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Inner Ear Pathology for the Cochlear Implant Surgeon
Built from Haynes-Glasscock-Shambaugh Surgery of the Ear, Seventh Edition
What’s inside
6 sections · 111 slides
Cochlear implantation and the temporal bone
- Current indications for cochlear implantation
- Residual hearing and the ageing candidate pool
- Variability in cochlear implant outcome
- Human temporal bones as a research resource
- Processing an implanted temporal bone
- Limitations of the temporal bone method
- Debates the histopathology informs
- Normal and implanted human cochlea compared
- Normal cochlea in mid-modiolar section
- Implanted cochlea with fibrosis and new bone
Anatomy of the inner ear
- Dimensions of the cochlear duct
- Clinical use of cochlear duct length
- Angular insertion depth versus array length
- Scala tympani morphometry
- Rosenthal canal and the spiral ganglion neurons
- The cochlear coordinate system
- Two versus three dimensional reconstruction
- Counting spiral ganglion neurons
- Causes of spiral ganglion neuron loss
- Approaches to the non-malformed cochlea
- Anatomy of the round window region
- Surgical exposure of the round window membrane
- False membranes and niche contents
- Round window membrane and adjacent structures
- Facial recess approach to the round window
- Structures medial to the round window
- Trajectory of electrode insertion at the round window
- The cochlear aqueduct
Response of the cochlea to implantation
- Acute insertion trauma
- Injury to the lateral cochlear wall
- Injury to the osseous spiral lamina
- Spiral ligament perforation and osseous spiral lamina fracture
- Translocated array in the scala vestibuli
- Trauma pattern by electrode design
- Intracochlear trauma mapped by electrode style
- Why long-term histopathology matters
- New fibrous tissue and bone formation
- Volume of fibro-osseous tissue after implantation
- Predictors of tissue formation
- Electrode length and tissue reaction
- Electric current and the fibrous sheath
- Three-dimensional reconstruction of an implanted cochlea
- Insertion approach and tissue formation
- Fibro-osseous tissue and the acoustic pathway
- Trauma, hydrops and new bone in the upper scalae
- Pathologic change at the cochleostomy site
- Biocompatible is not bio-inert
- Cellular components of the foreign body response
- Platinum and silicone particles in the cochlea
- Macrophages phagocytosing platinum particles
- Macrophages in the implanted inner ear
- Consequences of the foreign body response
- Effects on hair cells and ganglion cells
- Effects on the vestibular system
Intracochlear factors influencing outcome
- Sources of outcome variability
- Neuron count and speech perception: earlier studies
- Neuron count and speech perception: the meta-analysis
- New techniques for neuron analysis
- Spiral ganglion neurons plotted in three dimensions
- Electrical stimulation and neuron survival
- Imaging as a surrogate for neuron count
- New bone, fibrosis and speech outcome
- Translocation with lateral wall damage
- Vestibular function after implantation
- Vestibular histopathology after implantation
- Mechanisms of post-implant hydrops
- Lateral wall damage as an alternative trigger
- Vestibular effects: summary and open question
Special pathologies
- Requirements for implanting an ear with residual hearing
- Delayed loss of preserved hearing
- Proposed mechanisms of delayed hearing loss
- Causes of labyrinthitis ossificans
- Pathogenesis of post-meningitic ossification
- Timing and distribution of ossification
- Implications for the timing of implantation
- Neuronal loss after meningitic ossification
- Labyrinthitis ossificans after temporal bone fracture
- Otosclerosis reaching implant candidacy
- Surgical implications of advanced otosclerosis
- Advanced otosclerosis and the implanted cochlea
- Otosclerotic bone extending into the scala tympani
- Round window niche obliterated by otosclerosis
- Otosclerotic foci beside the labyrinthine facial nerve
- Facial nerve stimulation: mechanism
- Facial nerve stimulation: frequency and management
- Cavitary otosclerosis
- Temporal bone fracture involving the otic capsule
- Implantation after temporal bone fracture
- Vestibular findings after temporal bone fracture
- Cochlear reimplantation
Summary
- Surgical messages from the histopathology
- Chapter summary
- References
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- Haynes-Glasscock-Shambaugh Surgery of the Ear, Seventh Edition
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