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Clinico Radiological Series: Temporal Bone Imaging

Jayp

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rsAshu Seith Bhalla

MD MAMS FICRProfessor

Department of RadiodiagnosisAll India Institute of Medical Sciences

New Delhi, India

Manisha Jana MD DNB FRCR

Assistant ProfessorDepartment of Radiodiagnosis

All India Institute of Medical SciencesNew Delhi, India

New Delhi | London | Philadelphia | Panama

The Health Sciences Publisher

Surgical contents edited by

Suresh C SharmaProfessor and Head

Department of Otorhinolaryngology and Head-Neck SurgeryAll India Institute of Medical Sciences

New Delhi, India

Foreword

Raju Sharma

Clinico Radiological Series: Temporal Bone Imaging

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Jaypee Brothers Medical Publishers (P) Ltd.

Website: www.jaypeebrothers.comWebsite: www.jaypeedigital.com

© 2016, Jaypee Brothers Medical PublishersThe views and opinions expressed in this book are solely those of the original contributor(s)/author(s) and do not necessarily represent those of editor(s) of the book.All rights reserved. No part of this book may be reproduced, stored or transmitted in any form or by any means, electronic, mechanical, photo copying, recording or otherwise, without the prior permission in writing of the publishers. All brand names and product names used in this book are trade names, service marks, trademarks or registered trademarks of their respective owners. The publisher is not associated with any product or vendor mentioned in this book.Medical knowledge and practice change constantly. This book is designed to provide accurate, authoritative information about the subject matter in question. However, readers are advised to check the most current information available on procedures included and check information from the manufacturer of each product to be administered, to verify the recommended dose, formula, method and duration of administration, adverse effects and contra­indications. It is the responsibility of the practitioner to take all appropriate safety precautions. Neither the publisher nor the author(s)/editor(s) assume any liability for any injury and/or damage to persons or property arising from or related to use of material in this book.This book is sold on the understanding that the publisher is not engaged in providing professional medical services. If such advice or services are required, the services of a competent medical professional should be sought.Every effort has been made where necessary to contact holders of copyright to obtain permission to reproduce copyright material. If any have been inadvertently overlooked, the publisher will be pleased to make the necessary arrangements at the first opportunity.

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Clinico Radiological Series: Temporal Bone Imaging

First Edition: 2016

ISBN: 978­93­85891­90­8

Printed at

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Surgeons whose never-ending questions compel us to push the boundaries

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Contributors

Ankur Goyal MD DNB MNAMS Assistant Professor Department of Radiodiagnosis All India Institute of Medical Sciences New Delhi, India

Arvind Kumar Kairo MS Assistant Professor Department of Otorhinolaryngology and Head-Neck Surgery All India Institute of Medical Sciences New Delhi, India

Ashu Seith Bhalla MD MAMS FICR Professor Department of Radiodiagnosis All India Institute of Medical Sciences New Delhi, India

Atin Kumar MD DNB MNAMS Additional Professor Department of Radiodiagnosis Jai Prakash Narayan Apex Trauma Center (JPNATC) All India Institute of Medical Sciences New Delhi, India

Chirom Amit Singh MS Assistant Professor Department of Otorhinolaryngology and Head-Neck Surgery All India Institute of Medical Sciences New Delhi, India

Chandrashekhara SH MD DNB MNAMS Assistant Professor Department of Radiodiagnosis Institute Rotary Cancer Hospital (IRCH) All India Institute of Medical Sciences New Delhi, India

Devasenathipathy Kandasamy MD DNB FRCR Assistant Professor Department of Radiodiagnosis All India Institute of Medical Sciences New Delhi, India

Hitesh Verma MS DNB MAMS Assistant Professor Department of Otorhinolaryngology and Head-Neck Surgery All India Institute of Medical Sciences New Delhi, India

Jyoti Kumar MD DNB MNAMS Professor Department of Radiology and Imaging Maulana Azad Medical College (MAMC) New Delhi, India

Kapil Sikka MS DNB MNAMS Assistant Professor Department of Otorhinolaryngology and Head-Neck Surgery All India Institute of Medical Sciences New Delhi, India

