1ENT Department, Pitié-Salpêtrière, APHP, Sorbonne University, Paris, France.
2Technologies and Gene Therapy for Deafness (TGTD), Hearing Institute/Pasteur Institute/INSERM, Paris, France.
J Neurosurg. 2023 Sep 15;140(3):856-865. doi: 10.3171/2023.7.JNS23138. Print 2024 Mar 1.
The natural history of sporadic vestibular schwannoma (VS) is unpredictable, as tumors may or may not grow and can even spontaneously regress. A spontaneous VS shrinkage MRI-based pattern has been proposed with either a scalloped tumor aspect in the cerebellopontine angle or the appearance of a CSF-filled space surrounding the intracanalicular (IC) tumor within an enlarged canal. The authors of this retrospective study aimed to describe the evolution of sporadic VSs with radiological signs of VS regression and to identify prognostic factors for tumor shrinkage.
All MRI scans obtained during patient follow-up were reviewed for extracanalicular (EC) and IC size and tumor characteristics. Volumetric measurements were performed on the first and last MRI scans. Shrinkage was considered to have occurred if the tumor size had decreased by ≥ 2 mm in its largest diameter and/or if the volume had decreased by ≥ 20%. Audiometric data were also collected.
Among 512 patients under observation for sporadic VSs, 66 (13%) had at least one radiological sign of VS regression and 31 of these (6% overall) had confirmed tumor shrinkage. The mean follow-up was 4 ± 2.5 years. One radiological sign was present on initial MRI in 58% of patients and appeared during the follow-up period in the remaining 42%. Two groups were identified: 31 patients (47%) demonstrated progressive tumor regression during follow-up, and tumors in 35 patients (53%) remained stable once signs of regression were identified (assuming a stabilized regression). The prognostic factors for VS regression were as follows: EC VS extension (p = 0.02), cystic lesion (p = 0.002), and central necrosis (p = 0.02). The mean pure-tone average (PTA) was 43 ± 26.2 dB at the time of diagnosis and 53 ± 28.3 dB at the last visit (p < 0.0001). Among patients with an observed tumor shrinkage, ∆PTA was lower if the inner ear signal on the high-resolution T2-weighted image had improved (-3 ± 8.9 dB, n = 11) than if the inner ear signal had not improved (-10 ± 6.9 dB, n = 20) (p = 0.02) between the initial and last MRI scans.
Spontaneous shrinkage of sporadic VSs could be suspected based on two radiological aspects that are indicative of VSs in progressive or stabilized regression and is an additional argument for the conservative management of these tumors. During follow-up, recovery from a reduced to a normal cochlear fluid MRI signal is a good indicator for hearing preservation.
散发前庭神经鞘瘤（VS）的自然病程不可预测，肿瘤可能生长也可能不生长，甚至可能自发消退。有人提出了一种基于 MRI 的 VS 自发退缩模式，表现为桥小脑角处肿瘤呈扇贝状，或在扩大的管内出现围绕管内（IC）肿瘤的脑脊液填充空间。本回顾性研究的作者旨在描述具有 VS 消退影像学征象的散发 VS 的演变，并确定肿瘤退缩的预测因素。
对所有患者的随访 MRI 扫描进行了评估，以评估 EC 和 IC 大小以及肿瘤特征。在第一次和最后一次 MRI 扫描上进行了体积测量。如果肿瘤最大直径缩小≥2mm，或体积缩小≥20%，则认为发生了退缩。还收集了听力数据。
在 512 例接受散发 VS 观察的患者中，有 66 例（13%）至少有一处 VS 退缩的影像学征象，其中 31 例（总体 6%）经证实肿瘤退缩。平均随访时间为 4±2.5 年。58%的患者在初次 MRI 上存在 1 个影像学征象，其余 42%的患者在随访期间出现该征象。确定为肿瘤退缩的影像学征象后，患者被分为两组：31 例（47%）肿瘤持续退缩，35 例（53%）一旦出现退缩征象后肿瘤稳定（假设为稳定的退缩）。VS 退缩的预测因素如下：EC VS 延伸（p=0.02）、囊性病变（p=0.002）和中央坏死（p=0.02）。诊断时平均纯音平均听阈（PTA）为 43±26.2dB，最后一次就诊时为 53±28.3dB（p<0.0001）。在观察到肿瘤退缩的患者中，如果高分辨率 T2 加权图像内耳信号改善（-3±8.9dB，n=11），则与内耳信号未改善（-10±6.9dB，n=20）相比，△PTA 较低（p=0.02）。
根据预示 VS 持续或稳定退缩的两种影像学特征，可怀疑散发 VS 自发退缩，这为这些肿瘤的保守治疗提供了额外依据。在随访期间，从减小到正常的耳蜗液 MRI 信号恢复是听力保护的良好指标。
