Inner Ear Malformations: Classification, Evaluation and Treatment

Foreword
Preface
Acknowledgments
Contents
1: Classification of Inner Ear Malformations
1.1 Normal Cochlea
1.2 Cochlear Malformations
1.2.1 Complete Labyrinthine Aplasia (CLA, Michel Deformity)
1.2.2 Rudimentary Otocyst
1.2.3 Cochlear Aplasia
1.2.4 Common Cavity
1.2.5 Cochlear Hypoplasia
1.2.5.1 Types of Cochlear Hypoplasia (CH)
1.2.6 Incomplete Partition Anomalies of the Cochlea
1.2.6.1 Types of Incomplete Partition Groups
1.2.7 Enlarged Vestibular Aqueduct (EVA)
1.2.8 Cochlear Aperture Abnormalities
1.3 Cochlear Nerve Abnormalities
References
2: Histopathologic Findings in Inner Ear Malformations
2.1 Introduction
2.2 Classification of Inner Ear Malformations
2.3 Embryology of Inner Ear Malformations
2.4 Histopathologic Findings of Inner Ear Malformations and Their Clinical Implications
2.4.1 Malformations of the Membranous Labyrinth
2.4.2 Malformations of the Bony Labyrinth
2.4.2.1 Labyrinthine Aplasia (Michel aplasia)
2.4.2.2 Rudimentary Otocyst
2.4.2.3 Common Cavity
2.4.2.4 Cochlear Aplasia
2.4.2.5 Cochlear Hypoplasia
2.4.2.6 Incomplete Partition Anomalies
2.4.2.7 Enlarged Vestibular Aqueduct
2.4.2.8 Cochlear Aperture Abnormalities
2.5 Conclusions
References
3: Pathophysiology of IEMs
3.1 Embryology
3.2 Pathophysiology of Individual Inner Ear Malformations
3.2.1 Complete Labyrinthine Aplasia
3.2.2 Rudimentary Otocyst
3.2.3 Common Cavity
3.2.4 Cochlear Aplasia
3.2.5 Cochlear Hypoplasia
3.2.6 Incomplete Partition Type I
3.2.7 Incomplete Partition Type II
3.2.8 Incomplete Partition Type III
3.2.9 Enlarged Vestibular Aqueduct
3.2.10 Cochlear Aperture Abnormalities
References
4: Genetic Causes of Sensorineural Hearing Loss Associated with Inner Ear Malformations
4.1 Introduction
4.2 A Brief Molecular Embryology of the Inner Ear
4.2.1 Preplacodal Region
4.2.2 Development of Otic Vesicle
4.2.3 Molecules and Factors in the Neurogenesis of the Inner Ear
4.2.4 Cochlea Formation
4.2.5 Semicircular Canal Development
4.3 Syndromic Causes of Inner Ear Malformations in Humans
4.4 Non-syndromic Causes of Inner Ear Malformations
4.4.1 SLC26A4
4.4.2 POU3F4
4.4.3 COCH
4.4.4 ROR1
References
5: Preoperative Otolaryngology Examination
5.1 History Taking
5.2 ENT Examination
5.3 Radiological Evaluation
5.4 Management
5.5 Conclusion
References
6: Preoperative Audiological Evaluation
6.1 Preoperative Evaluation Process
6.2 Audiological Evaluation
6.2.1 History of Hearing Loss
6.2.2 Behavioral Testing
6.2.2.1 Behavioral Observation Audiometry
6.2.2.2 Visual Response Audiometry
6.2.2.3 Conditioned Play Audiometry
6.3 Electrophysiological Measurements
6.3.1 Electroacoustic Immitancemetry
6.3.2 Otoacoustic Emission Testing
6.3.3 Auditory Brainstem Response Testing
6.3.4 Electrical Auditory Brainstem Response Testing
6.4 Follow-Up with Hearing Aids
6.5 Case Studies
6.6 Take-Home Message
6.7 Putting the Pieces Together
References
7: Preoperative Radiological Evaluation
7.1 Introduction
7.2 Imaging Modalities
7.3 CT Imaging
7.3.1 MDCT
7.3.2 CBCT
7.4 MR Imaging
7.5 Imaging Evaluation
7.5.1 CT Evaluation
7.5.2 MR Imaging Evaluation
References
8: Preoperative Speech and Language Evaluation
8.1 Comprehensive Evaluation
8.2 Selection of Test Protocols
References
