A Novel Neuroimaging Phenotype in the Pediatric Paroxysmal Kinesigenic Dyskinesia

Abstract Paroxysmal kinesigenic dyskinesia (PKD) is a rare disorder characterized by recurrent attacks of hyperkinetic movements which can be isolated or associated with benign infantile seizures as part of the infantile convulsions with choreoathetosis syndrome. We present a case of hyperkinetic movement disorder in the form of choreoathetosis, ballismus, dystonia triggered by sudden movements with a past history of benign infantile convulsions in a 12-year-old girl. The contrast-enhanced brain and spine magnetic resonance imaging showed bilaterally symmetric superior cerebellar cytotoxic edema sparing the vermis with swollen cerebellar foliae. Whole-exome sequencing identified a homozygous frameshift duplication NM_145239.3(PRRT2):c.649dupC(p.Arg217Profs*8) in the PRRT2 gene. This case report highlights the frameshift duplication in the PRRT2 gene and rare neuroimaging findings which further expand the phenotypic characteristics of PKD in children.