Search

The effects of middle ear pressure pulses were studied in 37 patients with a diagnosis of definite Meniere's disease and active vestibular symptoms, 31 of whom had failed to respond to medical treatment including diuretics prior to pressure treatment. The number of vertigo spells during the 6 months prior to treatment and for 6, 18 and 24 months after the start of treatment were evaluated. The functionality level scores were three or worse according to the American Academy of Otolaryngology--Head and Neck Surgery (AAO-HNS) criteria. The results of the study were as follows: 19 patients experienced freedom from vertigo spells; 15 patients reported a significant decrease in the frequency of vertigo spells; and 3 patients did not respond to pressure treatment and were subjected to gentamicin injections, I of whom consequently became deaf in the affected ear. No patient became worse in connection with pressure treatment. With the exception of the three patients who did not respond to pressure treatment, all patients reported an improvement in functionality of at least two levels according to the AAO-HNS functionality scale. No side effects or adverse events were observed during the 2 years of pressure treatment. Overall, the results indicate that pressure treatment provides efficient control of symptoms in patients with intractable forms of Ménière's disease without producing any adverse effects on the inner ear.

Different medical and surgical methods have been tried in attempting to reduce endolymphatic pressure in Ménière's disease. Pressure treatment has a role on the treatment staircase, after pharmacological treatment and before destructive methods. Pressure chamber treatment has shown that some patients respond well to the treatment with diminishing inner ear symptoms and also some hearing improvement. Earlier studies have shown that electrocochlear measurements improve after local pressure treatment in the ear. The present study was a prospective randomized placebo controlled, multicentre clinical trial. 56 patients with active Ménière's disease, age 20-65 years, with a hearing loss of 20-65 dB PTA participated. A total of 31 patients completed 2 weeks use with an active apparatus (Meniett) and 25 patients completed the 2 weeks with the placebo gadget. Both machines were produced by Pascal Medical, Halmstad, Sweden. Two weeks before the start of treatment a grommet was placed in the tympanic membrane. A significant improvement concerning frequency and intensity of vertigo, dizziness, aural pressure and tinnitus was reported by the active group on the visual analogue scales (VAS) questionnaire. In the placebo group no change was the most common finding, followed by worsening of the symptoms and a few improvements. The function in professional and family life improved during active treatment and did not during placebo treatment. Pure-tone audiometry did not improve after placebo treatment, but improved at the frequencies 500 Hz and 1,000 Hz after active treatment. The study showed an improvement in the inner ear symptoms after Meniett treatment. The mechanism may be explained by the influence on the round window membrane pressure receptors or an endolymphatic flow out through the pressure release points, such as the endolymphatic duct and sac, thus activating the longitudinal flow. Other mechanisms are also possible.

Thirty patients with Menière's disorder, 11 patients with cochlear hearing loss of other aetiologies and 10 normally-hearing subjects, were investigated using transtympanic electrocochleography (TT ECochG). Alternating polarity clicks, condensation and rarefaction clicks and long tone-bursts of 1 kHz were used for stimulation. The latencies of the AP responses to click stimulation were evaluated. It was found that the latency differences between the condensation and rarefaction click-evoked responses were significantly larger in patients with Menière's disorder as compared to normal subjects and to patients with other cochlear hearing losses. It was found that the sensitivity of TT ECochG, obtained by using measurements of SP-AP ratios and the SP amplitude at 1 kHz burst stimulation, increased from 83 per cent to 87 per cent by addition of the con-rar shift measurement. The specificity of TT ECochG obtained by this combination of variables was 100 per cent in our material. The results of the study indicate that the latency shift found in responses evoked by clicks of opposite polarities in TT ECochG, can be a useful parameter in the detection of suspected endolymphatic hydrops.

Enhancement of the signal-to-noise ratio is a central issue in electrically evoked response techniques. Transtympanic electrocochleography requires careful methodological considerations as responses from the cochlea may easily be affected by various sources of electromagnetic noise. The final electrophysiological waveforms are acquired by advanced signal processing which influences the content of the recordings. A standard method of transtympanic electrocohleography is presented here to increase the feasibility of the measurements in daily clinical use and to facilitate uniform interpretation of the recordings. The electrocochleographic recordings were carried out in 61 patients with a clinical diagnosis of Meniere's disease and in 15 ears of normal hearing subjects. The electrophysiological data are presented and set in relation to the results reported by other laboratories under equivalent recording conditions. Methodological factors of consequence for the quality of the recordings, such as testing environment, properties of the equipment, mode to produce and deliver stimuli and properties of the electrodes, are analysed.

