Abstracts

Rationale: Episodic ataxia (EA) is a group of predominantly autosomal dominant inherited disorders characterized by recurrent bouts of truncal ataxia and incoordination lasting minutes to hours. There are 8 subtypes (EA1to EA8) with five known genes associated with EA. (Choi & Choi, 2016) Seizures have been reported in patients suffering from EA1, EA2, EA5, and EA6. (Paulhus, Ammerman, & Glasscock, 2020) A recent review showed 55% of cases with CACNA1A related disorders (12 EA2) had EEG abnormalities.

Methods: A single case study is presented to describe a patient’s journey to the presumed diagnosis of EA2 and significant improvement after treatment with acetazolamide.

Results: Patient is a 27-year-old right-handed woman born at term with mild intellectual disability, neonatal hypotonia, and history of febrile seizures who presents with paroxysmal events since the age of 2.

She describes distinct events that last for several minutes, occurring 1-2 times per month. The events include episodes of imbalance causing her to fall, dilated pupils, vertigo, diaphoresis, nausea, vomiting, and abnormal eye movements. She does not lose awareness, she is able to speak, describes no headaches, and has no stiffening or convulsion of her body during these events. After the episodes, she feels tremulous and fatigued for 24 hours or more. Her triggers include fevers, anxiety, and physical exertion. She has no family history of epilepsy, global developmental delay, or similar symptoms related to hers. Her examination includes a shy woman with a left upper extremity intention tremor and inability to perform tandem gait but is otherwise unremarkable.

However, she did present with abnormal EEGs including a prolonged stay in an epilepsy monitoring unit. Although no events were captured, the EEG demonstrated independent rhythmic, delta-theta slowing over the bi-temporal regions with occasional superimposed spike/sharp and slow wave discharges and occasional bilaterally independent temporal epileptiform discharges.

Magnetic Resonance Imaging (MRI) of her brain with and without contrast was unremarkable.

For several years she was treated for presumed focal seizures with preserved awareness of possible insular or temporal origin and trialed on adequate dosing of valproic acid, topiramate, lamotrigine, and eslicarbazepine with no improvement.

After 25 years, given the more prolonged nature of her episodes and the mild interictal cerebellar signs, she was clinically diagnosed with EA2 and empirically treated with acetazolamide. This produced a near resolution of her paroxysmal events, now occurring only twice per year. Although her initial EA genetic panel was negative, she is undergoing genetic counseling to consider further sequencing.

Conclusions: Clinicians should consider episodic ataxia (EA) in their differential diagnosis when treating patients with paroxysmal attacks of truncal ataxia, vertigo, autonomic symptoms, and intermittent nystagmus to prevent the misdiagnosis of focal epilepsy. EA1 and EA2 are most common and can be differentiated clinically and confirmed (usually) genetically. EA1, EA2, and EA3 are known to be responsive to acetazolamide which can greatly reduce morbidity.

Funding: Please list any funding that was received in support of this abstract.: None.