Transcranial Stimulation Treatments (rTMS & tDCS & tACS)

Neural metabolic activity in idiopathic tinnitus patients after repetitive transcranial magnetic stimulation
https://www.wjgnet.com/2307-8960/full/v7/i13/1582.htm

BACKGROUND
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.

AIM
To investigate the changes of neural metabolic activity after rTMS in chronic idiopathic tinnitus (IT) patients.

METHODS
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.

RESULTS
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).

CONCLUSION
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.

 

RTMS parameters in tinnitus trials: a systematic review

• Stefan Schoisswohl,
• Kushal Agrawal,
• Jorge Simoes,
• Patrick Neff,
• Winfried Schlee,
• Berthold Langguth &
• Martin Schecklmann

Scientific Reportsvolume 9, Article number: 12190 (2019) | Download Citation

Abstract
Over the past few years extensive body of research was produced investigating the effects of repetitive transcranial magnetic stimulation (rTMS) for the treatment of chronic tinnitus with heterogeneous results. This heterogeneity is exemplified by two recently published large-scale clinical trials reporting different outcomes. Technical aspects of rTMS were suspected as a potential source for this incongruency. The aim of this systematic review is to examine the overall efficacy as well as to identify possible technical factors relevant for the effectiveness of rTMS tinnitus trials. Via a literature search appropriate original research papers were identified and rTMS parameters were extracted from each study arm for subsequent statistical analysis with respect to observed effects (significant vs. not significant pre-post rTMS effects). Our findings indicate that verum rTMS is superior to sham rTMS as demonstrated by the proportion of significant pre-post contrasts. Some relevant rTMS parameters (e.g., pulse waveform) are not reported. Lower rTMS stimulation intensity was associated with significant effects in verum rTMS arms. An additional stimulation of the DLPFC to the temporal cortex was not found to promote efficacy. Future research should consider differential effects of rTMS induced by technical parameters and strive for an exhaustive reporting of relevant rTMS parameters.

Full text: https://www.nature.com/articles/s41598-019-48750-9

 

Daily high-frequency transcranial random noise stimulation of bilateral temporal cortex in chronic tinnitus – a pilot study

• Peter M. Kreuzer,
• Timm B. Poeppl,
• Rainer Rupprecht,
• Veronika Vielsmeier,
• Astrid Lehner,
• Berthold Langguth &
• Martin Schecklmann

Scientific Reportsvolume 9, Article number: 12274 (2019) | Download Citation

Abstract
Several studies emphasized the potential of single and multiple transcranial random noise stimulation (tRNS) sessions to interfere with auditory cortical activity and to reduce tinnitus loudness. It was the objective of the present study to evaluate the use of high-frequency (hf) tRNS in a one-arm pilot study in patients with chronic tinnitus. Therefore, 30 patients received 10 sessions of high frequency tRNS (100-640 Hz; 2 mA; 20 minutes) over the bilateral temporal cortex. All patients had received rTMS treatment for their tinnitus at least 3 months before tRNS. Primary outcome was treatment response (tinnitus questionnaire reduction of ≥5 points). The trial was registered at clinicaltrials.gov (NCT01965028). Eight patients (27%) responded to tRNS. Exactly the same number of patients had responded before to rTMS, but there were only two “double responders” for both treatments. None of the secondary outcomes (tinnitus numeric rating scales, depressivity, and quality of life) was significant when results were corrected for multiple comparisons. tRNS treatment was accompanied by tolerable side effects but resulted in temporal increases in tinnitus loudness in 20% of the cases (2 drop-outs). Our trial showed that hf-tRNS is feasible for daily treatment in chronic tinnitus. However, summarizing low treatment response, increase of tinnitus loudness in 20% of patients and missing of any significant secondary outcome, the use of hf-tRNS as a general treatment for chronic tinnitus cannot be recommended at this stage. Differences in treatment responders between tRNS and rTMS highlight the need for individualized treatment procedures.

Source: https://www.nature.com/articles/s41598-019-48686-0
Related post: https://www.tinnitustalk.com/threads/trns-the-next-neuromodulation-method.3010/#post-70034

 

An Exploratory Study on the Use of Event-Related Potentials as an Objective Measure of Auditory Processing and Therapy Effect in Patients With Tinnitus: A Transcranial Direct Current Stimulation Study.

Abstract
OBJECTIVE:
Treatment effect in tinnitus research is commonly evaluated by use of self-report questionnaires. As this is a solely subjective assessment method, the need for an objective measurement is paramount to genuinely evaluate the effects of therapeutic interventions. The current study explores the value of event-related potentials (ERPs) in the evaluation of high-definition transcranial direct current stimulation (HD-tDCS) for tinnitus treatment.

STUDY DESIGN:
Prospective exploratory study.

SETTING:
Tertiary referral center.

PATIENTS:
Twenty-two chronic tinnitus patients.

