Finally – An Objective Measure of Fatigue? An ME/CFS and FM Inquiry

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Making Fatigue Real

Self-tests and questionnaires to assess fatigue abound but are hardly trusted. What we really need is an objective test that really measures how much fatigue is present. Finding that has seemed kind of like the holy grail – a much desired goal but always seemingly out of reach. How do you measure such a subjective issue as fatigue?

One way is to identify a physiological attribute that changes depending on how much fatigue is present. The Japanese propose that a parasympathetic nervous system “collapse” that occurs after exertion in ME/CFS patients enables them to measure the amount of post-exertional malaise present.

Staci Steven’s two-day exercise test certainly shows up the functional impairments caused by exercise in ME/CFS in spades but is expensive, takes two days to complete and requires exercise. The two-day test is superb for proving disability and understanding the amount of activity an ME/CFS/FM patient’s system can handle. An ideal measure of fatigue that could be readily used in studies, though, would be non-invasive, cheap and easy to administer.

A cheap, easy to administer, non-invasive test which could be conducted using a wearable, no less, has actually been the focus of research lately.

The ramifications could be huge. Researchers could objectively determine if say, NK cell cytotoxicity or ATP output was actually correlated with increased fatigue. Or a clinical trial could determine more accurately how a drug or treatment protocol was affecting fatigue levels. Functional vs “non-functional” fatigue (depression?) could be identified.

The Eyes – A Window in Chronic Fatigue Syndrome (ME/CFS) and Fibromyalgia (FM)

The eyes are turning out to provide a surprisingly effective window into fibromyalgia and chronic fatigue syndrome (ME/CFS).  Non-invasive methods have been used to detect small fiber neuropathy in the eyes of fibromyalgia patients.  Recently, researchers have been using computational eyeglasses to assess the association between fatigue and rapid eye movements called ‘saccades’.

Saccades refer to a quick, simultaneous movement of both eyes which occurs in a kind of jumping motion. These types of movements occur when our eyes scan their immediate environment or when we’re reading. (Could reduced eye movements be involved with the reading problems some ME/CFS/FM patients have?).

These movements occur very, very quickly but their speed, amplitude (distance traveled) and other factors can be measured.

fatigue-eye

The eye could be a window into the fatigue experienced in ME/CFS and FM.

The link between a decrease in rapid eye movements and fatigue was first seen in 1979. Since then, studies of healthy controls have consistently shown that reduced rapid eye movements are associated with fatigue and/or sleepiness.  A 2012 and 2017 study found that people with multiple sclerosis – a severely fatiguing disorder – displayed significantly reduced eye movement velocity, amplitude and latency during a fatiguing task, relative to healthy controls. The authors of the 2012 study concluded that:

Assessment of peak velocity, amplitude and latency in a saccade fatigue task is a promising approach for quantifying fatigue in MS patients.

The studies suggest that measuring rapid eye movements or saccades could provide a measure of fatigue-limited functionality; i.e. the inability of the eyes to scan their surroundings properly.

Side Note – Central Fatigue, Chronic Fatigue Syndrome, Caffeine and Dopamine….

On a side note, studies have shown that, at least in healthy humans, caffeine, when taken after exercise, can reduce or prevent the reduction in rapid eye movements seen. This suggests that the normal fatigue associated with exercise is at least partially caused by what’s called “central fatigue” – or fatigue produced by the brain.

The idea of central fatigue actually has quite a history in ME/CFS. Years ago, Chaudhuri and Behan postulated that the fatigue occurring in chronic fatigue syndrome (ME/CFS) is “central” in nature. Their assertion was based on a number of findings (reduced motor performance, delayed central motor conduction, depressed cortical excitability, reduced ability to recruit muscles during exercise, reduced motor cortex activity), indicating that the inability of the brain to initiate motor activity was likely playing a major role in the fatigue found in ME/CFS.

In one remarkable finding, a researcher noted that the reduced muscle activation seen in CFS patients was similar to that seen in some stroke victims and ALS patients (!) (Schillings et. al. 2004).

