Cortical Inhibitory Imbalance in Functional Paralysis
Alberto Benussi, Enrico Premi, Valentina Cantoni, Silvia Compostella, Eugenio Magni, Nicola Gilberti, Veronica Vergani, Ilenia Delrio, Massimo Gamba, Raffaella Spezi, Angelo Costa, Michèle Tinazzi, Alessandro Padovani, Barbara Borroni, Mauro Magoni
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: < 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.