肌躍症的診斷與治療

Diagnosis and Treatment for Myoclonus

肌躍症是一種不規律、短時間的肌肉不自主收縮或不收縮，前者稱為正向型肌躍症，後者稱為負向型肌躍症。臨床診斷可依解剖學起源先做初步分類，病因診斷除了詳細的病史和現象學的記錄外，有時也須仰賴電生理、神經影像、血液生化或基因檢查等工具的輔助。源於腦皮質的肌躍症特點是對肢體的體感覺刺激敏感，記錄體感覺誘發電位時可能出現高振幅的誘發電位，肌肉收縮時間短，同步記錄腦波與肌肉收縮訊號時可發現相對應的時序關聯。源於腦幹的肌躍症易影響身體中軸或肢體近端肌肉。源於脊髓的肌躍症特點是肌肉收縮的時間較長，通常超過100毫秒。急性肌躍症常見原因包括藥物引起的serotonin syndrome等。年輕肌躍症病患則需留意是否屬於可用特殊藥物治療的代謝性疾病。

Myoclonus is an irregular, short-duration involuntary muscle contraction or loss of contraction. The former condition is recognized as positive myoclonus and the latter is termed negative myoclonus. Clinical diagnosis can be initially classified based on anatomical origin. In addition to detailed medical history and phenomenological records, etiological diagnosis sometimes relies on the assistance of electrophysiological, neuroimaging, blood biochemical or genetic examinations. Cortical-origin myoclonus is characterized by sensitivity to somatosensory stimuli in distal limbs. High-amplitude evoked potentials may occur when recording somatosensory evoked potentials from the scalp, and muscle contraction duration is usually short. The corresponding timing relationship can be found when EEG and muscle contraction signals are synchronously recorded. Brainstem-origin myoclonus is more likely to affect the axial or proximal muscles of the body. Myoclonus originating from the spinal cord is characterized by a long duration of muscle contraction, usually more than 100 milliseconds. Common causes of acute myoclonic syndrome include drug-induced serotonin syndrome and so on. For young patients with myoclonus, it would be necessary to carefully check whether it is a presentation of treatable metabolic diseases.