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Assessment and treatment of dizziness
  1. A P COATESWORTH
  1. Department of Otolaryngology, Leeds General Infirmary, Great George Street, Leeds LS1 3EX, UK
    1. G MICHAEL HALMAGYI,
    2. PHILLIP D CREMER
    1. Royal Prince Alfred Hospital, Sydney, Australia
    1. Dr G Michael Halmagyi

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    In a recent editorial, Halmagyi and Cremer consider Menière's disease in their discussion of recurrent spontaneous vertigo.1 Menière's disease is a diagnosis of exclusion. Many conditions may present with the triad of hearing loss, vertigo, and tinnitus, most importantly vestibular schwannomas.2 Gadolinium enhanced MRI imaging is the current gold standard for diagnosing vestibular schwannoma and is mandatory before giving somebody the diagnosis of Menière's disease. The Committee on Hearing and Equilibrium of the American Academy of Otolaryngology—Head and Neck Surgery have set out guidelines for the diagnosis and evaluation of therapy in Menière's disease.3

    Audiovestibular testing can be useful in Menière's disease. Caloric testing has poor sensitivity and specificity in diagnosing the disease. Electrocochleography and glycerol dehydration testing can be useful in the earlier stages of the disease before the hearing function is irreversibly and severely lost. In Menière's disease, the most common findings on electrocochleography are an increased summating potential to action potential ratio, a widened summating potential/action potential complex, and a disturbed cochlear microphonic potential.4

    For medical treatment, dietary advice with strict sodium restriction is useful. However, betahistine probably helps more patients with Menière's disease than any other drugs. Labyrinthine sedatives are also helpful in patients who have severe attacks of vertigo.5 Surgical treatment of Menière's disease treats only the vertigo. A wide range of operations have been described, from grommet insertion to vestibular nerve section, all of which have had a similar degree of success. These are particularly difficult to compare due to the huge variations in the natural history of the disease.

    Assessment and treatment of patients with balance disturbance covers many specialties, who all approach the problem from slightly different angles with different perspectives. It is important to liase closely with colleagues in associated specialties to optimise the diagnosis and treatment of these patients.

    References

    Halmagyi and Cremer reply:

    One cannot help but feel a certain sense of nostalgia reading Coatesworth's textbook description of Menière's disease: if only the real world was like that. We deal with his comments in order.

    Menière's disease is a diagnosis of exclusion—It is difficult to conceive what needs to be excluded in a patient who has repeated devastating attacks of acute spontaneous vertigo lasting several hours as well as unilateral tinnitus, aural fullness, and fluctuating hearing loss. When the audiogram shows a unilateral low frequency sensorineural hearing loss, the caloric test shows a canal paresis and the electrocochleogram shows a pathologically large summating potential to action potential ratio1-1 the patient has Menière's disease. Menière's disease is a clinical diagnosis supported by laboratory testing. It is no more a diagnosis of exclusion than is multiple sclerosis.

    The vestibular schwannoma story—This is a difficult one. Maybe the answer is that if someone else is paying and the lawyers are watching anyone with any unilateral balance or hearing problem should have a gadolinium enhanced MRI in case they are harbouring what might eventually become a symptomatic intracanalicular vestibular schwannoma (“acoustic neuroma”). If the patient actually does have one, then the problem becomes not so much the dizziness but what to do about the “tumour”. Vestibular schwannomas can, very rarely, present with one, at the most two attacks of acute spontaneous vertigo,1-2 just as they can, rarely, present as sudden hearing loss.1-2 We see about 2500 new patients each year in our balance disorders clinic and in the past 15 years we have seen three patients with acute spontaneous vertigo who had small vestibular schwannomas.

    Caloric testing has poor sensitivity and specificity in diagnosing Menière's disease— In part it depends who does it. Technical standards for caloric testing are in general not as rigorously enforced as those for audiological testing. Some factors that can have a profound influence on the quality of the results include: (a) method of recording—DC electro-oculography versus infrared and video methods; (b) method of removing fixation—eye closure versus darkness; (c) method or irrigation—water versus air.1-3 Caloric testing (or “ENG”) is no more specific for any disease than is EMG. It shows the site of lesion not the nature of the lesion. When one is confident in the technical standards of the caloric testing the most helpful finding in the diagnosis of Menière's disease is afluctuating unilateral vestibular loss—the vestibular equivalent of the classic fluctuating hearing loss.

    Electrocochleography (ECOG)—Again, it depends on who does it. An ECOG with extratympanic recording of the responses to clicks alone is generally useless or worse, misleading. A transtympanic recording of the responses to tone bursts can disclose, unequivocally, the presence of endolymphatic hydrops, the pathophysiological basis of Menière's disease.1-4 The test is, as Coatesworth notes, most useful in the early stages before a severe fixed hearing loss due to loss of hair cells.

    Surgery for Menière's disease—Vestibular nerve section stops the vertigo attacks without worsening the hearing but might cause chronic vestibular insufficiency.1-5Intratympanic gentamicin is a lot simpler and safer and might be just as good at stopping the vertigo but can worsen the hearing.1-6 Endolymphatic sac surgery ? The controversy still rages.1-7 1-8

    We certainly agree on the need for cooperation between specialties in the management of patients with dizziness. Neurologists needs to work with otolaryngologists who have expertise and interest in otology. The neurologists of Leeds should know how lucky they are to have one.

    References

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