Vestibular Schwannoma

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Vestibular Schwannoma

Otology/Audiology
Author Credentials 

Written By:
Gavriel D. Kohlberg, MD
Neurotology Fellow
Department of Otolaryngology – Head and Neck Surgery
University of Cincinnati College of Medicine
Cincinnati Children’s Hospital Medical Center
Cincinnati, OH
E-mail: kohlbegl@ucma.uc.edu

Edited By:
Ravi N. Samy, MD, FACS
Chief, Division of Otology/Neurotology
Program Director, Neurotology and International Advanced Otology Fellowships
Department of Otolaryngology – Head and Neck Surgery
University of Cincinnati College of Medicine
Cincinnati Children’s Hospital Medical Center
Neurosensory Disorders Center at University of Cincinnati Gardner Neuroscience Institute
Cincinnati, OH
E-mail: Ravi.Samy@UC.edu

Module Summary

Vestibular schwannoma is a benign tumor found in the internal auditory canal and the cerebellopontine angle.  Symptoms of VS most commonly include ipsilateral hearing loss, tinnitus, and imbalance.   ABR and can be used to screen for VS, but MRI is the definitive diagnostic tool.  About 5% of cases of VS are found in patients with neurofibromatosis type 2 (NF 2).  Patients with NF 2 are prone to develop bilateral VS.  Treatment options for both sporadic, unilateral tumors and bilateral tumors include observation, radiation therapy, and surgical resection with interventions to help maintain quality of life.  The three main surgical approaches for VS are via middle cranial fossa, retrosigmoid and translabyrinthine.  Vestibular, auditory, and facial rehabilitation serve important roles in patient care.  

Module Learning Objectives 
  1. Review the natural history of vestibular schwannoma.
  2. Describe the treatment options for vestibular schwannoma.
  3. Discuss the most common surgical approaches to vestibular schwannoma resection.
  4. Explain the advantages and disadvantages of specific treatment modalities.

 

Embryology

Learning Objectives 
  1. Review the development of the inner ear and eighth cranial nerve. 
References 
  1. Whitfield TT. Development of the inner ear. Curr Opin Genet Dev. 2015 Jun; 32:112-8.

Anatomy

Learning Objectives 
  1. Describe the anatomic location of vestibular schwannoma with respect to the internal auditory canal and cerebellopontine angle. 
  2. Discuss the contents of the internal auditory canal and the relative position of the cranial nerves within the internal auditory canal. 
  3. Review the anatomy of the temporal bone, lateral skull base, and cerebellopontine angle.

 

References 
  1. Zanoletti E, Martini A, Emanuelli E, Mazzoni A. Lateral approaches to the skull base. Acta Otorhinolaryngol Ital. 2012;32(5):281–287.
  2. http://med.stanford.edu/sm/ohns-skull-base-surgery-atlas/
  3. https://www.aans.org/Education/The-Rhoton-Collection

 

Pathogenesis

Learning Objectives 
  1. Name the cell type from which vestibular schwannoma originate.
  2. Discuss the growth patterns and average yearly growth rate of vestibular schwannoma.
  3. Describe neurofibromatosis type 2 (NF2) and review the burden of vestibular schwannoma in NF2 patients.
  4. Review the genetics of sporadic and NF2 related vestibular schwannoma.

 

References 
  1. Paldor I, Chen AS, Kaye AH. Growth rate of vestibular schwannoma. J Clin Neurosci. 2016 Oct; 32:1-8.
  2. Sass H, Cayé-Thomasen P. Contemporary Molecular Biology of Sporadic Vestibular Schwannomas: A Systematic Review and Clinical Implications. J Int Adv Otol. 2018 Aug;14(2):322-329.

 

Basic Science

Learning Objectives 
  1. Demonstrate knowledge of the function of the superior and inferior vestibular nerves and cochlear nerve and their attachments to the inner ear structures.
  2. Review the location of vestibular schwannoma along the vestibular nerve.

 

References 
  1. Koos WT. Criteria for preservation of vestibulocochlear nerve function during microsurgical removal of acoustic neurinomas. Acta Neurochir (Wien). 1988;92(1-4):55-66.
  2. Landau ME, Barner KC. Vestibulocochlear nerve. Semin Neurol. 2009 Feb;29(1):66-73.

