Surgery of the Cerebellopontine Angle

Preface
Contents
Contributors
Part I: Foundations for Treatment
	1: Historical Perspectives
		History of Vestibular Schwannoma Surgery
		Otology and the Operating Microscope
		Modern Surgery in the Cerebellopontine Angle
		Neurovascular Decompression
		Radiosurgery
		Conclusions
		References
	2: Microsurgical Anatomy of the Cerebellopontine Angle and Its Suboccipital Retromastoid Approaches
		Relationships Between the Cranial Surface and the CPA
		Osseous and Muscular Relationships, Transverse and Sigmoid Sinuses, and External Surgical Landmarks
		Relationships Among CPA Nerves and Brainstem
		CPA Upper Neurovascular Complex
		Middle Neurovascular Complex of the CPA
		Lower Neurovascular Complex of the CPA
		Summary
		References
	3: Radiology
		Technical Considerations
		Screening Studies
		General Classification of Lesions
			Extraaxial Lesions
			Vascular Lesions
			Extradural Lesions
			Intraaxial Lesions
		Angiography
		Preoperative and Follow-Up Imaging
			Preoperative Imaging of Vestibular Schwannomas
			Follow-Up Assessment After Treatment of Vestibular Schwannomas
		Imaging Pitfalls and Pseudomasses
		References
	4: Neurology
		Anatomy
		Etiologies
		Clinical Manifestations
		Neurological Examination of the CPA
		Additional Testing
		Brainstem Syndromes
		References
Part II: Surgical Approaches
	5: Approaches to the Cerebellopontine Angle
		Introduction
		Retrosigmoid Approach
			Surgical Technique
		Transpetrosal Approaches
			Retrolabyrinthine Approach
			Translabyrinthine Approach
			Transcochlear Approach
		Middle Fossa Approach
			Surgical Technique
			Extended Middle Fossa Approach
		Endoscopic Approach
		Neuromonitoring and Anesthetic Considerations
			Facial Nerve Monitoring
			Vestibulocochlear Nerve Monitoring
			Glossopharyngeal and Vagus Nerve Monitoring
		Summary
		References
	6: Combined Surgical Approaches
		General Considerations
		Transpetrosal Approaches
		Combined Open Approaches
		Endoscopic Endonasal Approach to the Petroclival Region
		Endoscopic Endonasal Approach Considerations
		Surgical Decision-Making
		References
	7: Functional Surgery of the Cerebellopontine Angle
		Vestibular Neurectomy
		Clinical Material and Methods
			Operative Technique for Vestibular Neurectomy
			Outcomes of Vestibular Neurectomy
			Advantages and Disadvantages of Different Approaches for Vestibular Neurectomy
		Neurectomy of the Nervus Intermedius
			Case Report
			Diagnosis of Geniculate Neuralgia
			Functional Anatomy
		Neurectomy of the Glossopharyngeal Nerve
			Natural History and Clinical Manifestations of Glossopharyngeal Neuralgia
			Functional Anatomy
			Differential Diagnosis
			Treatment Options
			Preoperative Preparation
			Patient Positioning
			Operative Technique
		Microvascular Decompression
			Case Report: Microvascular Decompression for Tinnitus
			Authors’ Experience: Microvascular Decompression for Trigeminal Neuralgia or Hemifacial Spasm
			Endoscopy as a Surgical Adjunct During Microvascular Decompression
		Auditory Brainstem Implantation
			Translabyrinthine Approach
			Retrosigmoid Approach
			Authors’ Clinical Experience
			Highlights of Auditory Brainstem Implantation
		Summary and Conclusions
		References
	8: Endoscopy in the Cerebellopontine Angle
		Equipment
		Overview of Endoscopic Techniques
		Operative Technique
		Avoiding Complications with the Endoscope
		Specific Applications of the Endoscope in the CPA: Cranial Nerve Decompression
			Trigeminal Neuralgia
			Hemifacial Spasm
			Glossopharyngeal Neuralgia
		Specific Applications of the Endoscope in the CPA: CPA Masses
			Vestibular Schwannoma
			Meningioma
			Epidermoid
			Arachnoid Cysts
		Conclusion
		References
Part III: Vestibular Schwannomas
	9: Biology and Genetics of Vestibular Schwannomas in Tumors of the Cerebellopontine Angle
		Background
		The NF2 Gene
		Structure and Function of the NF2 Protein, Merlin
		NF2 Mutations and Their Clinical Correlation
		Merlin Acts as a Tumor Suppressor