Manisha Jana MD DNB FRCR Assistant Professor Department of Radiodiagnosis All India Institute of Medical Sciences New Delhi, India

Suresh C Sharma MS Professor and Head Department of Otorhinolaryngology and Head-Neck Surgery All India Institute of Medical Sciences New Delhi, India

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Clinico Radiological Series: Temporal Bone Imagingviii

Shivanand Ramachandra Gamanagatti MD DNB Additional Professor Department of Radiodiagnosis Jai Prakash Narayan Apex Trauma Center (JPNATC) All India Institute of Medical Sciences New Delhi, India

Shuchita Singh MS Assistant Professor Department of Otorhinolaryngology and Head-Neck Surgery All India Institute of Medical Sciences New Delhi, India

Smita Manchanda MD DNB Assistant Professor Department of Radiodiagnosis All India Institute of Medical Sciences New Delhi, India

Vinit Baliyan MD Senior Resident Department of Radiodiagnosis All India Institute of Medical Sciences New Delhi, India

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Foreword

The sentiment that Temporal Bone Imaging is a complex topic, is echoed by most radiologists—both neophytes and experts. The advances in surgical technique and the growing number of cochlear implant surgeries over the last decade mandate accurate delineation of the anatomy of temporal bone region. The advent of multidetector computed tomography (MDCT) has revolutionized the understanding of the pathology of this region but has also made the reporting of temporal bone pathology more complex. Using post-processing tools on MDCT, it is now possible to trace even minute structures in multiple planes. Temporal Bone Imaging is a dynamic field requiring constant effort on the part of managing clinicians to keep abreast with recent advances.

This book Temporal Bone Imaging is the first volume of a series titled Clinico Radiological Series and the authors have chosen a team of experts mostly from the All India Institute of Medical Sciences (AIIMS), New Delhi, India. They have attempted to simplify this rather complex topic and give a “management” context to the radiologists while reporting. The book also has invaluable contributions from head and neck surgeons, presented in lucid chapters.

There is detailed coverage of anatomy in a user-friendly, compact, point-wise text complemented by high-quality illustrations throughout the book. There is no compromise on detail and the book should prove useful to the surgeons as well. A unique feature is the formulation of structured reporting format for various disease groups which is enhanced by illustrative cases.

The topic and format of this book should make it a “trusted guide” for postgraduates and residents of radiology as well as otorhinolaryngology. It will be an asset to practicing radiologists and surgeons as well and reminds me of the adage ‘less is more’!

Raju SharmaProfessor

Department of RadiodiagnosisAll India Institute of Medical Sciences

New Delhi, India

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Preface

‘What the mind does not know, the eyes do not see’; and head and neck radiology, especially temporal bone, essays the phrase better than any other radiology subspecialty. The head and neck anatomy is complex; and so is the radiology of head and neck diseases. The range of diseases involving the head and neck is wide and varies according to the anatomic regions involved. Among them, temporal bone probably harbors the most complex anatomic intricacies; and, hence, the most difficult area to interpret the abnormalities. Vital to hearing and equilibrium, temporal bone is the seat of various disease processes which are unique to it. A thorough knowledge of the regional anatomy and the normal variations is crucial in order to identify the imaging abnormalities, which can be quite subtle at times. And, even a trained eye may miss significant yet subtle findings unless a systematic approach is adopted for reporting.

Otorhinolaryngology and head and neck surgery is a rapidly expanding medical specialty which relies heavily on imaging. Practicing surgeons need to be aware of the basics of imaging involving their area of interest, as the same holds true for temporal bone surgeries. Similarly, radiologists practicing head and neck radiology need to be aware of the details of temporal bone anatomy and provide a structured and comprehensive report to the surgeon. Cochlear implant surgery is being performed quite frequently now and the radiologists need to be aware of the imaging requirements of the procedure. For the purpose, this book contains a separate dedicated section on cochlear implant imaging. This book is not intended to be a detailed text on temporal bone imaging, but we hope that it will help the busy radiologists and surgeons in interpreting images of the temporal bone. The structured reporting format and illustrative cases at the end of each section is aimed at this.

We welcome any feedback on enhancing the content of the book, which can be incorporated in the subsequent editions.

