2019 Tinnitus Research Review Series: Somatic Tinnitus

TINNITUS
RESEARCH
REVIEW
SERIES
2019
SOMATIC/
SOMATOSENSORY
TINNITUS
Dr Sarah Michiels
Tinnitus Research Review Series 2019

Tinnitus Research Review Series 2019
Copyright © British Tinnitus Association 2019.
Editors: Veronica Kennedy & Nic Wray
The editors would like to thank all the contributors
for their support and enthusiasm. We would also
like to thank the copyright owners of the images
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their permission to reproduce them either directly
or via licence. We believe that all such work has
been acknowledged, but please contact Nic
Wray on nic@tinnitus.org.uk if any have been
inadvertently omitted.
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SOMATIC/
SOMATOSENSORY
TINNITUS
DR SARAH MICHIELS
Principal Research Fellow
University of Antwerp/Antwerp University
Hospital
Sarah Michiels graduated as a master in
rehabilitation sciences and physiotherapy from
the Antwerp University College in 2005 and as a
master in manual therapy from the Free University
of Brussels in 2008. She completed her PhD on
the role of the physical therapist in diagnosis and
treatment of patients with tinnitus, with Professors
Paul Van de Heyning and Willem De Hertogh, at the
University of Antwerp in 2015.
Currently, she works at the University of Antwerp
and Antwerp University Hospital as a principal
research fellow, continuing her research on
somatic tinnitus.
Dr Sarah Michiels
Definitions
The somatosensory system is a part of the
sensory nervous system. This is a complex
network of sensory and neurons that respond to
changes at the surface or inside the body. These
changes can include movement, pressure, touch,
temperature or pain.
Somatic (also called somatosensory) tinnitus
(ST) is a subtype of subjective tinnitus, where
changed somatosensory information from the
cervical spine or jaw area causes or changes a
patient’s tinnitus perception.
Since Levine’s first publication in 1999 (1),
several animal and human studies have found
connections between the somatosensory system
of the cervical (neck) and temporomandibular
(jaw joint) area and the cochlear nuclei (CN),
offering a physiological explanation for ST
(2-4). According to these studies, cervical or
temporomandibular somatosensory information
is transported to the brain by neural fibres from
cell bodies located in the dorsal root ganglia or
the trigeminal ganglion. Some of these fibres
also project to the central auditory system. This
enables the somatosensory system to influence
the auditory system by altering spontaneous
rates or synchrony of firing among neurons in the
CN, inferior colliculus or auditory cortex. In this
way, the somatosensory system is able to alter
the pitch or loudness of the tinnitus (5).
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Somatic/somatosensory tinnitus
Tinnitus modulation criteria
The patient is able to modulate the tinnitus by voluntary movement of the head, neck, jaw or eyes
The patient is able to modulate the tinnitus by somatic manoeuvres (e.g. jaw clench)
Tinnitus is modulated by pressure on myofascial trigger points
Table 1: Tinnitus modulation abilities that strong suggest a somatosensory influence on tinnitus
Prevalence
Widely varying prevalence figures of ST have
been reported in literature. In a recent study (6),
using data from 1262 patients with tinnitus, ST
was present in 12%. This is in accordance with
the 16% prevalence reported by Ward et al (7) in
2015. Other studies though, reported prevalences
of between 43 and 83% of patients with tinnitus
(7-13). The most important reason for this wide
variation is probably the lack of unambiguous
diagnostic criteria for ST.
Diagnosis
In order to overcome this issue, we started
a Delphi process to reach consensus about
ST diagnosis among ST experts. The Delphi
method allows experts to work towards a mutual
agreement by conducting a circulating series of
questionnaires and releasing related feedback
to further the discussion with each subsequent
round.
In total, 13 ST experts from 10 different countries
completed this process. During the final
consensus meeting, the group of experts agreed
on a list of criteria, that if present, strongly
suggest an influence of the somatosensory
system on the patient’s tinnitus (Tables 1 to 3).
This consensus recommends aspects of tinnitus
modulation, tinnitus characteristics (such as
varying pitch and loudness), and accompanying
Tinnitus Research Review Series 2019
Tinnitus characteristics
Tinnitus and neck or jaw pain complaints
appeared simultaneously
Tinnitus and neck or jaw pain symptoms
aggravate simultaneously
Tinnitus is preceded by a head or neck trauma
Tinnitus increases during bad postures
Tinnitus pitch, loudness and/or location are
reported to vary
In the case of unilateral tinnitus, the
audiogram does not account for unilateral
tinnitus
Table 2: Tinnitus characteristics that strongly
suggest a somatosensory influence on tinnitus
symptoms that are strongly suggestive of ST in
an individual patient, while acknowledging that
the individual presentation of the condition can
vary from patient to patient.
To prevent under or over-diagnosis, it is important
to keep in mind the experts’ footnotes. When
looking at the ‘modulation’ items for instance,
our consensus meeting panel recognised the
importance of somatic modulation, especially
by voluntary movements, for the ST diagnosis,
but added that the absence of this ability does
not rule out ST. Hence, somatic modulation
should not be used as a simple ‘yes/no’ criterion

