In article <199504121533.LAA02686 at orichalc.acsu.buffalo.edu> xyz at ACSU.BUFFALO.EDU (Xiangyang Zheng) writes:
>Could anybody in this group know that if the Vestibular Nystagmus necessarily
>develops when one of the vestibular nerves---the Inferior Vestibular Nerve
>is sectioned? Please drop me a message in detail if possible.
Any event that causes a change in the tonic firing rate (either increase
or decrease from one end organ) entering the vestibular nuclei can produce
nystagmus and vertigo. The central nervous system will quickly act to suppress
the nystagmus by"clamping" the output of the vestibular nuclei, usually within
hours, then over time will recalibrate the nuclei in order to compensate for
the change.
Central compensation typically occurs within 2 to 3 days in the cat, and
can take 1 to 6 weeks in an otherwise healthy human. existsing CNS disease,
CNS suppressant medications, and inactivity can delay or stop compensation.
Head movements excercises (as are done in Vestibular Rehabilitation physical
therapy programs) can speed up the process.
The surgical procedure "vestibular nerve section" is performed frequently in
intractable Meniere's disease. The theory is that the CNS cannot compensate
for a damaged ear who's tonic firing rate is constantly changing. The nerve
section gives the CNS a stable lesion from which compensation can proceed.
