Timothy C. Hain, MD Page last modified: February 17, 2011
Vestibular nerve sections are delicate procedures and there is generally a desire to spare hearing, leaving the cochlear nerve intact. Because some vestibular fibers are intermingled with the cochlear nerve, this means that some VNS may be incomplete. An incomplete VNS is a potential reason for continued vertigo.
Here is an example of a person with Meniere's disease, having persistent vertigo spells after a left sided VNS, and an ENG that clearly shows retained vestibular function.
The audiogram below shows abnormal hearing on both sides, with the left operated side far worse. Because hearing is impaired on both sides, this person could be having vertigo from either side.
The ENG showed a nystagmus that reversed between warm and cold. Because the responses were low, our audiologist did ice water, which clearly shows a strong response that reverses with prone. This proves that there is retained vestibualr function on the left, and again that vertigo could be coming from either side.