Ashu Seith Bhalla Manisha Jana

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Acknowledgments

We wish to thank all the contributors for their efforts in compiling this text. We sincerely thank Professor Suresh C Sharma for guiding us in this new endeavor. We are also grateful to Dr Kapil Sikka for compilation of the surgical contents of the book.

We would also like to extend our appreciation to Shri Jitendar P Vij (Group Chairman), Mr Ankit Vij (Group President), Mr Tarun Duneja (Director–Publishing), Mr KK Raman (Production Manager), Mrs Samina Khan (Executive Assistant to the Director-Publishing), Mr Ashutosh Srivastava (Assistant Editor), Mr Himanshu Sharma (Proofreader), Mr Dilip Kumar (Typesetter), Mr Manoj Pahuja (Senior Graphic Designer) and all the staff of M/s Jaypee Brothers Medical Publishers (P) Ltd, New Delhi, India, for their efforts and input enabling timely publication of the book.

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Contents

Section 1 Normal Anatomy and Imaging

1. Imaging Modalities and Techniques 3 Ankur Goyal

Radiographs 4; High-Resolution Computed Tomography 5; Cone Beam Computed Tomography 10; Magnetic Resonance Imaging 10; Advanced Imaging Techniques 11

2. Normal Anatomy: Structure-wise 15 Jyoti Kumar

External Ear, 15; Middle Ear;16; Inner Ear 26

3. Normal Anatomy: Section-wise 36 Jyoti Kumar

Section 2 Congenital Anomalies of External and Middle Ear

4. Congenital Anomalies of External and Middle Ear: Imaging 51 Ashu Seith Bhalla

Structures Involved 51; Embryology 51; Imaging Modality 51; Pinna Deformities 52; External Auditory Canal 52; Middle Ear Space 53; Ossicular Anomalies 54; Round Window and Oval Window 56; Cholesteatoma 56; Mastoid Pneumatization 57; Facial Canal Anomalies 57; Inner Ear/Internal Auditory Canal Anomalies 59; Vascular Anomalies 59; Associations/Syndromes 59; CT Grading Systems 63; Critical Structures for Surgery 64; Minor Congenital Middle Ear Malformations 64; Management Issues 64.

5. Congenital External and Middle Ear Anomalies: Surgical Perspectives 66 Chirom Amit Singh, Suresh C Sharma

Terminology 66; Congenital Auricular/Pinna Deformities 66;Congenital Aural Atresia 67; Minor Congenital Malformations of Middle

Ear 70

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Clinico Radiological Series: Temporal Bone Imagingxvi

6. Reporting Template with Illustrative Cases 72(Congenital Anomalies of External and Middle Ear)

Smita ManchandaReporting Templates 72; Reporting Template 73; Case 1 74; Case 2 76; Case 3 78; Case 4 80; Case 5 82

Section 3 Infections of External and Middle Ear

7. Infections of External and Middle Ear: Imaging 87 Vinit Baliyan, Ashu Seith Bhalla

External Ear 87; Middle Ear and Mastoid 89; Postcholesteatoma Surgery Imaging 102

8. External and Middle Ear Infections: Surgical Perspectives 104 Shuchita Singh, Kapil Sikka

Clinical Presentation 104; Investigations 105; Surgical Interventions for CSOM 106; Surgical Intervention 109

9. Reporting Template with Illustrative Cases 111(Infections of External and Middle Ear)

Smita ManchandaCase 1 112; Case 2 114; Case 3 116; Case 4 118; Case 5 120

Section 4 Inner Ear, Internal Auditory Canal and Cochlear Implant

10. Congenital Inner Ear Anomalies: Imaging 125 Manisha Jana

Embryology 125; Michel Anomaly (Complete Labyrinthine Aplasia) 127; Cochlear Aplasia 128; Common Cavity Anomaly 129; Incomplete Partition Type I 130; Cochlear Hypoplasia 131; Incomplete Partition Type II (Mondini Deformity) 133;Incomplete Partition Type III (X-Linked Deafness) 135; Vestibule and Semicircular Canal Anomalies 135; Internal Auditory Canal Anomalies 137; Vestibular Aqueduct Anomalies 137

