前颞叶切除范围与视野缺损关系的弥散张量成像分析

Analysis of the impact of anterior temporal lobectomy on visual field in temporal lobe epilepsy patients with diffusion tensor imaging

目的 观察颞叶癫痫患者前颞叶切除术后视野缺损的发生率以及手术切除范围与视野缺损的关系.方法 25例前颞叶切除术的患者于术前及随访时行视野、磁共振（含DTI弥散张量序列）检查,根据视野缺损严重程度的不同将患者分为A、B、C三级.手术后视放射的各向异性分数（FA值）的下降（△FA）代表Meyer袢受损情况.比较不同视野缺损组之间前颞叶切除范围的差异;并对切除范围和△FA进行线性相关分析.结果 前颞叶切除术后22例患者出现象限盲.前颞叶平均切除长度：A组31.1 mm,B组42.5 mm,C组50.4 mm,A＜B＜C组（P＜0.05）.手术侧的△FA与切除范围旱线性相关.结论 前颞叶切除术破坏视放射导致视野缺损较常见.有必要术前应用DTI获得患者视放射的信息,进行术前风险评估.

Objective Anterior temporal lobectomy（ATL） for temporal lobe epilepsy （TLE） is the most commonly performed epilepsy surgery procedure.A visual field defect（VFD） due to the injury to the optic radiation may occur after ATL.DTI technique can visualize the optic radiation （OR） noninvasively.This study aimed at evaluating the incidence of VFD after ATL and investigating whether the resection size of lateral ATL correlated with the extent of VFD.We tried to explain the impact of ATL on the OR and to investigate the anterior extending of Meyer loop with DTI technology.Method 25 patients（ 14male, 11 female） underwent ATL for treatment of epilepsy.The patients were aged from 13 to 39 years old （ mean age：22.4 yrs）.All cases were classified into three groups on the basis of the severity of VFD（ A ～ C,with group C the most severe）.All patients had preoperative and follow up clinical and MRI（ including DTI series） examinations.The clinical and MRI（DTI） outcomes of these patients were retrospectively analyzed.Results At mean follow up period of 31.3 weeks （ range, 17 - 42 weeks）, we found 22 patients become quadrantanopia due to the injury to OR after ATL.A significant reduction of fractional anisotropy was demonstrated in the OR on the side of the temporal lobectomy.The severity of VFD decreased according to the reducing of the mean resection size（group A, 31.1 mm;group B 42.5 mm;C, 50.4 mm）, P ＜0.05.There was linearship between the resection size and the FA decrease.Conclusions VFD due to the injury to the OR was not uncommon after ATL There was an association between the resection size and severity of VFD.Optic radiation showed a decreased FA value in cases after ATL.There is considerable intersubjective variance about the OR, so it is necessary to get the patient＇s DTI information about the OR before the operation ,which could help to assess the preoperative risks.