Abstracts

Rationale: Covid-19 (Coronavirus 2 infection), initially described as a respiratory disease, has several neurological manifestations, such as headache, stroke and peripheral neuropathies. Covid-19 encephalopathy denotes an acute impairment of the CNS, with altered level of consciousness, focal neurological signs and epileptic seizures. Studying these patients can reveal specific EEG patterns and help in understanding their pathophysiology.

Methods: Retrospective study, between April/2020 and July/2021, with 32 patients admitted to the ICU of the Hospital de Clinicas de Porto Alegre (20 men, 12 women) for Covid-19 encephalopathy. The average age was 58 years. The patients underwent routine EEGs, lasting 20 minutes (7 patients under sedation), using the 10-20 electrode placement system, and auditory and noxious stimuli were applied at the end of the recording, on average 8 days after the laboratory diagnosis of the disease.

The main indications for the examination were altered consciousness (40%), prolonged awakening (35%) and epileptic seizures (15%). Sixteen patients had death as the outcome, 10 were discharged from the hospital, and 6 were still hospitalized at the end of the study.

Results: The main EEG finding was diffuse slowing of the tracing, and it was recorded in 75% of patients. Discontinuous tracing and alpha coma (both in 18%) were later attributed to the effect of sedatives. Inter-hemispheric asymmetry was present in 6% of the records, being attributed to localized structural lesions. Tracing non-reactivity occurred in 18 patients (56%), and was associated with a 70% mortality.

Periodic discharges, generally generalized, occurred in 30%; rhythmic, generalized and focal discharges, in 20%; and focal epileptiform discharges (all involving the frontal regions) in another 30%. No electrographic seizure or status were recorded.

Conclusions: Our results demonstrate that the EEG in Covid-19 presents patterns similar to those of encephalopathies due to other etiologies. The apparent low epileptogenicity found (no seizures, epileptiform discharges in 30%) can be attributed to the short duration of the recordings. Tracing non-reactivity was the main predictor of poor prognosis. In this study, the frontal location of epileptiform discharges stood out, and this was the most characteristic EEG pattern found in the studied sample.

Funding: Please list any funding that was received in support of this abstract.: No funds received in support of this abstract.