11. Internal Auditory Canal Anomalies: Imaging 139 Smita Manchanda

Structures 139; Normal Dimensions 140; Embryology 141; Congenital IAC Malformations 141; Vascular Loops 144; Tumors of the Internal Acoustic Canal 147; Abnormal Enhancement in Internal Acoustic Canal (Apart from Tumors) 151

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xviiContents

12. Cochlear Implant: Surgical Perspectives 153 Kapil Sikka, Hitesh Verma

Indications for Cochlear Implant 154; Contraindications for Cochlear Implant 154; Conditions that Modify Surgical Technique/Type of Cochlear Implant 154; Conditions that Increase Surgical Complications 155; Types of Surgical Implants 155; Surgical Approaches 155; Preoperative Evaluation for Cochlear Implant 157;Intraoperative Evaluation 158; Postoperative Evaluation 158

13. Cochlear Implant: Imaging 159 Manisha Jana

Preoperative Imaging 159; Intraoperative Imaging 165; Postoperative Imaging 165

14. Reporting Template with Illustrative Cases 166 (Inner Ear, Internal Auditory Canal and Cochlear Implant)

Smita ManchandaReporting Template Computed Tomography (CT) 166; Reporting Template Magnetic Resonance Imaging (MRI) 167; Case 1 168; Case 2 170; Case 3 172; Case 4 CT 174; Case 5 MRI 176; Case 6 CT 178; Case 5 MRI 180

Section 5 Tumors

15. Tumors of Temporal Bone: Imaging 185 Chandrashekhara SH

Classification of Temporal Bone Tumors 185; Imaging 186; External Ear and External Auditory Canal Tumors 187; Malignant Tumors of EAC 191; Middle Ear and Mastoid Tumors 195; Inner Ear Tumors 204; Fibro-Osseous Lesions 207

16. Tumors of Temporal Bone: Surgical Perspectives 210 Arvind Kumar Kairo, Suresh C Sharma

Temporal Bone Carcinoma 210; Jugulotympanic Paragangliomas 213

17. Reporting Template with Illustrative Cases 219(Tumors)

Smita ManchandaCase 1 220; Case 2 222; Case 3 224; Case 4 226

Section 6 Miscellaneous

18. Lesions of Petrous Apex 231 Ankur Goyal

Classification of Petrous Apex Lesions 231; Imaging Approach 240

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Clinico Radiological Series: Temporal Bone Imagingxviii

19. Temporal Bone Trauma 241 Atin Kumar, Shivanand Ramachandra Gamanagatti

Classification 241; Types of Fractures 244; Variants 248; Specific Situations 250; Teaching Points 251

20. Reporting Template with Illustrative Cases 253(Miscellaneous)

Smita ManchandaCase 1 254; Case 2 256; Case 3 258; Case 4 260

Section 7 Clinico-radiological Approach

21. Approach to Hearing Loss 265 Hitesh Verma, Vinit Baliyan

Types of Hearing Loss 265; Degree of Hearing Loss 266; Pattern of Hearing Loss 266; Diagnosis 267; Imaging 268; Congenital Hearing Loss 276

22. Approach to Vertigo 278 Shuchita Singh, Devasenathipathy Kandasamy

Relevant Imaging Anatomy 278; Causes 278; Classification of Vertigo 278; Clinical Presentation 279; Diagnostic Approach 279; Management 280; Imaging 280

23. Approach to Tinnitus 284 Devasenathipathy Kandasamy, Shuchita Singh

Pathophysiology 284; Clinical Presentation 285; Causes 285; Diagnosis 285; Management 285; Prognosis 287

24. Approach to Facial Nerve Palsy 294 Arvind Kumar Kairo, Chandrashekhara SH

Anatomy 294; Types 294; Diagnosis 297; Role of Imaging 299; Treatment 299

Index 301

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rsTERMINOLOGY• Microtia: Small ear refers to the deformity of pinna.• Auricle: Refers to external ear/pinna.• Aural: More inclusive term implying related to ear as a whole.

