運動神經元疾病(motor neuron diseases)是一群運動神經元漸進性退化而造成全身肌肉萎縮及無力的疾病，其中肌萎縮性脊髓側索硬化症(ALS)是成人最常見的運動神經元疾病。ALS在全世界的普及率約為5/100000左右，偶發性ALS患者的平均年齡多為55-75歲之間，而家族遺傳性ALS患者的發病年紀大多較早；男性罹病機率約為女性的1.5-2.5倍。臨床方面ALS會表現同側肢體的下運動神經元徵象(如無力、萎縮和肌束抽搐)及上運動神經元徵象(如肌腱反射上升、霍夫曼徵象(Hoffmann signs)、巴賓斯基反射(Babinski signs)或肌躍症)，並可參考El Escorial診斷基準來區分診斷確信度。若佐以肌電圖，應可發現三個肢體以上的活動性去神經現象(active denervation)。偶發性ALS的病因仍不明確，重金屬中毒、病毒感染、腫瘤、自體免疫、輻射及雷擊都被懷疑是危險因子。大約有10%的病人為家族遺傳性ALS患者，其中超氧化歧化酶(superoxide dismutase, SOD)的基因突變或缺失，約占遺傳性ALS的15-20%。目前研究認為ALS致病機轉是多因素的(multifactorial)，包括麩胺酸之興奮毒性(glutamate-induced excitotoxicity)、粒線體結構異常、鈉鉀離子幫浦功能不良、自體吞噬及軸突運輸系統中斷。在ALS治療及處置方面，美國神經醫學會建議使用Riluzole藥物治療，並考慮經皮內視鏡胃造口術(percutaneous endoscopic gastrostomy)導管以及導入早期非侵入性呼吸(non-invasive ventilation)以延長存活時間，亦可提升患者生活品質。隨著ALS的病理研究越來越多，許多標靶治療的藥物已進入臨床試驗，結果令人期待。
肌萎縮性脊髓側索硬化症（ALS, Amyotrophic lateral sclerosis），又稱盧•格裡克症（Lou Gehrig's disease），肌萎縮側索硬化症，俗稱為漸凍人症，是一個漸進和致命的神經退行性疾病。起因是中樞神經系統內控制骨骼肌的運動神經元（motor neuron）退化所致。ALS病人由於上、下運動神經元（upper/lower motor neurons）都退化和死亡並停止傳送訊息到肌肉，在不能運作的情況下，肌肉逐漸衰弱、萎縮。 最後，大腦完全喪失控制隨意運動的能力。這種疾病並不一定會如老人癡呆症般影響病人的心理運作。相反，那些患有晚期疾病的病人仍可保留發病前的記憶，同樣的人格和智力。
病因
除了少數遺傳性病人外（小於10%），大部份人得病的原因不明。[1]
美國西北大學研究團隊在2011年8月《自然》Nature發表一篇研究報告[2]指出病因可能出自Ubiquilin-2無法正常執行其功能引起運動神經元凋亡[3]。
一些科學研究 發現某些農藥和肌萎縮性側索硬化症的統計相關性。
What is amyotrophic lateral sclerosis?
Amyotrophic lateral sclerosis (ALS), sometimes called Lou Gehrig's disease, is a rapidly progressive, invariably fatal neurological disease that attacks the nerve cells (neurons)responsible for controlling voluntary muscles (muscle action we are able to control, such as those in the arms, legs, and face). The disease belongs to a group of disorders known as motor neuron diseases, which are characterized by the gradual degeneration and death of motor neurons.
Motor neurons are nerve cells located in the brain, brain stem, and spinal cord that serve as controlling units and vital communication links between the nervous system and the voluntary muscles of the body. Messages from motor neurons in the brain (called upper motor neurons) are transmitted to motor neurons in the spinal cord (called lower motor neurons) and from them to particular muscles. In ALS, both the upper motor neurons and the lower motor neurons degenerate or die, and stop sending messages to muscles. Unable to function, the muscles gradually weaken, waste away (atrophy), and have very fine twitches (called fasciculations). Eventually, the ability of the brain to start and control voluntary movement is lost.
ALS causes weakness with a wide range of disabilities (see section titled “What are the symptoms?”). Eventually, all muscles under voluntary control are affected, and individuals lose their strength and the ability to move their arms, legs, and body. When muscles in the diaphragm and chest wall fail, people lose the ability to breathe without ventilatory support. Most people with ALS die from respiratory failure, usually within 3 to 5 years from the onset of symptoms. However, about 10 percent of those with ALS survive for 10 or more years.
Although the disease usually does not impair a person’s mind or intelligence, several recent studies suggest that some persons with ALS may have depression or alterations in cognitive functions involving decision-making and memory.
ALS does not affect a person’s ability to see, smell, taste, hear, or recognize touch. Patients usually maintain control of eye muscles and bladder and bowel functions, although in the late stages of the disease most individuals will need help getting to and from the bathroom.
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