This is a pretty well done and thorough review paper, makes for a good reference to find papers you might've read long ago on particular neuroimaging studies of ME.
While most, if not all, the neuroimaging studies in ME had fairly small sample sizes (due to abysmal ME funding!) and most used Fukuda criteria because CCC and ICC didn't become mainstream for ME research until after many of these studies were published, seeing all the papers again in one document shows that there were indeed multiple replicated results, with some being replicated in a number of papers. Though of course there were also inconsistent results between some papers, so hopefully with CCC criteria selected patients and larger sample sizes (increased funding for ME research) that future neuroimaging studies can produce more highly statistically significant findings and possible markers of ME.
My first pleasant surprise about this review, and I didn't realize this about ME until I saw this with all the results in one place, is wow the cingulate cortex brain region appears to very implicated in ME. It was found to have abnormalities/impairments in cerebral blood flow studies, neuroinflammation and other PET studies (i.e. lower SERT transporter density, glucose hypometabolism), functional connectivity studies, EEG studies, and cognitive function fMRI and SPECT studies (and possibly a couple types I missed). And many of these cingulate cortex findings are replicated by multiple papers. Of course there are other brain regions with abnormalities discussed in the review that are important, but the cingulate cortex appeared to me to stand out as it has been implicated in almost all the different study modalities.
The cingulate cortex is a key brain region that has a lot of important and coordinating functions.
From Neuroanatomy, Cingulate Cortex:
The cingulate cortex is also involved in regulation of autonomic and neuroendocrine responses and pain perception.
A systematic review of neurological impairments in myalgic encephalomyelitis/chronic fatigue syndrome using neuroimaging techniques
Maksoud et al. PLOS One April 2020
Abstract
Background
Myalgic encephalomyelitis/ Chronic Fatigue Syndrome (ME/CFS) is a multi-system illness characterised by a diverse range of debilitating symptoms including autonomic and cognitive dysfunction. The pathomechanism remains elusive, however, neurological and cognitive aberrations are consistently described. This systematic review is the first to collect and appraise the literature related to the structural and functional neurological changes in ME/CFS patients as measured by neuroimaging techniques and to investigate how these changes may influence onset, symptom presentation and severity of the illness.
Methods
A systematic search of databases Pubmed, Embase, MEDLINE (via EBSCOhost) and Web of Science (via Clarivate Analytics) was performed for articles dating between December 1994 and August 2019. Included publications report on neurological differences in ME/CFS patients compared with healthy controls identified using neuroimaging techniques such as magnetic resonance imaging, positron emission tomography and electroencephalography. Article selection was further refined based on specific inclusion and exclusion criteria. A quality assessment of included publications was completed using the Joanna Briggs Institute checklist.
Results
A total of 55 studies were included in this review. All papers assessed neurological or cognitive differences in adult ME/CFS patients compared with healthy controls using neuroimaging techniques. The outcomes from the articles include changes in gray and white matter volumes, cerebral blood flow, brain structure, sleep, EEG activity, functional connectivity and cognitive function. Secondary measures including symptom severity were also reported in most studies.
Conclusions
The results suggest widespread disruption of the autonomic nervous system network including morphological changes, white matter abnormalities and aberrations in functional connectivity. However, these findings are not consistent across studies and the origins of these anomalies remain unknown. Future studies are required confirm the potential neurological contribution to the pathology of ME/CFS.
While most, if not all, the neuroimaging studies in ME had fairly small sample sizes (due to abysmal ME funding!) and most used Fukuda criteria because CCC and ICC didn't become mainstream for ME research until after many of these studies were published, seeing all the papers again in one document shows that there were indeed multiple replicated results, with some being replicated in a number of papers. Though of course there were also inconsistent results between some papers, so hopefully with CCC criteria selected patients and larger sample sizes (increased funding for ME research) that future neuroimaging studies can produce more highly statistically significant findings and possible markers of ME.
My first pleasant surprise about this review, and I didn't realize this about ME until I saw this with all the results in one place, is wow the cingulate cortex brain region appears to very implicated in ME. It was found to have abnormalities/impairments in cerebral blood flow studies, neuroinflammation and other PET studies (i.e. lower SERT transporter density, glucose hypometabolism), functional connectivity studies, EEG studies, and cognitive function fMRI and SPECT studies (and possibly a couple types I missed). And many of these cingulate cortex findings are replicated by multiple papers. Of course there are other brain regions with abnormalities discussed in the review that are important, but the cingulate cortex appeared to me to stand out as it has been implicated in almost all the different study modalities.
The cingulate cortex is a key brain region that has a lot of important and coordinating functions.
From Neuroanatomy, Cingulate Cortex:
As seen from the extensive neural pathways it shares with other brain regions, the cingulate cortex can be considered, in a sense, a connecting hub of emotions, sensation, and action. Some of these pathways are those involved in motivational processing, which is apparent through the connections with the orbitofrontal cortex, basal ganglia, and insula, which together make up the reward centers of the brain. Also, the cingulate cortex projects pathways to the lateral prefrontal cortex which is involved in executive control, working memory, and learning. Pathways between cingulate cortex and motor areas like the primary and supplementary motor cortices, spinal cord, and frontal eye fields, suggest an important role in motor control. Moreover, the cingulate cortex, frontal and parietal lobes comprise a neural network for orienting attention, and expectedly, injury to any of these areas is known to cause hemineglect. The neural circuits cingulate cortex shares with the hippocampus and amygdala suggest a role in consolidating long-term memories and processing emotionally-relevant stimuli, respectively.
A systematic review of neurological impairments in myalgic encephalomyelitis/chronic fatigue syndrome using neuroimaging techniques
Maksoud et al. PLOS One April 2020
Abstract
Background
Myalgic encephalomyelitis/ Chronic Fatigue Syndrome (ME/CFS) is a multi-system illness characterised by a diverse range of debilitating symptoms including autonomic and cognitive dysfunction. The pathomechanism remains elusive, however, neurological and cognitive aberrations are consistently described. This systematic review is the first to collect and appraise the literature related to the structural and functional neurological changes in ME/CFS patients as measured by neuroimaging techniques and to investigate how these changes may influence onset, symptom presentation and severity of the illness.
Methods
A systematic search of databases Pubmed, Embase, MEDLINE (via EBSCOhost) and Web of Science (via Clarivate Analytics) was performed for articles dating between December 1994 and August 2019. Included publications report on neurological differences in ME/CFS patients compared with healthy controls identified using neuroimaging techniques such as magnetic resonance imaging, positron emission tomography and electroencephalography. Article selection was further refined based on specific inclusion and exclusion criteria. A quality assessment of included publications was completed using the Joanna Briggs Institute checklist.
Results
A total of 55 studies were included in this review. All papers assessed neurological or cognitive differences in adult ME/CFS patients compared with healthy controls using neuroimaging techniques. The outcomes from the articles include changes in gray and white matter volumes, cerebral blood flow, brain structure, sleep, EEG activity, functional connectivity and cognitive function. Secondary measures including symptom severity were also reported in most studies.
Conclusions
The results suggest widespread disruption of the autonomic nervous system network including morphological changes, white matter abnormalities and aberrations in functional connectivity. However, these findings are not consistent across studies and the origins of these anomalies remain unknown. Future studies are required confirm the potential neurological contribution to the pathology of ME/CFS.
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