Paroxysmal hemicrania (PH) involves one-sided attacks (headaches) that have closely similar characteristics of pain and associated (autonomic) symptoms of cluster headache (CH). However, they tend to be very much shorter in duration. Each attack normally lasts between 10-30 minutes, but can be as short as two minutes or as long as 45 minutes. They also tend to occur on average more frequently than CH (five per day or more - and sometimes up to 40 per day) and appear to be more prevalent amongst females. As with both CH and migraine there are two variants of PH: chronic and episodic, defined in exactly the same way as in CH.
Like many of the other shorter lasting primary headaches, PH responds almost absolutely to a medication called indomethacin (a non-steroidal anti-inflammatory drug), and it is noteworthy that this course of action is often used as a screening investigation to rule out CH amongst some sufferers.
As with CH, the diagnosis of paroxysmal hemicrania is based purely on assessing the history of the sufferer coupled with a detailed neurological examination.