Alternating Hemiplegia of Childhood

Alternating hemiplegia of childhood (AHC) is a rare neurodevelopmental disorder, primarily caused by pathogenic variants in ATP1A3 that account for approximately 80% of cases. It is characterized by both paroxysmal and chronic neurologic features. Currently, no validated, disease-specific clinical outcome measures exist for AHC, limiting standardized assessment and longitudinal tracking. We aimed to develop and validate the AHC Rating Scale (AHC-RS), a tool applicable across all age groups. We hypothesized that the AHC-RS would demonstrate strong inter-rater reliability and construct validity.