Microstate in resting state: an EEG indicator of tinnitus?

Background: Tinnitus was a subjective auditory phantom phenomenon which could be highly distressing and had no objective indicators for evaluation. Objectives: The aim of this study was to investigate whether and how did electroencephalography (EEG) microstates of subjective tinnitus patients change in resting state and whether could be an objective indicator for tinnitus. Material and Methods: We enrolled chronic subjective tinnitus patients and matched age and gender with healthy controls. EEG recording, microstate analysis and statistical analysis were performed. Results: We finally had 10 male and 8 female age-matched participants in tinnitus group and healthy control group. Statistical differences were found in the microstate A, C and D durations between the two groups (class A, p = .024; class B, p = .018; class D, p  = .029). Microstate durations of class A and D had linear correlation with VAS scores in tinnitus patients (microstate A [R spare = 0.43, p  = .003*]; microstate D [R spare = 0.46, p  = .002*]). Conclusions: Microstates had changed in chronic tinnitus patients and provided an indicator or perspective to explore the mechanisms of tinnitus. The maintenance of chronic subjective tinnitus may be related to changes in cerebral cortex activity.