Vinpocetine Helps Maintain and Recover Hearing FunctionThe Resurrection of Sound
by Will Block
he film Immortal Beloved finds composer Ludwig van Beethoven lured to the palatial Viennese home of a woman who adores him. Confronted by a sparkling new pianoforte freshly imported from Italy - the first real piano he has ever encountered - Beethoven proceeds to play the incredible instrument. But first he reverently lays the side of his head flat against the top of the piano so that he can feel the vibrations in his skull as the keys strike the strings within. At this time, he is close to being totally deaf. When finally his hostess (who has been watching, hidden from him) chooses to appear, it exposes the great composer's vulnerability - the secret of his deafness - and he explodes in pain and anger. Slamming the cover of the piano, he storms out bitterly. Beethoven had written a letter about his deafness in confidence to a close friend:
"My ears continue to hum and buzz day and night. I must confess that I lead a miserable life. For almost two years I have ceased to attend any social functions, just because I find it impossible to say to people: I am deaf. If I had any other profession I might be able to cope with my infirmity; but in my profession it is a terrible handicap. And if my enemies, of whom I have a fair number, were to hear about it, what would they say?"
-- Ludwig van Beethoven
What would Beethoven have felt, if he "heard" that his hearing problem might have been curable, or their was some way to retard it?
THE FAMOUS AUTOPSY
Figure 1: Beethoven (as played by Gary Oldman) with his head pressed against the piano in order to hear.
Throughout his life, Beethoven had established a clear disdain for doctors, none of whose nostrums had even scratched the surface of his many medical problems. While there is disagreement about the ultimate cause of his death, the autopsy report of 1827 did confirm that the great composer had a number of ailments, including cirrhosis of the liver and kidney disease. According to one medical analysis, the description was clearly indicative of kidney disease, which can be caused by massive analgesic intake.1
Beethoven was an abuser of analgesics such as salicin (an aspirin-like salicylate derived from willow bark) which he habitually used for headaches, back pain, and attacks of rheumatism or gout. Was this the cause of his kidney disease? Another study points to acute onset diabetes mellitus complicated by chronic pancreatitis.2
In the folklore medicine of India and Southern Europe, extracts of the leaves of the subtropical plant Catharanthus roseus (sometimes known as Madagascar periwinkle) were reputed to be useful in the treatment of diabetes.3 Thus, it is reasonable to believe that early 19th Century Vienna would have had Madagascar periwinkle extract available, and that it might have been offered to Beethoven, had he not been so down on the medical profession.
Curiously, diabetes could easily have contributed directly to Beethoven's hearing problems. Metabolic conditions such as diabetes can alter lipid levels in the blood vessels of the inner ear, affecting the ability to hear (vestibular function).4 While today we believe that the periwinkle extract might not have helped control his diabetes (although an active component in it has been found to enhance the intellectual performance of diabetics),5 it does contain various levels of the vinca alkaloids, such as vinpocetine, which might have helped with Beethoven's hearing loss (most likely otosclerosis).6 Otosclerosis is a condition characterized by chronic progressive hearing loss in which fusion involving the inner ear bones leads to immobility and conductive hearing loss. The vinca extract could have reduced his tinnitus (the "hum and buzz" within his ear),7,8 reversed his cerebral atherosclerotic buildup,9 and provided some relief from his deafness, whether it was otosclerotic or due to some other cause.10
THE TOLL OF AGING
Beethoven's sense of loss can certainly be understood by many of us, when we discover through our own personal experience year after year that our hearing ability is declining. No longer are we able to pinpoint the exact source of a sound without effort. Music loses much of its luster and charm. We can find ourselves strangely alienated from conversation. "What did you say?" or "Could you repeat that?" become frequent requests. While not universal, this experience is very common. It is part of the "normal" aging process, so we are told.
Figure 2: Prevalence of hearing impairment in better ear. (Davis AC. The prevalence of hearing impairment and reported hearing disability among adults in Great Britain. Int J Epidemiol. 1989:18:911-917.
Approximately 28 million Americans have some form of hearing loss. Much of this loss can be preventable. Noise-induced occupational hearing loss is the most common occupational disease and the second most reported occupational illness or injury. Recent data indicates that as many as 16% of all adults and more than one-third of those over 60 years have a hearing loss of 25 decibels (dB) or more [see Figure 2].11 This level of loss means a hearing aid would be beneficial. As with Beethoven, social withdrawal is an all-too-frequent response to the reality of any significant hearing loss or to deafness. The National Institute on Aging reports that if hearing loss is ignored and untreated, communication and social activities may be limited or greatly reduced. People tend to withdraw, and may be incorrectly labeled as "confused," "unresponsive," or "uncooperative" by those around them.
