11 Tinnitus: Evaluation and Management

Tinnitus is the perception of sound in the absence of an apparent acoustic stimulus. This malady has afflicted humankind since antiquity. In the Ebers papyrus (2500 B.C.), treatment for this symptom is mentioned.1 Despite the significant advances in the evaluation and management of tinnitus, physicians often fail to address this symptom properly and advise their patients that there is nothing that can be done about their problem.

Although there is no cure for many types of tinnitus, something that applies to many other diseases including cancer, a thorough evaluation to rule out any significant pathology such as an acoustic tumor, explanation of the test results, a brief and simple overview of the auditory system physiology, and above all a sympathetic and positive attitude will often alleviate the associated fear and anguish of these patients.

The authors believe that the various modalities of tinnitus management outlined in this chapter often achieve satisfactory results and provide significant relief for these patients.

Tinnitus should always be considered a symptom and not a disease, and it warrants a thorough investigation to identify its etiology. Tinnitus can be classified according to its acoustic characteristics as the nonpulsatile or the pulsatile type. Although this classification is not ideal, it has been found to be simple and practical. Because these two types of tinnitus have very different etiologies and management, they are described separately in this chapter.

Nonpulsatile Tinnitus

Nonpulsatile tinnitus, also known as subjective tinnitus and hereafter referred to as tinnitus, is more common than pulsatile tinnitus and has a complex pathophysiology. Tinnitus can be characterized as mild or severe. Mild tinnitus is audible by the patient occasionally or only when in a quiet place and usually is not troublesome. Severe tinnitus is a very disturbing symptom, which often degrades the quality of the patient’s life.² Tinnitus in some patients can be associated with hyperacusis (decreased tolerance to sounds), which can be a very annoying symptom as well.

Epidemiology

Tinnitus has been estimated to affect up to 36 million Americans, and between 7.2 to 11.25 million have the severe form.^3–5 Factors related to tinnitus prevalence include age, gender, race, and presence of hearing loss. Tinnitus is more prevalent in patients between the ages of 50 and 71 years, although it can occur in younger individuals.⁶ In the 20- to 29-year-old age group, tinnitus has been reported in 4.7% of individuals versus 12.1% in the 60- to 69-year-old age group. Men over age 65 are afflicted more often than women of similar age (12% versus 7%).⁴ Tinnitus has been reported more often in Caucasians than African Americans (9% versus 5.5%).⁴ Finally, tinnitus prevalence increases with the severity level of any associated hearing loss.⁷

Tinnitus affects young individuals as well and has been reported in 13% of school-age children.⁸ The prevalence of tinnitus in children with associated hearing loss increases to 64%.⁹

Etiology

The majority of tinnitus patients have an associated hearing loss; however, many other etiologies can be responsible for this symptom.10 In one study, 75% of tinnitus patients had an average of a 30-dB hearing loss between 3 and 8 KHz.¹¹ The tinnitus pitch usually corresponds to the frequency of the hearing loss.² In one study, 93.7% of patients with noise trauma and 86.9% of those with presbycusis described their tinnitus as a stable, high-pitched whistling. Patients with active Meniere’s disease or Meniere’s-like syndrome described their tinnitus as a low-pitched buzzing noise.¹²

Noise exposure is the most common cause of tinnitus associated with hearing loss and has been reported as an etiologic factor in 32 to 62% of patients.^12,13 Other etiologies include presbycusis, Meniere’s disease, chronic otitis, otosclerosis, acoustic neuromas, head injury, whiplash injury, and autoimmune cochleovestibular disorders. Tinnitus can be a symptom of temporomandibular joint (TMJ) disorders as well, and in such cases it can be associated with aural fullness, pain/discomfort, and tenderness over the involved joint and pterygoid muscles. Dizziness and alteration of tinnitus pitch with jaw movements have also been reported.^14–16 Table 11–1 summarizes the various tinnitus etiologies.

