Migraine prevalence in visual snow with prior illicit drug use (hallucinogen persisting perception disorder) versus without

Abstract Background and purpose: This study was undertaken to investigate migraine prevalence in persons with hallucinogen persisting perception disorder (HPPD) presenting as visual snow syndrome (VSS). Methods: Persons with visual snow as a persisting symptom after illicit drug use (HPPD) were recruited via a Dutch consulting clinic for recreational drug use. A structured interview on (visual) perceptual symptomatology, details of drugs use, and medical and headache history was taken. As a control group, persons with visual snow who had never