Abnormalities of the Descending Inhibitory Nociceptive Pathway in Functional Motor Disorders
Giovanna Squintani1, Christian Geroin2, Alessia Pasquali2
1Neurology and Neurophysiology Unit, Azienda Ospedaliera Universitaria Integrata, Verona, Italy.
Background:
Pain is a common disabling non-motor symptom affecting patients with functional motor disorders (FMD).
Objective:
We aimed to explore ascending and descending nociceptive pathways with laser evoked potentials (LEPs) in FMD.
Methods:
We studied a "bottom-up and top-down" noxious paradigm applying a conditioned pain modulation (CPM) protocol and recorded N2/P2 amplitude in 21 FMD and 20 controls following stimulation of both right arm and leg at baseline (BS) (bottom-up), during heterotopic noxious conditioning stimulation (HNCS) with ice test (top-down) and post-HNCS.
Results:
We found a normal ascending pathway, but reduced CPM response (lower reduction of the N2/P2 amplitude) in FMD patients, by stimulating both upper and lower limbs. The N2/P2 amplitude ratio*100 (between the HNCS and BS) was significantly higher in patients with FMD than HC.
Conclusions:
Our results suggest that pain in FMD possibly reflects a descending pain inhibitory control impairment, therefore, providing a novel venue to explore the pathophysiology of pain in FMD. © 2024 International Parkinson and Movement Disorder Society.
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