Pressure-regulating mechanisms in the inner ear

Intermittent pressure therapy of intractable Ménière's disease using the Meniett device: a preliminary report

HYPOTHESIS

Treatment with the Meniett device, which applies intermittent micropressure pulses to the inner ear through a tympanostomy tube, is effective in controlling vertigo in people with intractable Ménière's disease.

STUDY DESIGN

Short-term, preliminary descriptive report.

METHODS

Ten patients with intractable vertigo despite adequate medical therapy elected to use the Meniett device. After placement of a standard tympanostomy tube, the patient self-administers the Meniett device three times daily.

RESULTS

The follow-up ranged from 3 to 11 months with an average of 8 months. All 10 patients responded to the therapy with vertigo control in 9 of 10 and a 50% reduction in the 10th case. There was a mean hearing gain of 6 dB, which was statistically significant. There were no major complications. Two subjects required tube reinsertion during the 8 months of follow-up.

CONCLUSIONS

Use of the Meniett device is an effective and safe option for people with intractable vertigo from Ménière's disease.

Monitoring inner ear pressure changes in normal guinea pigs induced by the Meniett20

The inner ear fluid pressure of guinea pigs was measured during a series of complex oscillating middle ear pressure changes induced by the Meniett20 (Pascal Medical, Sweden), a possible therapeutic pressure generator to be used by patients with Meniere's disease. Middle ear pressure changes were transferred instantly to the inner ear, although inner ear pressure declined while middle ear pressure stayed relatively stable. An average undershoot of -1.0 cm H2O with respect to the steady-state pressure was seen after application of a pressure pulse, which was released in a few seconds. The results did not fully comply with a simple linear model in which a constant flow resistance between the inner ear and cerebrospinal space was assumed.

Involvement of round and oval windows in the vestibular response to pressure changes in the middle ear of guinea pigs

Changes in ambient pressure can elicit the vertigo and bodily disequilibrium known clinically as alternobaric vertigo. Our previous studies showed that changes in middle ear pressure altered the activity of the primary vestibular neuron, and the finding suggests that the pressure-induced vestibular response causes alternobaric vertigo. To investigate the roles played by the round window (RW) and the oval window (OW) in the vestibular response induced by pressure, we measured the change in perilymphatic pressure and the firing rates of primary vestibular neurons after the application of positive or negative pressure to the middle ear. We found an increase in the pressure-induced vestibular response in the group with a closed OW, and a decrease in the group with a closed RW. Measurements showed that the amplitude of the change in perilymphatic pressure in the group with a closed OW did not differ from that in the control group, whereas the amplitude of the perilymphatic pressure change in the group with a closed RW was significantly reduced. A discrepancy between the number of neurons responding and the amplitude of the perilymphatic pressure change in the closed OW group suggests that the vestibular response induced by the change in middle ear pressure was not related solely to the magnitude of the pressure change in the inner ear, but also involved the oval and round windows.