Side effects from medications, especially aspirin-containing compounds, can cause or intensify preexisting tinnitus. Therefore, a review of all the medications that the patient is on is very important. Some patients are unaware that they are taking a product containing aspirin, and this should be identified and brought to their attention. Table 11–2 summarizes the various medications associated with tinnitus.^17,18

Stimulants such as caffeine contained in coffee, colas, and tea as well as smoking may aggravate tinnitus. Emotional disorders such as depression and anxiety are often present in tinnitus patients. Between 28% and 60% of patients with severe tinnitus have been reported as clinically depressed.¹⁹ Patients who develop depression secondary to tinnitus, often have a predilection to depressive episodes.¹⁹

Pathophysiology

There is recent evidence that tinnitus may arise not only from pathophysiologic processes affecting the cochlea, but also from disorders involving the auditory pathways and central nervous system. It has been hypothesized that peripheral pathologies can sensitize central nervous system structures, resulting in hyperactivity and tinnitus.²⁰ The following theories have been proposed for this “cochleofugal” origin of tinnitus:

Data from Schleuning AJ. Tinnitus. In: Gates GA, ed. Current Therapy in Otolaryngology–Head and Neck Surgery. St. Louis: Mosby-Year Book; 1994:91–97; and Brummett R. Drugs for and against tinnitus. Hear Res 1989;34–37.

1. Abnormal generation of neural activity in the auditory nerve^21–23

2. Primary involvement of the auditory nuclei in the absence of peripheral auditory pathology24

3. Decreased γ-aminobutyric acid (GABA) ergic inhibitory influence in the inferior colliculus resulting in increased neural activity²⁵

4. Irritation of the cochlear nerve as seen in eighth nerve vascular compression syndrome resulting in hyperactivity of areas of the ascending auditory pathways^26,27

5. Limbic and autonomic systems involvement^28,29: According to this theory, the limbic and autonomic systems are involved in processing tinnitus, and over-activation of the sympathetic part of the autonomic nervous system is largely responsible for the behavioral manifestation of tinnitus-induced problems.³⁰

6. Interactions between the extralemniscal ascending auditory system and the somatosensory system^31–34

7. A final common pathway for tinnitus has been hypothesized by Shulman³⁵ for all tinnitus patients. This mechanism is considered to be responsible for the transition of the sensory to the affective components of tinnitus. Single-photon emission computed tomography (SPECT) of the brain of patients with severe tinnitus has revealed perfusion asymmetries consistent with the clinical diagnosis of depression and memory disorders in these patients.³⁵

Evaluation

History

The history is of utmost importance in evaluating tinnitus patients. The time of onset and any possible causative event (s), such as noise exposure, viral infections, and head trauma, should be elicited. Other important information should include localization of the tinnitus (unilateral, bilateral, centered in the head), composition (ring, buzz, hiss, roar, cricket sounds, multiple sounds), loudness, annoyance, and pitch (high or low). The psychological impact of tinnitus also should be determined by seeking symptoms of depression, anxiety, insomnia, and inability to concentrate. The Tinnitus Handicap Inventory has been found helpful for evaluating patients with severe tinnitus.³⁶

Neuro-Otologic Examination

This examination should include otoscopy and tuning-fork testing. Cranial nerve, cerebellar, and vestibular testing should be individualized.

Audiologic Evaluation

An audiogram (air–bone conduction and speech discrimination) should be obtained in all tinnitus patients. Frequencies up to at least 8000 Hz should be tested because tinnitus often corresponds to the high tones. Impedance audiometry (tympanometry, acoustic reflexes, acoustic reflex decay) should be considered in selected cases.

Electrophysiologic Testing

Auditory brainstem responses (ABR) should be considered for patients with a low index of suspicion for an acoustic neuroma and electrocochleography for those suspected of endolymphatic hydrops. Electronystagmography (ENG) should be considered for patients with associated vestibular symptoms.

Radiologic Evaluation

Head magnetic resonance imaging (MRI) with gadolinium enhancement should be obtained for patients with the following:

• Unilateral, unexplained tinnitus with or without hearing loss

• Bilateral symmetrical or asymmetrical hearing loss suspicious for retrocochlear etiology (poor discrimination, absent acoustic reflexes, acoustic reflex decay, abnormal ABR, associated disequilibrium)

Tinnitus patients undergoing MRI should be supplied with earplugs to prevent exacerbation of their tinnitus by the loud noise produced by the MRI unit. Computed tomography (CT) of the temporal bone should be considered for patients suspected of otic capsule pathology such as otosclerosis and Paget’s disease.

Metabolic and Allergy Testing

Metabolic testing should be individualized and may include complete blood count, serum lipids, fasting blood sugar, sedimentation rate, antinuclear antibodies (ANA), rheumatoid factor, thyroid function tests, and fluorescent treponema (FTA)-absorption test. Allergy workup should be considered in selected cases.

