Guerrini R, Bonanni P, Parmeggiani L, Santucci M, Parmeggiani A, Sartucci F
Institute of Child Neurology and Psychiatry, University of Pisa, Italy.
Ann Neurol. 1998 Apr;43(4):472-9. doi: 10.1002/ana.410430410.
Rett syndrome (RS) is one of the most frequent causes of mental retardation in females. As there are no known biochemical, genetic, or morphological markers, diagnosis is based on clinical phenotype including severe dementia, autism, truncal ataxia/apraxia, loss of purposeful hand movements, breathing abnormalities, stereotypies, seizures, and extrapyramidal signs. Myoclonus, although reported in some series, has never been characterized. We studied 10 RS patients, age 3 to 20 years, and observed myoclonus in 9. Severity of myoclonus did not correlate with that of the other symptoms or with age. Multifocal, arrhythmic, and asynchronous jerks mainly involved distal limbs. Electromyographic bursts lasted 48 +/- 12 msec. Burst-locked electroencephalographic averaging generated a contralateral centroparietal premyoclonus transient preceding the burst by 34 +/- 7.2 msec. Motor evoked potentials showed normal latencies, indicating integrity of the corticospinal pathway. Somatosensory evoked potentials were enlarged. The C-reflex was hyperexcitable and markedly prolonged (62 +/- 4.3 msec), mainly due to increase in cortical relay time (28.4 +/- 4.5 msec). We conclude that RS patients show a distinctive pattern of cortical reflex myoclonus with prolonged intracortical delay of the long-loop reflex.
雷特综合征（RS）是女性智力发育迟缓最常见的病因之一。由于目前尚无已知的生化、遗传或形态学标志物，诊断主要基于临床表型，包括严重痴呆、自闭症、躯干共济失调/失用症、目的性手部运动丧失、呼吸异常、刻板动作、癫痫发作和锥体外系体征。肌阵挛虽然在一些系列报道中出现过，但从未被明确描述过。我们研究了10例年龄在3至20岁之间的RS患者，其中9例观察到肌阵挛。肌阵挛的严重程度与其他症状的严重程度或年龄无关。多灶性、无节律性和不同步的抽搐主要累及远端肢体。肌电图爆发持续48±12毫秒。爆发锁定脑电图平均显示，在爆发前34±7.2毫秒出现对侧中央顶叶肌阵挛前瞬变。运动诱发电位显示潜伏期正常，表明皮质脊髓通路完整。体感诱发电位增大。C反射兴奋性增高且明显延长（62±4.3毫秒），主要是由于皮质中继时间增加（28.4±4.5毫秒）。我们得出结论，RS患者表现出一种独特的皮质反射性肌阵挛模式，长环反射的皮质内延迟延长。