		Molecular Roles of the Merlin Tumor Suppressor and Consequence of Its Loss in Vestibular Schwannomas
			Merlin and CD44-Mediated Contact Inhibition of Cellular Proliferation
			Merlin-Rac1 Mediated Cytoskeletal Interactions
			Merlin Activates the Mammalian Hippo Pathway to Induce Growth Arrest
			Merlin Inhibits the Mammalian Target of Rapamycin Pathway
			Additional Merlin-Mediated Pathways
			Epigenetic Alterations in Vestibular Schwannomas
			Histone Modifications and the Role of Histone Deacetylase Inhibitors
			Vascular Endothelial Growth Factor in VS
			Bench to Bedside: Molecular Targets of VS Therapy
		Summary
		References
	10: Treatment Options for Acoustic Neuroma, Including Stereotactic Radiosurgery
		Introduction
		Observation
		Stereotactic Radiation and Radiosurgery
		Stereotactic Radiosurgery
			Tumor Control Rates
			Hearing Preservation
			Cranial Nerve Function
		Fractionated Radiotherapy
		Comparing Radiosurgery and Radiotherapy
		Proton Beam Therapy
		Risk of Secondary Malignancy
		Summary
		Microsurgery
		Hearing Results
		Facial Nerve Outcomes
		Cerebrospinal Fluid Leakage
		Patient Reported Quality of Life
		Conclusions
		References
	11: Translabyrinthine Approach
		Preoperative Evaluation
		Patient Selection
		Surgical Procedure
		Tumor Dissection
		Complications
		Outcomes
		Postoperative Care
		Conclusions
		References
	12: Hearing Rehabilitation Following Acoustic Neuroma Surgery
		Unilateral Hearing Loss
		Hearing Rehabilitation
		Contralateral Routing of Signal
		Osseointegrated Hearing Implants
		Auditory Brainstem Implants
		Cochlear Implantation
		References
	13: Acoustic Neuroma Surgery: Retrosigmoid Techniques
		Pathology and Pathophysiology
		Investigation
			Audiometry
			Classification
			Definition of Success
			Auditory Brainstem Responses
			Otoacoustic Emissions
			Vestibular Testing
			Radiology
			MRI Screening: When to Do It?
			Imaging Characteristics
		Complications
		Operative Techniques
			Retrosigmoid Approach
				Patient Position and Monitoring
				Incision
				Soft Tissue Dissection
				Craniotomy
				Dural Opening
				Retraction
				Identification of Nerves at Brainstem
				Removal of CPA Tumor
				Opening the Posterior Wall of the IAC
				Removal of Intracanalicular Tumor
				Closure
			Microsurgical Dissection
		Intraoperative Monitoring
		Hearing Results
			Which Approach?
			Follow-Up and Long-Term Outcomes
				Imaging
				Hearing
				Long-Term Risk of Recurrence
		References
	14: Acoustic Neuroma Surgery: Middle Fossa Approach
		Introduction
		Surgical Candidacy
		Surgical Technique
			Preoperative Preparation
			Surgical Technique
			Postoperative Care
		Complications and Outcomes
		Conclusion
		References
	15: Complications and Cranial Nerve Rehabilitation
		Cerebrospinal Fluid Leak and Meningitis
		Vascular Complications
		Venous Sinus Thrombosis
		Cranial Nerve Dysfunction
			Vestibular Dysfunction
			Facial Nerve
			Delayed Facial Paralysis
		Facial Paralysis and Eye Complications
			Lower Cranial Nerves
		Headache
		Conclusion
		References
	16: Facial Reanimation
		Anatomy of Facial Nerve
		Nerve Injury Classification
			First-Degree Injury
			Second-Degree Injury
			Third-Degree Injury
			Fourth-Degree Injury
			Fifth-Degree Injury
		Nerve Repair and Nerve Grafting
			Nerve Grafting
			Facial Reanimation
			Nerve Substitution Techniques
			Hypoglossal–Facial Transfer (Cranial Nerve XII–VII Crossover)
				Surgical Technique
			Trigeminal-to-Facial Nerve Transfer
				Surgical Technique
			Cranial Nerve VII–VII Cross-Facial Grafting
				Surgical Technique
			Regional Muscle Transfer Techniques
			Temporalis Muscle Transfer
				Surgical Technique
			Other Regional Muscle Transfers
			Free-Muscle Transfer
				Surgical Technique
			Static and Adjunctive Facial Reanimation
		Summary
		References
	17: Hearing and Surgical Considerations in Neurofibromatosis Type 2
		Diagnosis
		Genetics
		Vestibular Schwannomas
		Schwannomas Involving Other Cranial Nerves
		Meningiomas
