The cerebral network of COVID-19-related encephalopathy: a longitudinal voxel-based 18F-FDG-PET study

Purpose Little is known about the neuronal substrates of neuropsychiatric symptoms associated with COVID-19 and their evolution during the course of the disease. We aimed at describing the longitudinal brain metabolic pattern in COVID-19-related encephalopathy using 18F-FDG-PET/CT. Methods Seven patients with variable clinical presentations of COVID-19-related encephalopathy were explored thrice with brain 18F-FDG-PET/CT, once in the acute phase, 1 month later and 6 months after COVID-19 onset. PET images were analysed with voxel-wise and regions-of-interest approaches in comparison with 32 healthy controls. Results Patients' neurological manifestations during acute encephalopathy were heterogeneous. However, all of them presented with predominant cognitive and behavioural frontal disorders. SARS-CoV-2 RT-PCR in the CSF was negative for all patients. MRI revealed no specific abnormalities for most of the subjects. All patients had a consistent pattern of hypometabolism in a widespread cerebral network including the frontal cortex, anterior cingulate, insula and caudate nucleus. Six months after COVID-19 onset, the majority of patients clinically had improved but cognitive and emotional disorders of varying severity remained with attention/executive disabilities and anxio-depressive symptoms, and lasting prefrontal, insular and subcortical 18F-FDG-PET/CT abnormalities. Conclusion The implication of this widespread network could be the neural substrate of clinical features observed in patients with COVID-19, such as frontal lobe syndrome, emotional disturbances and deregulation of respiratory failure perception. This study suggests that this network remains mildly to severely impaired 6 months after disease onset.