Tinnitus Analysis

Tinnitus analysis should be considered mainly for patients with severe tinnitus^17,37 who are being considered for management with masking or tinnitus retraining therapy (TRT). Tinnitus analysis includes the following:

Pitch matching: This can be achieved in the majority of patients by using pure tones for tonal tinnitus or white, narrow band, or speech noise for complex tinnitus.¹³ When determining the pitch of tinnitus, it is important to test for octave confusion. In 60% of the patients tested, the identified pitch of the tinnitus was actually one octave below the proper pitch identification.

Loudness matching: With this technique, tinnitus is matched first by pitch and then by increasing the intensity level from threshold to a level that is equal to the intensity of the tinnitus. In one study, 93% of patients with tinnitus matched at 11 dB sound level (SL) or less with an average of 4.4 dB SL.38 In another study, 88% of 502 tinnitus patients, loudness matching occurred between 0 and 9 dB SL.³⁹ When a repeated loudness matching test reveals results within 2 to 3 dB SL, it can be used as an objective test for the presence of tinnitus.¹³

Minimum masking level (MML): This test is recorded in dB SL and determines the difference between the threshold intensity of the masking sound and the lowest intensity at which masking occurred.¹³ This test may provide some information regarding the use of a tinnitus wearable masker. If the MML is lower than or equal to the loudness matching, then it is likely that maskers will be effective.¹³

Residual inhibition: This phenomenon is characterized by decreased or absent tinnitus following exposure to MML plus 10 dB for 1 minute.¹³ Although residual inhibition cannot be used as a predictor of successful masking, nevertheless it demonstrates to patients that their tinnitus is amenable to change.⁴⁰

In a survey of ours of 4500 tinnitus patients, 3442 (76.5%) had tonal tinnitus and 1058 (23.5%) had noise tinnitus. When these patients were then requested to rank the severity on a 10-point scale, the average for the tonal tinnitus group was 7.5 and for the noise group the average was 5.5, suggesting that tonal tinnitus is more severe than is noise tinnitus.

Management

General Measures

A positive and compassionate attitude on the part of the treating physician is of paramount importance. Negative statements, such as “There is nothing much that can be done about your tinnitus and you just have to live with it,” have no place at all, and are counterproductive and strongly condemned. This unacceptable statement by physicians often has a highly negative impact on patients and may result in further despair, depression, and worsening of their tinnitus.

Although the majority of tinnitus patients are neither depressed nor bothered by their tinnitus, the ones who bitterly complain of their tinnitus are often found to have depression.⁴¹ In the author’s experience, tinnitus developing in patients with a preexisting history of depression is often recalcitrant to management, and psychiatric consultation should be considered at the initial evaluation. In patients with depression secondary to tinnitus, antidepressants may be considered at the initial visit. Patients need to understand that depression lowers their threshold of tinnitus perception, and effective management of this disorder not only makes them function better but often decreases the perception of tinnitus as well. Other comorbidities such as sleep apnea should be looked for and addressed properly.

Discussing the test results with patients is very important, and once serious pathology has been eliminated, they should to be properly informed. Going over the basic function of the ear in simple terms and by showing a diagram is very helpful.

Patients with recent onset of tinnitus should be informed that this symptom often decreases in intensity with time and it persists or increases in intensity only in a small percentage of cases.¹⁷ Many patients are very concerned about having a serious problem such as a brain tumor, or feel that they are becoming deaf. Others are concerned about not being able to sleep or concentrate and that this may result in losing their job. It is believed that in many tinnitus patients a “vicious cycle” exists between tinnitus and fear/anxiety, and the latter can enhance the perception level and duration of tinnitus awareness.³⁰ A significant number of these patients, especially the ones with mild tinnitus, find immediate relief once they are told about the benign nature of their problem and seek no further management. Patients are instructed to avoid exposure to loud noise and intake of stimulants, such as caffeine and nicotine. They should be reminded that caffeine is contained not only in coffee, but also in tea, colas, and chocolate. Intake of aspirin-containing medications and nonsteroidal antiinflammatory drugs should be avoided. Home masking techniques, such as a room humidifier, listening to music or broad-band masking by tuning the radio between stations, and devices producing environmental sounds can be very helpful as well.

The American Tinnitus Association (ATA) is a great source of reliable information material and patients should be encouraged to contact it either by mail (American Tinnitus Association, P.O. Box 5, Portland, OR 97207-0005) or by visiting its Web site (www.ata.org). Finally, a team approach with an experienced and sympathetic audiologist and when needed a psychiatrist, is of utmost important. Patients with severe tinnitus often necessitate management with one of the following techniques.

