Non-invasive perilymphatic pressure measurement in normal hearing subjects using the MMS-10 tympanic displacement analyser.

The MMS-10 Tympanic Displacement Analyser (TDA) is a new device to measure the perilymphatic pressure of the human inner ear in a non-invasive way. In this study, the instrument was used in 50 normal hearing subjects (100 ears) in three different conditions: i) sitting upright and supine; ii) in the morning and afternoon; iii) before and after physical exertion. The perilymphatic pressure in supine position was significantly higher than that in upright-sitting position. The measured perilymphatic pressure did not alter during the day, indicating the absence of diurnal variation. Also, the perilymphatic pressure did not change significantly following physical exertion. Our study showed the well known large inter-individual differences in the measurement variables. Nevertheless, the correlation of the test results within one subject and one ear was high. The TDA is an appropriate device for the follow-up perilymphatic and cerebrospinal fluid pressure alternations in subjects and patients with disorders of the inner ear and cerebro-spinal fluid pressure, provided they have a normal middle ear function.