CONGENITAL AURICULAR/PINNA DEFORMITIES

Classification• Classification is described in Table 5.1.• Weerda1 also divides the congenital auricular anomalies into similar three

grades (SeeChapter4).1

Aims of Treatment• Cosmetic pinna correction. Usually, Grade I microtia does not require any

correction. Grade II and III microtia can be treated with a variety of surgeries to improve cosmesis.

• Restoration of hearing.

Treatment OptionsCurrent widely accepted treatment options for higher grade of microtia are:• Autogenous reconstruction (Gold standard)• Implant-retained prosthesis.

Congenital External and Middle Ear Anomalies:

Surgical Perspectives

5

Table 5.1 Clinical classification of congenital auricular anomalies (Aguilar and Jahrsdoerfer classification2)

Grade Description

Grade I Pinna smaller in size in any dimension

Grade II External ear with structural deficiencies: absence of scapha, lobule; broadened helical rim; missing helix, missing conchal bowl or missing antihelical fold (Figs 5.1A and B)

Grade III Ear having the classic ‘peanut’ deformityNo recognizable structures present, anotia (Fig. 5.1C)

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67Chapter 5 Congenital External and Middle Ear Anomalies: Surgical Perspectives

Autogenous Reconstruction• This surgery is usually performed when the child reaches 6–10 years of age.• By this time, the chance of harvesting adequate amount of chest cartilage

is good to create a good cartilage framework. Additionally, the risk of post-harvest chest deformity is less at this age. Also, by 6 years, the child attained 95% of size of adult pinna.

• Involves complex multiple-staged surgeries which include construction of a three-dimensional cartilage framework and placement beneath the non-hair-bearing mastoid skin; lobule rotation, conchal excavation, tragus formation; and elevation of the pinna. This cartilage framework is carved from 6-8 costal cartilages.

• There is literature showing some role of preoperative 3-D computed tomography (CT) scan of the rib cage  to determine the length of costal cartilages from which the cartilage framework are planned to be made.

Implant-retained Prosthesis• This is a prosthetic rehabilitation in which an auricular prothesis is fixed to

the desired location of lateral face using two percutaneous osseointegrated fixtures/abutment (Figs 5.2A and B).

• For optimal position of the abutments, ideally there should be around 3 mm of cortical bone.

• Preoperative high-resolution computed tomography (HRCT) provides the following information for the surgery:– Bonethicknessofthecorticalbone where the abutments are to be placed.

The superior abutment is placed in the suprameatal crest. This place is chosen because there is a triangle of dense bone between the middle cranial fossa and middle ear cleft here. The inferior one is placed at least 2 cm from the superior fixture.

– Preoperative determination of the implant location.

CONGENITAL AURAL ATRESIAThis mainly refers to congenital combined abnormalities of external auditory canal and middle ear as they are closely related.

Figs 5.1A to C Clinical grading of microtia. Grade II microtia (A and B), and Grade III microtia (C). Note the preauricular tag (arrow)

A B C

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Section 2 Congenital Anomalies of External and Middle Ear68

Classification• Altman’sclassificationofauralatresia(Table5.2): It is one of the widely used

classifications of congenital aural atresia which was developed in 1955.• CT-based classification of aural atresia is described in Chapter4.

Table 5.2 Altman’s classification of aural atresia (modified from reference 3)

Group Description

Grade I Tympanic membrane hypoplasticVarious types of ossicular malformationsStapes is usually mobile

Grade II Atretic plate presentTympanic bone hypoplastic; or may even be absentFacial nerve course may be abnormalTympanic cavity within normal limits

Grade III Above-mentioned abnormalities, with severely hypoplastic tympanic cavity

Treatment Options• Atresiaplasty/Canalplasty• Bone-anchored hearing aid• Bone conduction hearing aid.

Atresiaplasty/CanalplastyThis surgery includes creation of skin-lined external auditory canal, tympanic membrane with or without ossicular reconstruction (ossiculoplasty).

Figs 5.2A and B Implant-retained prosthesis. (A) Two osseinegrated fixtures; (B) Postprosthesis photograph with good cosmetic result

Courtesy: Dr Rakesh Kumar and Dr Veena Jain, AIIMS, New Delhi.