CONDUCTIVE HEARING LOSS
There are many causes for hearing deterioration. These causes can be roughly divided into two main categories: conductive and sensorineural hearing loss. Conductive hearing loss occurs when sound is no longer conducted effectively from the environment to the sensing part of the inner ear. The causes of this type of hearing loss are usually due to problems with the sound conducting apparatus of the ear; either the external ear, the ear drum (tympanic membrane) or the middle ear. Conductive problems include:
- Buildup of wax or fluid in the external ear canal
- The presence of a foreign body in the external ear canal
- Buildup of secretions in the middle ear
- Swelling of the external canal caused by infection or inflammation
- Trauma causing disruption of the ear drum or the middle ear
- Severe or chronic infection leading to stiffness of the ear drum or the middle ear bones
- Accumulation of infection-caused scar tissue, which can become worse with age
- Hereditary factors
Among the inherited conditions is otosclerosis - from which it is believed Beethoven most likely suffered - in which repeated stiffness of the middle ear bone (called the stapes or the stirrup) leads ultimately to an immobilization or fusion of the inner bones. This fusion inhibits the effective conduction of sound.
SENSORINEURAL AND AGE-RELATED HEARING LOSS
Occasionally known as nerve deafness, sensorineural hearing loss (SN) is due to problems in the inner ear (cochlea). Degeneration of the auditory nerve which leads from the brain to the inner ear may also be involved. There are many types of SN including the following:
Sudden sensorineural hearing loss is a rather uncommon condition in which only one ear is affected. While there is a greater susceptibility to SN after the age of forty, it can affect anyone. Causes include autoimmune disease, stroke, viral or bacterial infection, syphilis, tuberculosis, Lyme's disease, and circulatory problems to the inner ear. Even though this condition can result from seemingly benign conditions, sudden SN is considered a medical emergency.
Noise induced hearing loss is a condition resulting from chronic exposure to loud noises of the industrial environment such as heavy power equipment. Repeated exposure to loud music is also a known culprit. Noise-induced hearing loss can also result from brief exposures to loud noises such as gunshots, explosions, jet engines, or any other very loud and sudden noises.
Hereditary hearing loss is inherited from the gene pool and occurs prematurely. Usually, people with this variety of hearing loss are otherwise healthy. Congenital hearing loss is associated with development of abnormalities which occur in the womb and may manifest in infancy. Inherited factors, prenatal infections, and premature birth are also involved.
Age-related hearing loss, is a type of sensorineural hearing loss called presbycusis. It is a progressive, perceptive hearing loss of both ears occurring with advancing age and it gradually deteriorates the inner ear. Presbycusis starts to take a serious toll by the time most people reach their sixties, and may be perceived as early as the age of forty.
All sensorineural and some conductive hearing loss can be accompanied by tinnitus, a condition in which sounds such as ringing, buzzing and/or humming are perceived in the ears without an external source to explain it. Dizziness or vertigo can also accompany tinnitus.
CLASSICAL MUSICIANS BEWARE
Amazingly, even though industrial noise pollution is now thought of as a primary cause of hearing loss, symphony orchestras have also recently been implicated in damage to hearing.12 In what may come as a blow to classical music lovers, many studies have concluded that not only are dangerous levels of noise present within the symphony orchestra, there is evidence of noise-induced hearing loss among symphony orchestra musicians. It has been suggested that the same kind of hearing protection designed for industrial use may be appropriate for professional musicians.
YOU MAY HAVE SOMETHIN' TO LOSE
Reviews of data gathered by the National Center for Health Statistics were found to support earlier predictions by the Center; that increased exposure to loud music by teenagers and young adults would result in high-tone hearing loss.13 When Chuck (Berry, Rhythm 'n Blues recording artist turned Rock 'n Roller) wrote Roll Over Beethoven, he had no any idea that there was somethin' to lose:
Roll Over Beethoven, I gotta hear it again today [. . .]
I got the rockin' pneumonia,
I need a shot of rhythm and blues.
I think I'm rollin' arthritis
sittin' down by the rhythm review. [. . .]