			Collision Tumors
			Ependymomas
		Ocular Findings
			Surgical Management of Vestibular Schwannomas and Hearing Rehabilitation in NF2
			Observation Without Surgical Intervention
			Middle Fossa Craniotomy with Decompression of the IAC
			Hearing Preservation Surgery with Total Tumor Removal
			Retrosigmoid Craniotomy with Partial Tumor Removal
			Nonhearing Preservation Surgery with Total Tumor Removal
		Hearing Rehabilitation Via an ABI or CI
		Radiation Therapy for NF2
			Surgical Management of Other Tumors in NF2
			Medical Management of NF2
		Conclusion
		References
	18: Prevention and Management of CSF Leakage Postoperatively
		Introduction
		Overall Rates
			Preoperative Issues
			Translabyrinthine Approach
			Retrosigmoid Approaches
			Middle Fossa Approach
			Other Approaches
		Management Options
		Recalcitrant Cases
		Conclusion
		References
Part IV: Nonschwannomatous Lesions of the CPA
	19: Temporal Bone Neoplasms
		Differential Diagnosis
		Temporal Bone Paragangliomas
			Pathology
			Clinical Manifestations
			Classification Schemes
			Operative Management
			Radiotherapy
		Endolymphatic Sac Tumors
			Pathology
		ELST and VHL
			Clinical Manifestations
			Diagnosis
			Treatment
		Hemangiomas of the Geniculate Ganglion and Internal Auditory Canal
		Carcinomas of the Temporal Bone
		Soft Tissue Sarcomas
			Rhabdomyosarcomas
			Diagnosis
			Treatment
		Hematologic Malignancies
		Metastasis of the Temporal Bone
		Cholesterol Granulomas
		Conclusion
		References
	20: Congenital Rest Lesions and Rare Tumors
		General Principles of the Lateral Suboccipital Retrosigmoid Approach
		Anatomical Considerations
		General Techniques of Surgical Resection
		Epidermoids and Dermoids
		Arachnoid Cysts
		Nonvestibular Schwannomas
		Metastatic and Exophytic Lesions
		Lipomas
		Conclusions
		References
	21: Vascular Lesions of the Cerebellopontine Angle
		Vascular Loop Compression
		Aneurysms
			Fusiform Aneurysms
			Saccular Aneurysms
		Treatment of Aneurysms
			Choice of Surgical Approach
			Endovascular Options for Aneurysms
		Arteriovenous Malformations
		Cavernous Malformations
		Hemangioblastomas
		Other Hypervascular Lesions
		Conclusion
		References
Part V: Cases and Approaches (Animations and Videos)
	22: Case 1: Retrosigmoid Approach for Vestibular Schwannoma
		Summary
		Case Presentation
		Approach
		Alternatives
		Positioning
		Incision
		Operation
		Post-op
		Outcome
		Pearls and Pitfalls
		Discussion
		Reference
	23: Case 2: Combined Transpetrosal Approach with Hearing Preservation for Resection of a Meningioma
		Summary
		Case Presentation
		Approach
		Alternatives
		Anatomy
		Positioning
		Incision
		Operation
		Post-op
		Outcome
		Pearls and Pitfalls
		Discussion
		Reference
	24: Case 3: Far-Lateral Approach for a Foramen Magnum Meningioma
		Summary
		Case Presentation
		Approach
		Alternatives
		Positioning
		Incision
		Operation
		Post-op
		Outcome
		Pearls and Pitfalls
		Discussion
	25: Case 4: Resection of an Acoustic Schwannoma Complicated by Tumor Encasement of the Anterior Inferior Cerebellar Artery Using a Translabyrinthine Approach
		Case Presentation
		Approach
		Alternatives
		Surgery
		Outcome
	26: Case 5: Transcondylar Approach for Giant Aneurysm with Posterior Inferior Cerebellar Artery Bypass
		Summary
		Case Presentation
		Approach
		Alternatives
		Positioning
		Incision
		Surgery
		Post-op
		Outcomes
		Pearls and Pitfalls
		Reference
	27: Case 6: Far-Lateral Approach for a Posterior Inferior Cerebellar Artery Aneurysm Clipping
		Summary
		Case Presentation
		Approach
		Alternatives
		Positioning
		Incision
		Operation
		Post-op
		Outcome
		Discussion
		Pearls and Pitfalls
		References
	28: Case 7: Right Retrosigmoid Craniotomy for Microvascular Decompression for Trigeminal Neuralgia (Endoscope-Assisted)
		Summary
		Case Presentation
		Approach
		Alternatives
		Anatomy
		Positioning
		Incision
		Operation
		Post-Op
		Outcome
		Pearls and Pitfalls
		Discussion
		Reference