9: Preoperative Neurosurgical Evaluation of Children Undergoing Auditory Brainstem Implantation
Reference
10: Genetic Evaluation in People with Sensorineural Hearing Loss
10.1 Introduction
10.2 Principles of General Evaluation
10.3 Genetic Etiology in Sensorineural Hearing Loss
10.4 Comprehensive Genetic Testing
10.5 Conclusion
References
11: Treatment Alternatives in Inner Ear Malformations
11.1 Normal Hearing
11.2 Hearing Aids
11.3 Stapedotomy
11.4 Cochlear Implantation
11.4.1 Surgical Approach
11.4.1.1 Facial Recess Approach
Abnormal Location of the Facial Nerve in the Facial Recess
Unfavorable Cochlear Anatomy Through the Facial Recess Area
11.4.1.2 Transcanal Approach
11.4.1.3 Transmastoid Labyrinthotomy
11.4.1.4 Canal Wall-Down Mastoidectomy with Blind Sac Closure of the External Auditory Canal
11.4.1.5 Oval Window
11.4.2 Electrode Choice
11.4.2.1 Special Electrodes for Malformations
FORM Electrodes
Common Cavity Electrode
Standard Electrodes
11.4.3 Type of Malformation and Electrode Choice
11.4.3.1 Common Cavity
11.4.3.2 Incomplete Partition Type I
11.4.3.3 Incomplete Partition Type II
11.4.3.4 Incomplete Partition Type III
11.4.3.5 Enlarged Vestibular Aqueduct
11.4.3.6 Cochlear Hypoplasia
11.5 Auditory Brainstem Implantation
11.5.1 Side Selection
11.5.1.1 Indications
Definite Indications
Probable Indications
11.5.1.2 Surgical Approach
11.6 Cochlear and Auditory Brainstem Implantation
References
12: CSF Fistula and Meningitis
12.1 Introduction
12.2 Histopathology and Pathophysiology
12.3 Literature Review
12.4 Radiology
12.5 Indications for Surgery
12.6 Treatment
12.6.1 Vaccination
12.6.2 Middle Ear Exploration
12.6.3 Subtotal Petrosectomy
12.6.4 Continous Lumbar Drainage
12.7 Clinical Experience
12.8 Site of Fistula
12.9 Cases
References
13: Facial Nerve Abnormalities
13.1 Introduction
13.2 Developmental Anatomy of the FN and Otic Capsule
13.3 Imaging of the FN
13.4 Facial Nerve Abnormalities
13.4.1 Background
13.4.2 A New Classification of FN Abnormalities
13.4.2.1 Classification of Inner Ear Malformations
13.4.2.2 A New Classification of FN Abnormalities
Meatal Segment
Labyrinthine Segment
Tympanic Segment
Mastoid Segment
13.4.3 Embryological Perspective from Inner Ear Malformations to Facial Nerve Abnormalities
13.4.3.1 Meatal Segment
13.4.3.2 Labyrintine Segment
13.4.3.3 Tympanic Segment
13.4.3.4 Mastoid Segment
13.5 Clinical Significance of FN Abnormalities
References
14: Stapedotomy
14.1 Introduction
14.2 Histopathology
14.3 Literature Review
14.4 Clinical Findings
14.5 Radiological Findings
14.6 Audiological Findings
14.7 Management
14.8 Surgery
14.9 Complications
14.10 Clinical Experience
14.11 Cases
14.12 Outcome
14.13 Conclusion
References
15: CSF Leakage and Its Management
15.1 Definition
15.2 Incidence
15.3 Types of CSF Leakage
15.4 Radiology
15.5 Treatment
15.5.1 Size of the Cochleostomy
15.5.2 FORM Electrode with “Cork” Stopper
15.5.3 Timing of Electrode Insertion
15.5.4 Use of Fascia Around the Electrode
15.5.5 Eustachian Tube Obliteration
15.5.6 Subtotal Petrosectomy
15.5.7 Continuous Lumbar Drainage (CLD)
15.5.8 Additional Measures
15.5.9 Intraoperative Radiology
15.6 Postoperative Radiology
15.7 Conclusion
References
16: First Consensus Meeting on Auditory Brainstem Implantation in Children and Non-neurofibromatosis Type 2 Patients