Tinnitus Masking

Tinnitus masking denotes applying an external sound to cover up tinnitus. Many patients find this sound more acceptable than their tinnitus, resulting in significant relief.⁶ The pioneering work of Vernon and his associates has shown that tinnitus is maskable in 95% of patients by using masking noise generated by specialized test equipment at the clinic.^6,40,42 For those with special interest in tinnitus masking, it is imperative to read Vernon’s original work because he is considered the founder of this technique. Masking of tinnitus can be achieved with wearable masking devices and by recorded sound.

Wearable Tinnitus Masking Devices

Hearing aids: As mentioned previously, the majority of tinnitus patients have a hearing loss, which usually corresponds to the frequency of their tinnitus. Hearing aids provide a form of tinnitus masking by amplifying ambient environmental noise. Hearing aids are appropriate for patients with hearing loss and tinnitus pitch at or below ~4 kHz because ambient environmental sounds are below this frequency. In-the-ear hearing aids have the potential of producing too much of an occlusion effect and amplification of the lower frequencies, which may exacerbate tinnitus. In these cases, changing to a behind-the-ear hearing aid may correct the problem.6 Patients with bilateral tinnitus usually require bilateral hearing aids.⁶

Tinnitus maskers: These are noise-generating devices with user-adjustable frequency emphasis that allow selection of optimum frequency for accomplishing masking at the lowest possible sound level.⁴² These devices are recommended for patients with normal or near-normal hearing.⁶ Tinnitus maskers are available in various configurations and are capable of producing noise bands ranging from ~1 kHz up to ~15 kHz. Patients with bilateral tinnitus usually require bilateral maskers.⁶

Tinnitus instruments: These devices are a combination of a high-frequency hearing aid and a tinnitus masker within the same unit. It is important that the hearing aid and masker components have separate volume controls to allow appropriate adjustments by the user.⁴² Tinnitus maskers are available as either in-the-ear or behind-the-ear devices. Vernon and Johnson have found this device to be very helpful, and long-term use seems to be safe with regard to hearing thresholds.^6,43,44

In a large series of patients who had been successfully using masking devices for at least 2 years, 95 (16%) were using hearing aids alone, 124 (21%) tinnitus maskers, and 373 (63%) tinnitus instruments.⁴⁵

Tinnitus Masking with Recorded Sound

Another effective modality of masking can be provided by commercially available compact digital disks (CDs). One of them provides music in the foreground with masking noise in the background (Petroff Audio Technologies, 2346 Bigelow Avenue, Simi Valley, CA 93065; phone 805-577-6679).

Another masking CD provides a variety of recorded noise in the form of seven different noise bands, each with different frequency range allowing the user to select the most effective frequency that masks tinnitus (Moses-Lang CD, The Tinnitus Clinic, Oregon Hearing Research Center, NRC 4, Oregon Health and Science University, 3181 S.W. Sam Jackson Park Road, Portland, OR 97239–3098; phone 503-494-7953). These CDs have been found to be very useful by many tinnitus patients.⁴²

Bone-Conduction Ultrasound for Tinnitus Masking

A wearable device that provides tinnitus masking by high-frequency bone conduction has been reported. This device is Food and Drug Administration (FDA) approved and has the advantage of avoiding occlusion of the ear canals. Preliminary results are encouraging, and it may provide more extended periods of residual inhibition than masking devices using audible sound.⁴⁶

Tinnitus Retraining Therapy

Tinnitus retraining therapy is based on the phenomenon of habituation, which is defined as a “method by which the nervous system reduces or inhibits responsiveness during repeated stimulation.”⁴⁷ It has been proposed that tinnitus habituation is accomplished by the weakening and disappearance of functional connections between the auditory pathways and the limbic/autonomic nervous systems.³⁰ This technique has been popularized by Jastreboff and his associates^30,48 and involves extensive counseling and the use of tabletop sound machines and wearable noise generators.

Tinnitus retraining therapy is different from masking. In TRT the sound level from the sound generator is set below the tinnitus level.³⁰ Sound generators should be used as long as possible during the waking hours at a steady level.³⁰ Administration of tranquilizers is contraindicated because they are thought to interfere with brain plasticity.³⁰ Recommended duration of treatment is at least 12 months, and significant improvement of tinnitus has been reported in more than 80% of cases.³⁰

Although the effectiveness of TRT has been duplicated by others,^49,50 the need for well-designed prospective studies, which include no-treatment and placebo-treated group, has been recommended.^51,52 In particular, studies addressing the efficacy of counseling and white noise separately are needed.⁵²

Electrical Stimulation

Transcutaneous electrical stimulation of the ear has been reported to provide prolonged relief of tinnitus in about one third of patients.⁵³ It has been speculated that this modality of treatment stimulates the cochlea and results in cessation of abnormal signals responsible for tinnitus.⁵⁴ Significant tinnitus control with this technique has also been reported by Shulman.⁵⁵ This method, however, warrants further evaluation with prospective and controlled studies. Again, the role of psychological support and counseling needs to be studied individually.

