The Basics
Paroxysmal hemicrania is a rare but treatable primary headache disorder, meaning that it’s not caused by another condition. The name paroxysmal hemicrania describes the hallmark features of this headache:
- Paroxysmal means sudden recurrence or attack
- Hemicrania means one-side of the head (unilateral or side-locked)
Thus, as the name implies, paroxysmal hemicrania is a recurrent one-sided headache usually located around or behind the eye. Episodes of paroxysmal hemicrania typically occur from 5 to 40 times per day and last 2 to 30 minutes. Along with the attacks of one-sided headache, it also causes episodes of redness or tearing of the eye, runny or stuffy nose, sweating or flushing of the face on the same side of the headache (called unilateral cranial autonomic symptoms). In addition, paroxysmal hemicrania resolves completely with taking indomethacin (a medicine in the NSAID family) and this exquisite responsiveness to indomethacin is required to make the diagnosis.
People suspected of having paroxysmal hemicrania should be carefully assessed by their doctor for an underlying cause. As well, they should be evaluated to make sure that they do not have a different primary headache disorder that can mimic paroxysmal hemicrania. Other primary headache disorders that mimic paroxysmal hemicrania include primary stabbing headache, cluster headache, short-lasting unilateral neuralgiform headaches with red-eye and tearing (conjunctival injection and tearing) (SUNCT/SUNA) and trigeminal neuralgia.
Brain imaging, preferably with MRI, is necessary at initial diagnosis or during the course if atypical features develop or if the person does not respond to treatment. The brain imaging should include focused views of the pituitary gland and posterior fossa. Remember, response to treatment does not tell you whether the diagnosis is correct or not.
Please refer to the International Classification of Headache Disorders 3rd edition (beta version) website for more information on the criteria used to diagnose paroxysmal hemicrania: https://www.ichd-3.org/3-trigeminal-autonomic-cephalalgias/3-2-paroxysmal-hemicrania/
Treatment
Indomethacin is the treatment of choice for paroxysmal hemicrania. If people cannot take indomethacin, there are case reports of verapamil or pericranial nerve blocks being used.
Summary
The cause of paroxysmal hemicrania is unknown. As with migraine disease and many other headache disorders, there is no definitive diagnostic test for paroxysmal hemicrania. When a person has symptoms of paroxysmal hemicrania, a trial of indomethacin may confirm the diagnosis. However, even people fitting all criteria for paroxysmal hemicrania, including a complete response to indomethacin, can have a secondary etiology. Tests such as an MRI may be performed to rule out other causes for the headache.
Resources:
The International Headache Society. https://www.ichd-3.org/3-trigeminal-autonomic-cephalalgias/3-2-paroxysmal-hemicrania/
Newman LC. Trigeminal autonomic cephalalgias. Continuum (Minneap Minn) 2015;21:1041-1057.
