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Trial registered on ANZCTR


Registration number
ACTRN12607000230459
Ethics application status
Not yet submitted
Date submitted
21/03/2007
Date registered
1/05/2007
Date last updated
1/05/2007
Type of registration
Retrospectively registered

Titles & IDs
Public title
Clinical Electrocochleography in Meniere's Disease: The Value of Low Frequency Stimulus Biasing
Scientific title
Comparing the change in electrocochleography results in those with Meniere's compared to controls when low frequency stimulus biasing is introduced to electrocochleography performed for the investigation of vertigo.
Universal Trial Number (UTN)
Trial acronym
Low Frequency Biasing in ECochG
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Diagnosing Meniere's disease in patients with vertigo 1761 0
Condition category
Condition code
Ear 1853 1853 0 0
Other ear disorders

Intervention/exposure
Study type
Interventional
Description of intervention(s) / exposure
Both patients with meniere's disease and a control group will undergo electrocochloegraphy with an added component of the test being introduction of a low frequency stimulus once the usual test is complete. Electocochleography is the placing of a small wire electrode through the ear drum then sending 8kHz, 2kHz, 1kHz and 500Hz sound through the wire and recording the potentials elicited from the ear in respose to these sounds. The test takes about 30min and the extra low frequency component would last about 10 minutes extra. The low frequency component would be a 50Hz sound played at the same time as the the 8kHz, 2kHz, 1kHz and 500Hz noises mentioned as the routine electrocochleographic process and the change in potentials elicited previously recorded.
Intervention code [1] 1662 0
Diagnosis / Prognosis
Comparator / control treatment
A control group will undergo electrocochloegraphy with an added component of the test being introduction of a low frequency stimulus once the usual test is complete. The control group will be those who attend the clinic of Prof Gibson for investigation of vertigo symptoms who are diagnosed on the Meniere's Clinical Score as having no Meniere's Disease- the current accepted gold standard for the diagnosis of Meniere's disease in the living patient - post mortem examination is the only certain diagnosis currently. Controls will be those who suffer from vertigo symptoms but who are would be unlikely to have endolymphatic hydrops (as found in Meniere's disease and diagnosed on electrocochleography) based on history. They may be suffering from such conditions as postural dizziness, benign positional vertigo, or labyrithitis, which do not cause endolymphatic hydrops so these patients would be expected to have a normal electrocochleogram.
Control group
Active

Outcomes
Primary outcome [1] 2596 0
The change in Summation potential (SP) of the electrocochleograph result when the low frequency stimulus bias is introduced (from electrocochleography SP without stimulus biasing).
Timepoint [1] 2596 0
The summating potential is first measured in the response elicited to the 8kHz, 2kHz, 1kHz and 500Hz stimuli in the absence of the low frequency bias. Then the low frequency noise is made at the same time as the 8kHz, 2kHz, 1kHz and 500Hz stimuli and the SP generated is again measured for each of these frequencies. The change in the SP amplitude from before to after the introduction of the low frequency bias is then calculated.
Secondary outcome [1] 4456 0
Improvement in diagnosis of Meniere's disease when correlated with the current gold standard of clinical diagnosis.
Timepoint [1] 4456 0
The outcome is measured at the same time as the clinical interview and a direct correlation done comparing the electrocochleography results (with the added low frequency noise)with the clincial score and the basic electrocochleograph results. This is a cross sectional analysis of diagnosis compared between diagnostic tests - which included the clinical interview, which is the current gold standard. There is no secondary time point.

Eligibility
Key inclusion criteria
All patients, undergoing electrocochleography for the investigation of vertigo under the care of Prof W Gibson will be invited to participate in the trial. The control group will be those with a very low Meniere's score obtained on clinical interview but are still undergoing electrocochleography -which is the current gold standard of diagnosis.
Minimum age
18 Years
Maximum age
No limit
Sex
Both males and females
Can healthy volunteers participate?
No
Key exclusion criteria
Hearing loss>70dB, concurrent ear pathology, stage 1 Meniere's - though the trial may change to include them based on initial results.

Study design
Purpose of the study
Diagnosis
Allocation to intervention
Non-randomised trial
Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
Masking / blinding
Blinded (masking used)
Who is / are masked / blinded?



Intervention assignment
Parallel
Other design features
There will be 2 investigators so that clinical assessor and the clinician performing the electrocochleography are blinded of the result of the other half. The patients will be not be informed of their results on clinical interview or electrocochleography until both compenents are complete so that there is no chance of them biasing the evaluating clinicians. The 2 investigators are both clinicians, who will be involved in assessment of outcomes and administration of the electrocochleography. There will be comparison of study groups based on demographics before analysis begins to ensure homogeneity of groups plus stratification analysis based on hearing level and stage of Meniere's disease.
Phase
Type of endpoint/s
Efficacy
Statistical methods / analysis

Recruitment
Recruitment status
Not yet recruiting
Date of first participant enrolment
Anticipated
1/04/2007
Actual
Date of last participant enrolment
Anticipated
Actual
Date of last data collection
Anticipated
Actual
Sample size
Target
50
Accrual to date
Final

