Post-surgical vestibular schwannoma remnant tumors: What to do?

BackgroundVestibular schwannomas (VS) are benign tumors of the vestibular nerve's myelin sheath. The current trend in VS surgery is to preserve at the facial function, even if it means leaving a small vestibular schwannoma tumor remnant (VSTR) after the surgery. There is no defined therapeutic management VSTR. The aim of this study was to assess the evolution of the VSTR to define the best therapeutic management and identify predictive factors of VSTR progression.MethodsAmong the 256 patients treated surgically for VS in the Department of Neurosurgery at Angers University Hospital, 33 patients with a post-surgical VSTR were included in this retrospective study. For all surgical patients, the data collected were age at diagnosis, the Koos classification, the surgical access, the existence of a type 2 neurofibromatosis (NF2), the TR location and size on control MRI-scans. Patients had a bi-annual follow-up with clinical status and VSTR size assessment with MRI-scan. Survival analyzes were performed to determine the time and rate of VSTR progression, and identify factors of progression.ResultsThe mean follow-up of the population was 51 months. All VS remnant progression occurred between 38 and 58 months after surgery. In non-NF2 patients with first follow-up MRI-scan three months after surgery, 43% presented a spontaneous regression, 50% a stability and 7% a progression of the VSTR. In the same population with the 1-year MR-scan after surgery as baseline, 25% presented a spontaneous regression, 62.5% a stability and 12.5% a VSTR progression. These data are consistent with the data reported in the literature. The post-operative facial function impairment and an initial remnant ≥ 1.5 cm³ were found to be significant risk factors of VS remnant progression in non-NF2 population in univariate analysis (P = 0.048 and 0.031) but not in multivariate analysis.ConclusionIn our experience, the best therapeutic management of the post-surgical VSTP in non-NF2 patients with no risk factor of progression is a simple clinical radiological follow-up otherwise complementary radiosurgery should be considered.     

Preoperative Identification of Facial Nerve in Vestibular Schwannomas Surgery Using Diffusion Tensor Tractography

Objective

Facial nerve palsy is a common complication of treatment for vestibular schwannoma (VS), so preserving facial nerve function is important. The preoperative visualization of the course of facial nerve in relation to VS could help prevent injury to the nerve during the surgery. In this study, we evaluate the accuracy of diffusion tensor tractography (DTT) for preoperative identification of facial nerve.

Methods

We prospectively collected data from 11 patients with VS, who underwent preoperative DTT for facial nerve. Imaging results were correlated with intraoperative findings. Postoperative DTT was performed at postoperative 3 month. Facial nerve function was clinically evaluated according to the House-Brackmann (HB) facial nerve grading system.

Results

Facial nerve courses on preoperative tractography were entirely correlated with intraoperative findings in all patients. Facial nerve was located on the anterior of the tumor surface in 5 cases, on anteroinferior in 3 cases, on anterosuperior in 2 cases, and on posteroinferior in 1 case. In postoperative facial nerve tractography, preservation of facial nerve was confirmed in all patients. No patient had severe facial paralysis at postoperative one year.

Conclusion

This study shows that DTT for preoperative identification of facial nerve in VS surgery could be a very accurate and useful radiological method and could help to improve facial nerve preservation.     

三叉神经鞘瘤的分型及手术入路的选择

目的 探讨三叉神经鞘瘤的诊断治疗及肿瘤的分型和手术入路的关系.方法 回顾分析156例经手术和病理证实的三叉神经鞘瘤的临床特点、分型、手术入路及预后.结果 面部感觉减退或异常和头痛头晕是最常见的临床表现,平均病程29.3个月,术前KPS评分平均79.70±8.10.颅眶型7例,海绵窦型48例,颞下窝型19例,后颅窝型11例,岩尖骑跨型71例.全切除145例(92.9%)、近全切除11例、无手术死亡.随访到131例患者(84.0%),平均随访35.5个月,124例正常生活(94.7%).结论 根据肿瘤的分型及生长方式选择合适的手术入路,可在最大限度切除肿瘤的同时,保护腩神经的功能,获得良好的手术效果.     

脑实质内神经鞘瘤并文献复习

目的初步探讨脑实质内神经鞘瘤发病机制,影像学表现,病理学特征,提高诊断率。方法通过对1例脑内神经鞘瘤,并结合文献复习进行分析。结果本例患者术前诊断胶质瘤,术中见肿瘤与脑组织无浸润,手术全切,术后病理及免疫组化证实为神经鞘瘤,痊愈后出院。结论脑实质内神经鞘瘤极为罕见,其发病性质不明,易误诊,确诊有赖于病理及免疫组化。     

Multiple unilateral schwannomas: segmental neurofibromatosis type 2 or schwannomatosis?

Schwannomas are benign solitary tumours of the peripheral nerve sheaths. The occurrence of multiple schwannomas usually implies hereditary disease. The most frequent syndrome associated with multiple schwannomas is neurofibromatosis type 2 (NF2), which is defined by bilateral vestibular schwannomas. Schwannomatosis is a distinct disease characterized by multiple pathologically proven schwannomas in the absence of vestibular schwannomas. It is not currently known if the presence of multiple schwannomas confined to a limb may represent a mosaic form of NF2 or a distinct disease, because mutation analysis of these tumours is not routinely performed. We report a 31-year-old patient who presented with multiple slowly growing subcutaneous tumours on his left arm. His family history was negative for cutaneous tumours or central nervous system disease, and he did not have additional features of NF2. Magnetic resonance tomography and ophthalmological examination excluded vestibular schwannoma and eye stigmata of NF2. After resection of three tumours, histological analysis confirmed the diagnosis of benign schwannomas. Molecular genetic analysis by temperature gradient gel electrophoresis and microsatellite marker analysis demonstrated two distinct mutations of the NF2 gene (NF2) in two different schwannomas, with concomitant loss of heterozygosity in both tumours. In contrast, neither normal skin nor peripheral blood lymphocytes revealed mutations of NF2. The clinical and molecular genetic findings suggest that the diagnosis in our patient is schwannomatosis rather than segmental NF2 because the mutations found in different tumours were not identical. The possibility of a localized predisposition for the acquisition of NF2 mutations is discussed.     

