AUTHOR=Benussi Alberto , Premi Enrico , Cantoni Valentina , Compostella Silvia , Magni Eugenio , Gilberti Nicola , Vergani Veronica , Delrio Ilenia , Gamba Massimo , Spezi Raffaella , Costa Angelo , Tinazzi Michele , Padovani Alessandro , Borroni Barbara , Magoni Mauro TITLE=Cortical Inhibitory Imbalance in Functional Paralysis JOURNAL=Frontiers in Human Neuroscience VOLUME=14 YEAR=2020 URL=https://www.frontiersin.org/journals/human-neuroscience/articles/10.3389/fnhum.2020.00153 DOI=10.3389/fnhum.2020.00153 ISSN=1662-5161 ABSTRACT=Background

Functional neurological disorders are characterized by neurological symptoms that have no identifiable pathology and little is known about their underlying pathophysiology.

Objectives

To analyze motor cortex excitability and intracortical inhibitory and excitatory circuits’ imbalance in patients with flaccid functional weakness.

Methods

Twenty-one consecutive patients with acute onset of flaccid functional weakness were recruited. Single and paired-pulse transcranial magnetic stimulation (TMS) protocols were used to analyze resting motor thresholds (RMT) and intracortical inhibitory (short interval intracortical inhibition – SICI) and excitatory (intracortical facilitation – ICF) circuits’ imbalance between the affected and non-affected motor cortices.

Results

We observed a significant increase in RMT and SICI in the affected motor cortex (p < 0.001), but not for ICF, compared to the contralateral unaffected side.

Conclusion

This study extends current knowledge of functional weakness, arguing for a specific central nervous system abnormality which may be involved in the symptoms’ pathophysiology.