SPM analysis of a brain 18F-FDG PET/CT in a patient with neurological impairment after covid-19 infection

ABSTRACT

Background-Aim: A 46 years old housewife patient with a bachelor's degree in Law contracted Covid-19 at the end of March 2021. She had a flu-like form with associated asthenia and drowsiness and no lack of sense of smell. It has been resolved in 25 days. Later, she developed progressive immediate memory loss, word-finding issues, motor and thinking slowing down. Methods: CT brain scan appeared as within the norm as well as liver enzymes, TSH, Vitamin B12, Folate and Rapid Plasma Reagine. Anti- ENA DNA ANA HIV TPO TG were negative too. In October, the patient had a further neuropsychological assessment that showed an overall picture characterized by partial orientation to space, working memory disorders, writing and comprehension (of complex tasks) issues, and immediate memory loss (possible sign both of attention span and concentration reduction). The auto-antibodies were assessed in November and they resulted negative. Moreover, the brain MRI scan and EEG (dated at the end of November) were both within the range. CSF neurodegenerative biomarkers and anti-neuronal antibodies appeared in the norm too. Results: Ultimately, in December 2021 she underwent an 18F-FDG PET brain scan and the SPM analysis showed an extensive hypometabolism in the bilateral frontal cortex and bilateral straight gyrus. Spared the cingulate cortex. Conclusions: The patient contracted Covid in March 2021. She developed neurological deterioration identified by FDG-PET. Negative autoantibodies and CSF biomarkers. PET scan was the only exam to define the brain damage in the patient above. Symmetrical bilateral frontal cortex and bilateral straight gyrus hypo-metabolism have been observed, the last one at the direct level of the olfactory bulb. In this area, in patients who died from Covid-19 it has been histologically demonstrated (data to be published) the presence of cellular inclusions named Corpore Amylacea. They would be a small hyaline mass that functions as a waste container that accumulates in the human brain in aging and in neurodegenerative and infectious processes. It is hypothesized to be that it can be involved in a sort of brain cleaning process1. Recently it has been described that they contain some neoepitopes that are recognized by natural IgMs, revealing a possible link between them and the natural immune system2. However, to now in our patient, the only diagnostic tool to evaluate the brain condition has been the 18F-FDG PET.