Meniere's disease

Abstract

In order to discern trends in surgical procedures used to treat Meniere's disease in the United States during the 1990s, we mailed a questionnaire to 700 members of the American Otological Society and the American Neurotology Society. These physicians were asked about the frequency, results, and complications of surgical procedures for Meniere 's disease that they had performed between Jan. 1, 1990, and Dec. 31, 1999. Questionnaires were returned by 137 surgeons (19.6%). Their responses indicated that the number of vestibular neurectomies, labyrinthectomies, and endolymphatic sac surgeries all decreased during 1999. Meanwhile, the use of office-administered intratympanic gentamicin therapy increased rapidly throughout the entire 10-year period, and by 1999 it had become the most frequently used invasive treatment for Meniere's disease. Surgeons now seem to reserve inpatient procedures for cases where intratympanic gentamicin fails to control vertigo.

Introduction

The surgical treatment of Meniere's disease has evolved significantly during the past decade. In 1992, we published a survey of 58 head and neck surgeons regarding their use of vestibular neurectomy, which at that time was gaining popularity as a surgical treatment for Meniere's disease. (1) Because more than 10 years had passed since the completion of our previous survey, we thought it appropriate to conduct another to ascertain any new trends in surgeons' treatment preferences and outcomes in the surgical management of Meniere s disease. Specifically, we attempted to determine the number of each type of procedure that had been performed, success rates, rates of hearing loss, complications, first- and second-line surgical treatment preferences, and respondents' opinions regarding changing trends. In this article, we elaborate on these findings and others.

Methods and materials

We mailed questionnaires to virtually every member of the American Otological Society and the American Neurotology Society (n = 700) to ascertain trends in surgical procedures used to treat Meniere's disease in United States citizens between Jan. 1, 1990, and Dec. 31, 1999. Response data were entered into a Microsoft Excel 2000 spreadsheet and statistically analyzed with the assistance of a personal computer.

Results

Of the 700 questionnaires mailed, we received 137 responses (19.6%). Results indicated that 79.6% of respondents were fellowship-trained, 81.0% had performed vestibular neurectomies, 89.8% had performed labyrinthectomies, 85.4% had performed endolymphatic sac surgery, and 72.3% had used intratympanic gentamicin therapy (table).

A clear trend emerged over the 10-year period in that there was an exponential increase in the use of intratympanic gentamicin therapy; the number of such procedures rose from fewer than 100 in 1990 to more than 900 in 1999 (figure 1). There was also an overall increase in the number of endolymphatic sac surgeries performed over the entire 10-year span, although a sharp decline was seen in the final year of the study. The number of labyrinthectomies remained fairly constant throughout the decade, and the number of vestibular neurectomies slowly declined. By the end of the decade, intratympanic gentamicin therapy had risen from the least-used modality to the most frequently used. More than half (53.8%) of the 106 respondents who answered this particular question said they were treating more Meniere s disease patients with intratympanic gentamicin because it is minimally invasive and can be performed in the office.

Vertigo-control rates varied among the four treatments. Cure rates of 90% or better were reported following 86.5% of the vestibular neurectomies, 90.2% of the labyrinthectomies, 6.0% of the endolymphatic sac surgeries, and 29.3% of the intratympanic gentamicin procedures (figure 2).

While information regarding the incidence of complications associated with each procedure was solicited in the questionnaire, responses were sparse; this made it difficult to draw generalizations or conclusions. We did determine that endolymphatic sac surgery resulted in a lower incidence of postoperative hearing loss than did either vestibular neurectomy or intratympanic gentamicin (figure 3).

As first-line surgical treatment, 48.9% of the 137 respondents chose endolymphatic sac procedures, while 33.6% opted for intratympanic gentamicin. For second-line treatment, vestibular neurectomy was preferred by 40.1% of respondents, followed by labyrinthectomy at 17.5%.

Discussion

For many years, the mainstay of therapy for symptoms of classic unilateral Meniere s disease included various medical regimens such as low-salt diets, diuretics, carbonic anhydrase inhibitors, betahistine and other vasodilators, calcium channel blockers, and vitamin supplements. Vertigo-control rates of 87% and higher have been reported with these conservative measures.

The management of patients who do not respond to such conservative therapy has been controversial. For patients who already have a significant hearing loss, labyrinthectomy is a viable and straightforward option. But for patients who still maintain functional hearing, vestibular nerve section, endolymphatic sac surgery, and intratympanic aminoglycoside therapy should be considered.

