Case Report Vestibular Evoked Myogenic Potentials in Subject With

J.Neurol.Sci.[Turk]
Journal of Neurological Sciences [Turkish] 29:(4)# 33; 832-835, 2012
http://www.jns.dergisi.org/text.php3?id=597
Case Report
Vestibular Evoked Myogenic Potentials in Subject With Superior Canal Dehiscence
Syndrome
Feray GÜLEÇ1, Neşe ÇELEBISOY2
1
TCSB Tepecik Eğitim ve Araştırma Hastanesi, Nöroloji Kliniği, İzmir, Türkiye 2Ege
Üniversitesi Tıp Fakültesi, Nöroloji Anabilim Dalı, İzmir, Türkiye
Summary
Superior canal dehiscence syndrome (SCDS) is characterized by absence of the roof of the
superior semicircular canal. Sound stimuli of higher decibels can cause vertigo and oscillopsia
in these patients. A 38-year-old lady complaining about vertigo attacks associated with loud
sounds as well as coughing and sneezing was evaluated. Her audiogram revealed a mild
conductive type hearing loss on the left side. The caloric responses were normal. Vestibular
evoked myogenic potential (VEMP) latencies recorded from the sternocleidomastoid muscles
(SCM) were normal bilaterally ( p13 and n 23 latencies were 13.0 ms, 20.7 ms on the left side
and 12.7 ms, 22.6 ms on the right side). The amplitude of the n13-p23 potential was 204 µV
on the left and 78 µV on the right side. Repeated recordings showed that the amplitude
asymmetry was persisting. Dehiscence of the superior canal acts as a third window and causes
pressure and sound sensitivity. VEMPs can be recorded easily in patients with the
abovementioned complaints to support the diagnosis before a high resolution temporal bone
CT is performed.
Key words: Vestibular evoked myogenic potentials, Superior canal dehiscence syndrom
Süperior Kanal Dehisans Sendromlu Bir Olguda Vestibular Uyarılmış Myojenik
Potansiyeller
Özet
Süperior kanal dehisans sendromu (SKDS) süperior semisirküler kanalın tepe kısmındaki
kemik çatının yokluğu ile karakterize bir tablodur. Bu hastalarda yüksek desibeldeki ses
uyaranı vertigo ve osilopsiye neden olur. 38 yaşında kadın olgu yüksek ses uyaranı ile ilişkili
vertigo atakları yakınması ile başvurdu. Atakların öksürük ve hapşırma gibi durumlar ile de
tetiklenebildiğini belirtiyordu. Odyogramında solda ılımlı iletim tipi işitme kaybı ortaya
kondu. Kalorik test yanıtları bilateral olarak normal bulundu. Sternocleidomastoid (SCM)
kastan kayıtlanan vestibular uyarılmış myojenik potansiyel (VEMP) latansları bilateral olarak
normaldi ( p13 ve n 23 latansları solda 13.0 ms, 20.7 ms ve sağda 12.7 ms, 22.6 ms olarak
bulundu). p13-n23 potansiyelinin amplitudü solda 204 µV ve sağda 78 µV olarak bulundu.
Tekrarlayan ölçümlerde amplitüd asimetrisinin sebat ettiği izlendi. Superior kanal dehisansı
üçüncü bir pencere rolü oynayarak ses ve basınca hassasiyet oluşturur. Bahsedilen
yakınmalarla başvuran olgularda yüksek çözünürlüklü temporal kemik tomografisinin
çekilmesinden önce ön tanıyı desteklemede kolayca kaydedilen VEMP'ler yararlı olabilir.
Anahtar Kelimeler: Vestibüler uyarılmış myojenik potansiyeller, süperior kanal dehisans
sendromu
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J.Neurol.Sci.[Turk]
INTRODUCTION
CASE PRESENTATION
Dehiscence of the superior semicircular
canal is a ‘relatively new' vestibular entity.
Diagnosis of this syndrome relies on
symptoms such as sound or pressure
induced
vertigo
or
oscillopsia,
demonstration of sound or pressure evoked
vertical/torsional eye movements, and the
presence of a defect in the bony roof
overlying the superior semicircular
canal(1,6,7). Vestibular evoked myogenic
potential (VEMP) recording is a
noninvasive and easy technique to support
the diagnosis before a high resolution
temporal bone CT is performed(2,5,6). Low
threshold VEMPs of higher amplitude has
been reported(6,7). In this presentation, we
intended to draw attention to SCDS which
is a rare cause of vertigo and also
emphasize the importance of VEMP as a
diagnostic test.
A 38-year-old lady complaining about
vertigo attacks associated with loud sounds
as well as coughing and sneezing was
evaluated. Her audiogram revealed a mild
conductive type hearing loss on the left
side. The caloric responses were normal.
Latency of the VEMPs recorded from the
sternocleidomastoid muscles were normal
bilaterally (p13 and n 23 latencies were
13.0 ms, 20.7 ms on the left side and 12.7
ms, 22.6 ms on the right side) (Figure 1).
p13/n23 amplitudes were 204 µV and 78
µV on the left and right sides respectively.
Repeated recordings showed that the
amplitude asymmetry was persisting. A
temporal bone computed tomography (CT)
performed revealed the dehiscence of the
superior semicircular canal on the left side
(Figure 2).
Figure 1: Vestibular evoked myogenic potential amplitudes are bigger on the left side with superior canal
dehiscence. Repeated recordings showed that the amplitude asymmetry was persisting.
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J.Neurol.Sci.[Turk]
Figure 2: A temporal bone computed tomography (CT) revealed dehiscence of the superior semicircular canal on the
left side
amplitude of responses increase with
increasing the stimulus intensity (Figure
1). Consequently, clicks evoke a highmagnitude, low-threshold vestibulo-spinal
reflex that suggests superior canal receptor
hypersensitivity to sound(4).
DISCUSSION
SCDS is a rare but well described
condition in which audiovestibular
symptoms are caused by noise or
straining(1,7). This syndrome was first
described in1998 by Minor and coworkers(1,2). Clinical features of the
syndrome are complex. Autophony,
dizziness/vertigo or conductive hearing
loss (CHL) without vertigo can be the
presenting symptoms and signs(3,4). When
it presents with conductive hearing loss the
clinical picture mimics otosclerosis(7).
VEMPs in association with a temporal
bone CT can help to identify patients with
SCDS presenting with conductive hearing
loss without vertigo(4).
Dehiscence of the superior canal acts as a
third window and causes pressure and
sound sensitivity. VEMPs can be recorded
easily in patients with the above mentioned
complaints to support the diagnosis before
a high resolution temporal bone CT is
performed. The test is highly sensitive and
specific for SCDS.
Identifying patients with this entity is
important, not only because the symptoms
can be very incapacitating, but also
because they are surgically treatable.
Surgical repair such as plugging of
dehiscence can relieve symptoms with low
morbidity(2,3).
Correspondence to:
Feray Güleç
E-mail: [email protected]
Received by: 12 February 2012
Revised by: 20 April 2012
Accepted: 03 July 2012
VEMPs are useful in the diagnosis and
follow-up of SCDS. The patients with
SCDS have very high amplitude VEMP
responses recorded at low stimulus
intensities(2,5,6). As it is in our patient the
834
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