refers to a group of related conditions that affect the nervous system and cause problems with movement. It is characterized by episodes of poor coordination and balance (ataxia). During these episodes, many people also experience dizziness (vertigo), nausea and vomiting, migraine headaches, blurred or double vision, slurred speech, and ringing in the ears (tinnitus). Seizures, muscle weakness, and paralysis affecting one side of the body (hemiplegia) may also occur during attacks. Episodes of ataxia and other symptoms can begin anytime from early childhood to adulthood, with the frequency of attacks ranging from several per day to one or two per year.
There are at least seven types of episodic ataxia, designated type 1 through type 7, which are distinguished by their signs and symptoms, age of onset, length of attacks, and, when known, genetic cause. Only types 1 and 2 have been identified in more than one family; episodic ataxia type 2 is the most common form of the condition. Source: Genetic and Rare Diseases Information Center (GARD), supported by ORDR-NCATS and NHGRI.