In our 1992 survey, we found that the popularity of vestibular neurectomy had grown significantly during the preceding decade. (1) In fact, by the end of the study decade, it had become the most favored procedure, and surgeons were achieving excellent vertigo-control rates in patients with serviceable hearing. A decade later, a gradual decline in the number of neurectomies is evident, and surgeons have shifted their treatment strategies toward more conservative initial surgical approaches-that is, endolymphatic sac surgery, which is associated with a low incidence of morbidity, and intratympanic gentamicin, which was new and not widely used in the United States at the time of ourprevious report. Today, vestibular neurectomy and labyrinthectomy appear to be reserved for patients who have not responded to the more conservative methods and for those without hearing.

Certainly, many limitations are inherent in the survey method of data collection in general and in our survey in particular. It is possible that some respondents did not review their results in detail before answering the questionnaire. Responses often appeared to reflect impressions rather than precisely calculated figures. Moreover, data were not gathered by each respondent in a controlled orprospective fashion. Finally, approximately 80% of the members of the American Otological Society and the American Neurotology Society did not respond. We are unable to draw any conclusions regarding the nationwide treatment of Meniere s disease, given such a large number of unrepresented surgeons. Nevertheless, we believe that the responses we did receive provide a great deal of valid information about changing trends in surgical techniques and thought processes.

Endolymphatic sac surgery. Numerous reports on endolymphatic sac surgery have appeared in the literature, and several procedures have been proposed to control or eliminate the symptoms of Meniere' s disease. (2,3) These procedures include the use of the endolymphatic sac-mastoid shunt, the endolymphatic sac-subarachnoid shunt, and wide endolymphatic sac decompression. Endolymphatic sac-mastoid shunt surgery was first described by G. Portmann in 1927. (4) In a 1969 report of a large series of patients who had undergone this procedure, M. Portmann found that vertigo was alleviated in 93% of patients. (5) Since then, variations on G. Portmann's original procedure have been described by Morrison, (6) Paparella and Goycoolea, (7) Goldenberg and Justus, (8) Gibson, (9) Huang and Lin, (10) and Arenberg, (11) and their vertigo-control rates ranged from 74 to 90%.

Perhaps the most controversial study of endolymphatic sac surgery was published in 1989 by Bretlau et al, who compared it with simple mastoidectomy. (12) One might think that their finding that good vertigo control was achieved in approximately 70% of patients in both groups would have quelled much of the enthusiasm that had been generated for endolymphatic sac surgery. But such was apparently not the case, as our survey found that use of this procedure increased throughout most of the 1990s. This finding suggests that our respondents harbored doubts about the findings of Bretlau et al. Because sac surgery poses a limited risk to cochlear function, many surgeons continue to use it as a mainstay of the surgical management of Meniere's disease symptoms in order to preserve hearing.

Vestibular neurectomy. Vestibular nerve section is the most successful method of curing vertigo while preserving hearing in patients with Meniere's disease. (13) Early vestibular neurectomies via the suboccipital approach were performed in the 1920s and 1930s by Dandy (14) and McKenzie. (15) However, the procedure then went virtually unused from 1945 until 1961, when House introduced the middle fossa approach. (16) In subsequent years, the use of the middle fossa approach was not uncommon, but it never achieved widespread popularity, largely because of its technical difficulty, limited applicability in older patients, and high incidence of complications, including hearing loss and facial weakness.

In 1972, Hitselberger and Pulec described the retrolabyrinthine approach for trigeminal nerve sections. (17) Later, Silverstein and Norrell reintroduced vestibular neurectomy via the posterior fossa approach. (18) Their method involved microsurgical techniques, the retrolabyrinthine approach, and mastoidectomy. (13,18) In the 1980s, this procedure and others that involved subsequent modifications of the posterior fossa approach became popular techniques for relieving vertigo while preserving hearing.

Intratympanic gentamicin. The popularity of the minimally invasive intratympanic aminoglycoside procedure increased dramatically during the 1990s. Developed in Europe by Beck and Schmidt (19) and Odkvist, (20) this treatment has become more common in North America largely as a result of the work of Nedzelski et al. (21) According to our latest survey, the number of gentamicin procedures increased more than 13-fold during the 1990s, and it is now the most widely used treatment modality.

