Study execution and time table: Meanwhile the final protocol is under evaluation for ethical approval by HUS, preparatory measures have been taken by informing the FMA about the planned study and asking their co-operation in encouraging the interested migraine patients to contact the study coordinator. Given the preliminary interest shown by the FMA, we are optimistic that the required cohort of volunteers can be enrolled within a short time, most likely by the end of 2013. However, because the subjects with episodic cluster headache must be enrolled during their on-going cluster episodes that typically follow a seasonal pattern, the enrolment of the total cohort (even n=60) inevitably needs to be completed over several months (up to one year).