三叉神经鞘瘤的手术入路探讨

目的探讨三叉神经鞘瘤的外科治疗方法。方法回顾性总结分析我院自1991年1月至2003年12月采用显微手术治疗的36例三叉神经鞘瘤。结果本组病例中肿瘤全切除32例，次全切除4例。术后颅神经功能障碍较术前改善16例，无明显变化12例，加重9例，出现新的颅神经麻痹4例（不完全性麻痹）；2例出现脑脊液漏和颅内感染，经腰穿置管脑脊液引流和抗生素治疗痊愈。术后随访6-48个月，除2例分别于手术后36个月、40个月复发并行二次手术治疗外，其余病人均恢复良好。结论三叉神经鞘瘤生长方式复杂，应根据肿瘤的生长方式选择手术入路。颅底入路对脑组织牵拉轻，术野显露好，可进行多角度操作，有助于提高肿瘤的全切率、降低病残率。     

alpha(v)beta(3) Integrin in central nervous system tumors

alpha(v)beta(3) Is an integrin specifically expressed in endothelial cells of newly forming blood vessels. Integrin-mediated angiogenesis is hypothesized to play a central role in the development and the progression of central nervous system neoplasms. Accordingly, it is considered a potential target for antiangiogenic therapy. In the current study, we compare the expression of alpha(v)beta(3) in ependymomas, oligodendrogliomas, pilocytic astrocytomas, medulloblastomas, and vestibular schwannomas (acoustic neuromas). Samples of 5 tumors of each of the 5 tumor types were harvested surgically and frozen. After the pathological diagnosis was confirmed, immunohistochemistry was performed using an anti- alpha(v)beta(3) monoclonal antibody (LM609). The expression of alpha(v)beta(3) was assessed using a 4-tiered (0-3) grading scheme reflecting the percentage of positively staining vessels. All vestibular schwannomas demonstrated strong (grade 3) alpha(v)beta(3) expression. The expression was uniformly prominent in Antoni B regions of the tumors. Of 5 ependymomas, 4 demonstrated uniformly strong alpha(v)beta(3). Oligodendrogliomas, medulloblastomas, and pilocytic astrocytomas demonstrated more variable alpha(v)beta(3). alpha(v)beta(3) may contribute significantly to angiogenesis in vestibular schwannomas and ependymomas. Despite the high vascular density of oligodendrogliomas, pilocytic astrocytomas, and medulloblastomas, these tumors had variable moderate alpha(v)beta(3) expression. This discrepancy suggests temporal and/or regional variability in the angiogenesis in these types of tumor. This study provides the first demonstration of alpha(v)beta(3) expression in vestibular schwannomas, medulloblastomas, and pilocytic astrocytomas.     

Hormone receptors in vestibular schwannomas

Summary The possibility that steroid hormones play a role in vestibular schwannoma proliferation has been suggested by a number of investigators. There is conflicting information about the presence of steroid hormone receptors in these tumors. The aim of this study was to examine the expression of androgen, progesterone, glucocorticoid and estrogen receptor messenger ribonucleic acid levels (mRNA) in twenty-one vestibular schwannomas by either Northern blot analysis or the polymerase chain reaction (PCR).Glucocorticoid receptor mRNA was expressed in all twentyone tumors examined. Only two male specimens were positive for androgen receptor mRNA expression by PCR-Southern blot analysis. Thirty-three percent of the schwannomas (7/21) showed a strong band for progesterone receptor mRNA by PCR-Southern blot analysis; there were an equal number of males and females in this group. Estrogen receptor mRNA levels were undetectable in all tumors examined by PCR-Southern blot analysis. These studies suggest that the pattern of steroid receptor expression is different in schwannomas than in meningiomas. Individual vestibular schwannomas need to be examined for their steroid receptor mRNA expression mRNA expression to know whether they will be responsive.     

Les neurofibromes de la maladie de Recklinghausen

Résumé L'examen en microscopie optique et électronique de 6 neurofibromes prélevés chirurgicalement chez des patients atteints de maladie de Recklinghausen autorise un certain nombre de conclusions:l'ultrastructure des neurofibromes est faite de 2 types de cellules (cellules de Schwann et fibroblastes) dispersées au sein d'un espace extra-cellulaire contenant de nombreuses fibres de collagène. Des axones myélinisés et amyéliniques sont présents;l'aspect ultrastructural de 3 neurinomes de l'acoustique a été comparé à celui des neurofibromes et apparaît comme différent. Les neurinomes sont faits d'un seul type cellulaire (très probablement cellule de Schwann), le collagène y est beaucoup moins abondant, les axones absents. Quelques déductions pathogéniques et nosologiques sont proposées.

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Neurofibromas in von Recklinghausen's Disease. Ultrastructural study and nosologic relation to neurinomas

Summary Six neurofibromas from patients with von Recklinghausen's disease have been examined by light and electron microscopy: 2 types of cells have been found (Schwann cells and fibroblasts) scattered in extracellular spaces rich in collagen fibers. Myelinated and nonmyelinated axons were observed.These data have been compared with other ones collected from 3 acoustic neurinomas. These latter contained only one cellular type (very likely to be Schwann cell), much less collagen and no axon at all. A pathogenic and nosologic discussion is given.