Aetna considers dehydration testing with glycerol, urea, or other osmotic diuretics to verify the suspicion of endolymphatic hydrops (Meniere's disease) medically necessary only in members with atypical presentations of this disease.
Aetna considers dehydration testing experimental and investigational for other indications because its effectiveness has not been established.
Aetna considers genetic testing of SLC26A4 gene mutation for the diagnosis of endolymphatic hydrops (Meniere's disease) experimental and investigational because its effectiveness has not been established.
Aetna considers testing for antibodies against inner ear antigens for the diagnosis of Meniere's disease experimental and investigational because its effectiveness has not been established.
Aetna considers vestibular evoked myogenic potential (VEMP) for the diagnosis of Meniere disease and monitoring of disease progression experimental and investigational because its effectiveness forthese indications has not been established.
Osmotic diuretics are able to reduce endolymphatic pressure and volume, and hence improve peripheral auditory and vestibular function. After baseline audiometric testing, a glycerol, urea or other osmotic diuretic is administered. Repeat audiometric testing is performed is performed at 3 hours (and sometimes at 1 and 2 hours) post-ingestion. The test is considered positive if: (i) there is a 10 dB or more improvement at 2 or more frequencies (250 to 2,000 Hz), or (ii) there is a 12 % or greater improvement in speech discrimination scores. The test is associated with a number of unpleasant side effects, including headache, nausea, thirst, diarrhea, emesis, diuresis, and dizziness.
Because dehydration tests are relatively specific for endolymphatic hydrops, they may be useful in confirming the presence of disease in patients with atypical presentations. However, because the tests are relatively insensitive, they are not useful to rule out endolymphatic hydrops or as screening tests for the disease.
Although the tests appear relatively specific for endolymphatic hydrops, they are relatively insensitive. Snyder (1974) reported the experience using the glycerol test in 122 patients with a combination of sensorineural hearing loss and tinnitus or vestibular symptoms, in whom endolymphatic hydrops was considered a diagnostic possibility. Fifty percent of patients ultimately found to have endolymphatic hydrops had positive tests. One false-positive was found among the positive tests. In a series of 95 patients with Meniere's disease, Akioka et al (1990) found 47 % to have a positive glycerol dehydration test. Stahle and Klockhoff (1986) reported 60 % of patients with Meniere's disease were found to have positive tests, and that positive tests were only found in ears with Meniere's disease.
Dehydration tests have not been proven to be useful in selecting patients with endolymphatic hydrops who are most likely to respond to surgery. Some authors have suggested that patients with positive glycerol tests are more likely to have beneficial responses to endolymphatic sac decompression, but statistical proof of such a relationship is lacking.
Whether a Meniere's disease patient will have a positive test or not seems to depend in part on the phase of the disease. Tests are more likely negative very early and very late in the course of disease, although the stage of the disease is not predictable from the results of the dehydration testing.
Critics of dehydration testing note that the test is unpleasant, not adequately sensitive, impractical, and subject to significant placebo effects. According to Fagan (1999), dehydration studies are little used these days because they are unpleasant and time consuming. There is only anecdotal evidence that positive responders to dehydration tests may be more likely to respond to endolymphatic sac decompression. Some investigators have found that the results of dehydration testing are highly affected by suggestion to the patients as to what they should expect. These investigators suggest that the use of the dehydration test to select patients for surgery risks induces a bias toward more placebo responders.
In a critical review of diagnostic testing in endolymphatic hydrops, Arts et al (1997) concluded: "At this point, the clinical use of dehydration testing is unclear at best. Despite many legitimate questions with regard to its practicality and sensitivity, there is considerable evidence that a real phenomenon, specific for endolymphatic hydrops, underlies this test. Given this, the test may be helpful in verifying the suspicion of endolymphatic hydrops in patients with atypical presentations. It is unlikely, however, that the choice of therapy will be altered by the results of this test in many instances".
An UpToDate review on “Meniere disease” (Dinces and Rauch, 2014) does not mention the use of dehydration testing as a diagnostic tool.
Note: Osmotic diuretics such as urea and isosorbide that can be taken orally have also been used as treatment for endolymphatic hydrops.
In a case-report, Yoshida et al (2015) reported magnetic resonance imaging (MRI) findings in a 13-year old girl with an SLC26A4 gene mutation who had low-frequency sensori-neural hearing loss (SNHL). The patient exhibited bilateral and symmetric low-frequency SNHL. Upon genetic testing, a heterozygous c.1105A > G (p.K369E) mutation of the SLC26A4 gene was detected. Mild endolymphatic hydrops in the right cochlea and marked endolymphatic hydrops in the left vestibulum were seen by MRI 4 hours after an intravenous gadolinium injection. The authors concluded that this was the first reported case of a patient with the SLC26A4 gene mutation c.1105A > G (p.K369E) who had low-frequency SNHL. They stated that co-occurrence of cochlear and vestibular endolymphatic hydrops suggested an association with that pathology. These preliminary findings need to be validated by well-designed studies.
An UpToDate review on “Meniere disease” (Dinces, 2015) states that “Laboratory testing -- Tests for antibodies against inner ear antigens have been described, but are not considered to be clinically useful and are not part of a routine evaluation for Meniere disease …. Tests for endolymphatic hydrops -- The vestibular evoked myogenic potential (VEMP) is a newer test that shows promise for diagnosis and monitoring. Cervical VEMP (cVEMP) is an inhibitory sacculocollic reflex test that shows characteristic changes in symptomatic ears of Meniere patients, and may detect early saccular hydrops before the onset of classic Meniere symptoms. Ocular VEMP (oVEMP) engages both utricular and saccular afferent nerve fibers and may also be useful in assessment of Meniere patients. In addition to diagnosis, VEMP may be useful for monitoring patients for disease progression, and to identify the active ear in patients with bilateral disease. VEMP is an emerging technology that has not yet been standardized or fully validated clinically”.
|CPT Codes / HCPCS Codes / ICD-10 Codes|
|Information in the [brackets] below has been added for clarification purposes.  Codes requiring a 7th character are represented by "+":|
|ICD-10 codes will become effective as of October 1, 2015:|
|There are no specific codes for dehydration testing for endolymphatic hydrops, vestibular evoked myogenic potential (VEMP), antibodies against inner ear antigens:|
|CPT codes not covered for indications listed in the CPB:|
|81406||Molecular pathology procedure, Level 7 (eg, analysis of 11-25 exons by DNA sequence analysis, mutation scanning or duplication/deletion variants of 26-50 exons, cytogenomic array analysis for neoplasia) [genetic testing of SLC26A4 gene mutation for the diagnosis of endolymphatic hydrops (Meniere's disease)]|
|Other CPT codes related to the CPB:|
|69805 - 69806||Endolymphatic sac operation|
|ICD-9 codes covered if selection criteria are met:|
|H81.01 - H81.09||Meniere's disease|
|H81.10 - H81.13||Benign paroxysmal vertigo|
|H81.311 - H81.399||Other peripheral vertigo|
|H81.41 - H81.49||Vertigo of central origin|
|H83.01 - H83.2X9||Labyrinthitis|
|R26.0 - R26.9||Abnormalities of gait and mobility|
|R42||Dizziness and giddiness|