Hey diddle diddle, I am playin' my fiddle,
ain't got nothin' to lose.
Roll Over Beethoven and tell Tchaikovsky the news.
Simply listening to loudly amplified music can be responsible for hearing damage similar to that caused by industrial noise. Even the use of personal cassette players can be as risky as the dangers associated with discotheques and rock concerts.14 One study (of 54 subjects) found a significant increase of average hearing thresholds in young people using a personal cassette player (PCP) for more than 7 hours per week. When comparing listeners using a PCP for between 2-7 hrs/week (195 subjects) to the control subjects who didn't listen to PCP at all, the damage done to the 7hr+ listeners was a loss of hearing up to 25 dB. Rock concerts? If you attend a concert at least twice a month, your hearing is likely to be injured. Of 87 rock concert attendees studied, signs of hearing loss were found in two-thirds (67%) as opposed to 12% in the control group.
Curiously, pop and rock performers may not be subject to as severe a risk as their fans. A study which followed 53 Swedish and British pop/rock musicians for 16 years (from 1975 to 1991) found that their hearing was comparatively well-preserved.15 They were still able to detect pure tone at lower (20 dB) test frequencies, an area where their fans had lost hearing ability. On an individual basis, 63% of the performers tested normal for high frequency pure tone and another 15% had a very limited hearing loss (< or = 25 dB). These results remain unexplained. However, the authors of the study concluded that the performers might have achieved a protective benefit from their generally positive attitude toward their performance and their audience. Even though the musicians were continually subjected to high sound levels above 85 dB, a continuous contraction of the stapedius muscle might also have provided a protective effect.
AEROBIC EXERCISE, MUSIC, AND HEARING LOSS
Hearing thresholds (the minimum level at which the ear can detect sounds) were measured in subjects who listened to music at high levels (96 dB) while they exercised and in subjects before and after riding an ergometer bicycle for 20 minutes.16 Compared to control subjects who either did not listen during exercise or those who listened but did not exercise, the results were surprising. There was a measurable and greater noise-induced temporary hearing loss for the music + exercise group than for either of the other two control groups (music alone or exercise alone). These results suggest an increased potential for permanent hearing loss when noise exposure is coupled with exercise. Beware of combining aerobics and music, especially loud music!
In another exercise study, vulnerability to certain parts of the inner ear were found with high impact aerobics.17 Thirty females with a mean age of 35 years (12 aerobics instructors and 18 aerobics enthusiasts) were examined for a variety of symptoms. While vertigo, dizziness and loss of balance were present in 24/30 (80%), tinnitus and/or a sensation of ear fullness was present in 20/30 (67%). The instructors, who worked out significantly longer than the enthusiasts, displayed a significantly higher proportion of hearing abnormalities. These include increased sensitivity to barometric pressure problems such as experienced with the activities of flying, scuba, and swimming and car travel motion. Heavy exercisers also experience hearing loss in the average range of 6,000 Hz suggesting that repetitive jarring and loud music produce damage to the inner ear.
THE RIGHT SUPPLEMENTS FOR GOOD EAR HYGIENE
All very well and good, you may be saying to yourself - but what can I do to avoid or diminish problems that affect my hearing? Is there anything I can do to compensate for the hearing impairment associated with age? A recent study indicates that the deafness gene may have been located, yet we are told that its implementation in halting the damage of age-associated hearing decline, let alone its reversal, is still in the distant future.18
You also might ask, Can I do anything to recover from any damage that may have already occurred? The best answer is to maintain a strong immune system and to provide yourself with adequate nutrition - this means abundant levels of the right types of dietary supplements, including the herbal extract vinpocetine.
"LISTENING" TO VINPOCETINE
The scientific reputation of vinpocetine and other related vinca alkaloids for retarding hearing loss and restoring proper auditory function is truly impressive and the results are worthy of "listening" to, much as we have been conjoined to "listen" to Prozac. Beginning in 1970's, research has shown a wide variety of applications, most involving its positive effect on atherosclerotic lesioning in the brain and elsewhere throughout the body. Vinpocetine has been of clear benefit for improving hearing problems that are due to different causes,19 including those of sensorineural20 as well as conductive origin.21
Vinpocetine was administered at a daily dose level of 15 to 35 mg to 18 subjects suffering from a range of degrees of perceptive hearing defects, from low to high.22 Eight subjects (44%) were found to have significant hearing function improvement (from 10 to 30 dB in four, and more than 40 dB in the other four subjects). This meant that there were measurable improvements in the understanding of speech, especially when a great deal of background noise was present. Results were best with the higher dose levels. According to the researcher's observations, significant hearing function improvement can be realized, especially by young or middle-aged patients.
