LAUSR

Chronic fatigue syndrome/myalgic encephalitis (CFS/ME) is a complex clinical condition defined by prolonged severe fatigue without medical or psychiatric causes, and by a subset of symptoms that mostly includes arthromyalgias, cognitive impairment, sleeping troubles, and unusual headaches [1]. Previous FDG-PET studies showed unspecific patterns of hypometabolism in the frontal and cingulate cortex in half of CFS patients compared to healthy controls [2]. We present F-FDG PET/MRI findings in a 21-year-old woman who fulfilled the criteria of CFS with a Fukuda score of 4. PET images (a) show severe and extensive hypometabolism in the posterior cortical regions (precuneus, parietal, temporal, and occipital), amygdalo-hippocampal complexes, and cerebellum. No structural abnormalities were found on T1 MPRAGE (b) or T2 FLAIR (c) MRI sequences. Interestingly, cerebral blood flow evaluated with Gadolinium first-pass method (d) was not decreased in these regions. This peculiar pattern of hypometabolism was recently described in a large series of patients with aluminium-induced macrophagic myofasciitis (MMF) followed in our reference center [3]. However, the present patient had negativemuscular biopsies for MMF. Neuropsychological testing showed severe impairment of short-term memory (immediate and working memory) in visual modality, and weakness of visual selective attention and executive functions, which are concordant with the pattern of hypometabolism. Finally, perfusion-metabolism uncoupling suggests that posterior hypometabolism may not be related to neuronal loss such as in degenerative diseases [4], but rather to an inflammatory or immunological process [5]. Further studies are warranted to investigate metabolism and perfusion using simultaneous PET/MRI in larger groups of patients with CFS/ME.