Split from Eye movements may be key to chronic fatigue syndrome diagnosis Bansal uses an eye reaction test I believe as part of his diagnosis process .
Investigating unexplained fatigue in general practice with a particular focus on CFS/ME Amolak S Bansal https://bmcprimcare.biomedcentral.com/track/pdf/10.1186/s12875-016-0493-0.pdf
https://ammes.org/2017/02/23/invest...al-practice-with-a-particular-focus-on-cfsme/ Some information on an unpublished study on pupil responses: Dr Bansal mentions he has observed unusual responses by the pupils to light. I thought I would highlight a study that was done in the late 1990s looking at this. Unfortunately the researcher passed away before it could be published. Perhaps there are better sources than these lay articles but I thought they might be of some use in the hope that the finding might be followed up again.
Smells a bit off to me, this. Pupillometry is used a lot in cognitive psychology because pupils are markers of all sorts of things. People's pupils will repond to changes in the nature of some repeating stimulus, even if its auditory (e.g, beep, beep, beep, boop, beep), they'll respond to pretty much any attention-grabbing stimulus. They are also pretty sensitive markers of changes in affect, and to painful sensations anywhere in the body. So there are dozens of reasons why PwME might show unusual pupil responses, which have nothing to do with abnormalities in the brain stem. These responses might be tracking some of the cognitive limitations associated ME that change the way people orient to new stimuli, or they could be tracking some other feature, such as automonic abnormaities. You really can't say, its just an outcome measure, and the trick is in teasing apart what factors are causing he abnormalties.
I think it would only be a "key" to chronic fatigue syndrome if it were very specific to ME/CFS patients as well as a common finding in ME/CFS patients. I've certainly experienced visual problems that I connect to ME - mainly related to difficulties with convergrance and "fusion" of the stereo image - but also with visual "flicker," which might be caused by rapid changes in pupil diameter, but I think there's also likely a strong link between the vestibular system and "aiming" difficulties with the eyes. The wide number of possible combinations of various visual and balance problems makes me sceptical that a single "signature" will cover a high percentage of patients, but I'm glad someone is actually studying this. It might at least lead to patients with these problems being further evaluated for possible ME/CFS
Abnormal quantitative pupillary light responses following COVID-19, 2022, Bitirgen et al new study out, finding issues with pupil contraction, although, at first glance, different to what Bansal reported.
Bansal doesn't use the term "Parasympathetic Nervous System Dysfunction" but it seems to cover some of the general pathology he (unreferenced) refers to - this paper: Parasympathetic Nervous System Dysfunction, as Identified by Pupil Light Reflex, and Its Possible Connection to Hearing Impairment includes a review of PNSD studies in addition to making the interesting connection with hearing impairment.
