Episodic ataxia type 2: unusual aspects in clinical and genetic presentation. Special emphasis in childhood.

OBJECTIVE: To describe aspects in clinical and genetic presentation in five patients with episodic ataxia type 2 (EA2).

METHODS: CACNA1A gene screening identified a mutation in three probands and in two of their children.

RESULTS: The three probands had attacks of imbalance, associated with dizziness/vertigo and/or headache. Two of them had independent migraine attacks. Interictal oculomotor examination revealed a gaze evoked nystagmus and central oculomotor signs. Two probands had a history of strabismus. All responded well to acetazolamide. Two children were found to have both clinical and genetic abnormalities. At 23 months, one child started to have short attacks of imbalance mimicking benign paroxysmal vertigo of childhood. Then, the frequency and duration of his attacks increased and some were associated with headache. The other child developed permanent imbalance with falls at the age of 2 years, strabismus, hyperactivity and slight to moderate cognitive deficiency. When aged 10 years, this was further complicated by episodic ataxia. Genetic analysis revealed three novel mutations in the calcium channel gene CACNA1A (chromosome 19p13). The two children had the same genetic abnormality as their parents.

CONCLUSION: EA2 may present with still unknown genetic mutations in adults, and with large and various phenotypes in children, such as short attacks of imbalance or permanent imbalance, cognitive deficiency, and possibly strabismus and hyperactivity.