Despite all the interesting findings, my recollection is that interest in motor cortex activation and reduced muscle recruitment in ME/CFS mostly died.

The interest in another part of Chaudhuri’s hypothesis has not, however. Behan and Chaudhuri suggested that problems relaying information from the basal ganglia to the motor cortices plays a key role in the fatigue in ME/CFS. Later studies by Miller have confirmed the basal ganglia problems in ME/CFS.

The basal ganglia connection is intriguing given recent studies which suggest that caffeine is able to reduce fatigue in part by increasing levels of norepinephrine and dopamine. Dopamine, it should be noted, is largely produced by the basal ganglia which Chaudhuri/Behan and Miller postulate is heavily involved in ME/CFS.

In conclusion, the eye studies suggest that similar brain issues to those studies may be occurring in ME/CFS and are responsible for the exertion-induced reduction in saccades eye motions found.

Back to the Eyes

The reduced eye movements seen after mental or physical exercise could, then, be due to problems in the brain.

The University of Mass. has begun a breast cancer fatigue study which will use computational eyeglasses to determine if fatigue levels in breast cancer are associated with declining rapid eye movements. Rachel Walker – a researcher associated with the study – explained why she hoped to validate a way to objectively assess the impact of fatigue on the eye movements.

“Often we ask breast cancer survivors to rate how fatigued they are feeling on a scale from 1 to 10. While this type of self-rating is critically important, it sometimes misses the functional aspect of the fatigue. The fact that someone not only feels fatigued – and what that might mean to them – but that the fatigue they are experiencing is having a measurable impact on their body.”

She described the wearable in the study (the computational eyeglasses) as being “low-cost”.

Could this upcoming study signal that the era of subjective questionnaires for fatigue is drawing to an end? Let’s hope so.

The post Finally – An Objective Measure of Fatigue? An ME/CFS and FM Inquiry appeared first on Health Rising.

Cort Johnson

Finally – An Objective Measure of Fatigue? An ME/CFS and Fibromyalgia Inquiry

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About MafibromaVie 5996 Articles
Bonjour, je n'ai même pas encore 40 ans, je suis fibromyalgique, j'ai un petit garçon de 2 ans, et je vis dans cette souffrance, mais dû a ma personnalité je ne peux pas rester sans rien faire, car ça me tue encore plus que la douleur. Je précise que j’écris le français que a 5 ou presque 6 ans maintenant et je parle et écris aussi d'autres langues, donc je fais des erreurs de orthographe et de grammaire. Le problème c'est que je ne peux presque plus marcher (béquilles et difficile), être assis durant plus de 15 à 30 minutes ça me tue le cul cul et le dos, même pour soulever mon petit qui pèse a peine 12 kg, mais on dirait un sac de ciment du type 50 kg. Lui changer la couche me fait trembler les jambes et on dirait qu'on me plante un couteau au fond du dos, même mes épaules et bras quand je soulève ces fesses me font mal, même quand je lui donne la soupe avec une petite cuiller mon bras se fatigue vite et les douleurs arrivent, L'autre jour on lui donnant la soupe j'ai appuyé mon bras sur le plateau de ça chaise et il a commencé à trembler violemment, que même mon petit de 2 ans a eu peur. Sur ma page j'assume l'identité de tous les fibromyalgiques du moins de ceux qui veulent me suivre sous le pseudonyme de "MafibromaVie" ou de "FiFi le clown", finalement nous sommes tous des Clows au yeux de trop de gens, d’État, de Pays, et de Communauté dans notre cas la UE! Je ne suis pas une personnalité et je ne recherche aucune reconnaissance publique. Je suis simplement une personne comme toutes les autres, comme vous qui souffrait peut être aussi de Fibromyalgie, et qui a ouvert une simple page privée ou j'ecris ma vie de fibromyalgique pour suivie médicale par mon médecin. Ben après avec le temps, l'histoire a changé beaucoup de monde a commencer a me suivre 50,100,1000 et maintenant plus de 3000. Je parlais plus de moi au début et maintenant plus de nous et pour vous, ainsi c'est crée une page de partage, aide, soutien, et de discussion pour tous les fibros.

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