	29: Case 8: Right Retrosigmoid Craniotomy for Microvascular Decompression of Hemifacial Spasm
		Summary
		Case Presentation
		Approach
		Alternatives
		Anatomy
		Positioning
		Incision
		Operation
		Post-op
		Outcome
		Pearls and Pitfalls
		Discussion
		Reference
	30: Case 9: Left Retrosigmoid Craniotomy for Microvascular Decompression of Glossopharyngeal Neuralgia
		Summary
		Case Presentation
		Approach
		Alternatives
		Anatomy
		Positioning
		Incision
		Operation
		Post-op
		Outcome
		Pearls and Pitfalls
		Discussion
		References
	31: Case 10: Anterior Transpetrosal Approach for Resection of Petroclival Meningioma
		Summary
		Case Presentation
		Approach
		Alternatives
		Anatomy
		Positioning
		Incision
		Operation
			Extradural Dissection: Subtemporal Corridor
			Dura Opening
			Tumor Resection
			Closure
		Post-op
		Pearls and Pitfalls
		References
	32: Case 11: Vestibular Schwannoma Resection with Facial Nerve Displaced Dorsally
		Summary
		Case Presentation
		Approach
		Alternatives
		Positioning
		Incision
		Operation
		Anatomy
		Post-op
		Pearls and Pitfalls
		References
	33: Case 12: Right Retrosigmoid Craniotomy for Pontine Cavernous Malformation
		Summary
		Case Presentation
		Approach
		Alternatives
		Anatomy
		Positioning
		Incision
		Operation
		Post-op
		Outcome
		Discussion
		Pearls and Pitfalls
		References
	34: Case 13: Lateral Transcondylar Craniotomy for PICA Aneurysm
		Summary
		Case Presentation
		Approach
		Alternatives
		Positioning
		Incision
		Operation
		Post-op
		Outcome
		Discussion
		References
	35: Case 14: Left Retrosigmoid Approach in Large Vestibular Schwannoma in Patient with NF2
		Summary
		Case Presentation
		Approach
		Alternatives
		Positioning
		Incision
		Operation
		Post-op
		Outcome
		Discussion
		Pearls and Pitfalls
	36: Case 15: Retrosigmoid Approach for a Left-Sided Trigeminal Schwannoma
		Summary
		Case Presentation
		Neurologic Exam
		Approach
		Alternatives
		Positioning
		Incision
		Operation
		Post-op
		Outcome
		Pearls and Pitfalls
	37: Case 16: Retrosigmoid Approach to Right-Sided Epidermoid Cyst
		Summary
		Case Presentation
		Approach
		Alternatives
		Positioning
		Incision
		Operation
		Post-op
		Outcome
		Pearls and Pitfalls
	38: Case 17: Translabyrinthine Transtemporal Approach for Left Vestibular Schwannoma
		Summary
		Case Presentation
		Imaging
		Approach
		Alternatives
		Positioning
		Incision
		Operation
			Mastoidectomy
			Labyrinthectomy
			Dura Opening
			Tumor Resection
			Hemostasis and Closure
		Post-op
		Outcome
		Pearls and Pitfalls
		Discussion
	39: Case 18: Middle Cranial Fossa Craniotomy for a Left Petrous Apex Lesion
		Summary
		Case Presentation
		Imaging
		Approach
		Alternatives
		Positioning
		Incision
		Operation
			Soft Tissue Dissection
			Craniotomy
			Lesion Removal
			Hemostasis and Closure
		Post-op
		Outcome
		Pearls and Pitfalls
		Discussion
	40: Case 19: Extended Translabyrinthine Approach for Left-Sided Vestibular Schwannoma
		Summary
		Case Presentation
		Imaging
		Approach
		Alternatives
		Positioning
		Incision
		Operation
			Mastoidectomy
			Labyrinthectomy
			Opening Dura
			Tumor Dissection
			Closure
		Post-op
		Outcome
		Pearls and Pitfalls
		Discussion
	41: Case 20: Right-Sided Retrosigmoid Approach to Small Vestibular Schwannoma
		Summary
		Case Presentation
		Approach
		Alternatives
		Positioning
		Incision
		Operation
		Post-op
		Outcome
		Pearls and Pitfalls
		Discussion
	42: Case 21: Transotic Approach to Left-Sided Jugular Paraganglioma/Glomus Tumor for Partial Debulking
		Summary
		Case Presentation
		Approach
		Alternatives
		Positioning
		Incision
		Operation
		Post-op
		Outcome
		Pearls and Pitfalls
		Discussion
Anatomic Dissection Appendix
	Translabyrinthine and Transcochlear Approaches
		Mastoidectomy
	Translabyrinthine Approach
		Labyrinthectomy
	Transotic and Transcochlear Approach
	Presigmoid/Retrolabyrinthine Approach
	Middle Cranial Fossa Approach
	Craniotomy and Extradural Dissection
	Anterior Petrosectomy (Kawase Approach)
Index