|Neurotology and Abnormal Sensory Phenomena
Pages: 117 - 121
Clinical Experiences of Steroid Targeting Therapy to Inner Ear for Control of Tinnitus
Keywords: inner-ear drug delivery system; steroid targeting therapy; tinnitus; trans tympanic perfusion technique
Tinnitus aurium is defined as a noise or ringing in the ears. It is derived from the Latin tinnire, to ring. The condition usually is subjective and audible only to the patient. When tinnitus is slight, the patient may not notice the ringing during most of the day. However, when tinnitus is continuous and loud, it can interfere with a person's quality of life and may be so annoying as to incite neurosis. Some patients with an inner-ear problem experience such overwhelming tinnitus that they would "cut off their ear" or "poke a hole in it with an ice pick" to try to relieve the noise. In rare instances of severe tinnitus, a patient might consider suicide.
The management of tinnitus has been the topic of many articles and special meetings of scientific societies. In this article, we describe some 15 years of clinical experience with steroid targeting therapy (STT) to the inner ear for control of tinnitus.
HISTORY OF OUR INNER-EAR DRUG DELIVERY SYSTEM
Our clinical trials of an inner-ear drug delivery system (DDS) for control of inner-ear problems began in 1974 . The inner-ear DDS that we employ consists of transtympanic perfusion of medicine to the round window via the middle ear. At the beginning of our clinical trials of this system, we used 4% lidocaine hydrochloride to alleviate distressing inner-ear symptoms of tinnitus, recruitment, fullness or stiffness in the ear, and vertigo. Although the injection of 4% lidocaine hydrochloride is very effective for controlling inner-ear problems, patients complained of vertigo for several hours after the injection of medicine .
Consequently, in 1981, we began to use liquid dexamethasone for STT to the inner ear, to control various kinds of inner-ear diseases and symptoms .
PATIENTS AND METHODS
The procedure we employed for our therapeutic modality has already been reported elsewhere [4-7]. The intratympanic injection was performed in our outpatient clinic with the patient in the sitting or the supine position. Dexamethasone, 2 or 4 mg, was introduced into the middle-ear cavity through a fine needle, just as is done in tympanic puncture. Before the procedure, the patient was asked to try to hold his or her posture steady and to avoid swallowing during the injection and for approximately 15 minutes thereafter to prevent the escape of dexamethasone through the Eustachian tube. The perfusion was repeated four times at an interval of 1-2 weeks. Depending on the clinical situation, some patients received a second course of four injections 3 months after the first course.
The investigation period spanned 63 months from January 1987 through March 1992. The subjects were 3,978 ears of 3,041 patients who received intratympanic dexamethasone perfusion for the management of vertigo, tinnitus, and the like. Patient ages ranged from 14 to 89 years, the average being 51.7 years. Most of the cases of tinnitus were assumed to be of cochlear origin. The ma-jority of the patients could not be treated successfully by oral administration of vasodilators or mild sedatives.
EVALUATION OF EFFECTIVENESS
To evaluate the control effects of this therapy on tinnitus, a 10-division subjective evaluation system was used. This system commonly is used for subjective evaluation of other sensory disturbances. The severity or annoyance of tinnitus before the injection was regarded as being at level 10, and the level after the injection of drug was expressed as a score from 1 to 10. A level of 0-2 for the residual symptoms represented good effects, 3-6 represented fair effects, and 7-10 represented poor effects. Overall effectiveness was defined as the sum of the good effects and fair effects.
Short-term effects on tinnitus were evaluated 2 weeks after the fourth intratympanic dexamethasone perfusion. Patients then were investigated 6 months after the injection, at which time the long-term effects on tinnitus were evaluated.
The short-term overall effects on tinnitus of dexamethasone perfusion into the tympanic cavity were positive in 75% of patients.
Age and Effects
Figure 1 shows the effects on tinnitus in various age groups. The effects ranged from 54% to 73%. No correlation could be demonstrated between patients' ages and improvement of tinnitus.
Figure 1. Effects on tinnitus of intratympanic dexamethasone perfusion in various age groups.
Diseases and Effects
Figure 2 depicts the effectiveness of drug management of tinnitus in the presence of various underlying diseases. Of patients with Meniere's disease, 74% experienced improvement of tinnitus. In contrast, the effec-tiveness of our therapeutic regimen on tinnitus accompanied by streptomycin deafness was 48% and, in the presence of head injury, this figure dropped to 42%. The improvement of tinnitus with labyrinthine hydrops was good, but effectiveness for noise-or druginduced tinnitus was poor.
Figure 2. Effects on tinnitus of intratympanic dexamethasone perfusion in the presence of various underlying diseases.
Duration and Effects
Figure 3 displays the effects on tinnitus control in relation to disease duration. Patients treated within 3 months of the onset of tinnitus had very good results. The effectiveness tended to decrease with longer disease duration.
Figure 3. Effects on tinnitus of intratympanic dexamethasone perfusion in relation to disease duration.
The effects of our DDS trials on tinnitus control and average hearing levels ranged between 64% and 72%. A good result was seen in patients with mild hearing disturbances.
Evaluation of the effects on various pitches of tinnitus indicates that high-tone tinnitus was less improved than was low-pitched tinnitus. Efficacy of our regimen in high-tone tinnitus was poor.
No correlation was confirmed between efficacy of management and loudness of the tinnitus.
Overall Long-Term Effects
The long-term effects on tinnitus of dexamethasone perfusion into the tympanic cavity were evaluated at approximately 6 months after the last injection. The same 10-division subjective evaluation was used as was applied for the short-term evaluation. Overall positive effects on tinnitus were seen in 75% of cases immediately after intratympanic dexamethasone perfusion and in 68% after 6 months. It appears that, to some degree, tinnitus control via our therapeutic regimen remained constant.
MECHANISM OF ACTION
In this intratympanic dexamethasone perfusion technique, it is assumed that the medicine that was introduced directly into the tympanic cavity acts on the plexus tympanicus, is absorbed through the round window, and acts on the inner ear [8-13] . The mechanism of action of this therapeutic modality is multifactorial, including sedative effects, a metabolic improving effect, and an edema-relieving effect, which may eliminate abnormal excitation of auditory hair cells, which are believed to cause tinnitus. In Meniere's disease, steroid injection to the middle ear might improve endolymphatic hydrops.
Figure 4. Long-term effects on tinnitus of intratympanic dexamethasone perfusion (after 6 months).
The short-term side effects of the inner-ear DDS that we describe include pain at the time of tympanic puncture and temporary vertigo immediately after the injection. The temporary vertigo probably is caused by caloric stimulation. This effect might be avoided by infusing the drug solution at body temperature. Acute otitis media was seen in 0.1% of 3,978 ears. Persistent side effects were rare; tympanic perforation in 0.2% lasted 15 years. No patients experienced rapid hearing reduction after the injection.
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Department of Neurotology, Saitama Medical School, Saitama, Japan
E. Sakata, M.D
Department of Neurotology, Saitama Medical School
Moro-hongo 38, Moroyamamachi
Iruma-gun, Saitama, 350-04 Japan
Telephone: 81-492-76-1335; fax: 81-492-94-8883