Faculty of Medicine, University of Toronto, ON, Canada/Division of Neurosurgery, Department of Surgery, Toronto Western Hospital, University Health Network, University of Toronto, Toronto, ON, Canada.
Division of Neurosurgery, Department of Surgery, Toronto Western Hospital, University Health Network, University of Toronto, Toronto, ON, Canada.
Mult Scler. 2020 Dec;26(14):1877-1888. doi: 10.1177/1352458519886070. Epub 2019 Nov 26.
Gamma Knife radiosurgery (GKRS) is a minimally invasive procedure for trigeminal neuralgia secondary to multiple sclerosis (MS-TN). Patients with MS-TN experience suboptimal response rates to treatment, and the relationship between trigeminal microstructure and treatment outcome is poorly understood.
To characterize imaging features of MS-TN pain and GKRS response.
3 T diffusion-weighted imaging (DWI), T1-w, T2-w, and fluid-attenuated inversion recovery (FLAIR) sequences were acquired for 18 MS-TN patients undergoing GKRS. Brainstem plaques were standardized into a common space to determine plaque distribution. Ratio of T1-w/T2-w or "myelin maps (MM)" was generated. Multi-tensor tractography was used to delineate the radiosurgical target (RT), root entry zone (REZ), and proximal pontine segment (PPS) of the trigeminal nerves.
Laterality of MS-TN is associated with increased axial diffusivity at the PPS, whereas decreased MM at the PPS correlated with poor GKRS response. Preoperatively, GKRS responders have higher fractional anisotropy at the RT, higher axial diffusivity at the REZ, and higher MM intensities at the PPS.
This study demonstrates that diffusivities and MM intensities are important correlates of pain and treatment response, respectively. Overall, preoperative multimodal assessment of the central trigeminal pathway is a better indicator of GKRS response than postoperative assessment of the reduction in fractional anisotropy peripherally.
伽玛刀放射外科手术（GKRS）是治疗多发性硬化症继发三叉神经痛（MS-TN）的一种微创方法。MS-TN 患者的治疗反应率不理想，而三叉神经微观结构与治疗效果之间的关系尚未得到充分了解。
描述 MS-TN 疼痛和 GKRS 反应的影像学特征。
对 18 例接受 GKRS 治疗的 MS-TN 患者进行了 3T 弥散加权成像（DWI）、T1-w、T2-w 和液体衰减反转恢复（FLAIR）序列采集。脑干斑块被标准化到一个共同的空间，以确定斑块的分布。生成 T1-w/T2-w 比值或“髓鞘图（MM）”。多张量轨迹描绘用于勾画放射外科靶点（RT）、神经根入口区（REZ）和三叉神经的近端脑桥段（PPS）。
MS-TN 的偏侧性与 PPS 处的轴向弥散度增加有关，而 PPS 处的 MM 减少与 GKRS 反应不良相关。术前，GKRS 反应者在 RT 处的各向异性分数较高，在 REZ 处的轴向弥散度较高，在 PPS 处的 MM 强度较高。
本研究表明，弥散度和 MM 强度分别是疼痛和治疗反应的重要相关因素。总体而言，中央三叉神经通路的术前多模态评估是 GKRS 反应的更好指标，而不是术后评估周围各向异性分数的降低。
