Retro-prospective survey on specific and overall prevalence and incidence of rare primary headaches (Part One, Chapter 3 and Chapter 4, ICHD-3 beta) in patients referred to Italian Tertiary Headache Centres in a 3-year (May 1, 2014-April 30, 2017 - retrospective data) and annually (from May 1, 2017 - prospective data).

We planned to collect data from May 1, 2014 and afterwards, by means of both retrospective and prospective approaches.

All patients who have received or will receive a diagnosis of rare primary headache will be asked to participate and, to this aim, to give their informed consent. Each participating Centre should have received the approval of the competent Ethics Committee before commencing any study procedures.

The registry will contain anagraphic information and data about diagnosis, treatment, comorbidity, and clinical features of the headache. Patients' data will be coded through the Italian Health System unique identifier, in order to avoid duplications of patients referring to more than one Centre and also to monitor multiple referrals.

A web-based open source platform (SurveyMonkey.org) will be used to collect data.

Inclusion Criteria:

• diagnosis of rare primary headaches (Part One, Chapter 3 and Chapter 4, ICHD-3 beta)
• signed informed consent

Exclusion Criteria:

• none

Retrospective data collection:

Patients referred to Italian Tertiary Headache Centres in a 3-year (May 1, 2014 to April 30, 2017) period

Prospective data collection:

Patients referred to Italian Tertiary Headache Centres after April 30, 2017