This month I would like to discuss tinnitus, a symptom that affects about 10% of the adult population. Despite its prevalence, there are still some surprisingly large gaps in our knowledge about it. Most of the time a cause or causes can be found but understanding the mechanism(s) is another matter.
For example, one cause of tinnitus is head trauma. However, how and where trauma affects the auditory mechanism is in most cases a mystery. A great deal of speculation about damaged cilia, etc in the inner ear passes for fact when in reality the inner ear is a difficult organ to study directly and little is known about local pathophysiology.
We know that not all tinnitus comes from the inner ear. Acoustic neuroma (8th nerve) is a possible cause. Surgical resection of the auditory nerve has shown that some tinnitus is central in origin and can be independent of the ear. Imaging studies indicate that tinnitus is linked to abnormal activity in the inferior colliculus, the auditory cortex and other related parts of the sound processing pathway termed "auditory association areas".
In recent years, the autonomic nervous system has been receiving increased attention. Sympathetic fibers from the carotid plexus are known to penetrate the ear through the tympanic cavity. These are presumably vasomotor in nature and most often act as vasoconstrictors. One interesting study has shown a correlation between "vibration-induced white finger" and tinnitus - presumably both conditions caused by prolonged vasoconstriction. Other studies have shown correlations between tinnitus and systemic manifestations of autonomic nervous system imbalance, such as suppression of heart rate variability and serum serotonin levels. The correlation was strongest in those patients who were experiencing the highest levels of distress from their tinnitus.
This last observation leads to another subject, namely the difference between the intensity of the tinnitus and the level of distress that is experienced. The vast majority of those experiencing tinnitus tolerate it well and feel only mild discomfort. Some however become upset and 1% experience it to the extent that it interferes with daily life. It is this smaller group that appears to have the strongest autonomic nervous system involvement.
Of course any pathophysiological process involving the autonomic nervous system is a candidate for treatment by neural therapy. The trick then is to find the interference field that may be triggering the abnormal response.
History can occasionally be helpful. Exposure to noise or ototoxic medication usually indicates irreversible structural damage, unlikely to be helped by neural therapy. (I have seen one case of tinnitus that began shortly after a vaccination). If head or neck trauma preceded the onset of symptoms, the mechanics of the head and neck should be examined carefully, ideally by someone competent in cranial osteopathy. The same applies if the intensity of the tinnitus is affected by posture, or by neck or jaw movement.
If the tinnitus is accompanied by nausea and vertigo, Meniere's Syndrome is likely. A pulsatile tinnitus may indicate a vascular malformation.
However much of the time the history provides no clues. And the standard physical examination is of little help. One exception is the discovery of impacted earwax, the removal of which may provide a cure! For those skilled in myofascial examination, Travel and Simons' textbook describes trigger points in the masseter muscles, the sternocleidomastoids and the temperomandibular joints. In my experience these trigger points are usually secondary to mechanical imbalances, dental problems or other interference fields.
The Dosch textbook suggests a series of test injections, starting with an intravenous bolus of procaine, followed by injections into various acupuncture points around the ear and the stellate and otic ganglia. Surprisingly, no mention is made of wisdom teeth as triggers of tinnitus, (except in a general discussion of dental interference fields). In my experience, upper wisdom teeth or the scars that remain after their extraction are not rare causes of tinnitus. At times, procaine injections alone will provide cures. At other times isopathics must be added to the procaine. More commonly extraction or surgical debridement of cavitations (or NICO lesions) is necessary.
For those reluctant to subject their patients to a series of often fruitless injections, autonomic response testing is a simple answer. It seems to shine especially in the mouth, where interference fields can be detected with great precision ‐ discriminating between the buccal and lingual aspects of a tooth for example.
Tinnitus is common and most of the time untreatable. However, as in so many medical conditions, the possibility of an easily treatable interference field should always be considered. You owe it to your patient and to your self to look for them!
Robert F. Kidd, MD, CM