Distinguishing functional from primary tics: a study of expert video assessments 2023 Rigas et al

Background
Reliably applied criteria to differentiate functional from primary tics are lacking. In the absence of biological markers, the development of new diagnostic criteria to assist clinicians is predicated on expert judgement and consensus. This study examines the level of diagnostic agreement of experts in tic disorders using video footage and clinical descriptions.

Methods
Using a two-part survey, eight experts in the diagnosis and management of tics were first asked to study 24 case videos of adults with primary tics, functional tics or both and to select a corresponding diagnosis. In the second part of the survey, additional clinical information was provided, and the diagnosis was then reconsidered. Inter-rater agreement was measured using Fleiss’ kappa. In both study parts, the factors which influenced diagnostic decision-making and overall diagnostic confidence were reviewed.

Results
Based on phenomenology alone, the diagnostic agreement among the expert raters was only fair for the pooled diagnoses (κ=0.21) as well as specifically for functional (κ=0.26) and primary tics (κ=0.24). Additional clinical information increased overall diagnostic agreement to moderate (κ=0.51) for both functional (κ=0.6) and primary tics (κ=0.57). The main factors informing diagnosis were tic semiology, age at tic onset, presence of premonitory urges, tic suppressibility, the temporal latency between tic onset and peak severity, precipitants and tic triggers and changes in the overall phenotypic presentation.

Conclusions
This study confirmed that in the absence of clinical information, the diagnostic distinction between primary and functional tics is often difficult, even for expert clinicians.

Open access, https://jnnp.bmj.com/content/early/2023/05/10/jnnp-2022-330822

 

As someone who has tics, the very idea of them being "functional" is blithely absurd.

 

Considering there is no way to validate the answers, this is puzzling. This is all becoming so damn spiritualistic. It's like training at some accuracy skill but with eyes covered and no one validating whether you are anywhere near the target. What is even the point of such an experiment?

Very little difference between this and debating how the air on Mars smells. No one can know what's right anyway. At least they somewhat admit that they can't do that, but I have no doubt that many physicians will continue doing that, believing they can do what obviously no one can do.

After all physicians are convinced that they can tell that we are "anxious", even when we're not. Even though they have no way of validating anything. Validity is clearly of no concern here, they clearly consider agreement as equivalent to validity. Even though all it does is cement failure in place.