Horizontal eye response to an abrupt lateral head drop in normal subjects and patients with Meniereʹs disease

Objective: To detect the endolymphatic hydrops by using the otolithic nature in patients with Meniereʹs disease and delayed hydrops. Methods: We developed a new technique for measuring horizontal eye movements, corresponding to lateral head drop in total darkness, ≈1g environment. Normal subjects (n=16, mean age: 27.3 years old) and patients (seven for pre-operative state, four for furosemide test at pre-operative state; two for post-operative state) were employed in the test. The principle of the test is to drop the head in a lateral position separately from the body with a rapid release exposing the head. Bitemporal EOG, accelometric and trigger signals for the releaser were recorded for processing at 1 KHz sampling time. Results: The drop was performed five times in succession. The latency of horizontal eye response was of 40 ms order in normal subjects on both sides and were never beyond 60 ms. Eye response of the patients was in different patterns from normal subjects and the latencies delayed either to normal side or to the affected side. Following furosemide intravenous injection, more certain information was obtained. Three of four patients were recovered to normal range as to the latency. Conclusions: We emphasize that this test may provide a new measure sensitive to the hydrops and can underline this test to detect the hydrops in Meniereʹs disease.