Structural changes in brains of patients with disorders of consciousness treated with deep brain stimulation

Marina Raguž,Fadi Almahariq,Ante Rotim,Ivica Kostović,Petar Marčinković,Vedran Deletis,Darko Chudy,Nina Predrijevac,Dominik Romić,Domagoj Dlaka,Darko Orešković

doi:10.1038/s41598-021-83873-y

Abstract

Disorders of consciousness (DOC) are one of the major consequences after anoxic or traumatic brain injury. So far, several studies have described the regaining of consciousness in DOC patients using deep brain stimulation (DBS). However, these studies often lack detailed data on the structural and functional cerebral changes after such treatment. The aim of this study was to conduct a volumetric analysis of specific cortical and subcortical structures to determine the impact of DBS after functional recovery of DOC patients. Five DOC patients underwent unilateral DBS electrode implantation into the centromedian parafascicular complex of the thalamic intralaminar nuclei. Consciousness recovery was confirmed using the Rappaport Disability Rating and the Coma/Near Coma scale. Brain MRI volumetric measurements were done prior to the procedure, then approximately a year after, and finally 7 years after the implementation of the electrode. The volumetric analysis included changes in regional cortical volumes and thickness, as well as in subcortical structures. Limbic cortices (parahippocampal and cingulate gyrus) and paralimbic cortices (insula) regions showed a significant volume increase and presented a trend of regional cortical thickness increase 1 and 7 years after DBS. The volumes of related subcortical structures, namely the caudate, the hippocampus as well as the amygdala, were significantly increased 1 and 7 years after DBS, while the putamen and nucleus accumbens presented with volume increase. Volume increase after DBS could be a result of direct DBS effects, or a result of functional recovery. Our findings are in accordance with the results of very few human studies connecting DBS and brain volume increase. Which mechanisms are behind the observed brain changes and whether structural changes are caused by consciousness recovery or DBS in patients with DOC is still a matter of debate.

Highlights

Disorders of consciousness (DOC) are one of the major consequences after anoxic or traumatic brain injury
Our study aimed to reveal if centromedian parafascicle (CM-pf) deep brain stimulation (DBS) could induce an impact on brain structural reorganization in DOC patients and lead to a changed volume of specific cortical and subcortical structures
Even on a small sample size included in the present study, we tried to emphasize the importance of morphometric magnetic resonance imaging (MRI) quantification which can expand our understanding of the relationship between brain structures and consciousness recovery

Summary

Introduction

Disorders of consciousness (DOC) are one of the major consequences after anoxic or traumatic brain injury. Several studies have described the regaining of consciousness in DOC patients using deep brain stimulation (DBS). These studies often lack detailed data on the structural and functional cerebral changes after such treatment. The aim of this study was to conduct a volumetric analysis of specific cortical and subcortical structures to determine the impact of DBS after functional recovery of DOC patients. Several studies used deep brain stimulation (DBS) of certain nuclei, such as centromedian parafascicle (CM-pf) complex and brain stem reticular formation, to regain consciousness in UWS and MCS patients[5,6,19,20,21,22,23]. Even though some studies claimed that there was no definitive evidence of the efficacy of this method for treatment of DOC patients, the usefulness of DBS was shown using controlled studies, as well as our previous s tudy[6,22,23]

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