Department of Neurology, Clínica Universidad de Navarra, University of Navarra School of Medicine, Pamplona, Spain; CIBERNED, Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas, Instituto de Salud Carlos III, Spain.
Parkinsonism Relat Disord. 2013 Nov;19(11):1013-7. doi: 10.1016/j.parkreldis.2013.07.004. Epub 2013 Aug 2.
Recently, orthostatic myoclonus (OM) has been suggested as a cause of gait impairment and unsteadiness in neurodegenerative diseases. The aim of this study was to investigate the frequency of orthostatic myoclonus, its clinical characteristics and the underlying associated neurological disorders.
A retrospective analysis of clinical data and electromyogram surface recordings from subjects with unexplained unsteadiness/gait impairment was performed. Diagnosis of OM was made when a pattern of non-rhythmic bursts was observed (duration range 20-100 ms; bursts per second ≤16).
Among 93 subjects studied, OM was the most frequent disorder (n = 16; 17.2%), followed by orthostatic tremor (13.9%) and low frequency tremors during orthostatism (12.9%). All patients with OM complained about unsteadiness during orthostatism and/or during gait. Leg jerking was only observed by visual inspection during orthostatism in four subjects and two also presented falls. Eleven out of 16 patients (68.7%) with OM had an associated neurodegenerative disease, such as multiple system atrophy (n = 3) Parkinson's disease (n = 2), Alzheimer's disease (n = 2), mild cognitive impairment (n = 2) and normal pressure hydrocephalus (n = 2). Although four subjects showed improvement of orthostatic myoclonus with antimyoclonic treatment, the follow-up was not systematic enough to evaluate their therapeutic effect on OM.
Orthostatic myoclonus is often underdiagnosed and can be considered a possible cause of unsteadiness in subjects with neurodegenerative diseases. Electromyography surface recording is thereby an aid for investigating unsteadiness of unknown origin.
最近，直立性肌阵挛（OM）被认为是神经退行性疾病导致步态障碍和不稳定的原因之一。本研究旨在调查直立性肌阵挛的频率、其临床特征以及潜在的相关神经障碍。
对不明原因步态不稳/步态障碍患者的临床数据和肌电图表面记录进行回顾性分析。当观察到非节律性爆发模式（持续时间范围 20-100 毫秒；每秒爆发次数≤16）时，诊断为 OM。
在研究的 93 名患者中，OM 是最常见的疾病（n=16；17.2%），其次是直立性震颤（13.9%）和直立位低频震颤（12.9%）。所有 OM 患者均主诉直立位和/或步态时不稳。仅通过视觉检查在 4 名患者中观察到腿部抽搐，其中 2 名患者也有跌倒。16 名 OM 患者中有 11 名（68.7%）有相关的神经退行性疾病，如多系统萎缩（n=3）、帕金森病（n=2）、阿尔茨海默病（n=2）、轻度认知障碍（n=2）和正常压力脑积水（n=2）。尽管 4 名患者接受抗肌阵挛治疗后 OM 有所改善，但随访不够系统，无法评估其对 OM 的治疗效果。
直立性肌阵挛常被漏诊，可被视为神经退行性疾病患者不稳定的可能原因。肌电图表面记录有助于调查不明原因的不稳定。
