The low and high frequency responses of peripheral vestibular system: Where do they coincide?

The low and high frequency responses of peripheral vestibular system:
Where do they coincide?
O. Nuri Ozgirgin

The trends on vestibular diagnosed have been changed considerably during the last few decades. Besides evaluating the type and location vestibular lesion by conventional methods that remain within low frequency ranges also known as static measures; the function of the affected vestibular organs during daily life also becomes important in regard to quality of life. And hence, the new evaluation methods can give us additional information about the individual parts of the vestibular organs such as semicircular canals.

The rationale for high-frequency testing VOR with active head movements is its close approximation to the physiologic conditions encountered in daily life. Head movements are generally complex, involving higher frequency harmonics. As head movements become faster, the VOR becomes the primary system operating to maintain visual fixation and stabilizes gaze to maintain unblurred vision whenever the head moves, and especially at head movement frequencies above 2 Hz. The predominant frequencies of head perturbations are normally between 1 and 4 Hz during locomotion and may range up to 8 Hz.
The new VOR evaluations examines responses to active head oscillations at frequencies between 2 and 6 Hz in the horizontal and vertical planes while the subject is fixating a visible target. These depend on two different type of vestibular cells; type II and type I cells.

In this lecture the new trends on vestibular diagnosis were emphasized as compared to conventional examination methods, by including the author’s experience.