Higher brain function changes after selective amygdala-hippocampai radiosurgery in medial temporal lobe epilepsy : Relationship between neuropsychological findings and functional MRI

放射外科治疗难治性颞叶癫痫已成为一种非侵入性替代切除的方法。我们报告伽玛刀放射治疗7例患者的结果，2男5女，医学上难治性内侧颞叶。患者接受了手术前和手术后的评估，包括视频脑电图、MRI、SPECT、PET、功能性MRI和神经心理测试。在前两个病例中，我们以18 Gy至50%等剂量线的边际剂量治疗，完全覆盖杏仁核、海马头部和体以及海马旁回。在这两个病例中，磁共振成像显示放射手术后内侧颞叶结构的发现没有明显改变，该手术未能控制癫痫发作。两例患者分别在放射术后30个月和16个月行前颞叶切除术后癫痫发作消失。切除标本的组织学检查显示海马硬化，星形胶质细胞反应性，坏死灶小或无坏死灶。这些发现提示低剂量放射手术不能达到足够的抗癫痫效果。此外，5例患者接受高剂量治疗，边际剂量为25gy至50%等剂量线，放射外科治疗。所有患者在伽玛刀放射治疗后仍有相同频率的癫痫发作。这些患者的磁共振成像显示内侧颞叶明显水肿。根据我们对7例失败的伽玛刀放射手术的有限经验，很难得出任何明确的结论。为了通过放射手术实现癫痫停止，可能需要完全破坏内侧颞结构，如切除。

The use of radiosurgery in the treatment of intractable temporal lobe epilepsy has emerged as a non-invasive alternative to resection. We report the results of gamma knife radiosurgery in seven patients, two males and five females, with medically refractory medial temporal lobe. The patients had received pre- and post-surgical evaluation that included video-EEG, MRI, ictal SPECT, octal PET, functional MRI, and neuropsychological tests. In first two cases, we treated with a marginal dose of 18 Gy to the 50 % isodose line, which completely covered the amygdala hippocampal head and body, and parahippocampal gyrus. In both cases, MR imaging revealed no remarkable change of findings in medial temporal lobe structure after radiosurgery and this procedure failed to control seizures. Both patients became seizure free after undergoing anterior temporal lobectomy 30 and 16 months, respectively, after radiosurgery. Histological examination of the resected specimen revealed hippocampal sclerosis, reactive astrocytes, and small or no necrotic focus. These findings suggests that low-dose radiosurgery failed to achieve sufficient anti-epileptic effects. In addition, five patients were treated with high dose, a marginal dose of 25 Gy to the 50% isodose line, radiosurgery. All patients continued to thave seizures with the same frequency after gamma knife radiosurgery. MR imaging in these patients revealed marked edema in the medial temporal lobe. It is difficult to draw any definite conclusion based on our limited experiencee with seven cases of failed gamma knife radiosurgery. To achieve seizure cessation by using radiosurgery, it may be necessary to destroy the medial temporal structures completely, as in a resection.