Third Mobile Window Syndrome of the Inner Ear: Superior Semicircular Canal Dehiscence and Associated Disorders

Description

This book aims to provide a deeper understanding of Third Mobile Window Syndrome and its various forms beyond just Superior Canal Dehiscence. It will illuminate the various presentations of Third Mobile Window Syndrome, provide the means for diagnosis, and elucidate treatments. The disorder Superior Semicircular Canal Dehiscence Syndrome was discovered in 1995 by Dr Lloyd Minor at The John Hopkins University School of Medicine in Baltimore. Though he published his findings in 1998, there remains no book wholly devoted to the topic. For this reason, many neurotologists and otorhinolaryngologists still misunderstand this condition and its presentation.   Structured in six parts, the first part will be important in providing a context, and drawing together all of the learning that has been acquired since 1998, as well as explaining the complexities of the condition. The second and third parts will set out to detail all the aspects that are necessary for diagnosing a patient and then deciding on the best form of treatment, surgical or otherwise. Part four covers special situations, including bilateral SCDS and the pediatric patient. In part five, Philippa Thomson, a patient herself, will describe the patient perspective of symptoms and the complicated journey of identifying a diagnosis and securing expert care. Finally, part six covers future research.   Third Mobile Window Syndrome of the Inner Ear: Superior Semicircular Canal Dehiscence and Associated Disorders will provide clinicians involved in the treatment of inner ear disorders, balance dysfunction, and dizziness with the expertise they need to assist patients with Third Mobile Window Syndrome. It will also supply useful information to neurotologists/otologists, otolaryngologists, and neurologists. Researchers in the field of inner ear disorders will also find this to be a valuable text.        Preface Contents Contributors Part I: Understanding Third Mobile Window Syndrome Introduction Chapter 1: History and Overview of Third Mobile Window Syndrome Clinical Phenotype Peripheral Vestibular Physiology and the Need for a Precise Lexicon Central Nervous System Pathway Activation that Produce Secondary Symptoms Autonomic Dysfunction Cognitive Dysfunction Altered Spatial Orientation Anxiety Sound-Induced Gravitational Receptor Dysfunction Type of Vertigo Autophony Migraine and Gravitational Receptor Dysfunction Type of Vertigo The Experiments of Pietro Tullio Semicircular Canal Fenestration Operations for Otosclerosis Cholesteatoma Early Stapedectomy Lessons Learned Perilymph Fistula Vestibular Evoked Myogenic Potentials Audiometry High-Resolution Temporal Bone CT Superior Semicircular Canal Dehiscence Spectrum of Known Sites Creating a Third Mobile Window Frontiers References Chapter 2: Etiology Background Proposed Etiologies of Superior Canal Dehiscence Abnormal Development and Congenital Factors Acquired Factors Age and Gender Chronic Conditions Other Causes for Acquired Dehiscence Associations Multifactorial Etiology Conclusion References Chapter 3: Pathophysiology of Third Mobile Window Syndrome Inner Ear Anatomy: Structure and Function Semicircular Canals Otolith Organs Semicircular Canals Mechanics Third Mobile Window Syndrome: Fluid Dynamics and the Balloon/Box Model The Vestibule What is a Dehiscence? Mechanics of a Mobile Third Window Pressure Misdirection in TMWS Causing Abnormal Stimulation Loss of Sound Energy Inner Ear Conductive Hearing Loss Autophonia and Amplification of Internal Body Sounds VEMP Physiology Why Are VEMP Thresholds Affected