 

Incidence

Learning Objectives 
  1. Review the incidence of sporadic vestibular schwannoma in the general population.
  2. Describe the incidence of NF2.

 

References 
  1. Kshettry VR, Hsieh JK, Ostrom QT, Kruchko C, Barnholtz-Sloan JS. Incidence of vestibular schwannomas in the United States. J Neurooncol. 2015 Sep;124(2):223-8.
  2. Evans DG. Neurofibromatosis type 2 (NF2): a clinical and molecular review. Orphanet J Rare Dis. 2009 Jun 19; 4:16.

 

Genetics

Learning Objectives 
  1. Report the inheritance pattern and penetrance of NF2.
  2. Review the diagnostic criteria of NF2.
  3. Describe the genetic mutations associated with sporadic vestibular schwannoma and NF2.

 

References 
  1. Kshettry VR, Hsieh JK, Ostrom QT, Kruchko C, Barnholtz-Sloan JS. Incidence of vestibular schwannomas in the United States. J Neurooncol. 2015 Sep;124(2):223-8.
  2. Evans DG. Neurofibromatosis type 2 (NF2): a clinical and molecular review. Orphanet J Rare Dis. 2009; 4:16. Published 2009 Jun 19.

 

Patient Evaluation

Learning Objectives 
  1. Review the most common presenting symptoms of vestibular schwannoma.
  2. Recognize that the majority of vestibular schwannomas present with unilateral sensorineural hearing loss but that the majority of individuals with unilateral sensorineural hearing loss do not have vestibular schwannoma. 
  3. Define the House – Brackmann facial nerve grading scale.
  4. Recognize audiometric testing results related to vestibular schwannoma including audiometric brainstem response (ABR).
  5. Describe potential cranial nerve abnormalities on physical exam, gait abnormalities and vestibular testing findings in patients with vestibular schwannoma.

 

References 
  1. Foley RW, Shirazi S, Maweni RM, et al. Signs and Symptoms of Acoustic Neuroma at Initial Presentation: An Exploratory Analysis. Cureus. 2017;9(11): e1846.
  2. Matthies C, Samii M. Management of 1000 vestibular schwannomas (acoustic neuromas): clinical presentation. Neurosurgery. 1997 Jan;40(1):1-9.
  3. House JW, Brackmann DE. Facial nerve grading system. Otolaryngol Head Neck Surg. 1985 Apr;93(2):146-7.

 

Measurement of Functional Status

Learning Objectives 
  1. Review methods for assessing functional status for vestibular schwannoma patients:
  • Penn Acoustic Neuroma Quality of Life Scale 
  • Dizziness Handicap Index
  • Karnofsky performance status

 

References 
  1. Carlson ML, Tveiten ØV, Driscoll CL, Neff BA, Shepard NT, Eggers SD, Staab JP, Tombers NM, Goplen FK, Lund-Johansen M, Link MJ. Long-term dizziness handicap in patients with vestibular schwannoma: a multicenter cross-sectional study. Otolaryngol Head Neck Surg. 2014 Dec;151(6):1028-37.
  2. Shaffer BT, Cohen MS, Bigelow DC, Ruckenstein MJ. Validation of a disease-specific quality-of-life instrument for acoustic neuroma: the Penn Acoustic Neuroma Quality-of-Life Scale. Laryngoscope. 2010 Aug;120(8):1646-54.
  3. Bir SC, Ambekar S, Bollam P, Nanda A. Long-term outcome of gamma knife radiosurgery for vestibular schwannoma. J Neurol Surg B Skull Base. 2014;75(4):273–278. 

 

Imaging

Learning Objectives 
  1. Evaluate the role of gadolinium enhanced MRI vs non-contrast MRI in screening for vestibular schwannoma. 
  2. Review the role of MRI in surveillance of vestibular schwannoma with observation, after radiation treatment or surgical resection.
  3. Describe the role of high-resolution temporal bone computed tomography (CT) in planning surgical resection of vestibular schwannoma (particularly the middle cranial fossa approach).

 

References 
  1. Fortnum H, O'Neill C, Taylor R, Lenthall R, Nikolopoulos T, Lightfoot G, O'Donoghue G, Mason S, Baguley D, Jones H, Mulvaney C. The role of magnetic resonance imaging in the identification of suspected acoustic neuroma: a systematic review of clinical and cost effectiveness and natural history. Health Technol Assess. 2009 Mar;13(18): iii-iv, ix-xi, 1-154.
  2. Krystkiewicz K, Skadorwa T, Szaro P, Ciszek B. Usefulness of the radiological planning for hearing preservation surgery in vestibular schwannoma. Surg Radiol Anat. 2016;38(9):1007–1011.

