Headache associated with COVID-19 vaccination: how to classify?

Introduction: In the setting of acute COVID-19 infection, headache occurs in 10-60% of patients and may last for days and, in a smaller proportion of patients, weeks (about 10%). However, it is less recognized that headache may also occur after vaccination with a short latency and may persist for a longer period in a still unclear number of patients.Methods: Retrospective description of headache and course in a case series of 32 outpatients with headache that changed or recurred after COVID-19 vaccination.Results: The majority of patients experienced an exacerbation of migraine headache; rare headache syndromes such as intracranial hypertension or thunderclap headache occurred in 2 patients. Headache manifested in more than 50% of patients within the first 48 h after vaccination. Over 50% of patients who received a triptan improved.Conclusion: The pathophysiological relationship between vaccination and persistent headache is not yet clearly understood. The short latency, partial efficacy of cortisone, and initial findings showing an increase of various inflammatory markers during the course of headache in COVID infection suggest a possible involvement of the innate immune system and here the inflammasome. Furthermore, the response to triptan in a proportion of patients also indicates activation of the trigeminovascular system.