16.1 In Which Children and Non-NF2 Patients Is the ABI a Viable Intervention?
16.2 Which Health Care Team Is Best Positioned to Undertake This Intervention?
16.3 Is It an Appropriate Procedure?
16.4 What Are the Radiologic Indications?
16.4.1 Group 1: Well-Defined Congenital Indications
16.4.2 Group 2: Possible Congenital Indications
16.4.3 Group 3: Acquired Indications
16.4.4 ABI Revision
16.5 What Are the Contraindications?
16.6 What Is the Age Limit for ABI in Children?
16.7 Surgical Procedure, Electrophysiologic Evaluation, and Rehabilitation
16.7.1 Surgical Approach
16.7.2 Importance of Electrophysiologic Tests
16.7.3 Electrophysiology at the Time of ABI Surgery
16.7.4 Electrophysiology Before ABI Activation
16.7.5 Activation
16.7.6 Rehabilitation
16.8 Do We Need Any Modification for ABI Electrode in Children?
16.9 How Many Centers in a Country?
16.10 Policy for Foreign Demands for ABI?
16.11 Conclusion
Reference
17: Cochlear Implantation Versus Auditory Brainstem Implantation in the Management of Complex Inner Ear Malformations
17.1 Consideration for Different Malformation Types
17.2 Potential Surgical Complications
17.3 Performance Outcomes
17.4 ABI Considerations
17.5 ABI Surgical Technique and Potential Complications
17.6 ABI Performance Outcomes
Bibliography
18: Auditory Brainstem Implantation in Children with Inner Ear Malformations
18.1 Introduction
18.2 Indications
18.2.1 Definite Indications
18.2.2 Probable Indications
18.3 ABI Models
18.4 Members of the ABI Team
18.5 Age Limit for ABI in Children
18.6 Preoperative Evaluation
18.7 Anatomy of the Cochlear Nuclei
18.8 Cranial Nerve Monitorization
18.9 Surgery
18.9.1 Retrosigmoid Approach
18.9.1.1 Disadvantages
18.9.2 Translabyrinthine Approach
18.9.2.1 Disadvantages
18.9.3 Retrolabyrinthine Presigmoid Approach
18.10 Intraoperative Monitoring
18.11 Surgical Complications
18.12 Initial Stimulation and Follow-Up
18.13 Conclusion
References
19: Complete Labyrinthine Aplasia (Michel Deformity)
19.1 Histopathology and Pathophysiology
19.2 Literature Review
19.3 Clinical Findings
19.4 Radiological Findings
19.5 Differential Diagnosis
19.6 Audiological Findings
19.7 Management
19.8 Outcome with ABI
References
20: Rudimentary Otocyst
20.1 Definition
20.2 Histopathology and Pathophysiology
20.3 Clinical Findings
20.4 Radiology
20.5 Audiological Findings
20.6 Management
20.7 Cases
References
21: Common Cavity
21.1 Definition
21.2 Radiology
21.3 Clinical Findings
21.4 Management
21.5 Surgery
21.6 Cases
21.6.1 CI Cases
21.6.2 ABI Cases
References
22: Cochlear Aplasia
22.1 Definition
22.2 Histopathology and Pathophysiology
22.3 Literature Review
22.4 Clinical Findings
22.4.1 Radiology
22.4.2 Audiological Findings
22.5 Cases
References
23: Incomplete Partition Type I
23.1 Definition
23.2 Histopathology and Pathophysiology
23.3 Literature Review
23.4 Clinical Findings
23.5 Radiology
23.6 Audiological Findings
23.7 Management
23.8 Surgery
23.8.1 Gusher
23.8.2 Facial Nerve Anomaly
23.9 Meningitis in IP-I
23.10 Clinical Experience
23.10.1 Revisions CI Surgery in IP-I
23.11 Cases
23.12 Outcomes with CI and ABI
References
24: Incomplete Partition Type II
24.1 Definition
24.2 Histopathology and Pathophysiology
24.3 Literature Findings
24.4 Clinical Findings
24.5 Radiology
24.6 Audiology
24.7 Management
24.8 Surgery
24.9 Experience with CI
24.10 Cases
References
25: Incomplete Partition Type III
25.1 Definition
25.2 Histopathology and Pathophysiology
