Somatosensory Tinnitus

Definition and epidemiology

Somatosensory (somatic) tinnitus is a subtype of subjective tinnitus in which sensory input from the neck, jaw or head changes the loudness, pitch or perceived location of the tinnitus (Michiels et al., 2018). Tinnitus affects roughly 10-15% of adults; the reported frequency of somatosensory tinnitus ranges from 16% to 83%, a spread largely explained by differences in diagnostic criteria (Michiels et al., 2018).

Modulation of tinnitus by somatic manoeuvres is common: across studies an average of 69% of patients, and 79.7% in a series of 310 patients, could change their tinnitus somatically (Ralli et al., 2017). However, the same manoeuvres produce tinnitus-like sounds in some people without tinnitus. The consensus panel therefore did not accept modulation as a criterion on its own and recommended interpreting it together with the history and accompanying findings (Michiels et al., 2018).

Symptoms and signs

People notice that their tinnitus gets louder, quieter or changes pitch when they clench their jaw, open and close the mouth, turn the head or when pressure is applied to neck and shoulder muscles. In the series of Ralli et al. (2017), the temporomandibular joint (TMJ) was the region that most often modulated tinnitus, and most TMJ manoeuvres made it louder. Loudness and location can vary through the day, increasing with poor posture, after long hours at a computer or during periods of teeth clenching.

Accompanying complaints guide the diagnosis: neck, head or shoulder pain, tender trigger points in the muscles, pain and clicking in the jaw joint, jaw fatigue on waking, and teeth clenching or grinding (bruxism). The tinnitus may have started at the same time as neck or jaw pain, or worsen alongside it; in some patients it starts after a head or neck injury (Michiels et al., 2018). In unilateral tinnitus, the audiogram may not account for the affected side.

Causes and risk factors

The basis of somatosensory tinnitus is the dorsal cochlear nucleus in the brainstem. Its fusiform cells receive input from the auditory nerve as well as sensory input from the trigeminal nerve and the neck, and integrate the two. Levine (1999) described the dorsal cochlear nucleus hypothesis, proposing that somatic tinnitus arises from this integration. Animal studies have shown that after cochlear damage, auditory nerve terminals in the dorsal cochlear nucleus decrease while somatosensory terminals increase, and fusiform cells fire spontaneously at higher rates (Ralli et al., 2017; Shore et al., 2016). In a system with reduced auditory input, the influence of somatosensory input therefore grows.

The association with neck and jaw problems has been examined systematically. In the review by Bousema et al. (2018), people with tinnitus were more likely to report cervical spine disorders (odds ratio [OR] 2.6; 95% CI 1.1-6.4). The relationship between tinnitus and temporomandibular disorders (TMD) runs in both directions, with odds ratios of 2.3 to 6.7 depending on the type of TMD. Because of evidence of publication bias, the authors describe the evidence for both associations as weak. A somatosensory influence does not mean that hearing loss and other causes of tinnitus are absent; in most patients these factors coexist.

Audiological and clinical assessment

There is no single confirmatory test for somatosensory tinnitus. The consensus criteria developed by Michiels et al. (2018) through a Delphi process and a face-to-face meeting comprise 16 items in three groups. No criterion has to be present in every patient, but their presence strongly suggests a somatosensory influence.

As with other forms of tinnitus, assessment starts with a full audiological battery.

• Otoscopy, pure-tone and speech audiometry: show any accompanying hearing loss and asymmetry. Unilateral tinnitus and asymmetric hearing loss are among the exceptions to the guideline’s recommendation against routine imaging (Tunkel et al., 2014).
• Tympanometry and acoustic reflexes: help identify middle ear problems and middle ear muscle contractions that can cause tinnitus.
• Measuring tinnitus characteristics: pitch and loudness matching and minimum masking level are recorded for comparison before and after treatment.
• Somatic manoeuvre testing: the person is asked to clench the jaw, push the jaw forwards and sideways, and turn and tilt the head against resistance, and pressure is applied to trigger points in the neck and jaw muscles. After each manoeuvre the person reports whether the tinnitus became louder, quieter or changed in pitch.
• Questionnaires: tools such as the Tinnitus Handicap Inventory document and track the impact of tinnitus on daily life.

The neck and jaw are examined together with a physiotherapist and dentist. The differential diagnosis includes pulsatile tinnitus (vascular causes), middle ear myoclonus, accompanying hearing loss and retrocochlear disease. Routine imaging is not recommended unless the tinnitus is unilateral or pulsatile, or there are focal neurological signs or asymmetric hearing loss (Tunkel et al., 2014).

Treatment and audiological rehabilitation

Treatment combines approaches aimed at the somatosensory influence with general tinnitus management. Evidence for physiotherapy and dental approaches is promising but limited. Of the six studies in the systematic review by Michiels et al. (2016), four examined neck treatment and two TMJ treatment. Neck manipulation, exercise and trigger point treatment, and occlusal splints, occlusal adjustment and jaw exercises, reduced tinnitus severity. Although every study reported a positive effect, the risk of bias was high and the evidence was of low quality.

In a randomised controlled trial of 80 patients receiving orofacial treatment as part of a multidisciplinary programme, Tinnitus Functional Index (TFI) scores fell by 13.8 points at week 9 in the early-start group and by 5.0 points in the delayed-start group; 41% of patients improved to a clinically relevant degree immediately after treatment and 61% by the end of follow-up (van der Wal et al., 2020). The review by Ralli et al. (2017) reported that an average of 69% of patients in studies of TMJ treatment had reduced or resolved tinnitus, although results varied widely between studies. Bimodal stimulation, in which auditory and somatosensory stimuli are paired with a set timing, is an experimental approach targeting the dorsal cochlear nucleus; it reduced tinnitus in a small human study but is not yet in routine use (Marks et al., 2018).

The components of general tinnitus management apply here too. The guideline recommends cognitive behavioural therapy for persistent, bothersome tinnitus, offers sound therapy as an option and recommends a hearing aid evaluation for patients with hearing loss. Medication and dietary supplements are not recommended as routine tinnitus treatment (Tunkel et al., 2014). Decisions on medication rest with the doctor. Audiological counselling matters for explaining why the tinnitus changes and helping the person not to see this change as a danger sign.

Impact on quality of life and advice

Tinnitus that changes with neck or jaw movement can cause anxiety; seeing their tinnitus change with their own movements makes some people feel a loss of control, while others find it reassuring that the problem can be understood. Explaining the mechanism reduces anxiety. Chronic neck pain, poor sleep and stress can heighten the perception of tinnitus, so these complaints also need attention.

People who spend long hours at a computer may ease their symptoms by adjusting screen and chair height, taking regular breaks and doing neck and shoulder exercises. Noticing daytime teeth clenching and relaxing the jaw muscles, and wearing a splint recommended by the dentist for night-time clenching, can help.

Note which movements or postures change your tinnitus and share this with your audiologist, physiotherapist and dentist. Treatments such as exercises and splints take time to work, so follow the recommended programme regularly. If your tinnitus is clearly affecting your sleep, work or mood, discuss psychological support options.