in SCD? Fistula Test and Hennebert’s Sign Tullio’s Phenomenon Advanced Pathophysiology Remaining Thin Bone Layer Near Dehiscence, Incomplete Dehiscence, and the Second Event Theory Intracranial Pressure and Increased Compliance Neurological Insensitivity Cognitive Adaptation Fluid Dynamics, Phase Shifts, and Dense Brain Resting on Fistula Dense Brain Resting on Fistula Phase Shifts Symptomatic Patients Without Evidence of SCD Other Sites Outside of the Semicircular Canals Enlarged Vestibular Aqueduct/Jugular Bulb Dehiscence Summary Conclusions References Chapter 4: Classification of Third Mobile Window Anomalies Introduction Material and Methods Vestibular and Audiological Evaluation Radiological Assessment Results Type I: OCD-Meningeal Subtype Ia Subtype Ib Type II: OCD-Vascular Subtype IIa Subtype IIb Subtype IIc Type III: OCD-Petrosal Bone Subtype IIIa Subtype IIIb Subtype IIIc Intralabyrinthine Third Mobile Window-Like Variants Multiple OCD Localizations CT-OCD or Not Identified OCD (NIOCD) Perspectives Conclusions References Chapter 5: The Otologic Mimicker: Vestibular and Auditory Symptoms Introduction Vestibular Symptoms Subjective Findings Physical Exam Findings Auditory Symptoms Subjective Findings Physical Exam Findings Imaging Differential Diagnosis for the Otologic Mimicker Otologic Mimickers Benign Paroxysmal Positional Vertigo (BPPV) Eustachian Tube Dysfunction Ménière’s Disease Otosclerosis Autoimmune Inner Ear Dysfunction Labyrinthitis Mass Lesions Involving the Labyrinth Neurologic Mimickers Multisensory Balance Dysfunction Migraine Mal de Débarquement Syndrome Psychiatric Mimickers Asymptomatic Labyrinthine Dehiscence Ockham’s Razor Bilateral Third Mobile Windows Diagnostic Algorithm Conclusion References Chapter 6: The Cognitive/Psychological Effects of Third Mobile Window Syndrome Central Nervous System Pathway Activation that Produce Secondary Symptoms Autonomic Dysfunction Cognitive Dysfunction Altered Spatial Orientation Anxiety Frontiers Summary References Chapter 7: Other Kinds of Dehiscences Introduction Cochlear-Facial Canal Dehiscence History Demographics and Prevalence Pathogenesis Symptoms Radiology Audiometry and VEMP Findings Special Considerations Treatment Cochlear-Carotid Dehiscence History Prevalence Pathogenesis and Relationship with Other Otologic Pathology Symptoms Treatment Posterior Semicircular Canal Dehiscence (PSCD) History Prevalence Pathogenesis and Relationship with Other Otologic Pathology Radiology Symptoms Audiometry, VEMP, and Other Test Findings Treatment Cochlear-Jugular Bulb Dehiscence (CJB) History/Pathogenesis and Relationship with Other Otologic Pathology Demographics and Prevalence/Radiology Symptoms/Audiometry, VEMP, and Other Test Finding Treatment Large Vestibular Aqueduct History Audiometry, VEMP, and Other Test Findings Pathogenesis and Relationship with Other Otologic Pathology Radiology Symptoms Treatment Other Dehiscences Conclusion References Chapter 8: Perilymphatic Fistula Introduction and Definition Etiology Pathophysiology Clinical Presentation Diagnosis Treatment Outcome Conclusion References Part II: Diagnosis Introduction Chapter 9: Vestibular Symptoms and Magnitude of Disease Burden Refining the Complaint of “Dizziness” Vestibular Disorders Prevalence and Symptoms of Various Third Mobile Window Syndrome Variants The Impact of TMWS and Dizziness Evolution of Vestibular Management Strategies Past Approaches to the Complaint Availability of Vestibular Function Testing Summary References Chapter 10: Taking the Patient History Presenting Complaint and History (Symptoms) Trigger Frequency and Duration of Symptoms Associated Symptoms Causative Mechanism Past