运用磁共振弥散张量成像观察显微血管减压术后三叉神经的结构变化

目的：利用磁共振弥散张量成像（DTI）序列，观察显微血管减压术（MVD）后，三叉神经痛（TN）患者三叉神经的微观结构改变。方法9例原发性 TN 患者术前及术后行 DTI 扫描，测算两侧三叉神经向异性分数（FA）、平均弥散率（MD）、轴向弥散率（AD）、垂直弥散率（RD）和两侧各弥散参数差值比。按手术疗效分为治愈和未治愈两组，分析两组患者在手术前后，两侧三叉神经各 DTI 参数及两侧间各弥散参数差值比的变化。结果男性6例，女性3例；平均年龄52．1岁，平均病程5．1年。于术后第一次复查（平均12．3个月）时行 DTI ，术后疗效随访平均66个月。治愈组6例，均有明显的血管压迫，三叉神经有受压变形；未治愈组3例，2例有血管压迫，1例患者仅有严重的蛛网膜粘连而无血管压迫。治愈组术前患侧明显下降的 FA 值及明显上升的 MD 、RD 值，术后复查时均恢复。而未治愈组的各弥散参数及差值比则在手术前后无明显变化。结论 MVD 术后疼痛消失的患者，患侧三叉神经的脱髓鞘变恢复正常。然而术后疼痛仍然存在的患者，神经的脱髓鞘变依然存在。三叉神经的脱髓鞘变与 TN 关系密切。

Structural changes of trigeminal nerve after microvascular decompression by magnetic resonance diffusion tensor imaging

Objective To evaluate the microstructural changes of trigeminal nerve by using mag-netic resonance diffusion tensor imaging (DTI) sequence in patients with trigeminal neuralgia (TN) after microvascular decompression (MVD) .Methods Nine patients with primary TN were evaluated by DTI before and after MVD .The FA ,MD ,AD ,RD and difference ratio of the bilateral dispersion parameters were calculated .Patients were divided into two groups according to final results of MVD :cure group and not cure group .The changes of parameters of DTI were compared between bilateral before and after MVD .Results Six male and three women were included .The mean age was 52 .1 years ,and mean course of disease was 5 .1 years .DTI was used at the first review (average 12 .3 months) ,the average follow -up was 66 months after operation .Six patients were complete recovery (all had obvious vascular com-pression ,the trigeminal nerve was compressive deformation) ,while 3 patients remaining suffered TN (2 patients had vascular compression ,1 patients had severe subarachnoid adhesions and without vascular compression) .In the cure group ,the decreased FA and increased MD and RD were all recovered after MVD .In the not cure group ,there was no significant differences in all the DTI parameters before and af-ter MVD .Conclusions The changes of demyelination of ipsilateral trigeminal nerve are recovered to be normal in the patients with pain disappeared after MVD ;while the changes of demyelination of ipsilateral trigeminal nerve still existe in the patients with pain after MVD .The relationship between the changes of demyelination of trigeminal nerve and TN is closely related .