What are the treatment options for vestibular schwannoma?

Treatment Options for Vestibular Schwannoma

Treatment selection for vestibular schwannoma depends primarily on tumor size and symptoms: observation is the management of choice for small asymptomatic tumors, stereotactic radiosurgery (SRS) is preferred for small-to-medium tumors when nerve preservation is paramount, and surgical resection is mandatory for large tumors causing mass effect. 1

Small Asymptomatic Tumors (Koos Grades I–II)

For small asymptomatic tumors with normal cranial nerve function, observation with serial MRI is the recommended first-line management. 1, 2

• Annual MRI with audiometry for 5 years is the standard surveillance protocol, with intervals doubled thereafter if the tumor remains stable 1, 2
• Observation causes significantly fewer complications and offers higher quality of life compared with active treatments 3
• Mean tumor growth rate ranges from 0.4 to 2.9 mm/year, and spontaneous shrinkage occurs in 3.8% of tumors 3

As an alternative to observation, SRS can be performed to stop tumor growth and preserve long-term nerve function (evidence level II, recommendation level B). 1, 2

• SRS carries a lower risk profile than surgery while achieving tumor control 2
• There remains a small risk of deterioration in nerve function or quality of life with SRS 1

Surgery is not recommended for small asymptomatic tumors because the risk of functional deterioration (up to 50%) outweighs potential benefits (evidence class III, recommendation level C). 1, 4

Small Tumors with Complete Hearing Loss

For small tumors with complete hearing loss, SRS is the preferred active treatment if tumor control is desired (evidence class II, recommendation level B). 2

• SRS carries a lower risk to facial nerve function compared with surgery 2
• Observation remains a valid first option since no hearing function is at risk for an extended period (evidence class III, recommendation level C) 1
• Surgery may provide long-term tumor control but carries higher risk of facial nerve damage 1

Medium-Sized Tumors

Both surgery and SRS can be recommended at similar evidence levels for medium-sized tumors. 2

• SRS has a lower risk profile overall 2
• Surgery offers potential for complete tumor removal 2
• Patients with medium-sized tumors should be discussed in multidisciplinary tumor boards to evaluate all treatment options and follow-up strategies 1, 4

Large Tumors

Surgery is the primary treatment for large tumors to reduce mass effect and address symptomatic or life-threatening brainstem compression. 1, 2

• The goal is total or near-total resection 2
• Surgical treatment must be performed at high-volume centers, as surgical experience significantly affects outcomes (evidence class IV) 1, 2, 4
• Intraoperative neurophysiological monitoring is mandatory, including facial nerve monitoring, brainstem auditory evoked responses, and lower cranial nerve electromyography (evidence class III, recommendation level B) 2
• Tumor mass reduction followed by SRS or observation is a valid option for large tumors 1

Surgical Approach Selection

• The middle fossa approach is recommended for intrameatal tumors to preserve hearing and facial nerve function 2
• The translabyrinthine approach may offer better facial nerve preservation compared with the retrosigmoid approach 2
• Choice depends on tumor location, hearing status, and surgeon expertise 2

Special Considerations

Neurofibromatosis Type 2 (NF2)

Bevacizumab shows positive effects on hearing and tumor growth in NF2 patients with bilateral vestibular schwannomas (evidence class II, recommendation level B). 2

• This is the only pharmacotherapy with an established role in vestibular schwannoma management 1

Residual or Recurrent Disease

Risk for tumor regrowth rises dramatically with residual tumor volume—subtotal resection patients experience recurrences over 13 times more often than near-total resection. 2

• Salvage surgery after prior SRS is more difficult and may result in increased likelihood of subtotal resection and decreased facial nerve function 2

Follow-Up Protocols

For conservatively managed, radiated, and incompletely resected tumors: annual MRI and audiometry for 5 years, then double intervals if stable. 1, 2, 4

For gross total resection: MRI postoperatively and at 2,5, and 10 years. 1, 2, 4

• In intracanalicular tumors stable for 5 years, no onset of growth has been documented 1
• However, 7.2% of extra- and intracanalicular tumors exhibit growth after a stable 5-year period, so continued surveillance at longer intervals is warranted 1

Critical Pitfalls to Avoid

Do not perform surgery on small asymptomatic tumors—the functional deterioration risk (up to 50%) outweighs any benefits (evidence class III, recommendation level C). 1, 4

• Quality of life cannot be predicted based on management strategy alone 1, 4
• Poor quality of life is more likely in patients with large, symptomatic tumors requiring resection 1, 4

Recognize that significant tumor growth is defined as an increase of at least 3 mm in the largest extrameatal diameter between scans. 3

• Larger tumor size at diagnosis increases odds of growth by 20% for each 1-mm increment 5
• Presence of tinnitus at diagnosis increases odds of tumor growth nearly 3-fold 5