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Médecine thérapeutique / Pédiatrie

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Primary episodic ataxias Volume 14, issue 2, Mars-Avril 2011

Author
AP-HP, Hôpital Trousseau, Service de neuropédiatrie, 26, rue du Dr Arnold Netter, 75571 Paris Cedex 12, France, Centre de référence neurogénétique, mouvements anormaux de l’enfant, Hôpital Trousseau, Service de neuropédiatrie, 26, rue du Dr Arnold Netter, 75571 Paris Cedex 12, France

Episodic ataxias (EA) are rare dominantly inherited neurological conditions characterized by spells of incoordination and imbalance, due to mutations of ion channels. At least six episodic ataxias syndrome have been described, but only EA type 1 (EA1) and EA type (EA2) have been documented in multiple families. The onset is typically early in life. The identification of the genetic broadened the clinical spectrum, which is variable within the same family. EA1 results from mutation in neuronal voltage gated potassium KCNA1. It is characterized by brief episode of ataxia (seconds to minutes) and interictal myokymia. The spells are precipitated by physical and emotional stress and sudden movements. EA2, the most frequent type, results from mutation in CACNA1 gene. The spells of ataxia last hours to days and are associated with vertigo vomiting and headache. Patients typically show interictal nystagmus. There is a wide range of phenotypes: familial hémiplegic migraine, EA2, and spinocerebellar ataxias 6 (SC6) are allelic diseases. Various treatment strategies are indicated.