Neck or jaw pain: does it ring a bell (in your ears)?

Whenever I tell someone I am conducting research on tinnitus, or ringing in the ears, the usual surprisingly enthusiastic response I get is: “Oh, interesting, my mom/dad/friend/… suffers from tinnitus!” Tinnitus, indeed, is a very common symptom, with a prevalence of 10 to 15% in the adult population. It is defined as the perception of a sound in the absence of a corresponding external sound (1).

However, what most people don’t know is that about two-third of tinnitus patients can modulate the loudness or pitch of their tinnitus by moving their jaw or neck, or by applying pressure to their jaw joint (temporomandibular joint) or masticatory muscles (2-5). This is one of the possible characteristics of somatic, or somatosensory, tinnitus (6).

Somato-what?!

Typically, tinnitus is related to hearing loss or a noise trauma (1). In most patients, however, tinnitus is triggered by several causes with many potential influencing factors (7), one of them being the somatosensory system (6). The somatosensory system is a component of the nervous system that detects and allows for perception of pain, temperature, head and body position and movement, and touch (8). When tinnitus is influenced by the cervical or temporomandibular somatosensory system, we refer to it as somatic or somatosensory tinnitus (9).

Diagnosis of somatic tinnitus

Patients with somatic tinnitus can present with a large set of different symptoms. There used to be no agreed standards for clinical assessment, which made it unclear how to diagnose somatic tinnitus. To resolve this, a group of somatic tinnitus experts created diagnostic criteria in 2018. This is a list of items that, if present, strongly suggests an influence of the somatosensory system on the patient’s tinnitus. Three sets of items were included in this list. The first one being the ability to modulate his or her tinnitus by voluntary movements, somatic manoeuvres, or pressure on myofascial trigger points. The ability to modulate their tinnitus strongly suggests somatic tinnitus, but is no absolute requirement. The second set of items includes characteristics that often exist in patients with somatic tinnitus, for instance: the simultaneous onset and aggravation of tinnitus and pain symptoms in the neck or jaw area, possibly preceded by a head or neck trauma. In addition, the increase in tinnitus during certain postures and the presence of variations in pitch, loudness, and location of tinnitus are also included in this set. The third and final set of items includes symptoms that accompany the patient’s tinnitus, including: frequent pain in the head, neck or shoulder girdle, temporomandibular disorders, pressure-tender myofascial trigger points in the head-neck region, increase in muscle tension in the neck extensor muscles, bruxism or teeth clenching, and dental diseases. It is generally accepted that the more criteria present, the stronger the somatic influence on tinnitus (6).

Treating tinnitus by treating the jaw

Our research group recently investigated whether we can treat somatic tinnitus by physical treatment of temporomandibular disorders or the neck. After nine weeks of treatment of temporomandibular disorders followed by a follow-up period of nine weeks, tinnitus decreased clinically significant in 61% of the patients (10). Michiels et al. (11) concluded that 53% of patients experienced a substantial improvement of tinnitus after six weeks of cervical physical treatment. This effect was maintained in 24% of patients after follow-up at six weeks. Moreover, research showed that patients who have a higher score on the somatic subscale in a tinnitus questionnaire (TQ) have a higher chance for better outcome with orofacial treatment. A greater somatic component in tinnitus might thus be a predictive factor for better treatment outcome (12).  

Tinnitus and the neck, more closely related than you might think

How is it possible that some people are able to alter their tinnitus loudness or pitch by moving their neck? And how can we explain tinnitus improvement following physical therapy? Up to today, the mechanisms behind (somatic) tinnitus are not fully discovered yet. Several animal studies have found connections between the somatosensory system of the cervical or temporomandibular area and the auditory system, more specifically at the dorsal cochlear nucleus situated in our brainstem (13-15). Scientists believe these connections are also present in humans, but direct evidence for this is still very limited, being demonstrated by one study only (16). Therefore, the door is still open to further study these connections in order to fully understand somatic tinnitus.

