1Department of Neurosurgery, Neurological Institute of Curitiba, Brazil.
2Department of Skull Base Surgery, Clinica Bio Bio, Concepción; and.
J Neurosurg. 2023 Mar 31;139(4):984-991. doi: 10.3171/2023.2.JNS222547. Print 2023 Oct 1.
The objective was to evaluate whether the position of the nerves within the internal auditory canal (IAC) has any effect on preoperative and postoperative cochlear and facial nerve function in patients with intracanalicular vestibular schwannoma (VS) resected through the retrosigmoid transmeatal approach.
Forty-four patients with sporadic intracanalicular VS, from a series of 710 patients with VS who underwent operations from January 1993 to April 2022, were retrospectively reviewed. The pattern of displacement of the cranial nerves and tumor within the IAC was recorded. Tumors were divided into 2 types: type T1A lesions had only anteriorly displaced nerves, and type T1B had posteriorly displaced vestibular nerves and anteriorly displaced facial and cochlear nerves. Differences in surgical outcomes between groups in terms of facial nerve function and hearing preservation were evaluated.
Thirty-five cases (79.5%) were T1A tumors and 9 were T1B (20.5%). Gross-total resection and anatomical preservation of the facial and cochlear nerves were achieved in all patients. Postoperatively, all patients with T1A VS maintained normal facial nerve function; however, among T1B VS patients, 6 (67%) retained House-Brackmann grade I, 2 worsened to grade II, and 1 worsened to grade III at 6 months (p = 0.006). The 27 T1A VS patients with serviceable hearing maintained this status, and an additional patient with nonserviceable hearing improved to serviceable hearing; among T1B VS patients, only 2 of the 5 patients with serviceable hearing remained as such, 2 evolved to nonserviceable hearing, and 1 lost hearing after surgery (p = 0.0022). T1B VS patients had a 24-fold risk of facial nerve deterioration (relative risk [RR] 25.2, 95% CI 1.42-448.57, p = 0.028) and a 32-fold risk of hearing deterioration (RR 32.7, 95% CI 1.93-553, p = 0.016) after surgery.
In intracanalicular VS, postoperative cochlear and facial nerve function are directly related to the location of the tumor in relation to the nerves, with worse outcomes in cases where the tumor is located between the vestibular and facial-cochlear nerves.
评估内听道（IAC）内神经的位置是否会影响通过乙状窦后经耳道入路切除的管内前庭神经鞘瘤（VS）患者的术前和术后耳蜗和面神经功能。
回顾性分析 1993 年 1 月至 2022 年 4 月期间接受手术的 710 例 VS 患者中，44 例散发性管内 VS 患者的神经和肿瘤在 IAC 内的移位模式。记录颅神经和肿瘤在 IAC 内的移位模式。肿瘤分为 2 型：T1A 病变只有神经向前移位，T1B 病变则为前庭神经向后移位，面神经和耳蜗神经向前移位。评估各组面神经功能和听力保留方面的手术结果差异。
35 例（79.5%）为 T1A 肿瘤，9 例为 T1B（20.5%）。所有患者均实现了肿瘤全切除和面神经及耳蜗神经解剖保留。术后，所有 T1A VS 患者面神经功能正常；然而，T1B VS 患者中，6 例（67%）保持 House-Brackmann Ⅰ级，2 例恶化至Ⅱ级，1 例恶化至Ⅲ级（p=0.006）。27 例 T1A VS 患者有可利用听力，1 例无听力患者改善至可利用听力；T1B VS 患者中，5 例有可利用听力的患者中仅 2 例保持，2 例恶化至无听力，1 例术后失聪（p=0.0022）。T1B VS 患者面神经恶化的风险增加 24 倍（相对风险[RR]25.2，95%CI 1.42-448.57，p=0.028），听力恶化的风险增加 32 倍（RR 32.7，95%CI 1.93-553，p=0.016）。
在管内 VS 中，术后耳蜗和面神经功能与肿瘤与神经的位置直接相关，肿瘤位于前庭神经和面神经-耳蜗神经之间时预后更差。
