Atypical clinical presentation of a girl with episodic ataxia type II

Introduction: Type 2 episodic ataxia is the most common form among the hereditary episodic ataxias and is caused by mutations in CACNA1A coding for a subunit of a cerebral calcium channel. Episodes can include dizziness, ataxia, vomiting, and migraine and are usually induced by stress or somatic strain.

Case report: We describe the case of a girl with paroxysmal migraine-like episodes and ocular movement disorder. At the beginning of nursery school, the girl started to vomit. Initially, vomiting occurred rarely, but the episodes became gradually more frequent and severe. Subsequently, multiple consecutive vomiting episodes occurred daily after 6.00p.m. and were partially triggered by stress or emotion. During the episodes, the patient sought relief by lying down and sleeping. She complained of phonophobia, and to a lesser extent of photophobia. Concurrently, she showed vegetative signs such as erythema of the cheeks, cold sweats, and pale lips. After sleep, the symptoms had always disappeared again. There were no evident balance problems during these episodes. Nevertheless, her parents reported that she showed problems with walking and fine motor activities. She stumbled frequently and was less skilled in comparison to other children. Neurological examination showed slow saccades, and slow saccade initiation as well as gaze-evoked nystagmus. There was mild truncal ataxia and dysdiadochokinesis. Cerebral MRI demonstrated discrete cerebellar atrophy mainly of the vermis. With the clinical diagnosis of an atypical form of episodic ataxia type II, we decided to investigate CACNA1A. Sequencing was normal, but MLPA could prove a deletion including exons 39–47 in CACNA1A.

Conclusions: The interictal ocular movement disorder and mild ataxia combined with the paroxysmal migraine-like symptoms indicated a channelopathy of the central nervous system although there was no classic episodic ataxia. Sequencing alone may miss larger genomic rearrangements as the deletion of several exons in our patient.