The fact that antibiotics cause ototoxicity became evident decades ago when streptomycin was first used for the treatment of tuberculosis. (22) In 1948, Fowler published one of the earliest reports of the intentional application of streptomycin toxicity. (23) We must credit Schuknecht, however, with developing a method of delivering topical antibiotics to patients with unilateral Meniere' s disease. In 1957, he published his report on the use of a middle ear catheter to perfuse streptomycin into eight vertigo patients. (24) Vertigo control was achieved in all eight, but five of them experienced a complete unilateral hearing loss. Since the publication of these pioneering studies, many other authors have reported excellent vertigo-control rates with intratympanic streptomycin, albeit at the expense of substantial associated hearing loss. Although it is still unclear which drug has the best profile with regard to maximum vestibulotoxicity and minimum cochleotoxicity in patients with Meniere's disease, most cli nicians use gentamicin.

Various protocols are used to deliver gentamicin to the inner ear, including direct transtympanic instillation, blind injection, round window membrane microcatheterization, and injection via the Silverstein MicroWick. (25-28) The standard gentamicin solution is a 40-mg/ml concentration. To minimize patient discomfort, most practitioners buffer the solution with sodium bicarbonate to achieve a final gentamicin concentration of 26.7 mg/ml. To determine when to discontinue therapy, many physicians use symptom control as the endpoint. Others titrate the doses to maintain good hearing or to achieve a desired reduction in vestibular response as measured by electronystagmography. These methods have been met with varying degrees of success, but hearing loss is still a concern.

Some surgeons have contemplated the benefits of low-dose continuous-infusion therapy in an effort to maximize vestibular ablation while minimizing damage to the cochlear reserve. DeCicco et al reported excellent results with microdoses of dilute gentamicin (10 mg/ml) delivered though a microcatheter implanted in the round window niche. (27) They reported no changes in hearing or reduction in vestibular response. Their findings suggest that gentamicin must relieve the vertigo of Meniere's disease by some mechanism other than the destruction of vestibular function. One possible explanation is that the gentamicin affects the dark cells of the vestibular labyrinth and the secretory cells in the stria vascularis, which reduces the secretion of endolymph, thereby reducing endolymphatic hydrops.

In 1998, Silverstein developed the MicroWick with these considerations in mind. (28) The cylindrical MicroWick is made of polyvinylacetate and measures 1 mm in diameter and 9 mm in length. It is placed through a silicone ventilation tube (inner ear diameter: 1.42 mm) that is equipped with a 3.25-mm diameter flexible flange (Micromedics; Eagan, Minn.). The patient places a dilute concentration of gentamicin (10mg/ml) into an eardropper and instills it three times per day. The MicroWick gives patients the convenience and flexibility to treat themselves at home, and it has the advantage of allowing for sustained low-dose infusion. The therapeutic endpoint is determined when the physician notes the appropriate balance between the amount of vestibular ablation (as measured by electronystagmography) and the progression of hearing loss.

In conclusion, our data provide evidence that surgeons are becoming increasingly comfortable with intratympanic gentamicin. Its ease of administration means that its popularity should continue to increase as both a first- and second-line treatment.

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References

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(21.) Nedzelski JM, Chiong CM, Fradet G, et al. Intratympanic gentamicin instillation as treatment of unilateral Meniere's disease: Update of an ongoing study. Am J Otol 1993;14:278-82.

(22.) Hirsch BE, Kamerer DB. Role of chemical labyrinthectomy in the treatment of Meniere's disease. Otolaryngol Clin North Am 1997;30:1039-49.

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(25.) Youssef TF, Poe DS. Intratympanic gentamicin injection for the treatment of Meniere's disease. Am J Otol 1998;19:435-42.

(26.) Silverstein H, Arruda J, Rosenberg SI, et al. Direct round window membrane application of gentamicin in the treatment of Meniere' s disease. Otolaryngol Head Neck Surg 1999;120:649-55.

(27.) DeCicco MJ, Hoffer ME, Kopke RD, et al. Round-window microcatheter-administered microdose gentamicin: Results from treatment of tinnitus associated with Meniere's disease. Int Tinnitus J 1998;4:141-3.

(28.) Silverstein H, Jackson LE, Rosenberg SI. Silverstein MicroWick for the treatment of inner ear disease. Operative Techniques in Otolaryngology-Head and Neck Surgery 2001;12:144-7.

From the Ear Research Foundation, Sarasota, Fla.

Reprint requests: Herbert Silverstein, MD, Florida Ear and Sinus Center, 1961 Floyd St., Suite A, Sarasota, FL 34239. Phone: (941) 366-9222; tax: (941) 365-2269; e-mail: hsilverstein@aol.com

This study was supported by a grant from the Ear Research Foundation of Sarasota, Fla., and was originally presented at the annual meeting of the American Academy of Otolaryngology-Head and Neck Surgery; Sept. 27, 2000; Washington, D.C.

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