Current imaging tools for vestibular schwannoma.

PURPOSE OF REVIEW: Of the tumors found in the cerebellopontine angle (CPA), vestibular schwannomas are by far the most common. Modern diagnostic imaging enables excellent visualization of the CPA and detection of very small tumors while optimizing patient comfort and time. This review addresses the current imaging tools available for diagnosis of vestibular schwannomas. RECENT FINDINGS: The current gold-standard imaging study for vestibular schwannomas is a gadolinium-enhanced T1-weighted MRI. The yield of this expensive study is only about 3-4% given the low incidence of vestibular schwannomas, thus there is utility in screening with noncontrast T2-weighted MRI, which is a quicker and more economical study. SUMMARY: Vestibular schwannomas are best evaluated with gadolinium-enhanced T1-weighted MRI, which can detect tumors as small as 2-3 mm. Recent studies have found that the reported sensitivity and specificity of noncontrast MRI is almost equivalent to that of gadolinium-enhanced T1-weighted MRI. As such, this modality is increasingly being adopted by institutions for both diagnosis and surveillance of vestibular schwannomas and shows promise for broader implementation. Newer protocols, such as FLAIR and DTI may provide additional information and further aid preoperative counseling and surgical planning in the future.

Cochlear FLAIR Signal Changes in Hearing Preservation Vestibular Schwannoma Surgery.

OBJECTIVE: Cochlear fluid-attenuated inversion recovery (FLAIR) magnetic resonance imaging (MRI) signal intensity has been shown to be elevated in patients with vestibular schwannomas (VS). This study evaluated the preoperative and postoperative cochlear signal on FLAIR sequences in patients undergoing hearing preservation surgery. STUDY DESIGN: Retrospective chart review. SETTING: Tertiary referral center. PATIENTS: All patients undergoing middle cranial fossa or retrosigmoid craniotomy for VS at a single institution from September 2013 to January 2017 were screened.Hearing was graded according to the American Academy of Otolaryngology-Head and Neck Surgery (AAO-HNS) hearing classification. Inclusion criteria included preoperative AAO-HNS class A or B hearing and available preoperative and postoperative FLAIR sequences. MAIN OUTCOME MEASURE: Signal intensity of cochlear FLAIR signal was measured in the affected cochlea and normalized to the contralateral cochlea. Hearing preservation was defined as AAO-HNS class A or B postoperatively. RESULTS: Eighteen patients met all inclusion criteria, and 12/18 experienced hearing preservation. There was no difference in preoperative FLAIR ratio between hearing preserved and nonpreserved groups (2.02 vs 2.32, p = 0.52). Postoperatively, FLAIR ratio was lower in the hearing preserved group compared to the nonpreserved group (1.19 vs 1.87, p = 0.033). CONCLUSIONS: The current study is the first to examine postoperative cochlear FLAIR changes in VS patients undergoing hearing preservation surgery. In our study population, abnormal hyperintense FLAIR signal normalized in patients experiencing successful hearing preservation, while those who lost hearing maintained abnormal signal. Future studies may investigate the role of FLAIR in guiding optimal timing of operative intervention in VS patients.