 

Pathology

Learning Objectives 

Recognize the histological appearance of vestibular schwannoma. 

References 
  1. Wippold FJ 2nd, Lubner M, Perrin RJ, Lämmle M, Perry A. Neuropathology for the neuroradiologist: Antoni A and Antoni B tissue patterns. AJNR Am J Neuroradiol. 2007 Oct;28(9):1633-8

Treatment

Learning Objectives 
  1. Review the three main categories of treatment options for vestibular schwannoma, including observation, radiation (both single fraction and fractionated) and surgery.
References 
  1. Tolisano AM, Hunter JB. Hearing Preservation in Stereotactic Radiosurgery for Vestibular Schwannoma. J Neurol Surg B Skull Base. 2019 Apr;80(2):156-164.

Medical Therapies

Learning Objectives 
  1. Evaluate the literature on the efficacy of aspirin and other non-steroidal medications in reducing growth rate of vestibular schwannoma.
  2. Examine the role of Bevacizumab (Avastin) as a medical therapy of vestibular schwannoma in NF2 patients.

 

References 
  1. Kandathil CK, Cunnane ME, McKenna MJ, Curtin HD, Stankovic KM. Correlation Between Aspirin Intake and Reduced Growth of Human Vestibular Schwannoma: Volumetric Analysis. Otol Neurotol. 2016 Oct;37(9):1428-34.
  2. Hunter JB, O'Connell BP, Wanna GB, Bennett ML, Rivas A, Thompson RC, Haynes DS. Vestibular Schwannoma Growth with Aspirin and Other Nonsteroidal Anti-inflammatory Drugs. Otol Neurotol. 2017 Sep;38(8):1158-1164.
  3. Marinelli JP, Lees KA, Tombers NM, Lohse CM, Carlson ML. Impact of Aspirin and Other NSAID Use on Volumetric and Linear Growth in Vestibular Schwannoma. Otolaryngol Head Neck Surg. 2019 Feb 5:194599819827812.
  4. Morris KA, Golding JF, Axon PR, Afridi S, Blesing C, Ferner RE, Halliday D, Jena R, Pretorius PM; UK NF2 Research group, Evans DG, McCabe MG, Parry A. Bevacizumab in neurofibromatosis type 2 (NF2) related vestibular schwannomas: a nationally coordinated approach to delivery and prospective evaluation. Neurooncol Pract. 2016 Dec;3(4):281-289.

 

Pharmacology

Learning Objectives 
  1. Review the use and mechanism of action of anti-VEGF agent bevacizumab (Avastin) in treatment of NF2 associated vestibular schwannoma. 
  2. Review the literature on cyclooxygenase 2 (COX-2) as a potential target in vestibular schwannoma therapy.

 

References 
  1. London NR, Gurgel RK. The role of vascular endothelial growth factor and vascular stability in diseases of the ear. Laryngoscope. 2014 Aug;124(8): E340-6.
  2. Plotkin SR, Stemmer-Rachamimov AO, Barker FG 2nd, et al. Hearing improvement after bevacizumab in patients with neurofibromatosis type 2. N Engl J Med. 2009;361(4):358–367.
  3. Dilwali S, Kao SY, Fujita T, Landegger LD, Stankovic KM. Nonsteroidal anti-inflammatory medications are cytostatic against human vestibular schwannomas. Transl Res. 2015;166(1):1–11.

 

Surgical Therapies

Learning Objectives 
  1. Describe the three main surgical approaches to vestibular schwannoma including relative indications, risks and complications of each.  
  • Middle cranial fossa
  • Retrosigmoid
  • Translabyrinthine
  1. Review the role of electromyographic (EMG) monitoring to identify the facial nerve in vestibular schwannoma surgery and evaluate the use of intraoperative facial motor-evoked potential (FMEP) monitoring.
  2. Review intraoperative monitoring techniques in hearing preservation vestibular schwannoma surgery (both auditory brainstem response testing and cochlear nerve action potential monitoring).

