Timothy C. Hain, MD. Tinnitus Page Page last modified: February 2, 2018
A rare source of troubling tinnitus is damage to structures outside of the ear or brain. The general idea is that sensory input from muscles or structures outside the ear can cause or change tinnitus. Subgroups include cervical tinnitus and TMD tinnitus.
One can be easily convinced that somatic tinnitus exists by simply clenching one's jaw. This maneuver often causes an increase in volume or change in pitch of tinnitus. Levine provided an extensive list of maneuvers (2007) including various types of jaw movements, isometric head/neck contractions, and pressure on muscle insurtions around the ear and SCM muscle, and were able to induce tinnitus in 80% of their study population of 62 volunteers. In 33 people with no tinnitus whatsoever, these procedures elicited tinnitus in almost 60%.
Electrical stimulation of the median nerve at the wrist can cause tinnitus (Moller and Rollins, 2002). Similarly, Moller et al (1992) found that tinnitus modulated with electrical stimulation at the wrist. As of course the median nerve sends input to the spinal cord, and cervical injuries are known to occasionally cause tinnitus, this is consistent with the general idea that sensory input from nearly any source can (rarely) cause or modulate tinnitus.
We have encountered patients who can change the pitch of tinnitus by moving their eyes. These patients generally are those who have had acoustic tumors removed.
Somatic tinnitus is not a popular research topic.
Ralli et al (2017) reported on 172 somatic tinnitus patients in Rome. They reported "Compared to those without hyperacusis, patients with somatic tinnitus and hyperacusis: (a) were older (43.38 vs 39.12 years, p = 0.05), (b) were more likely to have bilateral tinnitus (67.08% vs 55.56%, p = 0.04), (c) had a higher prevalence of somatic modulation of tinnitus (53.65% vs 36.66%, p = 0.02) and (d) scored significantly worse on tinnitus annoyance (39.34 vs 22.81, p<0.001) and subjective hearing level (8.04 vs 1.83, p<0.001)."
Basically then, patients with two symptoms are worse than patients with one symptom. No big surprise there.
Figure 1 from Levine et al, 2007.
In general, it is thought that cervical input can modulate hearing related neural structures in the brainstem (Shore et al, 2007). Levine (1999) suggested that it was due to modulation of the dorsal cochlear nucleus. The diagram above is a basic depiction of known neuroanatomy, with the addition of an arrow labeled "Inhibition".