Tinnitus relief has been accomplished in profoundly deaf individuals following cochlear implantation.^56,57 In a study by Hazell et al⁵⁸ of 256 patients who underwent cochlear implantation, 52% had bothersome tinnitus prior to surgery; 110 of these patients had evaluation of their tinnitus after implantation, and significant improvement of tinnitus was reported in 42%.58 Miyamoto and Bichey⁵⁹ also confirmed that cochlear implantation provides improvement of tinnitus for many cochlear implant users with a small risk of tinnitus worsening.

Medical Treatment

Antidepressant medications such as nortriptyline (Pamelor) and amitriptyline (Elavil) have been reported to be useful for patients with severe tinnitus and associated depression.^19,60 The presence of insomnia has been found by Dobie et al^41,61 to be the best predictive response factor to nortriptyline. It should be mentioned, however, that tricyclic antidepressants may occasionally exacerbate tinnitus.

Although there are no prospective randomized studies on the efficacy of serotonin reuptake inhibitors, there is evidence that they are effective as well. In a letter to the editor, Shemen⁶² reported three tinnitus cases treated with fluoxetine (Prozac) 10 mg per day. Tinnitus completely subsided in all of them within a week.

Lidocaine has been found to be effective; however, its use is limited because of the need for intravenous administration.^18,63 Melatonin has been reported to be helpful, especially for those tinnitus patients with associated insomnia.⁶⁴

Alprazolam (Xanax) has been found to be effective for tinnitus.^18,65 In a 12-week randomized, double-blind, placebo-controlled study of 40 tinnitus patients, alprazolam was found to be effective in 76% of those taking the medication versus 5% of the placebo group.⁴² According to the same authors, this medication, although it can be habit forming (development of withdrawal symptoms once medication is discontinued), is not addictive for tinnitus patients (lack of craving and need to increase dose). On the contrary, some patients can reduce the dose over time while maintaining relief of tinnitus. Alprazolam should be considered only for patients who have failed other modalities of treatment such as masking and TRT. A starting dose of 0.5 mg at bedtime for 2 weeks, followed by 0.5 mg two times a day for 2 weeks, and finally a maintenance dose of 0.5 mg three times a day has been recommended.⁴² Xanax XR has an extended half-life of 12 hours, and by taking 0.5 mg in the morning and 1 mg at bedtime, 24 hours of relief can be accomplished. Once the patient has experienced tinnitus relief for 4 or 5 months, progressive reduction of the medication dosage should be considered to find a lower effective level. If alprazolam is ineffective in controlling tinnitus, a gradual tapering-off regimen is indicated to avoid withdrawal symptoms.⁴² Finally, alprazolam has been reported to be effective for hyperacusis as well.⁴²

Intratympanic perfusion of gentamicin and steroids can be helpful for tinnitus patients with Meniere’s disease.⁶⁶ Intratympanic gentamicin for such patients has been reported to reduce severe tinnitus in 65% of cases.⁶⁷ Nimodipine, an L-calcium channel antagonist, has been reported to provide relief for a small number of tinnitus sufferers.⁶⁸ Anticonvulsive medications such as primidone (Mysoline), phenytoin (Dilantin), and carbamazepine (Tegretol) have been used for tinnitus without any significant success.²⁴ The effectiveness of medications with GABA or GABA-like effects such as Baclofen are promising; however, they remain investigational.²⁴

Table 11–3 is a summary of medications, herbs, vitamins, and minerals that have been reported for treating tinnitus.⁶⁹ The effectiveness of these substances, however, has not been established with prospective-controlled studies.

Surgical Management

Relief of tinnitus following labyrinthectomy and translabyrinthine section of the eighth nerve has been reported in up to 70% of patients.⁷⁰ Cochleovestibular neurectomy (CVN) has been effective in improving tinnitus in 45 to 76% of patients.^71–73 Retrolabyrinthine vestibular neurectomy, middle fossa vestibular neurectomy, and endolymphatic shunt surgery, procedures performed mainly for vertigo control, have been reported to relieve tinnitus in 50 to 65% of cases. However, in the same study, tinnitus worsened in 22% of cases.⁷³

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