Division of Neurology, University of Toronto.
Can J Neurol Sci. 2013 Sep;40(5):652-6. doi: 10.1017/s0317167100014876.
Patients with chromosome 22q11.2 deletion syndrome (22q11DS) are at a seven fold increased risk of developing seizures. However, only a fraction of these patients exhibit structural abnormalities such as polymicrogyria (PMG) and periventricular nodular heterotopia (PNH) that are known to cause seizures and to be associated with 22q11DS. In this study we used a dedicated seizure imaging protocol to look for additional structural abnormalities in these individuals that may explain the elevated risk of seizure disorder in this patient group.
Nineteen consecutive adult subjects with 22q11DS underwent a 3 Tesla MRI with a dedicated high-resolution seizure protocol. Neurological exam was performed in all patients. Genome-wide analysis excluded the presence of other pathogenic microdeletions or duplications.
Structural abnormalities were found in 11 of 14 subjects with sufficient image quality. These included three patients with PNH, one of whom had associated PMG. In addition, there was a surprisingly high prevalence of unilateral hippocampal malrotation (HIMAL), observed in 9 of 14 cases (64%). EEG findings showed interictal epileptiform discharges with focal distribution in four patients and generalized discharges in one patient.
The results suggest that, in addition to other known structural abnormalities, 22q11DS is associated with HIMAL. It has been suggested that this developmental abnormality of the hippocampus may predispose or otherwise contribute to epileptogenesis. However in this study we observed HIMAL in a large proportion of patients, with and without epilepsy. Therefore, other as yet unknown factors may contribute to the high prevalence of epilepsy in this population.
22q11.2 号染色体缺失综合征（22q11DS）患者癫痫发作的风险增加七倍。然而，只有少数患者表现出结构异常，如多微小脑回（PMG）和脑室周围结节性异位（PNH），这些异常已知会引起癫痫发作，并与 22q11DS 相关。在这项研究中，我们使用了专门的癫痫成像方案，以寻找这些个体中可能导致癫痫发作风险增加的其他结构异常。
19 名连续的 22q11DS 成年患者接受了 3T MRI 检查，采用了专门的高分辨率癫痫协议。所有患者均进行了神经系统检查。基因组分析排除了其他致病性微缺失或重复的存在。
在 14 名具有足够图像质量的患者中发现了结构异常。其中包括 3 名 PNH 患者，其中 1 名伴有 PMG。此外，令人惊讶的是，单侧海马旋转不良（HIMAL）的患病率很高，在 14 例中有 9 例（64%）。脑电图发现 4 例患者有局灶性分布的发作间期癫痫样放电，1 例患者有全身性放电。
结果表明，除了其他已知的结构异常外，22q11DS 还与 HIMAL 相关。有人认为，海马的这种发育异常可能易患或有助于癫痫的发生。然而，在这项研究中，我们观察到 HIMAL 在很大一部分有或没有癫痫的患者中存在。因此，其他未知因素可能导致该人群中癫痫的高患病率。
