WordNet

a unit of geological time during which a system of rocks formed; "ganoid fishes swarmed during the earlier geological periods" (同)geological period
(ice hockey) one of three divisions into which play is divided in hockey games
the end or completion of something; "death put a period to his endeavors"; "a change soon put a period to my tranquility"
the interval taken to complete one cycle of a regularly repeating phenomenon
a punctuation mark (.) placed at the end of a declarative sentence to indicate a full stop or after abbreviations; "in England they call a period a stop" (同)point, full_stop, stop, full point
happening or recurring at regular intervals; "the periodic appearance of the seventeen-year locust" (同)periodical
recurring or reappearing from time to time; "periodic feelings of anxiety" (同)occasional
loss of the ability to move a body part (同)palsy

PrepTutorEJDIC

(あることが続く)『期間』 / (歴史的な)『時代』 / (試合の)『一区切り』,ピリオド / 授業時間,時限: / (循環して起こる現象などの)周期 / (回転運動などの)周期 / 紀(地質時代の区分の一つ;era(代)の下,epoch(世)の上) / 《おもに米》『ピリオド』,終止符(《英》full stop;Mr.,U.S.など略語の符号(.)も含む) / 《複数形で》《文》掉尾(とうび)文(多くの節から成り,論理的に緊密な構成をもっている文) / 《名詞の前にのみ用いて》ある時代[特有]の,時代物の / (文の終わりに感嘆詞的に)以上,終わり・月経（期間）
定期的な,周期的な / ときぎき起こる: / 掉尾(とうび)的の:
(体の)麻痺(まひ),中風 / (…の)停滞《+『of』+『名』》

Wikipedia preview

出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2013/10/21 03:27:59」(JST)

wiki en

Periodic paralysis (also known as Myoplegia paroxysmalis familiaris) is a group of rare genetic diseases that lead to weakness or paralysis (rarely death) from common triggers such as cold, heat, high carbohydrate meals, not eating, stress or excitement and physical activity of any kind. The underlying mechanism of these diseases are malfunctions in the ion channels in skeletal muscle cell membranes that allow electrically charged ions to leak in or out of the muscle cell, causing the cell to depolarize and become unable to move (a channelopathy).

The symptoms of periodic paralysis can also be caused by hyperthyroidism, and are then labeled thyrotoxic periodic paralysis; however, if this is the underlying condition there are likely to be other characteristic manifestations, enabling a correct diagnosis.

Types[edit]

Periodic paralysis is an autosomal dominant myopathy with considerable variation in penetrance, leading to a spectrum of familial phenotypes (only one parent needs to carry the gene mutation to affect the children, but not all family members who share the gene are affected to the same degree). Specific diseases include:

Hypokalemic periodic paralysis (Online 'Mendelian Inheritance in Man' (OMIM) 170400), where potassium leaks into the muscle cells from the bloodstream.

Hyperkalemic periodic paralysis (Online 'Mendelian Inheritance in Man' (OMIM) 170500), where potassium leaks out of the cells into the bloodstream.

Paramyotonia congenita (Online 'Mendelian Inheritance in Man' (OMIM) 168300), a form which often accompanies hyperkalemic periodic paralysis, but may present alone. The primary symptom of paramyotonia congenita is muscle contracture which develops during exercise or activity. Paramyotonia congenita attacks may also be triggered by a low level of potassium in the bloodstream. This means people with both hyperkalemic periodic paralysis and paramyotonia congenita can have attacks with fluctuations of potassium up or down.

Andersen-Tawil syndrome (Online 'Mendelian Inheritance in Man' (OMIM) 170390), a form of periodic paralysis that includes significant heart rhythm problems, fainting and risk of sudden death. Potassium levels may be low, high, or normal during attacks of ATS. Patients with ATS may also have skeletal abnormalities like scoliosis (curvature of the spine), webbing between the second and third toes or fingers (syndactyly), crooked fingers (clinodactyly), a small jaw (micrognathia) and low-set ears.

Diagnosis[edit]

This disease is unusually difficult to diagnose. Patients often report years of wrong diagnosis and treatments that made them worse instead of better. Part of this may be that migraines are present in up to 50% of patients and can cause a confusing array of symptoms including headaches, speech difficulties and visual, auditory or sensory auras. DNA testing is available for only a half dozen common gene mutations, while dozens of known mutations are possible but are not routinely tested. Electromyography (EMG) findings are not specific. The old glucose/insulin provocative testing can cause life-threatening symptoms and should not be used.

Also of note is that potassium levels do not have to range outside of normal limits to cause serious, even life-threatening paralysis. These diseases are not the same as having a very low level of potassium (hypokalemia) or high potassium (hyperkalemia) and must not be treated as such. The total body store of potassium is usually normal; it is just in the wrong place.

Treatment[edit]

Treatment of the periodic paralyses usually includes carbonic anhydrase inhibitors (such as acetazolamide or dichlorphenamide), taking supplemental oral potassium chloride and a potassium-sparing diuretic (for hypos) or avoiding potassium (for hypers), thiazide diuretics to increase the amount of potassium excreted by the kidneys (for Hypers), and significant lifestyle changes including tightly controlled levels of exercise or activity. However, the exact gene mutation, the ion channel affected, and the amount of genetic change or expression can have significant impact on disability and treatment.

^[1] ^[2] ^[3]

Treatment of Andersen-Tawil syndrome is similar to that for other types of periodic paralysis. However, Pacemaker insertion or an implantable cardioverter-defibrillator may be required to control cardiac symptoms.

