Superior semicircular canal dehiscence: evaluation by thinsection computed tomography with reformations in the planes of Stenver and Pöschl.

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1 Superior semicircular canal dehiscence: evaluation by thinsection computed tomography with reformations in the planes of Stenver and Pöschl. Poster No.: C-1704 Congress: ECR 2011 Type: Authors: Keywords: DOI: Educational Exhibit A. L. CUNHA, A. A. S. M. Santos, R. A. Medina, M. L. O. Santos, C. A. P. Fontes, C. E. L. Cabral; Niterói - Rio de Janeiro, RJ/BR Technical aspects, Outcomes analysis, Observer performance, CT, Head and neck /ecr2011/C-1704 Any information contained in this pdf file is automatically generated from digital material submitted to EPOS by third parties in the form of scientific presentations. References to any names, marks, products, or services of third parties or hypertext links to thirdparty sites or information are provided solely as a convenience to you and do not in any way constitute or imply ECR's endorsement, sponsorship or recommendation of the third party, information, product or service. ECR is not responsible for the content of these pages and does not make any representations regarding the content or accuracy of material in this file. As per copyright regulations, any unauthorised use of the material or parts thereof as well as commercial reproduction or multiple distribution by any traditional or electronically based reproduction/publication method ist strictly prohibited. You agree to defend, indemnify, and hold ECR harmless from and against any and all claims, damages, costs, and expenses, including attorneys' fees, arising from or related to your use of these pages. Please note: Links to movies, ppt slideshows and any other multimedia files are not available in the pdf version of presentations. Page 1 of 16

2 Learning objectives Demonstrate the importance of using thin-section computed tomography (CT), whether additional reformations in the planes of Stenver and Pöschl change the diagnostic interpretation for semicircular canal dehiscence (SCD) when compared with the diagnostic interpretation of standard coronal reformations. To review the cases treated and underwent CT scan of the mastoid, with the objective of alerting health professionals of the existence of this disease by addressing its main clinical and diagnostic features Background 150 mastoid CT scans were retrospectively studied. The examinations were reviewed by two radiologists independently, and subsequently reviewed by the authors, and the results achieved by consensus. On routine examination, were performed with slices of 1.0 mm, in axial and coronal planes, with subsequent reconstructions: oblique coronal (with angulation of 45 / pitch 1.5) - Stenvers plan and oblique sagittal (with 45 angle / pitch 1.5) - Pöschl plan semicircular canal. ANATOMY: The human auditory system is divided into three parts each with its own functions and the three are essential for the proper functioning of hearing (FIG.1): #External ear #Middle ear #Inner ear The semicircular canals are three half-circular, interconnected tubes located inside each ear. The three canals are the horizontal semicircular canal (also known as the lateral semicircular canal), superior (or anterior) semicircular canal and the posterior semicircular canal (FIG.2). The canals are aligned approximately orthogonally to one another. # The horizontal canal detects horizontal head movements, while the superior and posterior canals detect vertical head movements Page 2 of 16

3 # The superior and posterior canals are aligned roughly at a 45 degree angle to a vertical plane drawn from the nose to the back of the skull. # Thus, the horizontal canal detects horizontal head movements, while the superior and posterior canals detect vertical head movements Each canal is filled with a fluid called endolymph and contains a motion sensor with little hairs (cilia) whose ends are embedded in a gelatinous structure called the cupula. As the skull twists in any direction, the endolymph is thrown into different sections of the canals. The cilia detect when the endolymph rushes past, and a signal is then sent to the brain. The semicircular canals are a component of the bony labyrinth (FIG 3,4). Semicircular canal dehiscence: Semicircular canal dehiscence (SCD) is an unusual abnormality of the temporal bone. Patients most frequently experience dizziness induced by loud noises (Tullio phenomenon). Since its initial description in 1998, SCD has rapidly become an accepted diagnosis in the evaluation of vertigo. The normal bony covering over the apex of the superior semicircular canal is absent in patients with superior semicircular canal dehiscence (SSCD) the most frequent semicircular canal stricken. The most affected age group was described in the literature around the 4th decade. In this study, the mean age was 48,27 years, with no preference for sex. Images for this section: Page 3 of 16

4 Fig. 1: Schematic figure of the division of human auditory system Page 4 of 16

5 Fig. 2: Three-dimensional VR CT image (view from the dissected medial portion of the temporal bone) shows the inner ear, including the cochlea (Co), vestibule (Ve), superior semicircular canal (SSCC), lateral semicircular canal (LSCC), and posterior semicircular canal (PSCC). The internal auditory canal (IAC) and the bony canal for the facial nerve (FN) are also seen. Page 5 of 16

6 Fig. 3: Normal anatomy of the bony labyrinth. Three-dimensional VR CT image (anterolateral view) shows the normal bony labyrinth, which consists of the cochlea (Co), vestibule (Ve), and semicircular canals (SCC). FN = facial nerve canal, IAC = internal auditory canal, OW = oval window. Page 6 of 16