 

References 
  1. Sweeney, A.D., Carlson, M.L., Ehtesham, M. et al. Curr Otorhinolaryngol Rep (2014) 2: 256.
  2. Tawfik KO, Walters ZA, Kohlberg GD, Lipschitz N, Breen JT, O'Neal K, Zuccarello M, Samy RN. Impact of Motor-Evoked Potential Monitoring on Facial Nerve Outcomes after Vestibular Schwannoma Resection. Ann Otol Rhinol Laryngol. 2019 Jan;128(1):56-61.
  3. Saliba J, Friedman RA, Cueva RA. Hearing Preservation in Vestibular Schwannoma Surgery. J Neurol Surg B Skull Base. 2019 Apr;80(2):149-155.
  4. Kosty JA, Stevens SM, Gozal YM, DiNapoli VA, Patel SK, Golub JS, Andaluz NO, Pensak M, Zuccarello M, Samy RN. Middle Fossa Approach for Resection of Vestibular Schwannomas: A Decade of Experience. Oper Neurosurg (Hagerstown). 2019 Feb 1;16(2):147-158.

 

Rehabilitation

Learning Objectives 
  1. Review the impact of vestibular schwannoma on balance function and the role of vestibular rehabilitation.  
  2. Discuss the indications, benefits and contraindications for each of the hearing rehabilitation options for patients with hearing loss related to vestibular schwannoma
  • Hearing amplification
  • CROS / BICROS
  • Bone anchored hearing amplification (osseointegrated implant placement)
  • Cochlear implantation
  • Auditory brainstem implantation
  1. Review options for facial rehabilitation after vestibular schwannoma therapy leading to facial nerve weakness or paralysis:
  • Facial exercises
  • Facial reanimation surgery
  • Oculoplastic procedures

 

References 
  1. Saman Y, Bamiou DE, Gleeson M. A contemporary review of balance dysfunction following vestibular schwannoma surgery. Laryngoscope. 2009 Nov;119(11):2085-93.
  2. Kitterick PT, Smith SN, Lucas L. Hearing Instruments for Unilateral Severe-to-Profound Sensorineural Hearing Loss in Adults: A Systematic Review and Meta-Analysis. Ear Hear. 2016 Sep-Oct;37(5):495-507.

 

Staging

Learning Objectives 
  1. Interpret the various grading systems for vestibular schwannoma: 
  • Sterkers
  • House
  • Koos
  • Samii

 

References 
  1. Wu H, Zhang L, Han D, Mao Y, Yang J, Wang Z, Jia W, Zhong P, Jia H. Summary and consensus in 7th International Conference on acoustic neuroma: An update for the management of sporadic acoustic neuromas. World J Otorhinolaryngol Head Neck Surg. 2016 Dec 24;2(4):234-239.

Case Studies

  1. A 16-year-old female presents with mild right sided hearing loss.  She is found to have a 2cm right vestibular schwannoma and a 0.5cm left vestibular schwannoma.  What diagnosis to you suspect?  What management options would you discuss with the patient?  What short and long-term hearing rehabilitation options might she need?
  2. A 40-year-old male presents with an incidentally discovered 3.5cm vestibular schwannoma.  What management options would you discuss with the patient?
  3. An 80-year-old male underwent MRI evaluation for asymmetric hearing loss and was found to have a 1cm vestibular schwannoma confined to the internal auditory canal.  What treatment options would you discuss with the patient?  

 

Complications

Learning Objectives 
  1. Review the complications of vestibular schwannoma surgery: 
  • Abdominal harvest site hematoma
  • Cerebrospinal fluid leak
  • Facial nerve injury
  • Extradural or intradural hematoma
  • Stroke
  • Seizure
  • Lower cranial nerve injury
  • Central venous thrombosis
  • Deep vein thrombosis
  • Pulmonary embolism

 

References 
  1. Sanna M, Taibah A, Russo A, Falcioni M, Agarwal M. Perioperative complications in acoustic neuroma (vestibular schwannoma) surgery. Otol Neurotol. 2004 May;25(3):379-86.

Review

Review Questions 
  1. What are common presenting symptoms of vestibular schwannoma?
  2. What diagnostic tests can be used to screen for vestibular schwannoma?
  3. How is vestibular schwannoma treated?
  4. What genetic condition is associated with bilateral vestibular schwannoma?

 

Resources 

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