Funding & Sponsors
Funding source category [1] 2000 0
Charities/Societies/Foundations
Name [1] 2000 0
Garnett Passe and Rodney Williams Foundation Scholarship
Country [1] 2000 0
Primary sponsor type
Individual
Name
Dr Claire Iseli
Address
Country
Secondary sponsor category [1] 1811 0
Individual
Name [1] 1811 0
Professor William Gibson
Address [1] 1811 0
Country [1] 1811 0

Ethics approval
Ethics application status
Not yet submitted
Ethics committee name [1] 3707 0
Royal Prince Alfred Hospital
Ethics committee address [1] 3707 0
Ethics committee country [1] 3707 0
Australia
Date submitted for ethics approval [1] 3707 0
Approval date [1] 3707 0
Ethics approval number [1] 3707 0
Ethics committee name [2] 3708 0
associated rooms of supervising specialist Professor W Gibson in Newtown
Ethics committee address [2] 3708 0
Ethics committee country [2] 3708 0
Australia
Date submitted for ethics approval [2] 3708 0
Approval date [2] 3708 0
Ethics approval number [2] 3708 0
Ethics committee name [3] 3709 0
associated rooms of supervising specialist Professor W Gibson in Gladesville
Ethics committee address [3] 3709 0
Ethics committee country [3] 3709 0
Australia
Date submitted for ethics approval [3] 3709 0
Approval date [3] 3709 0
Ethics approval number [3] 3709 0

Summary
Brief summary
Introduction: The inner ear is a fluid-filled bony cavity divided into 2 parts: the cochlea, which is responsible for hearing, and the vestibular apparatus, which is involved in the maintenance of balance. Meniere’s disease is a clinical syndrome whereby the patient suffers from deafness, tinnitus, ear fullness and vertigo which characteristically fluctuate. It is thought to be due to attacks of increasing fluid in the inner ear (known as endolymphatic hydrops) and currently is diagnosed using clinical history, examination and hearing and balance tests in combination with an electrical test of the cochlea in response to sound known as electrocochleography (ECochG). The changes in the ECochG responses seen in Meniere’s disease are considered to reflect the mechano-electric changes in the inner ear caused by endolymphatic hydrops. There are three main ways that the ECochG can be performed based on the position where the electrode is placed: extratympanic (ET), with the electrode placed external to the ear drum, transtympanic (TT), where the electrode is placed through the ear drum, and round window (RW), which requires a window to be opened in the ear drum for the electrode to be placed, therefore may require general anaesthesia. The closer to the round window that the electrode is placed the more robust the ECochG result is. Transtympanic is the preference of Prof Gibson as it can be done under local anaesthetic but maintains a robust result. The ECochG generates a waveform of which the most useful parts for diagnosing Meniere’s disease are termed the summating potential (SP) and the action potential (AP). There is ongoing debate as how best to use these parts for accurate diagnosis. The SP is thought to reflect the overall change in the electrical gradient in the cochlea created by sound. The basilar membrane is a membrane within the cochlea that is moved by a sound wave and is an important part of sound detection. A theory is that displacement of the basilar membrane is a primary component of generating the SP. If a continuous low frequency sound is transmitted to the ear it causes a shift in the position of the basilar membrane. This is known as low frequency biasing. When the low frequency biasing is transmitted at the same time as a normal ECochG stimulus we would therefore expect to see a change in the SP results, demonstrating that the basilar membrane is mobile. Experiments in guinea pigs using a low frequency bias have confirmed a marked modulation in the SP amplitude. Low frequency biasing studies in humans with endolymphatic hydrops should show less change in the SP because the basilar membrane is already displaced by the disease process and therefore less mobile compared to normal ears.

Aim: To determine if the presence of endolymphatic hydrops affects the results of ECochG when low frequency stimulus biasing is introduced.

Hypothesis: Low frequency biasing will not affect the basilar membrane as much in those individuals in which endolymphatic hydrops is present, compared to normal ears, because it is already displaced by the disease process present.

Potential Significance: This would give the use of ECochG greater diagnostic accuracy for endolymphatic hydrops and Meniere’s disease, making it more useful both as a clinical test and as a method of evaluating the inner ear structural changes occurring in Menie`re’s disease. This may be particularly beneficial for individuals who have unilateral symptoms of Meniere’s where a destructive surgical procedure is contemplated but hydrops in the other ear must be excluded.
Trial website
Trial related presentations / publications
Public notes

Contacts
Principal investigator
Name 27765 0
Address 27765 0
Country 27765 0
Phone 27765 0
Fax 27765 0
Email 27765 0
Contact person for public queries
Name 10851 0
Dr Claire Iseli
Address 10851 0
7/155 Missenden Rd
Newtown NSW 2041
Country 10851 0
Australia
Phone 10851 0
+61 2 95191489
Fax 10851 0
+61 2 95191454
Email 10851 0
[email protected]
Contact person for scientific queries
Name 1779 0
Dr Claire Iseli
Address 1779 0
7/155 Missenden Rd
Newtown NSW 2041
Country 1779 0
Australia
Phone 1779 0
+61 2 95191489
Fax 1779 0
+61 2 95191454
Email 1779 0
[email protected]

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