7 Fig. 4: Three-dimensional VR CT image (posteroinferior view) shows the singular canal (SC), through which courses a branch of the inferior vestibular nerve. The inferior vestibular nerve innervates the posterior semicircular canal (PSCC). Page 7 of 16

8 Imaging findings OR Procedure details IMAGING FINDINGS: The diagnosis of Semicircular canal dehiscence is confirmed by high resolution Computed Tomography of the temporal bone, in which there is exposure (gap) of the canal wall by the lack of bone overlying it. It is recommended, to reduce the number of false positives, use slices < 1mm (of 0.5mm) and / or reconstruction of the images in the plane of the semicircular canal. All examinations were performed on helical device (bone filter / 130 kv / mas 135), performed without intravenous contrast, with serial sections of 1.0 mm thickness and interval with subsequent reconstruction: # Axial: fixed position of the head and slightly bent, and the cutting plane parallel to orbitomeatal line or the hard palate, taking care with the lens # Coronal: head secured with cervical hyperextension avoiding vertebro-basilar insufficiency during hyperextension, with the cutting plane perpendicular to the maximum angle # Coronal oblique: (angled 45 / pitch 1.5) - Stenvers (FIG. 1) # Sagittal oblique: (angled 45 / pitch 1.5) - Pöschl (FIG. 2,3) In 150 patients, the transverse images, coronal and oblique reformations in planes of Stenver and Pöschl proved semicircular canal dehiscence in 11 patients (7,5%). One case was bilateral dehiscence (FIG.4-8). Seven cases were found with associated changes: thickening of the tympanic membrane, incomplete pneumatization of the mastoid, mastoidectomy, acute otomastoiditis, chronic otomastoiditis with cholesteatoma, chronic otitis (FIG. 9). CT has become the method of complementary examination of choice for evaluating patients with vestibular, since it allows to observe the internal organs with greater accuracy, without superimposition of images, reducing the time of diagnosis and treatment of patients with vestibular symptoms (dizziness and imbalance chronic) and avoiding inappropriate diagnostic or therapeutic approaches (such as anti-vertigo medications). CT reformations in the planes of Stenver and Pöschl change the diagnostic interpretation for superior semicircular canal dehiscence (SSCD) when compared with the diagnostic interpretation of standard coronal reformations. Page 8 of 16

9 Images for this section: Fig. 1: Plane of Stenver. (a) Angle of reformation demonstrated on transverse scout image. (b) Intact superior semicircular canal (arrowhead). (c) Dehiscent superior semicircular canal (arrow). Fig. 2: Plane of Pöschl:(a) Angle of reformation demonstrated on transverse scout image. (b)intact superior semicircular canal (arrowhead). (c)dehiscent superior semicircular canal (arrow). Page 9 of 16

10 Fig. 3: Plane of Pöschl:(a) Plane of reconstruction (white line) through the roof of the superior semicircular canal. (b) Oblique sagittal image shows integrity of the bone in the roof of the superior semicircular canal (SSC), as well as a normal appearance of the facial nerve (FN) and the lateral semicircular canal (LSC). (c) Single-oblique sagittal image shows dehiscence of the SSC (arrow). Fig. 4: In 150 patients, the transverse images, coronal and oblique reformations in planes of Stenver and Pöschl proved semicircular canal dehiscence in 11 patients (7,5%). Page 10 of 16

11 Fig. 5: Female, 72yo, right hearing loss. Fig. 6: Female, 83 yo, right otalgia.sscd. Coronal oblique reformation (plane of Stenver), in the right picture and sagittal oblique reformation (Plane of Pöschl) in the left one. Page 11 of 16

12 Fig. 7: Female, 74 yo, left otalgia.sccd. Coronal oblique reformation (plane of Stenver), in the right picture and sagittal oblique reformation (Plane of Pöschl) in the left one. Fig. 8: Male, 14 yo, asymptomatic. SSCD. Coronal oblique reformation (plane of Stenver), in the right picture and sagittal oblique reformation (Plane of Pöschl) in the left one. Page 12 of 16

13 Fig. 9: Male, 56 yo, pain. SSCD. Coronal oblique reformation (plane of Stenver), in the right picture and sagittal oblique reformation (Plane of Pöschl) in the left one. Associated change: Chronic otomastoiditis with cholesteatoma. Page 13 of 16