In a summary of treatment studies, vinpocetine was found to be helpful in improving hearing functions associated with various types of sensorineural hearing impairments, as well as vertigo.23 Age-related hearing loss (presbycusis), vascular impairment of hearing and in certain cases high-frequency hearing loss caused by environmental assault (occupational hypacusia) were also helped by vinpocetine. In Meniere's disease (recurrent vertigo accompanied by tinnitus), vinpocetine was proven to be superior to other vasodilators (agents which relieve the symptoms by relaxing the blood vessels, thereby improving circulation).
Perceptive deafness is usually an hereditary form of hearing loss, but it may also have other causes. With some forms of deafness and with otological (ear) problems accompanied by dizziness and tinnitus, vinpocetine has been reported to be worthwhile.24 In cases of vascular deafness, age-related hearing loss, and sudden deafness accompanying physiological dysfunction, vinpocetine has been valuable. Even in early, acute and toxic deafness cases, the periwinkle extract may again be useful. While there are many ways that vinpocetine may be operable, its most potent functional improvement may be its ability to slightly depress blood pressure and improve brain circulation without side effects.
Critical to the process of hearing is the cochlea -- the "seashell" shaped winding tube in the inner ear containing the organ of Corti, the receptor for hearing. In guinea pigs, vinpocetine was found to be protective to the cochlea during an experiment in which an ototoxic (toxic to the ear) drug was administered for 14 days.25 While this regimen normally would be expected to cause long term damage, vinpocetine was found to help maintain hearing acuity, amplification sensitivity and structural integrity. It boosts intercellular levels of cyclic guanosine monophosphate (cGMP) (a cell communication messenger needed in the production of nitric oxide) and increases vascular smooth muscle relaxation. Thus, vinpocetine may reduce resistance in the ear's capillaries and cochlear cells and protect and promote increased blood flow.26 Antibiotics, aspirin and diuretics, among other drugs, have been found to potentiate the activity of ototoxins such as free radicals which can ultimately lead to severe hearing loss. Remember that Beethoven was an "aspirin" abuser. Vinpocetine helps prevent damage from ototoxicity.
FREE RADICALS DAMAGE HEARING
At the University Hospital of Umea, Sweden, a study was designed to establish whether or not an increased production of oxygen-derived free radicals is involved in the causation of sclerotic lesions in the tympanic membrane, which can interfere with hearing.27 Rats with these lesions had their ears treated with a solution of the protective antioxidants, copper zinc-superoxide dismutase plus catalase. The result was an inhibition or reduction of the development of the sclerosis. Whereas, when the rat's ears were treated with copper sulfate plus iron chloride (which are not antioxidants) there was no benefit. This supports the idea that the formation of oxygen free radicals contributes significantly to the development of sclerosis of the tympanic membrane and probably otosclerosis as well, the hearing problem from which Beethoven suffered.
NUTRIENTS FOR OTOSCLEROSIS AND OTHER HEARING PROBLEMS
Hearing problems are often complex and one symptom may readily be confused with another. Some people who suffer from inner ear otosclerosis may have subtle disorders in which carbohydrate and lipid metabolism are the causal factors.28 Because this type of otosclerosis has been shown to be responsive to dietary therapy, it suggests that diabetes alone may be the problem. Other types of inner ear otosclerosis has been found to be manageable with supplemental sodium fluoride, calcium carbonate, and vitamin D. Vitamin D deficiency has been shown to cause cochlear deafness and therefore adequate supplementation with this vitamin should be an important component of any hearing dietary supplement program.29
A study was performed at the Semmelweis Medical University in Budapest, Hungary, which showed that bioflavonoids such as ipriflavone and quercetin could be beneficial in otosclerosis-like bone-remodeling processes in cultured guinea pig ossicles.30 These bioflavanoids caused a decrease in the sclerotic lesioning process by acting synergistically to enhance collagen synthesis. When collagen degenerates, it becomes a primary site for lesion formation.31 Because quercetin is superior to ipriflavone in its water-solubility the researchers believe that it will probably work even better in the control of the otosclerotic bone-remodeling disturbance.
