Congress of Neurological Surgeons Systematic Review and Evidence-Based Guidelines on the Role of Imaging in the Diagnosis and Management of Patients with Vestibular Schwannomas

Dunn IF1, Bi WL1, Mukundan S2, Delman BN3, Parish J4, Atkins T5, Asher AL5, Olson JJ6.


Question 1 
Is there a role for advanced imaging for facial nerve detection preoperatively?

T2-weighted MRI may be used to augment visualization of the facial nerve course as part of preoperative evaluation.


Question 2 
What is the expected growth rate of vestibular schwannomas on MRI, and how often should they be imaged if a "watch and wait" philosophy is pursued?

MRIs should be obtained annually for 5 years, with interval lengthening thereafter with tumour stability.


Question 3
Do cystic vestibular schwannomas behave differently than their solid counterparts?

Adults with cystic vestibular schwannomas should be counselled that their tumours may more often be associated with rapid growth, lower rates of complete resection, and facial nerve outcomes that may be inferior in the immediate postoperative period but similar to non-cystic schwannomas over time.


Question 4 
Should the extent of lateral internal auditory canal involvement be considered?

The degree of lateral internal auditory canal involvement by a tumour adversely affects facial nerve and hearing outcomes and should be emphasized when interpreting imaging for preoperative planning.


Question 5 
How long should vestibular schwannomas be imaged after surgery, including after gross-total, near-total, and subtotal resection?

For patients receiving gross total resection, a postoperative MRI may be considered to document the surgical impression and may occur as late as 1 year after surgery. For patients not receiving gross total resection, more frequent surveillance scans are suggested; annual MRI scans may be reasonable for 5 years. Imaging follow-up should be adjusted accordingly for continued surveillance if any change in nodular enhancement is demonstrated. U.S. National Library of Medicine, National Institutes of Health

Neurosurgery. 2018 Feb 1;82(2): E32-E34. doi: 10.1093/neuros/nyx510.