运动诱发性肌张力障碍

发作性运动诱发性运动障碍
发作性运动诱发性运动障碍(Paroxysmal Kinesigenit Dyskinesia，PKD)又称发作性运动诱发性舞蹈手足徐动症，由Kertesz(1967)首先报道并命名，是发作性运动障碍中最多见的一种类型，以静止状态下突然随意运动诱发短暂、多变的运动异常为特征。

PKD可为遗传性或散发性，有遗传家族史的病例约占60%，遗传方式大多为常染色体显性遗传，有外显不全现象。

致病基因定位于
16p11.2-q12.1、16p11.2-q11.2和16q13-q22.1，这种基因定位的不重叠，提示PKD可能存在遗传异质性。

PKD虽已有初步的基因定位，但迄今为止PKD的致病基因尚未知。

具发病机制不明，Menkes(1995)认为PKD是介于运动障碍与癫痢之间的一类疾病，目前倾向于是—种离子通道病，认为本病与癫痫可能有共同的生物学基础和离子通道缺陷，其病理生理机制之一很可能与Na+通道缺陷有关。

PKD起病于儿童和青少年期，发病年龄从4个月至57岁，多在6～16岁，以男性多见，男女之比为(2～4):1。

发作前少数患者可有感觉先兆，如受累部位肢体发麻、发凉、发紧等。

发作常由突然的动作触发，如起立、转身、迈步、举手等，也可由惊吓、恐惧、精神紧张、过度换气等诱发。

发作时患者表现为肢体和躯干的肌张力不全、舞蹈、手足徐动、投掷样动作等多种锥体外系症状。

症状可累及单肢、偏身，也可为双侧交替或同时出现，当面部和下颁肌肉受累时，可出现构音障碍。

发作时间短暂，一般持续数秒，80%以上的病例发作持续时间短于1min，很少超过5min。

发作时无意识障碍，停止动作或减慢动作常可终止发作。

发作次数不定，1年数次，1个月数次或1日数次，呈病初发作次数少，至青春期发作次数增多，再随年龄增长而发作逐渐减少或停止。

发作可以使患者丧失活动能力，干扰其行走、学习、工作和日常活动。

发作间期神经系统检查正常，发作时脑电图检查80%未见痫样放电。

SPECT检查在发作时可见基底节区血流灌注增强，说明本病在阵发性发作时有基底节区功能增强现象。

Bmno等在综合分析121例PKD后，提出PKD新的诊断标准为：特定的触发因素(如突然的运动)，短暂的发作持续时间(<1min)，发作时无意识障碍和疼痛，抗癫痫药物治疗有效，排除其他器质性疾病，起病年龄为1～20岁(有家族史的病例不受此限)。

本病虽非癫痫，但绝大部分患者服用卡马西平、苯巴比妥、苯妥英钠、丙戊酸、托吡酯、拉莫三嗪等抗癫痫药物均能控制发作，缘于阻滞钠离子通道作用。

Familial paroxysmal kinesigenic dyskinesia 家族性运动诱发运动障碍疾病特征
Familial paroxysmal kinesigenic dyskinesia (referred to as familial PKD in this entry) is characterized by unilateral or bilateral involuntary movements precipitated by other sudden movements such as standing up from a sitting position, being startled, or changes in velocity; attacks include combinations of dystonia, choreoathetosis, and ballism, are
sometimes preceded by an aura, and do not involve loss of consciousness. Attacks can be as frequent as 100 per day to as few as one per month. Attcks are usually a few seconds to five minutes in duration but can last several hours. Familial PKD has been associated with infantile- but not
adult-onset seizures. Severity and combinations of symptoms occur. Age of onset is typically in childhood and adolescence, but ranges from four months to 57 years. Familial PKD is predominantly seen in males.
诊断与测试
The diagnosis of familial PKD is based on the clinical findings of attacks of dystonia, chorea, ballismus, or athetosis triggered by sudden movements that occur many times per day and can be prevented or reduced in frequency by phenytoin or carbamezepine. The gene/s associated with PKD have not been identified. Linkage of familial PKD to chromosome 16q has been established in several families. Linkage testing is available on a research basis only.
治疗与处理
Attack frequency is reduced or prevented by the anticonvulsants phenytoin or carbamezepine, typically given at lower doses than are used to treat epilepsy. Other effective anticonvulsants include oxcarbazepine, ethosuximide, and lamotrigine.
遗传咨询
Familial PKD is inherited in an autosomal dominant manner. More than 90% of individuals with familial PKD have an affected parent.
The proportion of cases caused by de novo mutations is unknown. Offspring of affected individuals with familial PKD have a 50% chance of inheriting the gene mutation. Because familial PKD demonstrates incomplete penetrance, a clinically unaffected parent may still have a gene mutation, placing the sibs of the proband at a 50% risk of inheriting the mutation. Prenatal testing is not available.
最新研究进展
2011年，Nature Genetics上发表文章，发现大多数家族性PKD均由PRRT2基因的突变引起，该基因编码一种跨膜蛋白，突变后的蛋白无法定位于细胞膜。

之后，陆续有人在家族性良性婴儿惊厥BFIC以及发作性手足舞蹈徐动症ICCA中，发现PRRT2基因的突变，提示PKD与BFIC以及ICCA可能为同一致病
基因所导致的一类疾病。