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发布于:2017-11-3 14:31:12  访问:15 次 回复:0 篇
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Ve L. Levy Place, New York, NY 10029, USA J. Levitt Periodic
Levitt order R 667 periodic Paralysis Association, New York, NY, USAJ Neurol (2013) 260:2606?Introduction Hyperkalemic periodic paralysis (hyperPP) is definitely an autosomal dominant muscle sodium channelopathy with almost complete penetrance [1]. Tyler et al. [2] very first described the illness in 1951 in their study of a kindred of 7 generations of men and women with clinically standard periodic paralysis inside the absence of hypokalemia. In 1957, Gamstorp extensively investigated the condition and named it adynamia episodica hereditaria [3]. The name was later changed to hyperkalemic periodic paralysis in light on the provocative effects of potassium intake as well because the rise in serum potassium levels linked with spontaneous attacks [1]. Point mutations within the SCN4A gene encoding the alpha subunit from the skeletal muscle voltage-gated sodium channel Nav1.four cause defective channel function. This disrupts the typical exchange of ions in skeletal muscle tissues, consequently reducing their ability to contract and resulting in attacks of muscle weakness or paralysis [4, 5]. The situation impacts about 1 in every single 200,000 persons [1]. While usually hereditary, de novo mutations happen to be reported [6]. The following illness description summarizes the literature on hyperPP to date; our study calls some of this details into question. HyperPP is characterized by attacks of flaccid muscle weakness which might be in truth episodic, as an alternative to periodic, in nature. Attacks generally begin within the initial decade of life, progressing in frequency till their frequency plateaus in early adulthood. Sometime soon after midlife, attack frequency declines substantially [7, 8]. Typically older individuals knowledge a chronic progressive myopathy which will bring about permanent muscle weakness [8]. Attacks differ in severity, as well as the similar mutation can have variable expressivity within and in between households [5]. Attacks can final anywhere from 30 min to various hours [6], typically lasting 1? h [9] and infrequently days [10]. As opposed to those with hypokalemic periodic paralysis (hypoPP), these with hyperPP infrequently experience generalized flaccid paralysis but rather are inclined to have focal weakness; the thigh and calf muscle tissues are generally affected. Reflexes for the duration of an attack may be absent or diminished, and, hardly ever, the bulbar and respiratory muscles may be affected. Sphincter muscles keep tonicity through attacks. Sensation is not affected throughout attacks, despite the fact that folks might encounter an aura of muscle paresthesia and discomfort before the onset of weakness [11]. HyperPP has 3 clinically distinct manifestations: (1) without having myotonia, (2) with clinical or electromyographic (EMG) myotonia, or (3) with paraPA824 myotonia congenita (PMC). In all 3 types, the course with the paralytic attacks could be the similar fnins.2014.00058 [7, 11]. Electrical myotonia might be demonstrated on EMG in 50?five of sufferers with hyperPP, whilst significantly less than 20 manifest clinically [10]. In these with myotonia, i.e., a tonic spasm of muscle [12], themyotonia is normally mild and may be provoked with percussion or activity inside the face, tongue, forearms, and thenar eminence. The myotonia eases with repetitive activity [11]. From birth onwards, these with PMC experience muscle stiffness that increases with continued activity (paramyotonia) and is cold-induced abn0000128 [1]. Paralytic attacks can take place at any time, though frequently take place spontaneously inside the morning prior to breakfast, final as much as an hour, and unpredictably subs.Ve L.
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