Somatic/somatosensory tinnitus
Accompanying symptoms
Tinnitus is accompanied by frequent pain in the cervical spine, head or shoulder girdle
Tinnitus is accompanied by the presence of tender myofascial trigger points
Tinnitus is accompanied by increased muscle tension in the suboccipital muscles
Tinnitus is accompanied by increased muscle tension in the extensor muscles of the cervical spine
Tinnitus is accompanied by temporomandibular disorders
Tinnitus is accompanied by teeth clenching or bruxism
Tinnitus is accompanied by dental diseases
Table 3: Accompanying symptoms that strongly suggest a somatosensory influence on tinnitus
for diagnosing ST. Although the use of somatic
manoeuvres to assess tinnitus modulation was
voted in, some experts believe that the use of
these manoeuvres as a single criterion can
potentially lead to over-diagnosis.
It must also be noted that items, such as:
‘tinnitus accompanied by frequent pain in
the head, neck or shoulder girdle’ or ‘tinnitus
accompanied by temporomandibular disorders’,
should be used with a certain prudence if they
are the only criterion present. This is because
tinnitus and neck or jaw problems can also
co-occur without a causal relation (14). On the
other hand, when these items are combined with
another criterion, such as ‘tinnitus and neck or
jaw pain complaints appeared simultaneously’
or ‘the patient is able to modulate the tinnitus
by voluntary movement of the head, neck, jaw
or eyes’, the likelihood of a ST diagnosis gets
stronger.
Treatment
Several techniques and approaches have been
suggested for the treatment of ST, but generally,
ST treatment can be categorized in techniques
directed to the cervical spine, techniques directed
to the temporomandibular area and bimodal
stimulation treatment.
Cervical spine treatment
Figure 1: Cervical spine.
Image: BodyParts3D, © 2008 Life Sciences Integrated Database
Center licensed by CC Display-Inheritance 2.1 Japan
A systematic literature review published in
2016 (15) was able to identify four (randomized)
controlled trials investigating the effect of
cervical spine treatment on tinnitus severity.
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Somatic/somatosensory tinnitus
These studies showed a positive effect of cervical
spine manipulations, muscle trigger point
treatment, stabilizing and mobilizing exercises,
transcutaneous electrical nerve stimulation
(TENS) and a combination of stretching, postural
exercises and auricular acupuncture (16-19).
One more recent randomized controlled trial
(20) showed positive effects of a multimodal
cervical spine treatment on tinnitus severity.
This treatment consisted of a patient-tailored
combination of manual mobilizations, muscle
trigger point treatment, and stabilizing and
mobilizing exercises.
currently widely accepted.
Although experts agreed on a set of criteria to
identify patients with ST, it is still not easy to
make the diagnosis, especially because patients
often present with a combination of influencing
factors.
Once diagnosed, ST can be treated successfully
with cervical spine physiotherapy or with
orofacial physiotherapy combined with splint
treatment. The effect of bimodal auditorysomatosensory
stimulation is promising, but
needs to be confirmed in larger studies.
Temporomandibular treatment
Currently, only three controlled trials studying
the effect of temporomandibular treatment on
tinnitus severity are available. These studies
show that tinnitus severity significantly
decreased after splint treatment combined
with jaw exercises (21-23). One study did notice
that this effect was only present in patients
with severe to very severe tinnitus (Tinnitus
Questionnaire score: 47-84) and not in patients
with light to moderate tinnitus (Tinnitus
Questionnaire score: 0 – 46).
Bimodal stimulation treatment
One study from Marks et al (24) shows positive
effect on tinnitus loudness after bimodal
stimulation treatment in 20 patients with
unilateral ST. This treatment comprises a
combination of auditory stimulation and
electrical stimulation applied to the cervical
spine or temporomandibular area. This approach
is currently being tested in a large randomized
controlled trial.
Conclusion
The existence of a tinnitus subtype where tinnitus
is influenced by somatosensory information from
the cervical spine or temporomandibular area is
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Somatic/somatosensory tinnitush
References
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