World West Syndrome Day (Día Mundial del Síndrome de West) is observed worldwide every April 10 to highlight a rare epileptic disorder known as West syndrome, which typically manifests within the first year of life. The day aims to educate the public about the condition, which is characterized by infantile spasms, developmental regression, and a distinctive EEG pattern known as hypsarrhythmia. West syndrome was first described by English surgeon William James West in 1841, after observing seizures in his son. People participate by learning more about the syndrome, donating to organizations that support affected families, and sharing information on social media using hashtags like #WorldWestSyndromeDay. The observance appears to have originated in Spain or another Spanish-speaking country, though its exact origin remains unclear.