Written by Laura Jacxsens

MD and PhD student at the University of Antwerp.

For more information about this research project, feel free to contact me at  laura.jacxsens@uantwerpen.be

2021 MOVANTresearch

References

1.            Baguley D, McFerran D, Hall D. Tinnitus. The Lancet. 2013;382(9904):1600-7.

2.            Pinchoff RJ, Burkard RF, Salvi RJ, Coad ML, Lockwood AH. Modulation of tinnitus by voluntary jaw movements. Am J Otol. 1998;19(6):785-9.

3.            Rubinstein B, Axelsson A, Carlsson GE. Prevalence of signs and symptoms of craniomandibular disorders in tinnitus patients. J Craniomandib Disord. 1990;4(3):186-92.

4.            Levine RA. Somatic (craniocervical) tinnitus and the dorsal cochlear nucleus hypothesis. Am J Otolaryngol. 1999;20(6):351-62.

5.            Levine RA, Abel M, Cheng H. CNS somatosensory-auditory interactions elicit or modulate tinnitus. Exp Brain Res. 2003;153(4):643-8.

6.            Michiels S, Ganz Sanchez T, Oron Y, Gilles A, Haider HF, Erlandsson S, et al. Diagnostic Criteria for Somatosensory Tinnitus: A Delphi Process and Face-to-Face Meeting to Establish Consensus. Trends Hear. 2018;22:2331216518796403.

7.            Van de Heyning P, Gilles A, Rabau S, Van Rompaey V. Subjective tinnitus assessment and treatment in clinical practice: the necessity of personalized medicine. Curr Opin Otolaryngol Head Neck Surg. 2015;23(5):369-75.

8.            Jacobs KM. Somatosensory System. In: Kreutzer JS, DeLuca J, Caplan B, editors. Encyclopedia of Clinical Neuropsychology. New York, NY: Springer New York; 2011. p. 2320-4.

9.            Michiels S, Cardon E, Gilles A, Goedhart H, Vesala M, Schlee W. Somatosensory Tinnitus Diagnosis: Diagnostic Value of Existing Criteria. Ear Hear. 2021.

10.         Van der Wal A, Michiels S, Van de Heyning P, Braem M, Visscher C, Topsakal V, et al. Treatment of Somatosensory Tinnitus: A Randomized Controlled Trial Studying the Effect of Orofacial Treatment as Part of a Multidisciplinary Program. J Clin Med. 2020;9(3).

11.         Michiels S, Van de Heyning P, Truijen S, Hallemans A, De Hertogh W. Does multi-modal cervical physical therapy improve tinnitus in patients with cervicogenic somatic tinnitus? Man Ther. 2016;26:125-31.

12.         van der Wal A, Van de Heyning P, Gilles A, Jacquemin L, Topsakal V, Van Rompaey V, et al. Prognostic Indicators for Positive Treatment Outcome After Multidisciplinary Orofacial Treatment in Patients With Somatosensory Tinnitus. Front Neurosci. 2020;14:561038.

13.         Zhan X, Pongstaporn T, Ryugo DK. Projections of the second cervical dorsal root ganglion to the cochlear nucleus in rats. J Comp Neurol. 2006;496(3):335-48.

14.         Zhou J, Shore S. Projections from the trigeminal nuclear complex to the cochlear nuclei: a retrograde and anterograde tracing study in the guinea pig. J Neurosci Res. 2004;78(6):901-7.

15.         Davis KA, Miller RL, Young ED. Effects of somatosensory and parallel-fiber stimulation on neurons in dorsal cochlear nucleus. J Neurophysiol. 1996;76(5):3012-24.

16.         Lanting CP, de Kleine E, Eppinga RN, van Dijk P. Neural correlates of human somatosensory integration in tinnitus. Hear Res. 2010;267(1-2):78-88.