STARDEV Study: Neurodevelopmental Trajectory and Long‐Term Outcomes of Patients with Startle Disease/Hyperekplexia

BACKGROUND: Although initial clinical presentation of hyperekplexia/startle disease is well known, data regarding long-term clinical outcomes is lacking. OBJECTIVES: We provide a long-term evaluation from clinical and pharmacological perspectives, focusing on neurodevelopmental trajectory. METHODS: Twenty-eight patients from nine French hospitals were included based on clinical diagnosis criteria. Adaptive abilities were assessed using VABS-II. RESULTS: VABS-II showed preserved adaptive abilities, except in motor skills. Early development was marked by neurodevelopmental delay in 53% of patients, with 57% developing neurodevelopmental disorders, primarily specific learning disorders. Intellectual disability and/or autism spectrum disorder were present in five patients. Symptoms were most frequent during the first 3 years of life, with persistence of exaggerated startle reflex and falls. One-quarter of the patients discontinued clonazepam. A genetic variant was found in 85% of patients, involving one of the three main genes GLRA1, SLC6A5, or GLRB. CONCLUSIONS: Our findings highlight preserved adaptive abilities, frequent neurodevelopmental disorders and long-term pharmacodependence.