BBC: How Long Concussion could offer new insights into Long Covid

[Yann04]

Well there are a very specific set of symptoms and characteristics that nearly everyone with severe and very severe (and many people with mild-moderate) ME/CFS fits into. They roughly fit the ICC and represent somewhere around 0.1-0.5% of the population. These people experience severe functional limitation due to a disease involving immune mechanisms which presents as a deterioration of the illness after any exertion over baseline. This could be as simple as seeing too bright lights, or having to make a decision.

Further down the spectrum, are people who are functionally limited by unexplained fatigue that seems to get worse with activity. Using this definition you get much higher percentages, and biological abnormalities are much harder to find because the population becomes much more heterogenous.

If you water this down even more, you get the kind of thing we saw in that iranian study, basically just fatigue, and you start having really high prevalence figures >10%.

It is really difficult to properly draw the line, and until we figure out clear biological markers it is nearly impossible. But the line needs to be drawn somewhere.

It is terrible that people with symptoms that ressemble ME are being psychologised unfairly. However, it is not scientifically prudent to include these people in ME criteria simply for that reason, as it leads to a slippery slope which can water down definitions so much they don’t mean anything anymore.

The problem, in my opinion, very clearly lies with how medicine is structured/prejudiced, and not with current ME diagnostic criteria. The only way we can get objective diagnostic criteria is if we find a biomarker. Until then, the best we can do is group patients by symptoms and other characteristics.

 

[EndME]

All sides except the people still left out if the term is strict - left to get bulldozed by BPS theories.

In the short-term and possibly for the entire life of many of such people, that will possibly unfortunately be the case.

But should one loosen those definitions, which patients and researchers have fought for, just so that everyone gets bulldozed and any research becomes inherently useless due to it being too unspecific? Because that is what inevitably will happen if one returns to unspecific definitions along the lines of Chronic Fatigue. Many people with autoimmune diseases suffer from some form of fatigue, but that doesn't mean that they are all suffering from the same thing as research has shown and that is precisely what one could think if one looks at the specificity of their symptoms.

The picture ME/CFS patients have been describing has been rather consistent and especially rather interestingly specific from a biomedical viewpoint.

I believe the hope for those left out is that once good and specific research is able to figure out ME/CFS, whenever that may be, those that have something somewhat similar or something that "resembles atypical ME/CFS" will ultimately benefit from this as well. Which is certainly better than nobody benefiting from unspecific BPS ideologies.

 

[forestglip]

When they applied standard concussion tests to Long Covid patients, the University of Denver researchers noticed the same tell-tale issues. One was problems with eye-tracking movements, as assessed via the King-Devick test, which measures the ability to scan numbers on a card from left to right in a zig-zag fashion under time pressure.

King-Devick Rapid Reading Test, from
Post-Concussion Assessment as a diagnostic and mechanistic framework for treating
patients with Long COVID, 2022

We used the King-Devick (KD) rapid number reading test, which functionally combines saccadic eye motion and neurocognitive demand. The KD has shown to have a high specificity, 86% correct, for predicting concussions (Galetta et al. 2016). The subject is presented with four number reading cards that gradually increase in difficulty. The test is designed with a habituation anticipated; therefore, the difficulty of the number reading task increases as habituation occurs. The participant reads the numbers in order on each card aloud as quickly and accurately as possible and their time and errors are counted. The first card is a warmup and the last three are recorded, then the times for the three cards are summed to obtain a “Total KD.” Although it is easy to collect, the error counting hasn’t been an effective clinical measure, so we will not report number of errors in this manuscript and focus on the time taken to perform the task for each card.

Example card

This investigation was a prospective cohort design where we recruited participants into one of two groups: Acute or Long COVID. During the screening phone call we asked: “Have you ever been diagnosed with “Long COVID” or “COVID -19 Long Hauler’s Syndrome”?”. At the start of the test, we verified this information and placed them into the Acute or Long COVID group. Inclusion criteria: Between the ages of 18 and 75; Was infected with COVID-19; First date of symptoms was more than 12 weeks prior to scheduled testing date. Exclusion criteria: Prior concussion or other head trauma within the last 10 years; Known balance problems or dizziness prior to having COVID-19; Parkinson’s Disease; Neurodegenerative disorder; History of vestibular disease; Otolithic surgery; Chronic pain; Multiple sclerosis; Fibromyalgia; Medications that affect their cognitive ability or balance; or Use recreational drugs more than once a week.

The time taken to read in all three King-Devick Cards and the Total KD composite of the three cards was higher in the Long COVID Group compared to the Acute Group (Figure 3). All four dependent variables were highly statistically significant (p<0.01) and had large effect sizes that ranged from 1.00 to 1.47. Age was not correlated with any of the four dependent variables (r=0.27, 0.22, 0.21, 0.24), so is not considered a confounder in the KD. The difference in means of 19.2 sec is much larger than the standard error of measurement, SEM=2.29 sec, and over 3 times larger than the minimum detectable change, MDC=6.35 sec (Heick, 2016).

 

[Sean]

So it seems they're just arbitrarily gathering the most common symptom presentation into one thing.

That is exactly what they have done.