Tinnitus and Cervical Spine Injury
Tinnitus is an auditory disorder in which the patient hears a noise that is not actually present. "Tinnitus is common; estimates of its prevalence range up to 80% of all adults. About 10% of people complain of chronic tinnitus, whereas 0.5% of adults describe it as interfering with their ability to lead a normal life."
Many patients who have a whiplash injury or temporomandibular pain report tinnitus as one of their symptoms. The problem with these patients is that seldom are there the objective signs of nerve dysfunction commonly associated with tinnitus.
The reason for this is that there are two different types of tinnitus: "otic" and "nonotic." "Otic" tinnitus can be directly associated to disorders of the inner ear or auditory nerve through testing. "However, there are many other patients who have either no detectable ear/nerve disorders or there is no close temporal relationship between such a disorder and tinnitus, so that the initiating event of the "nonotic" tinnitus is obscure."
The author of this study uses a review of the literature and case reports to describe the phenomenon of "somatic" tinnitus, or tinnitus that originates in the lower head or the cervical spine.
The article describes nine patients with tinnitus and describes the various details of their cases. Here are brief descriptions of three of these cases:
- Case 1 was a 52-year-old woman who had surgery on her right shoulder. She developed a frozen shoulder from the surgery, and immediately upon injection of the local anasthetic being administered (for treatment of the frozen shoulder) she developed tinnitus in her right ear that has persisted since 1994. Clinical examination reported spasm of the right occipital muscles.
- Case 2 was a 39-year-old woman who had tinnitus since her teens. "Head position has always modulated her tinnitus loudness. On a 0 to 10 loudness scale, she rates her tinnitus as 3/10. When turning the head to either side or tilting to the left, loudness increases to 5/10, whereas with tilting to the right, the loudness was barely perceptible (1/10). Clenching her teeth increased the loudness only slightly (4/10). On examination, 2 regions of increased muscle tension and tenderness were noted in the right neck as compared with the corresponding regions on the left, namely the upper sternocleidomastoid and the medial suprascapular regions."
- Case 8 was a 50-year-old woman who developed tinnitus after neck manipulation. Her symptoms were intermittent, and, "When initially examined, she was not having tinnitus. Her left suboccipital muscles, however, were noted to be tender and under increased muscle tension compared with the corresponding muscles on her right side. Within an estimated 5 minutes of examining the cervical musculature, she reported that her left-sided tinnitus has started. On reexamination, her left suboccipital muscle tension had become much more pronounced. Within another 5 minutes, her tinnitus abated, and her suboccipital muscles were more relaxed."
The author cites a number of whiplash and TMJ studies that refer to tinnitus, and suggests that these conditions are not related to any pathology in the auditory nerve or inner ear, but are based in the cervical spine and jaw.
The key component in this neurological model is the Dorsal Cochlear Nucleus, or DCN. Disturbance of the DCN (which resides in the brain stem) has been found in other studies to be related to tinnitus. The author’s proposed model goes something like this:
- The nerves in the head and neck converge as they enter the brainstem and upper cervical spine (shown at right as the "CST," where they all meet in the medullary somatosensory nuclei (MSN).
- The MSN is directly connected via neural pathways to the DCN.
- Stimulation of the nerves in the head and neck (from injury or stress) could result in activation of the MSN and, in turn the DCN, resulting in tinnitus.
The details of this proposed model are really only useful to theorists. The importance of this study is that there is some strong evidence that neck and facial injury can result in tinnitus:
"Whether or not the proposed model for somatic (craniocervical) tinnitus is correct in all its details, it represents a focus for future systematic studies of somatic tinnitus and a framework for approaches to treatment. Moreover, we have presented a series of patients in whom the evidence argues for a craniocervical, nonotic basis for their tinnitus. As such, it seems likely that some cases of somatic tinnitus may result from interactions between the somatic and auditory pathways within the central nervous system with no involvement of the auditory periphery (cochlea or auditory nerve)."
Levine RA. Somatic (craniocervical) tinnitus and the dorsal cochlear nucleus hypothesis. American Journal of Otolaryngology 1999;20(6):351-362.