A B

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69Chapter 5 Congenital External and Middle Ear Anomalies: Surgical Perspectives

Goalofreconstructivesurgery

• Main goal:To restore sufficient hearing so that amplification is no longer needed (postoperative air-bone gap within 20 to 30 dB)

• Create a patent and skin-lined external auditory canal• Stable long-term hearing result

Timingofsurgery

• Child with unilateral canal atresia may not require any intervention as the contralateral ear is normal and the parents can be reassured that the language, and intellectual development will be normal.

• Child with bilateral canal atresia needs some intervention from early age as his hearing is impaired.

• Atresia repair surgery should be performed after the pinna reconstruction surgery (usually after 6 years of age).

• Before the surgery, child should be kept on bone conduction hearing aid.• Bone-anchored hearing aids may be considered in children older than 5

years of age.

Surgicalapproach(Fig.5.3)

• Anterior approach• Transmastoid approach• Modified anterior approach.

Fig. 5.3 Surgical approaches of atresioplasty

Outcome

Long-term hearing result (air bone gap <30 dB) with atresiaplasty ranges from 47.8% to 84.4%.4,5

Preoperativeevaluation

The preoperative imaging study is HRCT of the temporal bone in both axial and coronal planes to look for:• The status of the inner ear• The size and status of the middle ear cavity• The extent of pneumatization in temporal bone• The facial nerve course, with emphasis on the relationship of the horizontal

portion to the footplate of stapes; and the location of the mastoid segment• The presence of the oval window and stapes footplate

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Section 2 Congenital Anomalies of External and Middle Ear70

• Delineation of the thickness and form of the atretic bone• Soft tissue contribution to the atresia• The presence or absence of congenital cholesteatoma• Temporomandibular joint.

Bone-anchored Hearing Aid• Works with the concept of bone conduction hearing mechanism and

osseointegration.• Bone-anchored hearing aid (BAHA) fixture is usually implanted around

50–55 mm posterosuperior to ear canal.• Preoperative 3D CT can be done to determine the optimal implant site.

MINOR CONGENITAL MALFORMATIONS OF MIDDLE EARThough HRCT of temporal bone is the imaging modality of choice for congenital malformations of middle ear, definitive diagnosis of the minor malformations is made by findings on exploratory tympanotomy only (Table 5.3).

Table 5.3 Teunissen and Cremer’s classification of minor congenital malformations (modified from reference 6)

Class Malformations Percentage

1 Ankylosis or isolated congenital stapes fixation• Superstructurefixation• Footplatefixation

30.6%

2 Stapes ankylosis associated with other ossicle malformations• Deformitiesof the incusand/ormalleus,oraplasiaof the

long process of the incus• Bonefixationofmalleusand/orincus

38.1%

3 Congenital anomalies of the ossicular chain with mobile stapes footplate• Disruptionoftheossicularchain• Tympanicfixation• Epitympanicfixation

21.6%

4 Congenital aplasia or severe dysplasia of the oval and round windows (SeeChapter4)• Aplasia• Dysplasia• Prolapseofthefacialnerve• Persistentstapedialartery

9.7%

Other nonossicular congenital middle ear anomalies which should be looked for are:• Congenital perilymphatic fistula (mainly intraoperative diagnosis)• High jugular bulb• Aberrant internal carotid artery

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71Chapter 5 Congenital External and Middle Ear Anomalies: Surgical Perspectives

REFERENCES 1. Weerda H. Classification of congenital deformities of the auricle. Fac Plast Surg.

1988;5:385-8. 2. Aguilar EA, Jahrsdoerfer RA. Surgical repair of microtia and atresia. Otaolaryngol

Head Neck Surg. 1988;98:600-6. 3. Altmann F. Congenital aural atresia of the ear in men and animals. Ann Otol Rhinol

Laryngol. 1955;64:824-58. 4. De la Cruz A, Teufert KB. Congenital aural atresia surgery: long-term results.

Otolaryngol Head Neck Surg. 2003;129:121-7. 5. Patel N, Shelton C. The surgical learning curve in aural atresia surgery.

Laryngoscope. 2007;117:67-73. 6. Teunissen EB, Cremers WR. Classification of congenital middle ear anomalies.

report on 144 ears. Ann Otol Rhinol Laryngol. 1993;102:606-12.