Scientists are still investigating  potential triggers for the three types of primary headaches: recurring, long-lasting migraines; intensely painful,  rapid-fire cluster headaches; and, most common of all,  the tension headache.
Os científicos seguen pescudando os potenciais precipitantes dos tres tipos de cefaleas primarias: as xaquecas recorrentes e prolongadas; as cefaleas en salvas, de dor aguda e súbita; e a máis común: a cefalea tensional.