Perceptual and neurophysiological characteristics of intermittent tinnitus

Tinnitus is a very common and potentially devastating condition. It is related
to peripheral hearing loss. A key hypothesis is that tinnitus is caused by
changes in brain function as a result of hearing loss. Clinical evidence
suggest that tinnitus may not constitute a single entity. Instead, tinnitus may
comprise several subgroups of tinnitus, who*s pathophysiology is currently
unknown. One specific tinnitus subgroup may be intermittent tinnitus.
Participants with intermittent tinnitus describe changes in the loudness of
their tinnitus over the course of a day, between days, or from week to week.
They may be free of tinnitus on some days (tinnitus *OFF*), and may be heavily
bothered on other days (*ON*). Earlier studies, on participants with continuous
tinnitus, showed that tinnitus is related to abnormal functional connectivity
in the brain. That is, the brain connectivity is abnormal in comparison to
participants without tinnitus. This study further investigates whether these
abnormalities occur in a similar fashion in intermittent tinnitus, and whether
they appear only when the tinnitus is ON. Alternatively, the abnormal brain
activity may not be related to the tinnitus percept itself and simply reflect a
brain state that is prone to generate tinnitus.

The study consists of two parts.

Objective 1 to document the day by day changes of tinnitus that participants
with intermittent tinnitus experience. This objective is aimed for in part 1 of
the study. In addition, this part allows the selection of a subgroup that is
compatible with the scanning protocol in part 2.

Objective 2: to document whether the changes in tinnitus co-occur with changes
in functional brain connectivity, and whether brain connectivity patterns
differ from those in participants with continuous tinnitus.

Observational study.

Part 1: Participants receive an iPhone/Android app, which they use for 30 days.
The app prompts them 3 times per day to fill in a brief questionnaire on their
tinnitus. Filling in the questionnaires takes about 15 seconds. This has no
benefit to the participant, except that the app provides an overview of results
to the participants that is informative about their own tinnitus
characteristics.

Part 2: A subgroup of participants from part 1 will be invited to participate
in an fMRI experiment. This involves filling in 5 standard clinical
questionnaires (30 minutes), 1 standard MRI compatibility questionnaire (5
minutes), measuring an audiogram (20 minutes) and two fMRI session in a 3.0
Tesla MRI scanner (30 minutes each). This part provides no individual benefit
to the patient. We rate the inconvenience as mild. None of the procedures
expose the participants to known risks.