Paroxysmal Dyskinesias in Paediatric Age: A Systematic Review

Background: Paroxysmal dyskinesias (PDs) are rare, episodic movement disorders characterized by sudden and involuntary hyperkinetic motor events. In paediatric populations, their diagnosis is often complicated by clinical overlap with epilepsy and other neurological conditions. Genetic underpinnings have increasingly been recognized as key to understanding phenotypic heterogeneity and guiding treatment. Objectives: This systematic review aims to provide a comprehensive overview of paediatric PD, with a focus on genetic aetiologies, clinical features, subtype classification, and therapeutic approaches, including genotype-treatment correlations. Methods: We systematically reviewed the literature from 2014 to 2025 using PubMed. Inclusion criteria targeted paediatric patients (aged 0-18 years) with documented paroxysmal hyperkinetic movements and genetically confirmed or clinically suggestive PD. Data were extracted regarding demographics, dyskinesia subtypes, age at onset, genetic findings, and treatment efficacy. Gene categories were classified as PD-specific or pleiotropic based on functional and clinical features. Results: We included 112 studies encompassing 605 paediatric patients. The most common subtype was Paroxistic Kinesigenic Dyskinesia (PKD). Male sex was more frequently reported. The mean onset age was 5.99 years. A genetic diagnosis was confirmed in 505 patients (83.5%), involving 38 different genes. Among these, PRRT2 was the most frequently implicated gene, followed by SLC2A1 and ADCY5. Chromosomal abnormalities affecting the 16p11.2 region were identified in ten patients, including deletions and duplications. Among the 504 patients with confirmed monogenic variants, 390 (77.4%) had mutations in PD-specific genes, while 122 (24.2%) carried pleiotropic variants. Antiseizure drugs-particularly sodium channel blockers such as carbamazepine and oxcarbazepine-were the most frequently reported treatment, with complete efficacy documented in 59.7% of the studies describing their use. Conclusions: Paediatric PDs exhibit significant clinical and genetic heterogeneity. While PRRT2 remains the most common genetic aetiology, emerging pleiotropic genes highlight the need for comprehensive diagnostic strategies. Sodium channel blockers are effective in a subset of genetically defined PD, particularly PRRT2-positive cases. Patients with pathogenic variants in other genes, such as ADCY5 and SLC2A1, may benefit from specific therapies that can potentially change their clinical course and prognosis. These findings support genotype-driven management approaches and underscore the importance of genetic testing in paediatric movement disorders.