Reduced responsiveness is an essential feature of chronic fatigue syndrome: A fMRI study

Masaaki Tanaka,Hiroki C Tanabe,Tetsuya Sasabe,Kei Mizuno,Yasuyoshi Watanabe,Hirotaka Onoe,Daisuke N Saito,Tomohisa Okada,Norihiro Sadato,Hirohiko Kuratsune

doi:10.1186/1471-2377-6-9

Abstract

BackgroundAlthough the neural mechanism of chronic fatigue syndrome has been investigated by a number of researchers, it remains poorly understood.MethodsUsing functional magnetic resonance imaging, we studied brain responsiveness in 6 male chronic fatigue syndrome patients and in 7 age-matched male healthy volunteers. Responsiveness of auditory cortices to transient, short-lived, noise reduction was measured while subjects performed a fatigue-inducing continual visual search task.ResultsResponsiveness of the task-dependent brain regions was decreased after the fatigue-inducing task in the normal and chronic fatigue syndrome subjects and the decrement of the responsiveness was equivalent between the 2 groups. In contrast, during the fatigue-inducing period, although responsiveness of auditory cortices remained constant in the normal subjects, it was attenuated in the chronic fatigue syndrome patients. In addition, the rate of this attenuation was positively correlated with the subjective sensation of fatigue as measured using a fatigue visual analogue scale, immediately before the magnetic resonance imaging session.ConclusionChronic fatigue syndrome may be characterised by attenuation of the responsiveness to stimuli not directly related to the fatigue-inducing task.

Highlights

The neural mechanism of chronic fatigue syndrome has been investigated by a number of researchers, it remains poorly understood
We evaluated the responsiveness of task-independent and -dependent brain regions simultaneously during a fatigueinducing visual search task in normal and Chronic fatigue syndrome (CFS) patients groups using a 3.0 tesla MR scanner
We demonstrated that the responsiveness in the task-dependent brain regions was decreased after the fatigue-inducing continual visual search task in the normal and CFS patient groups and that the decrement of the responsiveness in those brain regions was equivalent between the 2 groups

Summary

Introduction

The neural mechanism of chronic fatigue syndrome has been investigated by a number of researchers, it remains poorly understood. Chronic fatigue syndrome (CFS) is a disorder characterised by profound disabling fatigue that persists for at least 6 months without relief and is not lessened by ordinary rest [1]. Magnetic resonance imaging (MRI) studies have shown anatomical anomalies of cortical [6,7] and subcortical [810] brain regions of CFS patients. Other studies using single-photon emission computed tomography have demonstrated reduced regional cerebral blood flow throughout the brain of CFS patients [11,12]. A positron emission tomography study confirmed reduced level of cerebral blood flow [13], and CFS patients showed reduced cerebral glucose metabolism in some brain regions [14,15]. Overall, neuroimaging studies are generally consistent in demonstrating abnormalities of CNS in CFS patients

Methods

Results

Discussion

Conclusion