^[4]

Prognosis[edit]

While the disability can range from minor, occasional weakness to permanent muscle damage, inability to hold a normal job and use of a powerchair, most people function fairly well with drugs and lifestyle changes.

References[edit]

^ Kim, SJ; Lee, YJ; Kim, JB (Jan 2010). "Reduced expression and abnormal localization of the KATP channel subunit SUR2A in patients with familial hypokalemic periodic paralysis". Biochemical and Biophysical Research Communications 391: 974–8. doi:10.1016/j.bbrc.2009.11.177. PMID 19962959.
^ Kim, JB; Kim, MH (Dec 2007). "The Genotype and Clinical Phenotype of Korean Patients with Familial Hypokalemic Periodic Paralysis". J Korean Med Sci 22: 946–51. doi:10.3346/jkms.2007.22.6.946.
^ Lee, GM; Kim JB (June 2011). "Hyperkalemic periodic paralysis and paramyotonia congenita caused by a de novo mutation in the SCN4A gene". Neurology Asia 16 (2): 163–6.
^ Kim, JB; Chung, KW (Dec 2009). "Novel de novo Mutation in the KCNJ2 gene in a Patient with Andersen-Tawil Syndrome". Pediatric Neurology 41 (6): 464–466. doi:10.1016/j.pediatrneurol.2009.07.010.

Bibliography[edit]

Song, YW; Kim, SJ; Heo, TH; Kim, MH; Kim, JB (Dec 2012). "Normokalemic periodic paralysis is not a distinct disease". Muscle & Nerve 46 (6): 908–913. doi:10.1002/mus.23441. PMID 22926674.

External links[edit]

Periodic Paralysis Association
Periodic Paralysis News Desk
NIH information page on periodic paralysis
Cleveland Clinic
eMedicine

UpToDate Contents

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1. 低カリウム性周期性四肢麻痺 hypokalemic periodic paralysis
2. 甲状腺中毒性周期性四肢麻痺 thyrotoxic periodic paralysis
3. 高カリウム性周期性四肢麻痺 hyperkalemic periodic paralysis
4. 筋力低下を呈する小児の病因および評価 etiology and evaluation of the child with muscle weakness
5. 救急外来における急性の筋力低下を訴える成人の評価 evaluation of the adult with acute weakness in the emergency department

English Journal

Mutations in SCN4A: A Rare but Treatable Cause of Recurrent Life-Threatening Laryngospasm.

Singh RR1, Tan SV2, Hanna MG3, Robb SA4, Clarke A5, Jungbluth H6.
Pediatrics.Pediatrics.2014 Oct 13. pii: peds.2013-3727. [Epub ahead of print]
Laryngospasm is a rare but potentially life-threatening occurrence in infants and usually has infective, allergic, metabolic, or anatomic causes. Underlying genetic conditions are rarely considered. Mutations in SCN4A encoding the voltage-gated sodium channel NaV1.4 have been implicated in a wide sp
PMID 25311598

Insights in KIR2.1 channel structure and function by an evolutionary approach; cloning and functional characterization of the first reptilian inward rectifier channel KIR2.1, derived from the California kingsnake (Lampropeltis getula californiae).

Houtman MJ1, Korte SM2, Ji Y2, Kok B2, Vos MA2, Stary-Weinzinger A3, van der Heyden MA2.
Biochemical and biophysical research communications.Biochem Biophys Res Commun.2014 Oct 3;452(4):992-7. doi: 10.1016/j.bbrc.2014.09.031. Epub 2014 Sep 16.
Potassium inward rectifier KIR2.1 channels contribute to the stable resting membrane potential in a variety of muscle and neuronal cell-types. Mutations in the KIR2.1 gene KCNJ2 have been associated with human disease, such as cardiac arrhythmias and periodic paralysis. Crystal structure and homolog
PMID 25223803

Post-exercise increment in compound muscle action potential amplitude in hyperkalemic periodic paralysis.

Cleland JC1, Tawil R2.
Clinical neurophysiology : official journal of the International Federation of Clinical Neurophysiology.Clin Neurophysiol.2014 Oct;125(10):2134-5. doi: 10.1016/j.clinph.2014.02.005. Epub 2014 Feb 17.
PMID 24583090

Japanese Journal

症例報告低カリウム血症性周期性四肢麻痺症状を契機にBasedow病の診断に至った1例

壹岐陽一,中村由恵,中田昌利 [他]
日本小児科学会雑誌 = The journal of the Japan Pediatric Society 118(8), 1219-1223, 2014-08
NAID 40020188276

症例報告 2週間持続する脱力発作を呈したナトリウムチャネル異常症の1家系

滋賀健介,水田依久子,能登祐一 [他]
臨床神経学 = Clinical neurology 54(5), 434-439, 2014-05
NAID 40020092812

家族性低カリウム性周期性四肢麻痺が疑われる慢性ミオパチーの1例

小林正樹,竹内恵,鈴木美紀,内山真一郎,KOBAYASHI Masaki,TAKEUCHI Megumi,SUZUKI Miki,UCHIYAMA Shinichiro
東京女子医科大学雑誌 84(臨時増刊1(医学部神経内科学教室内山真一郎教授退任記念特別)), E188-E191, 2014-01-31
NAID 120005424020

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★リンクテーブル★

リンク元	「周期性四肢麻痺」
拡張検索	「primary hyperkalemic periodic paralysis」「sodium-responsive normokalemic periodic paralysis」「hyperkalemic periodic paralysis」「hypokalemic periodic paralysis」
関連記事	「periodic」「period」