An objective method for the pre-operative diagnosis and the post-operative assessment of a presumed perilymphatic fistula (PLF) using transtympanic electrocochleography is presented. Three cases are reported in which the history of the disease and the symptoms strongly suggested the presence of a PLF. Pre-operative transtympanic electrocochleography (TT ECoG) recordings at rest showed changes similar to those of endolymphatic hydrops and signs of instability of the inner ear hydrodynamic system during raised intrathoracic pressure. Surgery revealed a visible leak in two of the three cases. Both windows were repaired in all the patients. All patients were relieved from their vestibular symptoms at the time when the post-operative TT ECoG was conducted 3-6 months later. The post-operative recordings were stable during raised intrathoracic pressure and the previously elevated summating potentials decreased which was interpreted as an objective indication of the recovery of the hydrodynamic system. However, later one of the patients again developed recurrent vertigo. Twenty patients with well-documented Ménière's disease were used as a control group. TT ECoG was conducted during raised intrathoracic pressure. The Ménière patients showed stable recordings. It is suggested that among patients with suspected PLF and signs of hydrops in TT ECoG, a dependence on the intrathoracic pressure reflected in the recordings may indicate a possible fistula.

Objective: The aim of the study was to evaluate effects of middle ear pressure changes on the electrocochleographic responses in patients with well-defined Menière's disease. STUDY DESIGN AND INTERVENTIONS: The investigation was conducted as a placebo-controlled, randomized clinical study. Electrocochleographic measurements were performed before and after the insertion of a transtympanic ventilation tube and immediately after the exposure to active or placebo treatment., Setting: The study was carried out in one secondary referral center and one tertiary referral center on an ambulatory basis., Patients: Thirty-nine patients with well-defined Menière's disease were included in the study., Main Outcome Measures: The summating potential/action potential ratio of the electrocochleographic response complex was chosen as the main variable for statistical evaluation of results. Other parameters of the recordings such as responses to low-frequency burst stimulation also were evaluated. Subjective symptoms (e.g., vertigo, tinnitus, and aural pressure) were assessed before and after insertion of the ventilation tube and before and after exposure to treatment., Results: A statistical difference was shown in the electrocochleographic response in the active group before and after exposure to middle ear pressure changes. In the placebo group, no change was found. Changes in electrocochleographic parameters in the active group indicated an improvement in inner ear electrophysiology. No significant changes were found in subjective symptoms in the active or the placebo group. Evaluation before and after insertion of the ventilation tube showed no significant improvement in any variable., Conclusions: This is the first study in which electrophysiologic parameters were evaluated in a placebo-controlled clinical trial of overpressure treatment in Menière's disease. The results show that electrophysiologic parameters can be improved by the application of positive pressure pulses of low amplitude in the middle ear.

Electrocochleographic recordings were made in 17 patients with Menièr's disease before and immediately after exposure to pressure applications in their middle ear. The variables of the response to clicks such as the SP/AP ratio and the width of the complex as well as the amplitudes of the SP in response to long tone bursts were evaluated. Improvement of electrocochleographic recordings, characterized by normalization of the waveforms and reduction of the SP, was found to be significant. The results indicate a mechanoelectric change in the hydroptic cochlea registered directly after exposure to middle ear pressure changes.

The reproducibility of transtympanic electrocochleographic components was investigated in normal-hearing subjects and in patients with Menière's disease. The electric responses to short clicks and long tone bursts were studied using repeated stimuli within the same test (intratest), and after replacement of all electrodes (intertest). The parameters of the response to clicks, such as the SP/AP (summating potential/action potential) ratio and the width of the complex as well as the amplitudes of the response to clicks presented at fast repetition rate, were analyzed. Absolute amplitudes of the SP were measured using long tone bursts of 4, 2 and 1 kHz. It was found that the intratest reproducibility of the responses was good for all the parameters. The intertest responses showed a larger variability, particularly when long bursts were used. Parameters obtained from hydroptic ears, which could be considered mainly representative for the SP, showed the largest variability of the responses. The effect of replacement of the electrodes amounted to less than 35% of the total intertest variability which would indicate that replacement of the electrodes did not significantly influence the recordings obtained at different measurement occasions in the same patient. The upper normal limit value indicating changes which could be contributed to biological fluctuations and the method of measurements were calculated for each response parameter. Changes exceeding these values could thus be attributed to a real change in the electric cochlear potentials, at the 95% confidence level.

The relationship between ambient pressure changes and hearing function was investigated in 14 patients with well-defined sensorineural hearing losses caused by Meniere's disease. The period of exposure to pressure changes varied individually between one and 4 months. The evaluation of hearing function was made by means of pure-tone audiometry, speech discrimination tests and psychoacoustic measurements of the inner ear frequency selectivity. Significant changes were found in the hearing parameters in relation to the period of pressure application. The use of psychoacoustic tuning curves allowed spatial observations on changes in the frequency selectivity. This method proved to be of particular value in the assessment of the inner ear function in Meniere's disease. The results support the hypothesis that the use of overpressure creates a change in the hydrodynamic properties of the cochlea, reflected in an improvement of the inner ear frequency analysis.

