What is the treatment for vestibular schwannoma?

Treatment for Vestibular Schwannoma

Treatment selection depends primarily on tumor size and symptoms: small asymptomatic tumors should be observed, small-to-medium tumors benefit most from stereotactic radiosurgery (SRS), and large symptomatic tumors require surgical decompression. 1

Treatment Algorithm by Tumor Size and Clinical Presentation

Small Asymptomatic Tumors (Koos Grades I-II)

Observation is the management of choice for small asymptomatic tumors with normal cranial nerve function. 1

• Annual MRI follow-up with audiometry for 5 years is recommended, with intervals doubled thereafter if stable 1
• This approach carries evidence level III, recommendation level C 1

As an alternative, SRS can be performed to stop tumor growth and preserve long-term nerve function (evidence level II, recommendation level B). 1

• SRS carries a small risk of nerve function deterioration or quality of life impairment 1
• This represents a higher level of evidence than observation alone 1

Surgery is NOT recommended for small asymptomatic tumors due to functional deterioration risk up to 50% (evidence class III, recommendation level C). 1

Small Tumors with Complete Hearing Loss (Koos Grades I-II)

Observation remains the first option since no hearing function is at risk. 1

SRS is the preferred active treatment if tumor control is desired because it carries a lower risk profile than surgery while preserving facial nerve function (evidence class II, recommendation level B). 1

• Surgery can provide cure but carries higher facial nerve damage risk 1

Medium-Sized Tumors (Koos Grades III-IV, <3 cm)

Both surgery and SRS can be recommended at similar evidence levels (recommendation level C). 1

• SRS has a lower risk profile than surgery 1
• Surgery offers potential for complete tumor removal 1
• Subtotal resection to preserve function followed by observation or SRS is a valid strategy 1

This decision requires multidisciplinary tumor board discussion to evaluate all options with the patient. 1

Large Tumors (Koos Grade IV, ≥3 cm)

Surgery is the primary treatment to reduce mass effect and address symptomatic or life-threatening compression. 1

• Goal should be total or near-total resection, as residual tumor volume correlates with recurrence rates 1
• Gross total resection yields 3.8% recurrence, near-total resection 9.4%, and subtotal resection 27.6% 1

Partial resection followed by SRS has become increasingly popular for large tumors, showing superior facial nerve and hearing preservation compared to total resection with comparable tumor control (evidence class IV). 1

Surgical Considerations

Surgery must be performed at high-volume centers since surgical experience significantly affects outcomes (evidence class IV). 1

Intraoperative neurophysiological monitoring is mandatory (evidence class III, recommendation level B): 1

• Somatosensory evoked potentials
• Facial nerve monitoring with direct electrical stimulation and free-running electromyography
• Brainstem auditory evoked responses when hearing preservation is attempted
• Lower cranial nerve electromyography for large lesions

Surgery-related mortality is 0.5% in large series. 1

Facial palsy risk ranges from 3% to 46% depending on tumor size and immediate postoperative paresis. 1

Hearing preservation probability in patients with normal preoperative hearing is >50-75% immediately after surgery and at 2 and 5 years, declining to >25-50% at 10 years. 1

Stereotactic Radiosurgery Outcomes

SRS provides excellent tumor control with only 2-4% requiring additional treatment. 2

Hearing preservation is achieved in 44-66% of cases with contemporary reduced marginal doses. 2, 3

Gamma knife radiosurgery demonstrates the best outcomes for stabilizing hearing (64%), increasing hearing capability (10%), and decreasing tumor size (53%). 3

Special Population: Neurofibromatosis Type 2

Bevacizumab shows positive effects on hearing and tumor growth in NF2 patients with bilateral vestibular schwannomas (evidence class II, recommendation level B). 1, 4

• This represents the only pharmacotherapy option with evidence support 1

Follow-Up Protocol

For conservatively managed, radiated, and incompletely resected tumors: 1

• Annual MRI and audiometry for 5 years
• Double intervals thereafter if stable

For gross total resection: 1

• MRI postoperatively and at 2,5, and 10 years

Critical caveat: Even after 5 years of stability, 7.2% of tumors may exhibit growth, necessitating continued surveillance. 1

Key Pitfalls to Avoid

Do not perform surgery on small asymptomatic tumors - the functional deterioration risk outweighs benefits. 1

Recognize that residual tumor volume after subtotal resection dramatically increases recurrence risk - subtotal resection patients experience recurrences over 13 times more often than near-total resection. 1

Be aware that facial nerve preservation risk is higher after previous irradiation if reoperation becomes necessary. 1

Distinguish pseudoprogression from true progression after SRS through multidisciplinary evaluation to avoid unnecessary interventions. 5