Thursday, 2 August 2012

Effective TDCs Tinnitus Protocols Undefined

I am still researching appropriate electrode placements for tinnitus treatment. I am not going to risk placing them in the wrong area so this may take some time. 


Both hemispheres of the Dorso Lateral Prefrontal Cortex are commonly treated but this is a relatively large surface area. 


From:http://www.tinnitusresearch.org/en/patients/newintinnitusresearch_en.php







Many different functional and structural imaging techniques have been used to identify structures in the central nervous system which are believed to play an important role in the pathophysiology of many forms of tinnitus.

The neuroimaging methods functional magnetic resonance (fMRI) and positron emission tomography (PET) enable to measure regional changes of cerebral blood flow, which in turn is an indirect measurement of neuronal activity. Electro- (EEG) and Magnetoencephalography (MEG) measure neuronal activity directly. Alterations in the central auditory pathways in tinnitus patients have been shown already 15 years ago. However it has been only very recently that neuroimaging studies have systematically been used to differentiate the different forms of tinnitus (unilateral versus bilateral, pure tone versus noise like, with more and less distress, with shorter and longer duration) (Schecklmann et al. 2011;Vanneste, Van de Heyning, & De Ridder 2011a;Vanneste, Van de Heyning, & De Ridder 2011b). It has been demonstrated that all these forms differ in their brain activity pattern, especially in non-auditory brain areas. Also for the first time brain activity changes related to acute tinnitus after noise trauma have been studied (Ortmann et al. 2011) and it has been found that these differ substantially from those in chronic tinnitus.EEG and MEG have revealed consistent results across many studies in the sense that in tinnitus the normal activity pattern in the auditory cortex is changed. In the auditory cortex of tinnitus patients alpha activity is reduced, whereas delta and gamma activity is increased. Successful treatment reverses these abnormalities, indicating that they represent the neuronal correlate of tinnitus loudness. Syst Neurosci. 2012;6:15. Epub 2012 Apr 9. Neuroimaging and neuromodulation: complementary approaches for identifying the neuronal correlates of tinnitus. "...In conclusion, these preliminary studies indicate that both anodal stimulation of the left auditory cortex and bifrontal tDCS with the cathode left and the anode right can have beneficial effects on tinnitus in some individuals. The interindividual variability of treatment effects is high in all studies, suggesting that there may be pathophysiologically distinct forms of tinnitus that respond particularly well to different tDCS protocols (Vanneste et al.,

2011c).
In order to unravel the mechanism by which tDCS suppresses tinnitus EEG
measurements were performed before and after single sessions of bifrontal tDCS
in 12 patients who responded to tDCS. Reduction of tinnitus intensity and
tinnitus-related distress was related to modulation of neuronal activity in
pregenual anterior cingulate cortex, parahippocampal area, and right primary
auditory cortex regions (Vanneste et al., 2011a). These findings are comparable
to those obtained in healthy controls after a similar tDCS intervention (anode
positioned over the left DLPFC and the cathode over the right supraorbital
region), that revealed a tDCS induced modulation of regional electrical activity
in the left subgenual prefrontal cortex, the anterior cingulate cortex and the
left parahippocampus (Keeser et al., 2011b) and significant changes of regional
brain connectivity both for the default mode network and the fronto-parietal
network (Keeser et al., 2011a)."




Neuroanatomical correlates of tinnitus revealed by cortical thickness analysis and 
diffusion tensor imaging.

Abstract

INTRODUCTION: Tinnitus is a poorly understood auditory perception of sound in
the absence of external stimuli. Convergent evidence proposes that tinnitus
perception involves brain structural alterations as part of its pathophysiology.
The aim of this study is to investigate the structural brain changes that might
be associated with tinnitus-related stress and negative emotions.


METHODS: Using high-resolution magnetic resonance imaging and diffusion tensor
imaging, we investigated grey matter and white matter (WM) alterations by
estimating cortical thickness measures, fractional anisotropy and mean
diffusivity in 14 tinnitus subjects and 14 age- and sex-matched non-tinnitus
subjects.

RESULTS: Significant cortical thickness reductions were found in the prefrontal
cortex (PFC), temporal lobe and limbic system in tinnitus subjects compared to
non-tinnitus subjects. Tinnitus sufferers were found to have disrupted WM
integrity in tracts involving connectivity of the PFC, temporal lobe, thalamus
and limbic system.

CONCLUSION: Our results suggest that such neural changes may represent neural
origins for tinnitus or consequences of tinnitus and its associations.
Neuroanatomical correlates of tinnitus revealed by cortical thickness analysis
and diffusion tensor imaging.
Abstract
INTRODUCTION: Tinnitus is a poorly understood auditory perception of sound in
the absence of external stimuli. Convergent evidence proposes that tinnitus
perception involves brain structural alterations as part of its pathophysiology.
The aim of this study is to investigate the structural brain changes that might
be associated with tinnitus-related stress and negative emotions.
METHODS: Using high-resolution magnetic resonance imaging and diffusion tensor
imaging, we investigated grey matter and white matter (WM) alterations by
estimating cortical thickness measures, fractional anisotropy and mean

diffusivity in 14 tinnitus subjects and 14 age- and sex-matched non-tinnitus
subjects.
RESULTS: Significant cortical thickness reductions were found in the prefrontal
cortex (PFC), temporal lobe and limbic system in tinnitus subjects compared to
non-tinnitus subjects. Tinnitus sufferers were found to have disrupted WM
integrity in tracts involving connectivity of the PFC, temporal lobe, thalamus
and limbic system.
CONCLUSION: Our results suggest that such neural changes may represent neural
origins for tinnitus or consequences of tinnitus and its associations.

http://www.springerlink.com/content/d67t81vx500870l2/

Some research:http://proceedings.ebea2011.org/modules/request205f.pdf?module=oc_program&action=view.php&id=5178


Bifrontal transcranial direct current stimulation (tDCS), with the anodal electrode overlying the right and the cathodal electrode overlying the left dorsolateral prefrontal cortex, has been shown to suppress tinnitus significantly in 30% of patients.



So there are various types of tinnitus with different neurological correlates. On top of this there are individual brain structures and neural layouts. At present the research is ongoing and a partial reduction of symptoms in 30% of subjects is not sufficient for me to undertake TDCs for Tinnitus as of this time.



2 comments:

  1. Agreed. With so much tDCS research going on at the clinical level, it makes sense to wait. I wasn't aware that Tinnitus was so slippery.

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