PET定位致痫灶γ-刀治疗难治性癫痫的临床研究

Sublesion-dose gamma knife treatment for intractable epilepsy through positron emission tomography localization

目的探讨正电子发射断层扫描(PET)对难治性癫痫的定位价值,评价γ-刀治疗难治性癫痫的效果及脑电图改变。方法43例患者主要依据PET显像,结合癫痫发作特点、EEG、MRI等检查综合定位致痫灶,应用MASEP-SRRS型旋转式γ-刀治疗,单纯性致痫灶照射边缘剂量为9～14Gy,等中心曲线40%～60%。需加照射杏仁核和海马时,边缘剂量25～30Gy;照射胼胝体时中心剂量75～100Gy,均为50%等剂量曲线。随访3～36个月,观察发作频率、脑电图变化情况,评价治疗效果。结果43例患者中,39例(90.7%)为发作间期的PET图像,表现皮层局限性低代谢灶,其中单发灶33例(84.6%),多发灶6例(15.4%);4例(9.3%)为发作期的PET图像,表现皮层单发的局限性高代谢灶;异常代谢灶常见于颞叶,其次为额叶。发作频率术前5.2±2.6次/月,术后12个月降至1.3±0.9次/月,随访结束时降至0.9次/月左右,与治疗前相比差异具有显著性意义(P<0.01)。对随访6～36个月的病人进行Wieser疗效评定,Ⅰ～Ⅱ级为31.4%～38.9%,Ⅲ～Ⅳ级为43.6%～51.4%,Ⅴ～Ⅵ级为15.3%～23.1%,其中Ⅰ～Ⅳ级(有效率)为76.9%～84.6%。EEG逐渐恢复正常为7.7%～16.7%,53.8%～62.9%好转,22.2%～38.5%无变化,好转率61.5%～77.8%。主要并发症为放射性脑水肿,发生率为16.7%,经对症治疗后均能缓解。结论PET辅助定位下,低剂量γ-刀治疗顽固性癫痫具有较高的有效率,无严重并发症,是一种有效的癫痫微侵袭外科治疗方法;采用9～14Gy的周边剂量照射PET提示的致痫灶可取得良好效果。

Objective To discuss the clinical value of ^18F- Fluoroaeoxygmcose （^18F-FDG）PET cerebral imaging in focus localization of patients with intractable epilepsy, and evaluate the clinical effect in intractable epilepsy treatred by gamma knife with sublesion-dose. Methods PET examination based on ^18F-Fluorodeoxyglucose （^18F-FDG） was carried out in 43 patients in order to localize epileptogenic foci, and the treatment target was comfirmed by the combi- nation of CT, MRI, AEEG, Clinical manifestation, according to the results of examination. The treatment outcomes of 43 patients with intractable epilepsy treated by Masep-SRRS Gamma Knife were retrospectively analyzed. Peripheral radiation dose of 9~14 Gy to isodose line of 40%-60% was managed when target was pointed to the epileptogenic focus, and 25-30 Gy to 50% was managed to the homolateral amygdala and hippocampus if necessary, and 38-50 Gy to 50% was managed to the callosum if necessary. The follow-up time were 3-36 months. The seizure frequency of epilepsy and was recorded to evaluate the therapeutic effect. Results In interictal PET images, 39 patients （90.7 %） showed focal hypometabolism, single focus 33 cases, multiple focus 6 cases. 4 patients （9.3%） showed focal hypermetabolism. The seizure frequency declined from （5.2±2. 6） times permonth before gamma knife permonth（1.3±0. 9）times permonth 12 months after treatment, and 0. 9 permonth till the end of the follow--up. The follow--up time were 6-36 months. 31.4%-38. 9% was classified as Wieser grades I and lI , which were regarded as cured, 43. 6-51. 40% as grades Ⅲ and IV, as effective, and 15. 3-23. 1% as grades V and Vl, as ineffective. According to EEG follow--up data, there were 7. 7%-16.7% with normal recording, 53. 8%-62. 9% with improving recording, 22. 2%-38. 5% with no change of recording. The main complication was radiation-induced cerebral edema with an incidence rate of 16. 7%, and relieved after symptomatic treatment. Conclusion Stereotactic gamma knife treatment with low radiation dose under the guidance of PET provides a safe, effective and minimally invasive surgical approach for patients with intractable epilepsy, and peripheral radiation doses of 9 to 14 Gy for the epileptic loci localized by PET is sufficient to ensure good clinical outcome.