Neurology Department, Royal Prince Alfred Hospital, Camperdown, NSW 2050, Sydney, Australia
Address for correspondence: Dr. G.M. Halmagyi, Neurology Department, Royal Prince Alfred Hospital, Missenden Road, Camperdown, NSW 2050, Sydney, Australia. Voice: +61 2 515 8300; fax: +61 2 9515 8347.
michael{at}icn.usyd.edu.au
Ann. N.Y. Acad. Sci. 956: 306-313 (2002).
Sudden, spontaneous, unilateral loss of vestibular function
without simultaneous hearing loss or brain stem signs is generally
attributed to a viral infection involving the vestibular nerve
and is called acute vestibular neuritis. The clinical hallmarks
of acute vestibular neuritis are vertigo, spontaneous nystagmus,
and unilateral loss of lateral semicircular function as shown
by impulsive and caloric testing. In some patients with vestibular
neuritis the process appears to involve only anterior and lateral
semicircular function, and these patients are considered to
have selective
superior vestibular neuritis. Here we report
on two patients with acute vertigo, normal lateral semicircular
canal function as shown by both impulsive and caloric testing,
but selective loss of posterior semicircular canal function
as shown by impulsive testing and of saccular function as shown
by vestibular evoked myogenic potential testing. We suggest
that these patients had selective
inferior vestibular neuritis
and that contrary to conventional teaching, in a patient with
acute spontaneous vertigo, unilateral loss of lateral semicircular
canal function is not essential for a diagnosis of acute vestibular
neuritis.
