Managing NF2-associated vestibular schwannomas in children and young adults: review of an institutional series regarding effects of surgery and bevacizumab on growth rates, tumor volume, and hearing quality

Abstract

We reviewed our experience in managing of NF2-associated vestibular schwannoma (VS) in children and young adults regarding the effect of surgery and postoperative bevacizumab treatment. A total of 579 volumetric and hearing data sets were analyzed. The effect of surgery on tumor volume and growth rate was investigated in 46 tumors and on hearing function in 39 tumors. Long-term hearing follow-up behavior was compared with 20 non-operated ears in additional 15 patients. Sixteen operated VS were treated with bevacizumab. Mutation analysis of the NF2 gene was performed in 25 patients. Surgery significantly slowed down VS growth rate. Factors associated with a higher growth rate were increasing patient age, tumor volume, and constitutional truncating mutations. Immediately after surgery, functional hearing was maintained in 82% of ears. Deterioration of hearing was associated with initial hearing quality, larger tumor volumes, and larger resection amounts. Average hearing scores were initially better in the group of non-operated VS. Over time, hearing scores in both groups worsened with a similar dynamic. During bevacizumab treatment of residual tumors, four different patterns of growth were observed. Decompression of the internal auditory canal with various degrees of tumor resection decreases the postoperative tumor growth rates. Carefully tailored BAEP-guided surgery does not cause additional hearing deterioration. Secondary bevacizumab treatment showed heterogenous effects both regarding tumor size and hearing preservation. It seems that postoperative tumor residuals, that grow slower, behave differently to bevacizumab than reported for not-operated faster growing VS.

Intracranial paragangliomas versus schwannomas: Role of dynamic susceptibility contrast perfusion and diffusion MRI

“…Prior studies have shown that vascular permeability can be related to schwannoma growth, 23 and NF2-related schwannomas can grow faster than sporadic schwannomas. 24 Further studies with a larger sample size would be necessary to confirm our results. Second, a combination of 1.5-T and 3-T scanners were used, which may add heterogeneity to the calculated ADC and DSC-MRI parameters.…”

“…Interestingly, NF2‐related schwannomas showed higher CBV and CBF than sporadic schwannomas with diagnostic performance of .91 and .95 AUCs in this study. Prior studies have shown that vascular permeability can be related to schwannoma growth, 23 and NF2‐related schwannomas can grow faster than sporadic schwannomas 24 . DSC‐MRI technique can be more helpful to differentiate sporadic from NF2‐related schwannomas than DCE‐MRI technique, which revealed diagnostic performance of .90 AUC by permeability parameters of Ktrans and Ve in prior studies 18 .…”

Neurofibromatosis type II and facial paralysis - clinical evaluation and management.

“…This approach is justified because remnant tumors after subtotal resection demonstrate a much slower postoperative growth rate of 0.68 mm 3 per year. 12,13 The patient's perception of facial paralysis within the broader setting of NF2, in our experience, cannot be overemphasized. In distinction to most other facial paralysis patients, the timing of surgery for facial paralysis seems less "urgent" for NF2 patients.…”

Clinical trials targeting neurofibromatoses-associated tumors: a systematic review

“…In addition, some centers use radiation therapy and bevacizumab in selected patients. 54 In the modern era, few patients with NF2 who have access to specialized neuro-otologic treatment die due to vestibular schwannomas. Operative mortality is less than 1% and recurrence rates are minimal.…”