MAGNESIUM AND HEARING LOSS
Many people do not realize hearing loss is a common problem, especially among the elderly. Repeated exposure to ongoing noise, a common cause of hearing loss, is one cause of which most people are unaware. There is a great deal of daily noise pollution from the steady hum of appliances to the jarring sound of sirens, to the roar of autos, buses and trucks. This is more so for those living in large cities where there is a constant bombardment of potentially damaging noise.
Magnesium has been shown to be of value in helping to protect one's hearing from the assault of noise pollution. In one study, 300 young healthy male military recruits undergoing two months of basic training were repeatedly exposed to high levels of impulse (sudden) noises.32 At the beginning of each day a dose of either 167 mg of magnesium (as magnesium aspartate) or a placebo (sodium aspartate) was given. At the end of the study, the results were impressive. Those recruits taking the placebo were found to have significantly more permanent hearing loss. The damage was significantly more frequent and more severe in the placebo group than in the magnesium group. Other studies have demonstrated similar results.33
GINKGO BILOBA FOR TINNITUS
Ginkgo biloba leaves have been used therapeutically by the Chinese for centuries for the treatment of asthma and bronchitis. In 1986, a study statistically proved the effectiveness of treatment with ginkgo extract for tinnitus. The ringing completely disappeared in 35% of the patients tested, with a distinct improvement in as little as 70 days!34 Then 350 patients with hearing defects due to old age were treated with ginkgo extract, the success rate was 82%.35 Furthermore, a follow-up study of 137 of the original group of elderly patients 5 years later revealed that 67% still had better hearing.36
DHEA MAY HELP REDUCE OTOSCLEROSIS
When levels of steroid hormones were evaluated in 11 men and 11 women suffering from otosclerosis, in one third of the cases serum levels of these steroid hormones were abnormal.37 Men had lower levels of DHEA compared with normal levels of those without otosclerosis. Subjects with otosclerosis and lower levels of DHEA were found to have low threshold values for hearing pure tone. Additionally, audiometry showed a hearing loss of 25 dB.
IMMMORTAL UNLOVED: BEETHOVEN'S HEARING LOSS
Ludwig van Beethoven's hearing loss has fascinated physicians as well as audiologists and musicologists for 170 years.38 It seems clear that whatever the succession of medical events leading to his death, Beethoven's hearing problem more than likely entailed cochlear otosclerosis. This has been concluded by a significant number of otologists as the most likely diagnosis for his hearing loss and eventual deafness. It is a sad commentary that if Beethoven were alive today, these otologists would have little or no concurrence about how to treat the Great Master. The world would still remain otologically impoverished by the absence of many great musical works, the form of which would undoubtedly be beyond our current ability to conceive.
Free me of only half this affliction and I shall be a complete, mature man. You must think of me as being as happy as it is possible to be on this earth - not unhappy. No! I cannot endure it. I will seize Fate by the throat. It will not wholly conquer me! Oh, how beautiful it is to live - and live a thousand times over!- Ludwig van Beethoven
- Schwarz A. Beethoven's renal disease based on his autopsy: a case of papillary necrosis. Am J Kidney Dis. 1993;21:643-652.
- Davies PJ. Beethoven's nephropathy and death: discussion paper. J R Soc Med. 1993;86:159-161.
- Noble RL. The discovery of the vinca alkaloids -- chemotherapeutic agents against cancer. Biochem Cell Biol 1990;68:1344-1351.
- Rybak LP. Metabolic disorders of the vestibular system. Otolaryngol Head Neck Surg. 1995;112:128-132.
- Boda J, Karsay K, Czako L, Fugi S, Kovacs A, Koncz I, Maczko PA. Examination of Cavinton effect in elderly diabetic patients. Ther Hung. 1989;37:176-180.
- Shearer PD. The deafness of Beethoven: an audiologic and medical overview. Am J Otol 1990;11:370-374.
- Jasper A. Action of Cavinton on hearing defects of different origin. Ther Hung. 1978;26:181-184.
- Nikolaev MP, Konstantinova ZD, Mertsalova ON, Sheremet AS. Prospects of using Cavinton in Meniere's disease. Vestn Otorinolaringol. 1980; 42:18-22.
- Zykov VP. Cerebral hemodynamics in patients with circulatory encephalopathy. Zh Nevropatol Psikhiatr Im S S Korsakova 1992;92:31-34.