14 Conclusion The CT scan is the gold standard for diagnostic confirmation of superior semicircular canal dehiscence and it is important to note that images should be obtained with smaller slices than 1.0 mm thick with reformation plans Stenvers and Pöschl. Personal Information Alexandre Limpias Cunha. Student of the Specialization Course in Radiology - Institute of Postgraduate Medical Carlos Chagas (IPGMCC). Rio de Janeiro. Brazil. dr.alexandrecunha@yahoo.com.br Alair Augusto Sarmet M. D dos Santos. MD, PhD. Corresponding Author. Associate Professor, Department of Radiology and Head of the Radiology and Diagnostic Imaging Service of University Hospital Antônio Pedro (HUAP) / UFF (Federal Fluminense University) - Niterói, RJ, Brazil. Coordinator of Image Center- HCN (Hospital Clinicas de Niterói) and Coordinator of the Specialization Course in Radiology Institute of Postgraduate Medical Carlos Chagas (IPGMCC).Rio de Janeiro, Brazil. alairsarmet@globo.com e-curriculum: Rafael de Araújo Medina. Student of the Specialization Course in Radiology - Institute of Postgraduate Medical Carlos Chagas (IPGMCC). Rio de Janeiro. Brazil. cesarrgjunior@gmail.com Maria Lucia Oliveira Santos. MD, PhD. Associate Professor, Department of Radiology University Hospital Antônio Pedro (HUAP) /UFF (Federal Fluminense University) - Niterói, RJ, Brazil. Page 14 of 16

15 Cristina Asvolinsque Pantaleão Fontes. MD. Assistent Professor. Departament of Radiology, and Diagnostic Imaging Service of University Hospital Antônio Pedro (HUAP) /UFF (Federal Fluminense University) - Niterói, RJ, Brazil. Medical radiologist in Image Center-HCN (Hospital Clinicas de Niterói). cristinasvolinsque@gmail.com Carlos Eduardo Lassance Cabral.MD Assistent Professor of the Specialization Course in Radiology Institute of Postgraduate Medical Carlos Chagas (IPGMCC).Rio de Janeiro, Brazil. Medical radiologist in Image Center-HCN (Hospital Clinicas de Niterói).RJ. Brazil. caducabral@gmail.com Study site Hospital de Clínicas de Niterói, Institute of Postgraduate Medical Carlos Chagas (IPGMCC) and Federal Fluminense University (UFF) - Niterói, Rio de Janeiro, Brazil. Potential Conflict of Interest No potential conflict of interest relevant. Funding Sources This study did not have funding source. References 1. Belden CJ, Weg N, Minor LB, Zinreich SJ. CT evaluation of bone dehiscence of the superior semicircular canal as a cause of sound- and/or pressure-induced vertigo.. Radiology Feb;226(2): Page 15 of 16

16 2. Branstetter BF 4th, Harrigal C, Escott EJ, Hirsch BE. Superior semicircular canal dehiscence: oblique reformatted CT images for diagnosis. Radiology Mar;238(3): Epub 2006 Jan Lemmerling M, Vanzieleghem B, Dhooge I, Van Cauwenberge P, Kunnen M. CT and MRI of the semicircular canals in the normal and diseased temporal bone. Eur Radiol. 2001;11(7): Review. 4. Crovetto M, Whyte, Rodriguez OM, Lecumberri I, Martinez C, Eléxpuru J. Anatomo-radiological study oh the Superior Semicircular Canal Dehiscence. Radiological considerations of Superior and Posterior Semicircular Canals. Eur J Radiol 2009 Jun Krombach GA, Schmitz-Rode T, Haage P, DiMartino E, Prescher A, Kinzel S, Günther RW. Semicircular canal dehiscence: comparison of T2-weighted turbo spin-echo MRI and CT.Neuroradiology 2004;46(4): Mikulec AA, Poe DS. Operative Management of a Posterior Semicircular Canal Dehiscence. The Laringoscope 2006;116: Manzari L, Modugno GC. Bilateral Dehiscence of Both Superior and Posterior Semicircular Canals. Otology & Neurotology 2009;30: Merchant SN, Rosowski JJ. Conductive Hearing Loss Caused by Third-Windows Lesions of the Inner Ear. Otology & Neurotology 2008;29(3): John IL, Lindell EP, Witte RJ, De Lone, DR, Driscoll, CLW. Middle and Inner Ear: Improved Depiction with Multiplanar Reconstruction of Volumetric CT. RadioGraphics 2006;26: Krombach GA, DiMartino E, Schmitz-Rode T, Prescher A, Haage P, Kinzel S, Günther RW. Posterior semicircular canal dehiscence: a morphologic cause of vertigo similar to superior semicircular canal dehiscence. Eur Radiol Jun;13(6): Epub 2003 Feb Venema HW, Phoa SS, Mirck PG, et al. Petrosal bone: coronal reconstructions from axial spiral CT data obtained 0,5-mm collimation can replace direct coronal sequential CT scans. Radiology 1999;213: Curtin HD et al. Superior semicircular canal dehiscence syndrome and multidetector row CT. Radiology Feb;226(2): Fatterpekar GM, Doshi AH, Dugar M et a.l Role of 3D CT in the Evaluation of the Temporal Bone. RadioGraphics 2006; 26:S117-S132. Page 16 of 16