Influence of ambient pressure changes on the hearing levels in Meniere's disease was previously demonstrated, using a pressure chamber. The present report concerns a new method for management of Meniere's disease by local application of overpressure. The experimental background and methodologic considerations in therapy are summarized. Five illustrative cases of verified Meniere's disease are presented. The patients had advanced, nonfluctuating hearing loss and incapacitating vestibular symptoms. Long periods of remission were obtained in all cases. Improvement of hearing was a major clinical consideration in the treatment. Use of local overpressure seems to offer possibilities of improving hearing even in advanced stages of Meniere's disease. Despite the disabling pretreatment hearing loss, hearing in these 5 patients was restored to normal or serviceable levels. The follow-up period was about 2 years from start of treatment.

The inner ear hydrodynamics have been studied in a series of experiments on cats. A detailed analysis has been made of the perilymphatic pressure response to square wave pressure pulses applied to the ear canal and middle ear. It was found that the initial pressure response was followed by a rebound pressure response of the opposite phase. It was also found that in most cases each phase of the pressure response could be expressed in terms of two time constants. When the cochlear aqueduct was patent, the perilymphatic pressure response showed almost equal positive and negative pressure changes. However, when the cochlear aqueduct was surgically blocked, the perilymphatic pressure response consisted almost exclusively of the first phase of the response, while the rebound phase disappeared almost completely. The possibility of influencing the inner ear fluid balance in Meniere's disease by external pressure changes is discussed in the light of the present experimental results.

The response of the perilymphatic fluid to complex pressure waves, composed of low-frequency sine waves superimposed on square-wave pressure pulses of varying amplitude was studied. In cats with a patent cochlear aqueduct a pronounced positive pressure change could be induced in the perilymphatic fluid when complex pressure waves were used. The time constants associated with the stabilization of the perilymphatic pressure after the application of pressure complexes were longer than those associated with square-wave pulses alone. The results indicate that the functional patency of the cochlear aqueduct could be influenced by the transmission of complex pressure waves. The results also indicate that when trying to influence the inner ear hydrodynamic balance in patients with Meniere's disease, the effect of complex pressure waves is far superior to the effect of square-wave pressure pulses in patients with an open cochlear aqueduct.

The perilymphatic (PP) and cerebrospinal fluid (PCSF) pressures were investigated in relation to pressure variations in the ear canal, middle ear and intracranial compartment before and after occlusion of the cochlear aqueduct (CA). Experiments using intracranial infusion showed that the CA was responsible for a perfect hydrodynamic balance between the CSF and the perilymph. There are indications of additional pressure release factors but their capacities were not sufficient to prevent the appearance of a longstanding and substantial pressure gradient following occlusion of the CA. A gradual PP build-up, from zero to its original level after the CA was opened and occluded, indicated perilymph production within the labyrinth. Investigation of pressure transfer from the ear canal and middle ear to the perilymph showed that the CA was the major pressure release route from the cochlea. Occlusion of the CA reduced the compliance of the inner ear and severely reduced the pressure release capacity. In such a situation the inner ear is almost incapable of equilibrating ambient pressure changes.

Psychoacoustic tuning curves (PTCs) were obtained in a number of normal-hearing and hearing-impaired subjects using a simultaneous tone-on-tone masking technique. PTCs at three different centre frequencies (500, 1,000 and 2,000 Hz) were studied. In order to estimate the degree of frequency selectivity of the inner ear, an algorithm for quantification of PTCs was constructed. The method of linear regression was used to calculate the slopes of the linearized curves. Three different parameters of the curve, the low and high frequency slope and the height of the curve, were calculated using computer programs which allowed automatic evaluation of the data. The values of these parameters concerning normal and hearing-impaired subjects are presented in terms of scores and percentages of normal values. The algorithm for quantification of PTCs presented in this paper may in clinical work serve as a method of evaluating auditory frequency selectivity, particularly for very abnormal PTCs.

Equal loss in sensitivity for air and bone conduction and poor speech discrimination are considered characteristic of the hearing impairment in Menière's disease. Periodic pressure changes applied to the middle ear produced an air-bone gap in 16 out of 19 patients with advanced Menière's disease. The air-bone gap was associated with an improvement in speech discrimination scores. Subsequently, the air-conduction hearing loss decreased. The shapes of psychoacoustic tuning curves of patients with the air-bone gaps showed an improvement in frequency resolution. The curves remained elevated in threshold, however, which indicates an attenuation of the sound stimuli. The relative change in bone conduction sensitivity was interpreted as an early sign of improvement in the inner ear mechanics, caused by exposure to pressure changes.