Vestibular Schwannoma Surgical management and outcomes Ching-Jen (Jared) Chen Visiting Sub-Intern University of Virginia

Patient MM 48yo M w/ L-sided tinnitus and dysequilibrium since 2009. MRI 2010 revealed 5mm L vestibular schwannoma (purely intracanalicular). No intervention, followed with serial scans. MRI 2012 revealed schwannoma had extended to just outside the IAC. Audiogram showed mild L sensorineural hearing loss. Referred to MGH for surgical consideration.

Patient MM (cont’d) PMH: SH: Denies tobacco and illicits, rare EtOH. Hx of Afib w/ spontaneous conversion to NSR Viral pericarditis S/p R knee surgery S/p R shoulder surgery SH: Denies tobacco and illicits, rare EtOH. FH: Non-contributory, no hx of vestibular schwannomas. MEDS: ASA 81 QDaily ALL: NKDA EXAM: NI, except slightly decreased hearing in L ear Decided to undergo microsurgical resection via retrosigmoid approach

T1-PostGad 2010 2012 2013 5mm L Vestibular Schwannoma, purely intracanalicular. Enlarging L Vestibular Schwannoma, 11mm. Projects just beyond medial aspect of porous acusticus. 6 mo s/p microsurgical GTR, via retrosigmoid approach. W/o evidence of residual/recurrent tumor.

Vestibular Schwannoma Usually arise from the superior division of vestibular n. Histology: Antoni A, Antoni B, and Verocay Bodies. Comprising 8-10% of intracranial tumors. Annual incidence ~1.5 cases/100,000. Typically become symptomatic after age 30. Most common symptoms: hearing loss, tinnitus, and dysequilibrium. >95% are unilateral. B A Wippold FJ et al.

Treatment options Microsurgery Radiosurgery Middle Fossa approach Translabyrinthine approach Retrosigmoid approach Radiosurgery Mayfield clinic

Middle Fossa Approach Gonzalez LF et al. Usually selected for smaller (<25mm) and laterally place tumors. Potential damage to temporal lobe w/ risk of seizures.

Retrospective review; 46 patients, middle fossa approach. Mean follow-up time: 1.8 yr. Mean tumor size 8.3mm. Facial n. Excellent/good (House-Brackmann Grade I-II) functional preservation: 89.1%. Not correlated w/ tumor size. Cochlear n. Functional hearing (AAO-HNS Class A-B) preservation: 63.2% Hearing preservation related to tumor size.

Translabyrinthine Approach Allows resection of tumors of different sizes. Disadvantage: Sacrifices hearing Longer procedure Gonzalez LF et al.

Retrospective review, 1244 patients, translabyrinthine approach. All patients at least 12mo of f/u. Gross total resection 84%, near-total 13.7%, subtotal 2.2%. Facial n. Excellent/good (House-Brackmann Grade I-II) functional preservation: 70.3% Tumor size significantly correlates w/ post-op facial n. function.

Retrosigmoid Approach Most commonly used approach. Allows resection of tumors of different sizes and wide view of cisternal component of tumor. Disadvantage: Cerebellar retraction (not a problem for smaller tumors, <40mm) Less access to facial/cochlear n. in distal IAC Headaches Gonzalez LF et al.

Retrospective review; 200 consecutive patients, retrosigmoid approach. Mean follow-up time: 24 mo. Gross total resection: 98%, Subtotal resection: 2%. Tumor recurrence: 0.5%. Facial n. Excellent/good (House-Brackmann Grade I-II) functional preservation: 62%. Tumor size significantly correlates w/ post-op facial n. function (p<0.05). Cochlear n. Functional hearing (New Hannover Classification Grade I-III) preservation: 51%. Hearing preservation related to tumor size and extension, and pre-op hearing level (p<0.05).

Radiosurgery Alone or in conjunction with surgery. Usually reserved for small to medium sized tumors, or patients who are poor surgical candidates.

Retrospective review, 190 patients treated with GKRS. Primary treatment 70.5% and adjunctive 29.5%. Median margin dose 13Gy, tumor volume 3.6cm3, f/u 109mo. Overall tumor control rate 89.5%. Estimated 3-, 5-, 10- and 15-year tumor control rates: 95%, 93%, 86%, and 70%, respectively. Hearing preservation rate 75%. Estimated 3-, 5-, and 10-year tumor control rates:, 96%, 92%, and 70% respectively. Facial n. function (House-Brackmann Grade I-II) preservation 98.6%. Tumor control was significantly affected by tumor volume.

Patient MM (cont’d) At 6mo f/u, pt has been doing well. Stable tinnitus and hearing loss. Exam unchanged, incision c/d/i. No specific complaints. F/u visit in 6mo w/ MRI and audiogram.

Conclusions Microsurgery appears to offer better tumor control rates, whereas radiosurgery seems to have higher hearing preservation. Treatment selection should be tailored to each individual patient and tumor characteristics. Surgeon/institution experience should also be taken into consideration. Gonzalez LF et al.

Acknowledgements Mark E. Shaffrey, MD John A. Jane Sr., MD PhD Justin S. Smith, MD PhD Christopher I. Shaffrey, MD Jason P. Sheehan, MD PhD Robert L. Martuza, MD William T. Curry, MD Department of Neurosurgery

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