Medical History Family History Psycho-social Comorbidity Paediatric Patients Summary Conclusion References Chapter 11: Diagnostic Testing of Third Mobile Window Disorders Introduction Basic Audiovestibular Physiology Relevant to Diagnostic Testing for SSCD Historical Aspects Making the Diagnosis of SSCD and Other TMWD Symptoms Clinical Examination Eliciting Hennebert’s Sign Fistula Test: The Use of Tympanometry Equipment to Demonstrate Hennebert’s Sign Observing Tullio Phenomenon Investigations Middle Ear Assessment Immittance Testing Stapedial Reflex Testing Laser Doppler Vibrometry Speech Testing Otoacoustic Emission Testing Investigations Undertaken to Provide Physiological Evidence of TMWD Video-Oculography Recordings: Tullio Testing and Eliciting Hennebert’s Sign A Suggested Tone-Evoked Nystagmus Protocol A Suggested Skull Vibration Induced Nystagmus Protocol Pure Tone Audiometry Vestibular-Evoked Myogenic Potentials Testing Basic Principles of VEMP Testing cVEMP vs. oVEMP Testing Combining VEMP and Audiometric Data VEMP Testing vs. Testing in Other Causes of Otolith Dysfunction Example cVEMP and oVEMP Protocols cVEMP Test Protocol [68] oVEMP Test Protocol [69] VEMP Testing: Key Points and Summary Electrocochleography Quality of Life Measures Diagnostics: An Illustrative Case of SSCD What Are Other Physicians and Surgeons Doing When It Comes to Diagnostics? Other Diagnostic Testing That May Be Helpful for TMWD Diagnosis Video Head Impulse Testing Caloric Testing Rotational Chair Testing Blood Tests Imaging Paediatric TMWD Summary Concluding Remarks Appendix References Chapter 12: Imaging of Third Mobile Window Syndromes Introduction Technical Considerations Superior Semicircular Canal Dehiscence Posterior Semicircular Canal Dehiscence Lateral Semicircular Canal Dehiscence and Perilymphatic Fistula Enlarged Vestibular Aqueduct X-Linked Stapes Gusher Cochlear Dehiscence and Bony Dyscrasias Summary References Part III: Treatment Introduction Chapter 13: Medical Therapy Avoidance of Triggers Diet Medication Microprism Lenses Sleep Apnea Evaluation Other Medical Problems Postoperative Medical Therapy Physical Therapy Conclusion References Chapter 14: Visual Manifestations and Treatment: The Intersection of Third Mobile Window Syndrome and Vertical Heterophoria Introduction Third Window Syndrome and Vertical Heterophoria Diagnosis and Treatment of Vertical Heterophoria Pathophysiology of Binocular Vertical Heterophoria Third Window Syndrome Feinberg Method for Identifying and Treating Vertical Heterophoria Conclusion References Chapter 15: Surgery, Complication, Revisions Surgical Candidacy Preop Counseling Types of Surgery Occlusion Repair/Capping Transmastoid vs. Middle Fossa vs. Combined Approach Window Reinforcement Posterior Canal Dehiscence Ancillary Procedures Outcomes Complications Revision Surgery Conclusions References Chapter 16: Endovascular Therapy for Third Mobile Window Syndrome Introduction Preliminary Otoneurological and Radiological Investigations Surgical Treatment Endovascular Management Vestibular Aqueduct: Jugular Bulb Dehiscence Posterior Semicircular Canal: Jugular Bulb Dehiscence Dehiscence of the SSCD Involving the Superior Petrous Sinus (SPS) Post-Treatment Findings Conclusion References Part IV: Special Situations Introduction Chapter 17: Bilateral Superior Semicircular Canal Dehiscence Syndrome Clinical Presentation Management Outcomes References Chapter 18: Otosclerosis Introduction Otosclerosis Third Window Syndromes Enlarged Vestibular Aqueduct Superior Semicircular Canal Dehiscence Identification/Diagnosis of Otosclerosis, SCD, and Concomitant Otosclerosis and SCD Management/Treatment of Concomitant