Several central nervous system phenomena have been proposed to explain the emergence
of tinnitus. In individuals with tinnitus, changes in the electroencephalograph (EEG)
are pronounced in recordings from temporal regions which strongly correlate with
the level of tinnitus related perception and distress.
Research also suggests that in tinnitus the midbrain auditory nuclei receive substantial
sensory innervation from higher centres and the subjective experience of sensory
phenomena is strongly modulated by attentional affects which can cause changes in
auditory cortex activity levels.
Modulation of these parameters can be achieved through the specialised application
of either one or a combination of tinnitus counselling, neurofeedback and/or hypnosis.
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 2011;Vanneste, Van de Heyning,
& De Ridder 2011). 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.
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Flowchart for Patient Management will contribute to a better diagnosis and treatment
of the many tinnitus patients worldwide,