Hyperventilation-induced (exercise-induced) nystagmus is an uncommon condition most often associated with a disorder of the vestibular nerve.
Clinical features:
(1) presence of nystagmus after the person hyperventilates or exercises
(2) absence of nystagmus while at rest
(3) The patient may complain of vertigo or disequilibrium.
(4) A patient with vestibular nerve dysfunction may have reduced hearing.
The onset may be associated with a sufficiently elevated end-tidal CO2 (Et CO2).
Causes of HIN:
(1) vestibular nerve dysfunction (vestibular schwannoma, vestibular neuritis, vascular compression, other)
(2) tremor
(3) multiple sclerosis
(4) cerebellar dysfunction
