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

This study was undertaken to investigate migraine prevalence in persons with hallucinogen persisting perception disorder (HPPD) presenting as visual snow syndrome (VSS). 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 used illicit drugs prior to onset were included. The primary outcome was lifetime prevalence of migraine. Symptom severity was evaluated by the Visual Snow Handicap Inventory (VHI), a 25-item questionnaire. None of the 24 HPPD participants had migraine, whereas 20 of 37 (54.1%) controls had migraine (p