EEG spindles integrity in critical care adults. Analysis of a randomized trial

Abstract

Objectives Occurrence of EEG spindles has been recently associated with favorable outcome in ICU patients. Available data mostly rely on relatively small patients' samples, particular etiologies, and limited variables ascertainment. We aimed to expand previous findings on a larger dataset, to identify clinical and EEG patterns correlated with spindle occurrence, and explore its prognostic implications. Methods Retrospective observational study of prospectively collected data from a randomized trial (CERTA, NCT03129438) assessing the relationship of continuous (cEEG) versus repeated routine EEG (rEEG) with outcome in adults with acute consciousness impairment. Spindles were prospectively assessed visually as 12‐16Hz activity on fronto‐central midline regions, at any time during EEG interventions. Uni‐ and multivariable analyses explored correlations between spindles occurrence, clinical and EEG variables, and outcome (modified Rankin Scale, mRS; mortality) at 6 months. Results Among the analyzed 364 patients, spindles were independently associated with EEG background reactivity (OR 13.2, 95% CI: 3.11–56.26), and cEEG recording (OR 4.35, 95% CI: 2.5 – 7.69). In the cEEG subgroup (n=182), 33.5% had spindles. They had better FOUR scores (p=0.004), fewer seizures or status epilepticus (p=0.02), and lower mRS (p=0.02). Mortality was reduced (p=0.002), and independently inversely associated with spindle occurrence (OR 0.50, CI 95% 0.25–0.99) and increased EEG background continuity (OR 0.16, 95% CI: 0.07 – 0.41). Conclusions Besides confirming that spindle activity occurs in up to one third of acutely ill patients and is associated with better outcome, this study shows that cEEG has a higher yield than rEEG in identifying them. Furthermore, it unravels associations with several clinical and EEG features in this clinical setting.

Continuous versus Routine Electroencephalography in the Intensive Care Unit: A Review of Current Evidence

“…Of relevance, in a diagnosis-related group reimbursement system (which is common to many European countries, but also beyond) cEEG does not significantly generate more costs [ 68 ], unlike in the USA [ 5 ], and thus does not represent any financial incentive. Considering prognostic EEG features, cEEG allows, in comparison to rEEG, a significant increased detection not only of ictal events but also of generalized rhythmic delta [ 69 ] and sleep spindles [ 70 ], which are both related to favorable prognosis. On the other hand, EEG background frequency, continuity, and reactivity (if performed during the recording) are readily assessable in rEEG [ 69 ].…”

Diagnostic and prognostic EEG analysis of critically ill patients: A deep learning study

“…Therefore, we compared the network output with the EEG given as input. Visual examination of epochs classified with high confidence confirmed the presence of features used also by human specialists, such as a continuous rhythmic background ( Beuchat et al, 2021 , Hofmeijer et al, 2015 , Westhall et al, 2016 ), sleep spindles ( Vassallo et al, 2021 ), G-RDA ( Beuchat et al, 2021 ) in epochs classified as favorable outcome; or such as suppressed background and burst-suppression ( Hofmeijer et al, 2015 , Ruijter et al, 2019 , Westhall et al, 2016 ), or epileptiform activity ( Zafar et al, 2021 ) in epochs classified as unfavorable outcome.…”

“…Most studies using computational methods for EEG-based prognostication in the ICU are conducted on homogeneous groups, typically on patients with HIE ( Beudel et al, 2014 , Tzovara et al, 2016 , Zubler et al, 2017 , Tjepkema-Cloostermans et al, 2017 , Tjepkema-Cloostermans et al, 2019 , Jonas et al, 2019 , Alnes et al, 2021 ). Only a handful have been conducted on patients with impaired consciousness of various etiologies, using predefined visual ( Müller et al, 2020 , Zhang et al, 2011 , Vassallo et al, 2021 , Kang et al, 2015 , Selioutski et al, 2019 ) or quantitative ( You et al, 2018 , Zubler et al, 2016 ) or mixed ( Zafar et al, 2021 ) features. To the best of our knowledge, it is the first time that DL is used for this task.…”

Continuous versus routine EEG in patients after cardiac arrest

“…On the other side, several aspects of EEG prognostication were not evaluated in the present study, such as identical bursts, time to a continuous background or to ictal-interictal continuum patterns, seizure burden, or sleep elements; these features may provide additional prognostic information and be more easily available from cEEG. 48 One of the study strengths is the randomized allocation to the EEG recording length; also, the multicenter design supports generalizability to other clinical cohorts. All data were prospectively acquired using standardized and pre-defined measures, which underscores its internal validity.…”