25.3 Literature Findings
25.4 Clinical Findings
25.5 Radiology
25.6 Audiological Findings
25.7 Management
25.8 Surgery
25.9 Audiological Outcomes
References
26: Cochlear Hypoplasia
26.1 Definition
26.2 Histopathology and Pathophysiology
26.3 Literature Review
26.4 Clinical Findings
26.5 Radiology
26.6 Audiological Findings
26.7 Management Options
26.8 Outcome After Stapedotomy
26.9 Outcome with CIs and ABIs
26.10 Surgical Approach
26.10.1 Difficulties During CI Surgery in Cochlear Hypoplasia
26.11 Cases
References
27: Enlarged Vestibular Aqueduct
27.1 Definition
27.2 Anatomy of Vestibular Aqueduct (VA), Endolymphatic Duct (ED), and Sac (ES)
27.3 Histopathology and Pathophysiology
27.3.1 Literature Findings
27.3.2 Clinical Findings
27.3.3 Audiological Findings
27.3.4 Radiology
27.4 Management
27.5 Surgery
27.6 Hacettepe Experience
27.7 Cases
References
28: Cochlear Aperture Abnormalities
28.1 Definition
28.2 Histopathology and Pathophysiology
28.3 Literature Review
28.4 Radiological Evaluation
28.5 Cochlear Aperture Abnormalities (Fig. 28.3a–c)
28.6 Audiological Findings
28.7 Management
28.8 Cases
28.9 Auditory Rehabilitation
References
29: Current Indications and Long-Term Results of Auditory Brainstem Implantations in Children with Inner Ear and Cochlear Nerve Malformations
29.1 Introduction
29.2 Indications
29.3 Contraindications
29.4 Timing of the Intervention
29.5 Audiological and Electrophysiological Assessment
29.6 Radiological Evaluation
29.7 Surgical Technique
29.8 Expected Results
29.9 Complications
29.10 Postoperative Follow-Up
29.11 Conclusions
References
30: Audiological Outcome with Cochlear Implantation
30.1 Introduction
30.2 Literature Review
30.3 Results of Hacettepe University
30.3.1 Common Cavity (CC)
30.3.2 Cochlear Hypoplasia (CH)
30.3.3 Incomplete Partition Anomalies of the Cochlea
30.3.3.1 Incomplete Partition Type I (IP-I)
30.3.3.2 Incomplete Partition Type II (IP-II)
30.3.3.3 Incomplete Partition Type III (IP-III)
30.3.4 Dilatation of Vestibule
30.3.5 Enlarged Vestibular Aqueduct (EVA)
30.4 Hacettepe Experience of Cochlear Implantation in Children with IEMs
30.4.1 Common Cavity (CC)
30.4.2 Cochlear Hypoplasia (CH)
30.4.3 Incomplete Partition Anomalies of The Cochlea
30.4.3.1 Incomplete Partition Type I (IP-I)
30.4.3.2 Incomplete Partition Type II (IP-II)
30.4.3.3 Incomplete Partition Type III (IP-III)
30.4.4 Dilatation of Vestibule
30.4.5 Enlarged Vestibular Aqueduct (EVA)
30.5 Summary
References
31: Audiological Outcome with ABI
31.1 Introduction
31.2 Audiological Outcomes
31.3 Auditory Perception Outcomes
31.4 Speech Perception Outcomes
31.5 Language Development Outcomes
31.6 Speech Intelligibility Outcome
31.7 Recent Results of Pediatric ABI Patients
31.8 Educational Settings
31.9 Conclusion
References
32: Cochlear Nerve Deficiency and Current Management of Inner Ear Malformations
32.1 Introduction
32.2 Definition
32.3 Classification of Cochlear Nerve Abnormalities
32.3.1 Normal Cochlear Nerve (CN)
32.3.2 Hypoplastic CN
32.3.3 Absent CN
32.3.4 Normal CVN
32.3.5 Hypoplastic CVN
32.3.6 Absent CVN
32.4 CI and ABI Indications
32.5 Preoperative Workup
32.5.1 Radiology
32.5.2 Audiology
32.5.3 Language Evaluation
32.6 Intracochlear Test Electrode
32.7 Literature Review: CI in Hypoplastic CN
32.8 ABI in CN Hypoplasia
32.9 Sequential CI and ABI in Hypoplastic CN
32.10 Simultaneous CI and ABI
32.11 Bilateral ABI
32.12 Current Management Strategy
32.13 Cases
32.14 Conclusion
References