Neurophysiological findings and their prognostic value in critical COVID-19 patients: An observational study

Abstract

Objective: To describe EEG patterns of critical Coronavirus Disease 2019 (COVID-19) patients with suspicion of encephalopathy and test their association with clinical outcome.

Methods: EEG after discontinuation of sedation in all patients, and somesthesic evoked potentials and brainstem auditive evoked potentials when EEG did not show reactivity, were performed. Clinical outcome was assessed at day 7 and 14 after neurophysiological explorations.

Results: 33 patients were included for analysis. We found slowed background activity in 85% of cases, unreactive activity in 42% of cases, low-voltage activity in 21% of cases and rhythmic or periodic delta waves in 61% of cases. EEG epileptic events were never recorded. Clinical outcome at day 14 was associated with unreactive background activity and tended to be associated with rhythmic or periodic delta waves and with low-voltage activity. Results of multimodal evoked potentials were in favor of a preservation of central nervous system somatosensory and auditory functions.

Conclusions: Among critical COVID-19 patients with abnormal arousal at discontinuation of sedation, EEG patterns consistent with encephalopathy are found and are predictive for short term clinical outcome.

Significance: The abnormal EEG with presence of periodic discharges and lack of reactivity could be related to encephalopathy linked to COVID-19.

Keywords: COVID-19; Electroencephalography; Encephalopathy; Evoked potentials; Neurophysiology.

Fig. 1

EEG selection and clinical outcome at day 7 and 14 after EEG. Abbreviation: ICU, intensive care unit.

Fig. 2

EEG pattern from two different patients. EEG recording performed with 21 scalp electrodes, a bipolar montage and epochs of 30 seconds. A. EEG recording showing periodic delta waves (Filter settings 0.53–70 Hz, amplitude 70 μV/cm). B. Low-voltage activity, with no reactivity to nociceptive stimulation (Filter settings 0.53–70 Hz, amplitude 100 μV/cm).

Fig. 3

Evaluation of EEG reactivity and relation to clinical outcome. A. EEG recording showing rhythmic delta-waves and no reactivity to nociceptive stimulation (Filter settings 0.53–70 Hz, amplitude 100 μV/cm): patient was still hospitalized in ICU 14 days after EEG. B. EEG recording showing rhythmic delta-waves and reactivity to auditive stimulation (Filter settings 0.53–70 Hz, amplitude 100 μV/cm): patient was hospitalized in regular medical department 14 days after EEG.

Fig. 4

ROC curve of EEG patterns for clinical outcome. A. at day 14 and B. at day 7. Abbreviations: AUC, area under curve; ROC, receiver operating characteristic.