Case Report Vestibular Evoked Myogenic Potentials in Subject With
Transkript
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 832 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. 833 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: fferaygulec@yahoo.com 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 J.Neurol.Sci.[Turk] The Online Journal of Neurological Sciences (Turkish) 1984-2012 This e-journal is run by Ege University Faculty of Medicine, Dept. of Neurological Surgery, Bornova, Izmir-35100TR as part of the Ege Neurological Surgery World Wide Web service. Comments and feedback: E-mail: editor@jns.dergisi.org URL: http://www.jns.dergisi.org Journal of Neurological Sciences (Turkish) Abbr: J. Neurol. Sci.[Turk] ISSNe 1302-1664 REFERENCES 1. 2. 3. 4. 5. 6. 7. Banerjee A, Whyte A, Atlas MD. Superior canal dehiscence: review of a new condition. Clin Otolaryngol. 2005; 30(1):9-15. Brantberg K, Bergenius J, Tribukait A. Vestibularevoked myogenic potentials in patients with dehiscence of the superior semicircular canal. Acta Otolaryngol. 1999; 119(6):633-40. Hope A, Fagan P. 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