conscious” (following simple commands; e.g., “show me two fingers”).…”

“…In addition to the above outlined protocol of stopping sedation for all behavioural assessments we collected the cumulative doses of all sedative medications administered within the two elimination half-lives preceding clinical assessments. [17].…”