Litre Claude F, Gourg Grégoire P, Tamura Manabu, Mdarhri Driss, Touzani Adil, Roche Pierre H, Régis Jean
Neurosurgery. 2007 May;60(5):853-9; discussion 853-9. doi: 10.1227/01.NEU.0000249282.46514.DA.
Radical resection of facial nerve schwannomas classically implies a high risk of severe facial palsy. Owing to the rarity of facial palsy after gamma knife surgery (GKS) of vestibular schwannomas, functional evaluation after GKS seems rational in this specific group of patients. To our knowledge, no previous similar evaluation exists in the literature.
Of 1783 schwannomas of the cerebellopontine angles treated by GKS at Timone University Hospital between July 1992 and May 2003, 11 were diagnosed as originating from the facial nerve. Criteria for this diagnosis were the involvement of the tympanic or mastoid segment of the facial nerve (n = 9) and/or preoperative observation of a facial nerve deficit that had occurred during previous microsurgery (two patients). The rare occurrence of facial palsy after vestibular schwannoma radiosurgery, usually within 18 months of treatment, has been considered only in the patients with more than 2 years of follow-up (n = 9).
Six of these patients experienced a previous spontaneous facial palsy on one (n = 4) or several occasions (n = 2). A normal motor facial function was observed in only three patients before GKS (House-Brackmann Grade II in six patients, Grade III in one patient, Grade IV in one patient). The median follow-up period was 39 months (range, 18-84 mo). At the time of the last follow-up examination, no patients had developed a new facial palsy or experienced deterioration of a preexisting facial palsy and three patients had improvement of a preoperative facial palsy. Ten out of the 11 tumors are stable or decreased in size; in the other, a microsurgical resection of the tumor had been recommended owing to the development of a cyst. Clinical management owing to the specificity and heterogeneity of this group of patients has required the development of an original classification of four anatomic subtypes presenting different clinical and surgical difficulties.
This first study demonstrates that radiosurgery allows treatment of these patients while preserving normal motor facial function. Such an advantage should lead to the consideration of GKS as a first treatment option for small- to medium-size facial nerve schwannomas.
面神经鞘瘤的根治性切除通常意味着严重面瘫的高风险。由于前庭神经鞘瘤伽玛刀手术（GKS）后面瘫罕见，对这一特定患者群体进行GKS后的功能评估似乎是合理的。据我们所知，此前文献中尚无类似评估。
1992年7月至2003年5月在蒂蒙大学医院接受GKS治疗的1783例桥小脑角神经鞘瘤中，11例被诊断为起源于面神经。诊断标准为面神经鼓室段或乳突段受累（9例）和/或术前观察到先前显微手术期间出现的面神经功能缺损（2例患者）。仅在随访超过两年的患者（9例）中考虑了前庭神经鞘瘤放射外科治疗后罕见的面瘫情况，通常发生在治疗后18个月内。
这些患者中有6例曾有过一次（4例）或多次（2例）自发性面瘫。GKS前仅3例患者面部运动功能正常（6例患者为House-Brackmann二级，1例患者为三级，1例患者为四级）。中位随访期为39个月（范围18 - 84个月）。在最后一次随访检查时，没有患者出现新的面瘫或原有面瘫恶化，3例患者术前面瘫有所改善。11个肿瘤中有10个大小稳定或缩小；另一个因囊肿形成而建议进行肿瘤显微切除术。由于该患者群体的特殊性和异质性，临床管理需要制定一种原始的解剖学亚型分类，该分类呈现出不同的临床和手术难题。
这项首次研究表明，放射外科能够在保留面部正常运动功能的同时治疗这些患者。这一优势应促使将GKS视为中小型面神经鞘瘤的首选治疗方案。
