The experiment revealed that there are indeed differences, which corroborates the data of studies carried out in accordance with other protocols (in particular, with positron emission tomography and with electroencephalography) in other centers. In addition, these differences in connectivity concern the cortical and sub-cortical regions and include the attentional, emotional and memory systems. “It seems logical that someone who attributes a lot of importance to their tinnitus and is having difficulty living with it will see an increase in their attentional and emotional networks which interact with the auditory areas. As for the regions involved in memory, such as the parahippocampal region, we think that they ‘decide’, after comparison with the other sounds picked up as usual, if a perceived noise –in this case the tinnitus- must be ‘stifled’ or dealt with more deeply because it represents a danger” explains Audrey Maudoux.

Evidently, if the results recorded by the researchers at the CRC and the ENT department of the University of Liège seem ‘logical’, the fact remains that the “set of influences” remain hazy. Indeed, the studies carried out do not make it possible to define the initial meaning of dialogue between the cerebral areas. Is it the auditory region that influences the activity of the attentional, emotional and memory areas or is it the latter that initiates the exchange of information? This question is highly significant, as it is at the center of questions relative to the etiology of the problem and the way to treat it. “Using  electroencephalogy, the dynamic casual modeling technique (DCM) makes it possible to define the direction of relations but it has not yet been used in the context of tinnitus. We hope to initiate studies in fMRI which would use a similar technique”, comments Audrey Maudoux.

Defining sub-types

Published in the journal PLoS ONE(1), the study by the Liège researchers suggests no less than that the different cerebral regions   appear to be involved in the persistent awareness of the phenomenon as well as in the development of the associated distress, leading to disabling chronic tinnitus

Backed up by data from fMRI and questionnaires, the researchers also asked if the intensity of the connection between these brain regions was correlated with an important clinical marker  of tinnitus. The answer would appear to be yes. “The results of this work have been the subject of a publication in Brain Research (2) in May 2012. However, with a sample of only 13 tinnitus patients, we have only been able to show a trend. We are going to try to refine and reinforce the results of our different work by analyzing a group of around one hundred patients”, says Audrey Maudoux.

The results published in PLoS ONE are the results of a group study. They express average values. Future work based on a larger sample will perhaps enable us to distinguish several types of tinnitus and to define their individual characteristics. In addition, longitudinal “resting-state FMRI” monitoring would be of great interest because it would make it possible to determine the variations in the cerebral activity of a subject according to whether his tinnitus remained stable, disappeared, is better tolerated or becomes intolerable. This would pave the way for more individualized treatments.