BACKGROUND AND OBJECTIVES Lance-Adams syndrome (LAS), or chronic posthypoxic myoclonus, is a long-term disabling neurologic disorder occurring in survivors of anoxia. The cortical or subcortical origin of this myoclonus is unclear. We aimed to identify the neuroanatomical origin of myoclonus in LAS. METHODS We conducted a cross-sectional study and investigated patients diagnosed with LAS from the Department of Neurology of Pitié-Salpêtrière Hospital, using multimodal neurologic explorations: EEG with quantitative analyses, polygraphic EMG recording of myoclonus, coupled EEG-EMG analyses with jerk-locked back averaging, and 18fluorodeoxyglucose PET/CT imaging. RESULTS All 18 patients had action multifocal or generalized myoclonus. Eleven patients also presented seizures, mainly generalized tonic-clonic seizures. For 8 patients, myoclonus decreased after seizures for a variable duration, from 1 day to 2 weeks. Epileptiform discharges were identified over the central median region (n = 14), with a maximal amplitude on the Cz (65 ± 20 µV, n = 12) and Fz (107 µV, n = 1) electrodes, and a significantly increased frequency during non-rapid eye movement sleep stages 1 (12 ± 8.5 events/minute, p = 0.004, n = 9) and 2 (11 ± 8.8 events/minute, p = 0.016, n = 7) compared with wake (5.5 ± 5.4 events/minute). The duration of the cortical and muscular events was significantly and positively correlated (ρ = 0.58, p < 0.001, n = 9). Action myoclonic jerks with a duration of <50 ms were confirmed in all patients, with a fast-descending corticospinal way organization with a mean biceps brachii-first interossei dorsalis delay of 9.8 ± 1 ms (n = 8). A central cortical transient preceding the muscular jerks was identified (n = 14), with a mean latency of -31.9 ± 2.9 ms for the tibialis anterior muscle (n = 7). A regional metabolism decrease was observed in the precentral cortex, supplementary motor area, paracentral lobule (n = 6), and postcentral cortex and precuneus (n = 5). This metabolism decrease was bilateral in the precentral cortex for 83% of the patients and in the postcentral cortex for 100%. Hypometabolism in the precentral, supplementary motor, and postcentral areas was confirmed with a voxelwise analysis (p < 10-3, n = 6). DISCUSSION Our findings, based on a large cohort of patients with LAS, strongly suggest a cortical myoclonus, originating within the motor cortex and related to epileptiform mechanisms.

中文翻译：

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Lance-Adams 综合征肌阵挛起源的多模式评估。


背景和目标 Lance-Adams 综合征 （LAS） 或慢性缺氧后肌阵挛，是一种发生在缺氧幸存者中的长期致残性神经系统疾病。这种肌阵挛的皮质或皮质下起源尚不清楚。我们旨在确定 LAS 中肌阵挛的神经解剖学起源。方法 我们进行了一项横断面研究，并使用多模式神经学探查调查了来自 Pitié-Salpêtrière 医院神经病学科诊断为 LAS 的患者：脑电图定量分析、肌阵挛多图肌电图记录、耦合 EEG-EMG 分析与混蛋锁定回平均，以及 18 氟脱氧葡萄糖 PET/CT 成像。结果 所有 18 例患者均患有动作多灶性或全身性肌阵挛。11 例患者还出现癫痫发作，主要是全身强直阵挛发作。对于 8 例患者，肌阵挛在癫痫发作后减少，持续时间不一，从 1 天到 2 周不等。在中央正中区域 （n = 14） 上确定了癫痫样放电，在 Cz （65 ± 20 μV，n = 12） 和 Fz （107 μV，n = 1） 电极上振幅最大，在非快速眼动睡眠阶段 1 （12 ± 8.5 事件/分钟，p = 0.004，n = 9） 和 2 （11 ± 8.8 事件/分钟， p = 0.016，n = 7）与唤醒（5.5 ± 5.4 个事件/分钟）相比。皮质和肌肉事件的持续时间呈显著正相关 （ρ = 0.58，p < 0.001，n = 9）。所有患者均证实了持续时间为 <50 ms 的行动肌阵挛性抽搐，皮质脊髓方式组织快速下降，平均肱二头肌第一骨间骨延迟为 9.8 ± 1 ms （n = 8）。确定了肌肉抽搐之前的中央皮质短暂性 （n = 14），平均潜伏期为 -31.9 ± 2。胫骨前肌 9 毫秒 （n = 7）。在中央前皮层、辅助运动区、中央旁小叶 （n = 6） 以及中央后皮层和楔前叶 （n = 5） 观察到区域代谢下降。这种代谢下降在 83% 的患者的中央前皮层和 100% 的患者在中央后皮层中是双侧的。通过体素分析证实了中央前区、辅助运动区和中央后区的代谢减退 （p < 10-3， n = 6）。讨论 我们的研究结果基于一大群 LAS 患者，强烈表明皮质肌阵挛起源于运动皮层，与癫痫样机制有关。