Otosclerosis and SCD Conclusion References Chapter 19: Increased Intracranial Pressure Introduction Etiology of SSCD Idiopathic Intracranial Hypertension Role of IIH in Skull Base Defects and SSCD TMW Diagnosis and Management IIH Diagnosis and Management Conclusion References Chapter 20: Endolymphatic Hydrops Introduction Concomitant EH and TWS Diagnostic Testing Audiometry cVEMP/oVEMP ECOG Imaging Treatment Surgical Medical Conclusion References Chapter 21: Superior Canal Dehiscence Syndrome in the Only Hearing Ear Introduction Hearing Loss and Superior Canal Dehiscence Syndrome Surgical Approaches to Superior Canal Dehiscence in the Only Hearing Ear The Decision to Operate Hearing Rehabilitation in Superior Canal Dehiscence Syndrome Conclusions References Chapter 22: The Pediatric Patient Semicircular Canal Dehiscence Presenting as a Third Mobile Window Syndrome in the Pediatric Population A Basis for a Congenital Etiology of Superior Semicircular Canal Dehiscence Diagnosing TMWS in a Pediatric Patient with Semicircular Canal Dehiscence Epidemiological Considerations in SSCD Management Challenges to Diagnosing SSCD in Children Proposed Standard Diagnostic Criteria Enlarged Vestibular Aqueduct Syndrome Causing TMWS Characteristic of Enlarged Vestibular Aqueduct Syndrome Other Causes of Third Mobile Window Syndrome in Children Ongoing Research into Causes of Pediatric TMWS Conclusion References Chapter 23: The Geriatric Patient References Chapter 24: Cerebrospinal Fluid Fistulas and Encephaloceles in the Setting of Superior Semicircular Canal Dehiscence Introduction Association of CSF Fistula and Encephaloceles with Superior Canal Dehiscence Presentation and Complications of Spontaneous CSF Fistulas and Encephaloceles Imaging and Laboratory Evaluation for CSF Fistula and Encephaloceles Surgical Repair of CSF Fistula and Encephaloceles Treatment of Asymptomatic Superior Canal Dehiscence During Repair of CSF Fistulas and Encephaloceles Postoperative Considerations References Chapter 25: Migraine, Headache, and Third Mobile Window Syndrome Headache and Migraine Pathophysiology of Chronic Migraine Measuring the Impact of Headache Headache and Migraine in Third Mobile Window Syndrome Summary References Chapter 26: Postoperative Third Mobile Window Syndrome Introduction: Iatrogenic Third Window Phenomena Stapes Surgery Surgery for Cholesteatoma Surgery of the Lateral Skull Base Diagnosis of Postoperative TMWD Case Example Case Details Case Discussion Conclusions References Part V: From the Patient Perspective Introduction Chapter 27: Patient Stories When Despair Sets In The Psychological Impact A Diagnostic Maze The Knock-Backs Affliction at a Young Age Deciding on Surgery Happier Days Ahead Like Mother, Like Daughter Conclusion Chapter 28: Patient Experiences of Living with Superior Semicircular Canal Dehiscence Syndrome Experiencing New and Strange Symptoms Cochlear Symptoms Vestibular Symptoms A Restricted Life Due to SCDS Disease Coping Strategies Encounters with Healthcare Why Surgery? The Place of Questionnaires References Chapter 29: Doctor-Patient Communication Symptoms Diagnosis Surgery Post-surgery The Future References Part VI: The Future Introduction Chapter 30: Future Research Introduction Prevalence, Etiology, Pathophysiology, Natural History Prevalence Etiology Idiopathic Intracranial Hypertension Metabolic Disorders Genetics Symptoms and Natural History Pathophysiology Classification Diagnosis History Audiometric Testing Imaging Treatment Models for Study Advanced Technology Special Situations Patient Outcome Measures Conservative/Medical Management Round Window Reinforcement Migraine Conclusion References Index