Published online Jul 6, 2019. doi: 10.12998/wjcc.v7.i13.1582
Peer-review started: March 8, 2019
First decision: April 18, 2019
Revised: April 21, 2019
Accepted: May 2, 2019
Article in press: May 2, 2019
Published online: July 6, 2019
The central mechanism of idiopathic tinnitus is related to hyperactivity of cortical and subcortical auditory and non-auditory areas. Repetitive transcranial magnetic stimulation (rTMS) is a well-tolerated, non-invasive potential treatment option for tinnitus.
To investigate the changes of neural metabolic activity after rTMS in chronic idiopathic tinnitus (IT) patients.
Eleven patients underwent rTMS (1 Hz, 90% motor threshold, 1000 stimuli/day for consecutive 10 d) on the left temporoparietal region cortex. Tinnitus handicap inventory (THI) and visual analogue score (VAS) were assessed at baseline and posttreatment. All patients underwent 18F-fluorodeoxyglucose (FDG) positron emission tomography to evaluate the neural metabolic activity. Data were preprocessed using statistical parametric mapping and Gretna software to extract the regions of interest (ROIs). The correlation between brain areas involved and THI scores was analyzed.
Baseline and posttreatment parameters showed no significant difference regarding THI score (t = 1.019, P = 0.342 > 0.05) and VAS (t = 0.00, P = 1.0 > 0.05). Regions with the highest FDG uptake were the right inferior temporal gyrus (ITG), right parahippocampa gyrus (PHG), right hippocampus, rectus gyrus, left middle frontal gyrus, and right inferior frontal gyrus in IT patients. After rTMS treatment, IT patients showed increased activities in the right PHG, right superior temporal gyrus, right superior frontal gyrus, anterior insula, left inferior parietal lobule, and left precentral gyrus, and decreased activities in the left postcentral gyrus and left ITG. The ROIs in the right parahippocampa gyrus and right superior frontal gyrus were positively correlated with THI scores (r = 0.737, P = 0.037 < 0.05; r = 0.735, P = 0.038 < 0.05).
Our study showed that 1-Hz rTMS directed to the left temporo-parietal junction resulted no statistically significant symptom alleviation. After treatment, brain areas of the limbic and prefrontal system showed high neutral metabolic activity. The auditory and non-auditory systems together will be the target for rTMS treatment.
Core tip: In this study, we focused on changes of neural metabolic activity in idiopathic tinnitus (IT) patients after repetitive transcranial magnetic stimulation (rTMS) treatment and further investigated changes in cortical activities of the whole brain. We found that after rTMS treatment, IT patients had increased activities in auditory, non-auditory, and limbic systems, and the activity decreased only in the target area with no statistically significant symptom alleviation. Our study may provide a new direction for rTMS target area.