INTERVENTION:
HD-tDCS.

MAIN OUTCOME MEASURES:
ERPs.

RESULTS:
The results show a significant shortening of the N1, P2, N2, and P3 latencies after HD-tDCS treatment. Moreover, the increased amplitude of the P2 and N2 peaks result in more salient and clear peaks, with the amplitude of N2 being significant larger after HD-tDCS. However, the ERP changes are not significantly correlated with the change in tinnitus functional index (TFI) total score.

CONCLUSIONS:
The current study was the first to explore ERPs as objective measure in a study with HD-tDCS in tinnitus patients. Adding ERPs to the outcome measures in tinnitus research may lead to a better understanding of the therapeutic effect in the future. The results showed a shortening of ERP latencies and an increased N2 amplitude, possibly reflecting more effective sound processing with higher recruitment of synchronized neurons in the auditory cortex. Future studies should elaborate on these results, by collecting control data and adding a sham group, to provide a better insight in the underlying mechanism of the ERP changes after tinnitus treatment.

https://journals.lww.com/otology-ne...tory_Study_on_the_Use_of_Event_Related.4.aspx

 

Can someone ELI5 the results of these studies?

 

What is 'ELI5'?

 

Explain like I'm 5.

In didn't know either, had to GOOGLE it.

 

Hah! Got it.

I can provide some ELI5 summaries tomorrow.

 

ELI5 of "Neural metabolic activity in idiopathic tinnitus patients after repetitive transcranial magnetic stimulation":

They used transcranial magnetic stimulation - which sends magnetic pulses into the brain to alter neuronal activity levels - to see if they could quiet over-active neurons associated with tinnitus.

They ran 11 people, which is too small a study to do much good.

They found no evidence that TMS lowered tinnitus severity, which is unsurprising, because with only 11 people the chances that they got statistically significant effects was slim to none.

Changes in neuronal activity in two brain regions did correlate with tinnitus severity scores. But the authors provide no indication (in the abstract, at least) of whether these were correlations pertained to pre-TMS or post-TMS tinnitus ratings. And without that information there's not very much that can be conclusively determined.

So ELI5 summary: this study needs more people before we can conclude an awful lot from it.

 

ELI5 of "RTMS parameters in tinnitus trials: a systematic review".

This paper is, as the title suggests, a review paper. It summarizes work to date on the potential benefits of TMS for tinnitus reduction.

They suggest that two recent large (yay for large) studies came to differing conclusions. Presumably one worked and one didn't. The authors of the review try to tease apart why this may have been. They suggest that TMS to the front of the brain had little effect. And they suggest that lower intensity levels of stimulation may have been effective. But then they also lament that not all TMS measures were reported in the reviewed studies, and so their hands are a bit tied re how much they can conclude.

ELI5 summary: The review begs researchers to report their findings more comprehensively.

 

ELI5 of "Daily high-frequency transcranial random noise stimulation of bilateral temporal cortex in chronic tinnitus – a pilot study":

I actually know (of) one of these researchers - so this is a good team.

They used a different kind of stimulation - rTNS or random transcranial noise stimulation. I actually wasn't familiar with this technology, so found it interesting.

They ran 30 people, and administered this rTNS on 10 different occasions. They found that the rTNS helped for 27% of participants, but *hurt* for 20% of participants. So this is obviously not so good, and the author's note this.

Perhaps most interestingly, all patients had previously received TMS (magnetic), and while TMS also helped 27% of people, it was a completely non-overlapping set of people. This suggests that different things may work for different people, and that a more personalized medicine approach will likely be the way forward.

ELI5 summary: good, preliminary, study. Well designed, conclusive. But, sadly...rTNS didn't really seem to work.

 

ELI5 of "An Exploratory Study on the Use of Event-Related Potentials as an Objective Measure of Auditory Processing and Therapy Effect in Patients With Tinnitus: A Transcranial Direct Current Stimulation Study."

This study used a third kind of stimulation - tDCS, which uses electricity. But the point of the study was apparently not to measure tinnitus efficacy, but rather to see if using electrical measurements could accurate measure the tinnitus percept (because right now all we have to go on is people's subjective ratings).

What they found was that, no, electrophysiological measurements do not track well with tinnitus symptoms. No word on whether tDCS had any benefits.

ELI5 summary: This was a highly experimental study that doesn't appear to have completely panned out.

 

Were these summaries useful for anyone? Would people appreciate if I continue summarizing the literature?

 

Yes they are for me! Thank you.

 

Cool. I'm happy to keep reviewing, as new papers/findings are posted.

 

I've actually been doing a review of tDCS papers, and I gotta say, it's pretty depressing. Very little work has been done, and the majority of work that has occurred remains of poor to moderate quality. Studies without control conditions, studies without blinded procedures, studies without validated tinnitus metrics. It's a bit of a nightmare.

The good news is there are LOTS of opportunities for improvement.