Prepulse inhibition of the blink reflex in functional neurological disorder and fibromyalgia 2025 Edwards, Serranová et al

Andy

Andy

Senior Member (Voting rights)

Abstract​

Prepulse inhibition reflects subcortical sensory integration, where a low-intensity peripheral stimulus (prepulse) reduces the amplitude of a reflex response to a subsequent high-intensity stimulus. As a measure of pre-attentive sensory gating, prepulse inhibition has been found to be altered in small cohorts of patients with functional disorders, including functional motor disorder and fibromyalgia, suggesting a shared deficit in sensory information processing. However, prior studies have not demonstrated consistent associations between prepulse inhibition abnormalities and clinical measures.

We hypothesized that widespread pain and somatic symptoms in somatic symptom disorders may result from a general deficit in the interpretation of bodily signals, potentially linked to abnormalities in sensory filtering as measured by prepulse inhibition.

In this study, we examined 140 participants across four age- and sex-matched groups: 35 patients clinically categorized with functional motor disorder without fibromyalgia, 35 with both functional motor disorder and fibromyalgia, 35 with fibromyalgia only, and 35 healthy controls. A weak electrical stimulus to the index finger served as the prepulse, delivered 100 ms before supraorbital nerve stimulation to elicit the R2 component of the blink reflex. Prepulse inhibition was calculated as the percent reduction in R2 amplitude.

Across all groups, lower prepulse was significantly associated with higher scores on the Fibromyalgia Severity Scale, consisting of Widespread Pain Index and Symptom Severity Scale. In patients with functional motor disorder, no association was found between prepulse inhibition size and objectively rated motor symptom severity.

These findings suggest that impaired early sensory processing at subcortical level is related to “fibromyalgianess” in people with functional motor disorder and fibromyalgia. Abnormal prepulse inhibition may serve as an objective transdiagnostic marker of fibromyalgia symptomatology or fibromyalgianess, including widespread pain and other non-motor symptoms in functional disorders, highlighting a potential role of sensory gating deficits in the pathophysiology of fibromyalgia-spectrum manifestations.

Open access
 
Andy said:
We hypothesized that widespread pain and somatic symptoms in somatic symptom disorders may result from a general deficit in the interpretation of bodily signals, potentially linked to abnormalities in sensory filtering as measured by prepulse inhibition.
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So the hypothesis is that both FM and FMD is caused by a shared mechanism.
Andy said:
Across all groups, lower prepulse was significantly associated with higher scores on the Fibromyalgia Severity Scale, consisting of Widespread Pain Index and Symptom Severity Scale.
Click to expand...
Does «all groups» include the healthy people as well? So none of the HC had lower prepulse?
Andy said:
In patients with functional motor disorder, no association was found between prepulse inhibition size and objectively rated motor symptom severity.
Click to expand...
Seems like FMD doesn’t share the same mechanism as FM. I wonder why the authors did not explicitly mentioning that their hypothesis was disproven?
 
Utsikt said:
Does «all groups» include the healthy people as well? So none of the HC had lower prepulse?
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IMG_0470.jpeg
Seems like there is a pretty clear separation between the three subgroups, in the order HC, FMD, [FMD+FM & FM].

Which implies that FMD might attenuate the effect of FM on this measurement.
Edit thanks to forestglip.
 
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Utsikt said:
So FMD doesn’t have an effect on the measurements in addition that what FM already does?
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Yeah it looks like being diagnosed with fibromyalgia is associated with a decrease in PPI, with a comorbidity of FMD making little difference.

More generally, higher scores on the Fibromyalgia Severity Scale, no matter what your diagnosis, correspond to lower PPI. And people with FMD without fibromyalgia have higher scores on FSS than healthy controls, but lower scores than people with fibromyalgia.

For reference, I'll link to the method of symptom scoring. There are two sections, the symptom severity scale (SSS) and the widespread pain index (WPI). The scores for each of these correlated on their own with PPI in the study, as well as the score when the two scales were combined into a total fibromyalgia severity scale (FSS) score. The combination of scores (FSS) is what was most significant and what is shown in the charts.

 
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