Episodic Ataxias (EA) are autosomal dominant channelopathies characterized by recurrent spells of incoordination, dizziness, and imbalance. The two most recognized subtypes are EA-1 and EA-2:
Episodic Ataxia Type 1 (EA-1)
Gene: KCNA1 (Voltage-gated potassium channel).
Duration: Very short (seconds to minutes).
Triggers: Sudden movement, startle, or sudden exercise.
Interictal Finding: Myokymia (continuous fine muscle twitching around eyes/hands).
Response: Carbonic anhydrase inhibitors (Acetazolamide).
Episodic Ataxia Type 2 (EA-2)
Gene: CACNA1A (Calcium channel subunit).
Duration: Longer duration (hours to days).
Triggers: Stress, exertion, caffeine, alcohol.
Interictal Finding: Interictal nystagmus (often downbeating nystagmus) and progressive cerebellar signs.
Response: Dramatic response to Acetazolamide.