- Van Geert G, Hennebert D. Vincamine and treatment of sudden deafness (2 cases). Bruxelles Med. 1979;59:515-518.
- Steel KP. Progress in progressive hearing loss. Science 1998;279:1870-1871.
- Teie PU. Noise-induced hearing loss and symphony orchestra musicians: risk factors, effects, and management. MD Med J 1998;47(1):13-18.
- Jekel JF. Rainbow reviews. VII: Recent publications of the National Center for Health Statistics. J Clin Epidemiol. 1996;49:765-768.
- Meyer-Bisch C. Epidemiological evaluation of hearing damage related to strongly amplified music (personal cassette players, discotheques, rock concerts) -- high-definition audiometric survey on 1364 subjects. Audiology 1996;35:121-142.
- Axelsson A, Eliasson A, Israelsson B. Hearing in pop/rock musicians: a follow-up study. Ear Hear 1995;16:245-253.
- Vittitow M, Windmill IM, Yates JW, Cunningham DR. Effect of simultaneous exercise and noise exposure (music) on hearing. J Am Acad Audiol. 1994;5:343-348.
- Weintraub MI. Vestibulopathy induced by high impact aerobics. A new syndrome: discussion of 30 cases. J Sports Med Phys Fitness. 1994;34:56-63.
- Vahava O, et al. Mutation in transcription factor POU4F3 associated with inherited progressive hearing loss in humans. Science 1998;279:1950.
- Jasper A. Effectivity of Cavinton and Lucidril in the treatment of hearing defects of different origin. Ther Hung. 1979;27:29-31.
- Ordogh B, Sarossy D, Klimstein G. Therapeutic action of Cavinton in hearing defects of neurological origin. Ther Hung. 1978;26:16-19.
- Heckrodt K. Treatment of acoustic trauma with Cetal retard. Med Klin. 1979;Suppl:55-56.
- Ordogh B, Sarossy D, Klimstein G. Therapeutic action of cavinton in hearing defects of neurological origin. Ther Hung. 1978;26:16-19.
- Ribari O, Zelen B, Kollar B. Ethyl apovincaminate in the treatment of sensorineural impairment of hearing. Arzneimittelforschung. 1976;26:1977-1980.
- Jasper A. Action of Cavinton on hearing defects of different origin. Ther Hung. 1978;26:181-184.
- KosztyLa-Hojna B. Effect of ethyl ether of apovincaminic acid (Cavinton) on the ototoxic action of sisomicin in guinea pigs. Otolaryngol Pol. 1990;44:122-129.
- Pickrell JA, Oehme FW, Cash WC. Ototoxicity in dogs and cats. Semin Vet Med Surg (Small Anim) 1993;8:42-49.
- Mattsson C, Marklund SL, Hellstrom S. Application of oxygen free radical scavengers to diminish the occurrence of myringosclerosis. Ann Otol Rhinol Laryngol 1997 Jun;106(6):513-518.
- Brookler KH, Glenn MB. Meniere's syndrome: an approach to therapy. Ear Nose Throat J 1995;74:534-538.
- Brookes GB. Vitamin D deficiency -- a new cause of cochlear deafness. J Laryngol Otol. 1983;97:405-420.
- Sziklai I, Ribari O. Flavonoids alter bone-remodeling in auditory ossicle organ cultures. Acta Otolaryngol. 1995;115:296-299.
- Friedmann I, Galey FR. Initiation and stages of mineralization in tympanosclerosis. J Laryngol Otol. 1980;94:1215-1229.
- Attias J, Weisz G, Almog S, Shahar A, Wiener M, et al. Oral magnesium intake reduces permanent hearing loss induced by noise exposure. Am J Otolaryngol. 1994;15:26-32.
- Abdulla S. Pills may replace ear-muffs for protection against damaging noise. Lancet 1998;351:1411.
- Coles R. Trial of an extract of Ginkgo biloba (EGB) for tinnitus and hearing loss. Clin Otolaryngol 1988;13:501-502.
- Meyer B. Tinnitus-multicenter study. A multicentric study of the ear. Ann. Oto-Laryng. 1980;103:185-188.
- Koeppel FW. Tebonin-therapy with old hard-of-hearing people. Therapiewoche 1980;30:6443-6446.
- Ribari O, Faredin I, Sziklai I. Endogenous steroids and otosclerosis. HNO 1985;33:183-186.
- Shearer PD. Ibid.