A Case of Psychogenic Myoclonus Responding to a Novel Transcranial Magnetic Stimulation Approach: Rationale, Feasibility, and Possible Neurophysiological Basis.

Luana Billeri,Rocco Salvatore Calabrò,Bruno Porcari,Antonino Naro,Simona Portaro,Paolo Tonin,Loris Pignolo

doi:10.3389/fnhum.2020.00292

Luana Billeri, Rocco Salvatore Calabrò + Show 5 more

Open Access

https://doi.org/10.3389/fnhum.2020.00292

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Abstract

Repetitive transcranial magnetic stimulation (rTMS) can relieve motor symptoms related to psychogenic movement disorders (PMDs), but the subtending neurophysiological basis is unclear. We report on a 50-year-old woman with a diagnosis of psychogenic myoclonus in the right lower limb, who was treated with a daily session (in the late morning/early afternoon) of 1 Hz rTMS over the left premotor cortex (PMC), five times a week for 6 weeks. Clinical data and EEG at rest were collected before and immediately and 2-month after the rTMS protocol completion. The patient reported a significant reduction of involuntary movement frequency and intensity and the related disability burden up to the follow-up. In parallel, any abnormality in terms of source current density within and connectivity between the frontal and parietal areas was reset. The short follow–up period, the lack of extensive neurophysiological measures, and the lack of control treatment represent the main limitation of the study. However, low-frequency rTMS over PMC seems a safe and promising approach for the management of psychogenic myoclonus owing to the combination of cortical neuromodulation and non-specific mechanisms suggesting cognitive-behavioral effects.

Highlights

Movement disorders (MDs) are clinical syndromes characterized by either involuntary movements or a paucity of movements
Abnormal connectivity between the limbic and motor networks, altered top-down regulation of motor activities from the anterior cingulate cortex (ACC) and insular cortex, and a decreased activation of the supplementary motor area (SMA) and pre-SMA are among the main pathophysiological features of psychogenic movement disorders (PMDs) (Baizabal-Carvallo et al, 2019)
We report on a 50-yearold woman with a diagnosis of psychogenic myoclonus, who was managed with a long-duration, low-intensity, low-frequency (1 Hz) Repetitive transcranial magnetic stimulation (rTMS) protocol over the left premotor cortex (PMC), assessing the clinical and EEG aftereffects

Summary

INTRODUCTION

Movement disorders (MDs) are clinical syndromes characterized by either involuntary movements (hyperkinetic MD) or a paucity of movements (hypokinetic MD; Fahn et al, 2011; Donaldson et al, 2012; Morgante et al, 2013; Martino et al, 2016). A combination of findings suggested the psychogenic nature of the myoclonus, including the clinical features incongruous with organic myoclonus (inconsistent in frequency and amplitude, and involving more than one muscle groups), the movement improvement with distraction maneuvers, and the incongruous sensory loss or weakness (Fahn and Williams, 1988; Peckham and Hallett, 2009). The patient was provided with several electrophysiological examinations to assess organic myoclonus (Peckham and Hallett, 2009), which were all negative, including EEG (no potentials associable with epileptic myoclonus), TMS testing (normal cortical responsiveness to paired associative stimulation, normal intracortical facilitation and inhibition, cortical silent period (CSP) duration, and motor evoked potential (MEP) amplitude and recruitment curve), and surface EMG (showing long bursts of muscle activation with a highly variable agonist-antagonist muscle relationship). After 2 months (February, 2020), the patient’s clinical conditions were unvaried

DISCUSSION

Findings

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