What is the treatment approach for a patient diagnosed with a Schwannoma?

Treatment Approach for Schwannoma

The primary treatment options for schwannomas include observation ("wait and scan"), stereotactic radiosurgery (SRS), and surgical resection, with the choice depending on tumor size, location, symptoms, and patient factors. 1

Initial Evaluation and Diagnosis

• MRI is the gold standard for diagnosis using:
  • T1-weighted sequences before and after gadolinium
  • T2-weighted sequences
  • Thin slice spin echo or turbo spin echo T1-weighted sequences 1
• For vestibular schwannomas, audiometric evaluation is recommended to document hearing loss 1

Treatment Algorithm

1. Small Asymptomatic Tumors (Koos grades I-II)

• Observation ("wait and scan") is the management of choice 2, 1

  • Annual MRI follow-up for 5 years
  • Intervals can be extended thereafter if stable 2
  • Growth is defined as an increase of at least 3mm in the largest diameter 3
  • Mean growth rate varies from 0.4 to 2.9 mm/year 3

• Alternative: Stereotactic Radiosurgery (SRS)

  • Can be performed to stop tumor growth and preserve nerve function
  • Evidence level II, recommendation level B 2
  • Lower risk profile than surgery 1
  • Small risk of deterioration of nerve function or quality of life 2

2. Small Tumors with Complete Hearing Loss (Koos grades I-II)

• Observation is usually the first option (evidence class III, recommendation level C) 2
• SRS or surgery carries low risk of facial nerve damage 2

3. Symptomatic or Large Tumors

• Surgical resection is indicated for:

  • Tumors causing brainstem compression (mandatory) 1
  • Symptomatic lesions causing neurological deficits 4
  • Large tumors with mass effect 1

• Surgical approaches:

  • Suboccipital retrosigmoid approach: favored for tumors in cerebellopontine cistern 1
  • Translabyrinthine approach: for tumors of all sizes but sacrifices hearing 1
  • Middle fossa approach: for small tumors when hearing preservation is desired 1

• Resection goals:

  • Total or near-total resection when possible
  • Gross total resection: 3.8% recurrence rate
  • Near-total resection: 9.4% recurrence rate
  • Subtotal resection: 27.6% recurrence rate 1

4. Combined Approach for Large Tumors

• Partial resection followed by SRS has become increasingly popular
• Shows superior outcomes for facial nerve function and hearing preservation compared to total resection alone 1

Special Considerations

Schwannomatosis (Multiple Schwannomas)

• Surgery indicated only for symptomatic lesions
• Asymptomatic tumors should be followed conservatively
• Regular surveillance recommended 4

Intralabyrinthine Schwannomas

• Regular monitoring with MRI as tumors grow slowly
• Surgical removal considered if growth is documented or disturbing vestibular symptoms are present 5

Neurofibromatosis Type 2 (NF2)

• More frequent imaging due to variable growth rates
• Growth rate of vestibular schwannoma may increase after resection of contralateral tumor 6
• Bevacizumab is the only pharmacotherapy with a role in NF2-associated schwannomas 1

Follow-up Recommendations

After Conservative Management or Incomplete Resection

• Annual MRI and audiometry for 5 years
• Intervals can be doubled thereafter if stable 2, 1

After Gross Total Resection (GTR)

• MRI controls postoperatively and after 2,5, and 10 years 2

Important Pitfalls to Avoid

1. Treatment at low-volume centers: Outcomes are better at high-volume centers with experienced surgical teams 2, 1

2. Neglecting intraoperative monitoring: Mandatory for preservation of neurological function during surgery 1

3. Inadequate follow-up: Even completely resected tumors require long-term monitoring 1

4. Overlooking quality of life impact: Poor quality of life is more likely in patients with large, symptomatic tumors that were resected 2

5. Misinterpreting imaging growth: Volume measurements are more accurate than two-dimensional measurements for evaluating growth 7

6. Failing to consider NF2: Especially in patients with unilateral vestibular schwannoma at age <30 years 1

7. Overlooking cystic components: Cystic vestibular schwannomas may be associated with rapid growth and lower rates of complete resection 6