Electrophysiological Signatures of Intrinsic Functional Connectivity Related to rTMS Treatment for Mal de Debarquement Syndrome

Yoon-Hee Cha,Benjamin C Doudican,Lei Ding,Han Yuan,Diamond Gleghorn,Guofa Shou

doi:10.1007/s10548-018-0671-6

Abstract

To determine intrinsic functional connectivity (IFC) related to symptom changes induced by rTMS in mal de debarquement syndrome (MdDS), a motion perceptual disorder induced by entrainment to oscillating motion. Twenty right-handed women (mean age: 52.9 ± 12.6 years; mean duration illness: 35.2 ± 24.2 months) with MdDS received five sessions of rTMS (1 Hz right DLPFC, 10 Hz left DLPFC) over consecutive days. High-density (128-channel) resting-state EEG were recorded prior to and following treatment sessions and analyzed using a group-level independent component (IC) analysis. IFC between 19 ICs was quantified by inter-IC phase coherence (ICPC) in six frequency bands (delta, theta, low alpha, high alpha, beta, gamma). Correlational analyses between IFCs and symptoms were performed. Symptom improvement after rTMS was significantly correlated with (1) an increase in low alpha band (8–10 Hz) IFC but a decrease of IFC in all other bands, and (2) high baseline IFC in the high alpha (11–13 Hz) and beta bands (14–30 Hz). Most treatment related IFC changes occurred between frontal and parietal regions with a linear association between the degree of symptom improvement and the number of coherent IFC changes. Frequency band and region specific IFC changes correlate with and can predict symptom changes induced by rTMS over DLPFC in MdDS. MdDS symptom response correlates with high baseline IFC in most frequency bands. Treatment induced increase in long-range low alpha IFC and decreases in IFC in other bands as well as the proportion of coherent IFC changes correlate with symptom reduction.

Highlights

Mal de debarquement Syndrome (MdDS) is a motion-triggered disorder of persistent oscillating vertigo that occurs after prolonged exposure to passive motion (Bisdorff et al 2009; Brown and Baloh 1987)
Cross-subject Pearson correlation analysis was performed on the pre- to post-Repetitive transcranial magnetic stimulation (rTMS) IC phase coherence (ICPC) differences and visual analogue scale (VAS) scores to identify symptom change-related intrinsic functional connectivity (IFC)
An independent cross-subject Pearson correlation analysis was performed between pre-rTMS ICPC values and VAS score changes to identify IFCs whose baseline values correlated with treatment response

Summary

Introduction

Mal de debarquement Syndrome (MdDS) is a motion-triggered disorder of persistent oscillating vertigo that occurs after prolonged exposure to passive motion (Bisdorff et al 2009; Brown and Baloh 1987). As opposed to motion sickness that occurs during the motion exposure, MdDS occurs after the motion stimulus has ended (Golding 2016). It represents the consequence of the human brain’s entrainment to external oscillating motion such as during sea travel, the most common trigger (Cha 2009; Hain et al 1999). While brief episodes of post-motion exposure dizziness and vertigo lasting less than two days are common, persistent episodes of MdDS lasting for months or years can occur in an important minority of individuals While brief episodes of post-motion exposure dizziness and vertigo lasting less than two days are common, persistent episodes of MdDS lasting for months or years can occur in an important minority of individuals (Cha 2012; Hain et al. Vol.:(0123456789)

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