Just over 10 percent of patients with severe coronavirus disease 2019 (Covid-19) show signs of brain damage during the course of their illness, a study published Monday by JAMA Network Open found.

All of these patients experienced delirium, or confusion, as well as seizure-like events and “delayed awakening in the intensive care unit” after discontinuing treatment with sedatives, the researchers said.

On routine scans, the patients had evidence of metabolic-toxic encephalopathy, a brain disease caused by infection that can cause behavioral changes.

They also had abnormalities in the frontal lobe region of the brain and structural changes similar to those experienced by people with epilepsy.

The frontal lobe is the area of the brain that controls emotions, problem solving, memory, language and judgment, among other functions.

In addition, patients who underwent magnetic resonance imaging were found to have brain lesions, or damage to the tissues, according to the researchers.

“Neurological symptoms are relatively common in severe forms of Covid-19,” study co-author Dr. Virginie Lambrecq, a neurologist at the Sorbonne in Paris, said.

The disease “can cause a wide range of neurological manifestations, and among them … a high proportion of delirium, epileptic seizures and movement disorders,” she said.

The findings are based on analysis of 644 French patients hospitalized with severe Covid-19 between March 30 and June 11 last year.

All 644 patients underwent an electroencephalogram, a test that detects electrical activity in the brain using small, metal electrodes attached to the scalp.

The EEGs revealed signs of brain damage in 69 of the patients, including encephalopathy and other structural changes.

Of these patients, 57 also underwent MRI exams, in which brain lesions were found, the researchers said.

Fifty-five of these patients also had evidence of dysnatremia, kidney failure and liver function problems. Dysnatremia, or abnormal sodium levels, is common in people with critical illness.

“Patients [with] Covid-19-related encephalopathy [had] cognitive impairment,” Lambrecq said.

However, “patients suffering from Covid-19 related encephalopathy seem to be improved by” treatment with plasma or antibody transfusion, she said­.