Abstract Details

Title Episodic status epilepticus with hemiplegia and involuntary movements associated with novel ATP1A2 mutation

Topic Child Neurology and Developmental Neurology

Presentation(s) P4 - Poster Session 4 (5:30 PM-6:30 PM)

Poster/Presentation
Number 7-071

Objective To describe a severe case of alternating hemiplegia of childhood (AHC) associated with a de novo ATP1A2 mutation with unique imaging features and phenotype.

Background AHC is characterized by episodic hemiparesis with onset in infancy in addition to oculomotor abnormalities, seizures, ataxia, movement disorders and developmental delay. Hemiplegic episodes last from minutes to weeks but often remit with sleep. Brain MRI is generally normal in the acute setting. Most cases are linked to ATP1A3 mutations, but AHC exists on a spectrum with familial hemiplegic migraine which involves ATP1A2, CACNA1A, and SCN1A.

Design/Methods A two year-old male presented with left hemiplegia. He had a history of episodic right hemiplegia starting at a year of age. Episodes lasted 10-45 minutes and always happened after awakening. His presenting episode was prolonged in comparison and later involved left sided jerking that evolved into status epilepticus. MRI brain revealed extensive cortical diffusion restriction involving the right cerebral hemisphere. EEG showed seizures arising from the right hemisphere. During his admission, the patient also began to demonstrate non-epileptic left hemi-myoclonus and hemichorea. Nearly a month later, he developed focal status epilepticus and right hemiplegia. Again extensive diffusion restriction was seen, this time involving the left cerebral hemisphere, along with right cerebral atrophy. After the second presentation he developed cortical blindness and persistent encephalopathy.

Results Whole exome sequencing demonstrated a heterozygous de novo likely pathogenic variant (c.2438T>A; p.M813K) in ATP1A2.

Conclusions

While ATP1A3 mutations are responsible for most cases of AHC, mutations in ATP1A2 should also be considered. Although brain imaging in the acute setting of hemiplegic episodes is generally normal, diffusion restriction can be seen and may be associated with significant disability. This particular variant appears to represent a new phenotype associated with ATP1A2. ATP1A2 mutations should be considered in young patients presenting with new onset non-epileptic hemi-myoclonus or hemichorea.

Authors/Disclosures
Daniel Calame, MD, PhD (Baylor College of Medicine, Child Neurology) PRESENTER	Dr. Calame has nothing to disclose.
Mered Parnes, MD	Dr. Parnes has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Teva Pharmaceuticals. Dr. Parnes has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Teva Pharmaceuticals. The institution of Dr. Parnes has received research support from NIH. The institution of Dr. Parnes has received research support from Alexion.

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