Objective

To determine whether diffusion-weighted imaging (DWI) can help differentiate peri-ictal signal abnormality from limbic encephalitis (LE) among patients with medial temporal lobe T2-hyperintensity.

Methods

We retrospectively identified patients with peri-ictal medial temporal lobe T2-hyperintensity using a Mayo Clinic database, and reviewed their DWI to look for unique diffusion restriction patterns. We then identified patients with medial temporal lobe T2-hyperintensity and LE, and reviewed their DWI to see if these patterns were ever present. Presence of diffusion restriction patterns was confirmed by a blinded neuro-radiologist.

Results

We identified 10 patients without LE who had peri-ictal unilateral medial temporal lobe T2-hyperintensity, ipsilateral to focal seizure onset. Nine of 10 (90%) had at least one of two diffusion restriction patterns potentially unique to seizure activity; four had gyriform hippocampal diffusion restriction (“Pattern 1”), three had diffuse hippocampal diffusion restriction that spared the most medial temporal lobe structures (“Pattern 2”), and two had both diffusion restriction patterns. The median patient age was 62 years (range 2–76 years) and 3/9 (33%) were female. In comparison, among patients with medial temporal lobe T2-hyperintensity and LE, only 5/57 (9%) had one of the diffusion restriction patterns (“Pattern 2”) identified (P < 0.0001); all five had seizures reported.

Conclusions

In patients with medial temporal lobe T2-hyperintensity and one of the diffusion restriction patterns described herein, the signal abnormality may be a peri-ictal phenomenon rather than indicative of LE and should prompt investigation for seizure. Even in patients with LE, these patterns should raise concern for seizure.

中文翻译：

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使用扩散加权成像来区分与癫痫相关的改变与边缘性脑炎。

目的

为了确定弥散加权成像（DWI）是否可以帮助区分颞叶内侧T2型高强度患者的周壁信号异常与边缘性脑炎（LE）。

方法

我们使用Mayo Clinic数据库回顾性鉴定了患有尖周周围颞叶T2型高强度的患者，并回顾了他们的DWI以寻找独特的扩散限制模式。然后，我们确定了颞中叶T2高血压和LE患者，并对其DWI进行了检查，以查看是否存在这些模式。盲人神经放射科医生证实了扩散限制模式的存在。

结果

我们确定了10例无LE的患者，这些患者患有围发性单侧颞叶内侧颞叶T2高血压，与局灶性癫痫发作同侧。10个中的9个（90％）具有可能对癫痫发作活动特有的两个扩散限制模式中的至少一个；四个具有回旋状海马扩散限制（“模式1”），三个具有弥散的海马扩散限制，其保留了最内侧的颞叶结构（“模式2”），两个具有两个扩散限制模式。患者中位年龄为62岁（2-76岁），女性为3/9（33％）。相比之下，在颞叶内侧T2高血压和LE的患者中，只有5/57（9％）的患者出现了一种扩散限制模式（“模式2”）（P  <0.0001）；五人均报告有癫痫发作。

结论

在患有颞中叶T2高血压和本文描述的扩散限制模式之一的患者中，信号异常可能是一种眼周现象，而不是LE的征兆，应及时调查癫痫发作。即使在LE患者中，这些模式也应引起癫痫发作的关注。