From the Paris Brain Institute (G.V., E.A., P.B., V.N.), ICM, Inserm, CNRS, Sorbonne University; AP-HP (G.V., V.N.), EEG Unit, Department of Neurophysiology, Pitié-Salpêtrière Hospital; AP-HP (E.A.), Neurophysiology of Movement Disorders Unit, Department of Neurophysiology, Saint-Antoine and Pitié-Salpêtrière Hospital; AP-HP (M.A.D.R.Q., V.N.), Epilepsy Unit, Department of Neurology, Reference Center of Rare Epilepsies, ERN-EpiCare, Pitié-Salpêtrière Hospital; AP-HP (D.V.C., A.K.), Department of Nuclear Medicine, Pitié-Salpêtrière Hospital, APHP Sorbonne University; Sorbonne University (A.K.), Inserm, CNRS, Laboratoire D'Imagerie Biomédicale, LIB, Paris, France.
Neurology. 2024 Dec 10;103(11):e209994. doi: 10.1212/WNL.0000000000209994. Epub 2024 Nov 5.
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.
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 fluorodeoxyglucose PET/CT imaging.
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, = 0.004, n = 9) and 2 (11 ± 8.8 events/minute, = 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, < 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 ( < 10, n = 6).
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.
Lance-Adams 综合征（LAS），又称慢性缺氧后肌阵挛，是一种长期致残性的神经系统疾病，发生于缺氧幸存者中。该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。
我们进行了一项横断面研究，使用多模态神经检查调查了来自皮提-萨尔佩特里埃医院神经内科诊断为 LAS 的患者：定量分析的脑电图、肌阵挛的多导睡眠描记术记录、与抽搐锁定后平均相结合的脑电图-肌电图分析，以及氟脱氧葡萄糖 PET/CT 成像。
所有 18 例患者均有动作性多灶性或全身性肌阵挛。11 例患者还出现了癫痫发作，主要是全身性强直阵挛性发作。对于 8 例患者，肌阵挛在癫痫发作后会持续不同时间减少，从 1 天到 2 周不等。在中央中线区域识别出癫痫样放电（n = 14），在 Cz（65 ± 20 µV，n = 12）和 Fz（107 µV，n = 1）电极上具有最大振幅，并且在非快速眼动睡眠阶段 1（12 ± 8.5 事件/分钟， = 0.004，n = 9）和 2（11 ± 8.8 事件/分钟， = 0.016，n = 7）期间显著增加，与清醒时（5.5 ± 5.4 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， < 0.001，n = 9）。所有患者均证实存在持续时间＜50ms 的动作性肌阵挛抽搐，具有快速下行皮质脊髓途径组织，肱二头肌-第一骨间背侧延迟 9.8 ± 1ms（n = 8）。在肌肉抽搐之前确定了中央皮质的短暂变化（n = 14），对于胫骨前肌（n = 7）的平均潜伏期为-31.9 ± 2.9ms。在前中央皮质、辅助运动区、旁中央小叶（n = 6）和后中央皮质和楔前叶（n = 5）中观察到局部代谢降低。该代谢减少在 83%的患者的前中央皮质和 100%的患者的后中央皮质呈双侧性。基于体素的分析（ ＜ 10，n = 6）证实了前中央、辅助运动和后中央区域的低代谢。
我们的研究结果基于 LAS 大量患者队列，强烈提示皮质肌阵挛起源于运动皮质，并与癫痫样机制有关。
