COVID-19-Associated Neurological Manifestations: An Emerging Electroencephalographic Literature

Abstract

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has spread worldwide since the end of year 2019 and is currently responsive for coronavirus infectious disease 2019 (COVID-19). The first reports considered COVID-19 as a respiratory tract disease responsible for pneumonia, but numerous studies rapidly emerged to warn the medical community of COVID-19-associated neurological manifestations, including encephalopathy at the acute phase and other postinfectious manifestations. Using standard visual analysis or spectral analysis, recent studies reported electroencephalographic (EEG) findings of COVID-19 patients with various neurological symptoms. Most EEG recordings were normal or revealed non-specific abnormalities, such as focal or generalized slowing, interictal epileptic figures, seizures, or status epilepticus. Interestingly, novel EEG abnormalities over frontal areas were also described at the acute phase. Underlying mechanisms leading to brain injury in COVID-19 are still unknown and matters of debate. These frontal EEG abnormalities could emphasize the hypothesis whereby SARS-CoV-2 enters the central nervous system (CNS) through olfactory structures and then spreads in CNS via frontal lobes. This hypothesis is reinforced by the presence of anosmia in a significant proportion of COVID-19 patients and by neuroimaging studies confirming orbitofrontal abnormalities. COVID-19 represents a new viral disease characterized by not only respiratory symptoms but also a systemic invasion associated with extra-respiratory signs. Neurological symptoms must be the focus of our attention, and functional brain evaluation with EEG is crucial, in combination with anatomical and functional brain imaging, to better understand its pathophysiology. Evolution of symptoms together with EEG patterns at the distance of the acute episode should also be scrutinized.

Changes in Electrical Brain Activity and Cognitive Functions Following Mild to Moderate COVID-19: A one-Year Prospective Study After Acute Infection

“…Many studies have reported that SARS-CoV-2 spike proteins can be detected in the brain. 45 , 46 Some studies have observed changes in EEG function, such as the distribution of EEG bands, structure of spectral entropy, and hemispheric connectivity. 25 , 26 Vellieux et al 45 showed that frontal EEG abnormalities could emphasize the hypothesis that SARS-CoV-2 enters the brain through olfactory structures and then spreads to the central nervous system via the frontal lobes.…”

Comparison of Brain Activation Patterns during Olfactory Stimuli between Recovered COVID-19 Patients and Healthy Controls: A Functional Near-Infrared Spectroscopy (fNIRS) Study

“…Despite the potential neuropathogenesis, neuroimaging studies on patients with COVID-19 and other respiratory infections are limited. Electroencephalography of patients with COVID-19 infection have shown frontal lobe abnormalities [13,14], while positron emission tomography (PET) of these patients has identified altered glucose metabolism in several brain areas. These include hypometabolism in the bilateral parahippocampal and fusiform gyri, left insula [15], dorsolateral prefrontal cortex, bilateral frontal eye fields and right anterior cingulate cortex, as well as hypermetabolism in the left orbitofrontal cortex, right posterior parietal cortex and right thalamus [16].…”

Evaluation and Treatment of Seizures and Epilepsy During the COVID-19 Pandemic

“…There have also been reports of seemingly novel EEG abnormalities, specifically frontally predominant abnormalities, in patients hospitalized with acute COVID-19 infections [28,29]. However, based on an overall review of the literature to date, there is no EEG pattern that is specific for patients with neurological manifestations of COVID-19, and a more thorough investigation of these findings with attention to confounding variables is needed to establish correlation [28,[30][31][32]. Potential confounding variables include body positioning (prone vs supine positioning in ventilated ICU patients), imaging findings, and medical comorbidities.…”