Hemicrania that mimics CH

[CHfather]

This sounds like a situation that is sometimes described here.  A reason to give indomethacin a fair try with treatment-resistant symptoms that seem to be CH.
https://www.docguide.com/case-remitting-hemicrania-continua-seasonal-variation-and-clustering-diagnostic-confusion-cluster-he?tsid=5

                    A case of remitting hemicrania continua with seasonal variation and clustering: a diagnostic confusion with cluster headache (May 2019)

Hemicrania continua (HC) is an indomethacin responsive primary headache that is characterised by a continuous strictly unilateral headache with periodic exacerbations. About 15% may have a remitting subtype of HC. Herein, we are reporting a 36-year-old man who had a 5-year history of episodic right-sided headaches. The headaches used to occur in a discrete series lasting 4-6 weeks, separated by pain-free remissions of 10-11 months. In each relapse, he had continuous background pain with superimposed exacerbations. The superimposed exacerbations were 1-2 attacks per day, lasting for 2-5 hours, and were associated with ipsilateral cranial autonomic symptoms. However, the patient did not respond to usual therapies of custer headache (CH). He had a complete response to indomethacin. We suggest that remitting subtype of HC may mimic CH. A therapeutic trial of indomethacin should be done in all strictly unilateral headaches that are not responding to other drugs.

[Siegfried]

That is a very good recommendation ! 

I would say.. if your pain does not respond on triptans, then it's time to look at hemicrania. I have an excellent response to triptans but my CH is so hemicrania alike that I still tried Indocin. Of course it was negative... it did not work. 

My doctor told me not to think too fast it's hemicrania. Because hemicrania is very rare. The rate for paroxysmale is 1/50000 while for CH is 1/1000. 2/3 of the hemicrania patients are women so if you are a man, the chances are much bigger that your CH diagnosis is the correct one. 

[CHfather]

Thank you for this thoughtful response, Siegfried.  I'll just add a few notes. One is that recommended dosing for indomethacin is all over the place, between 50mg/day and 300mg/day.  And while some sources say the effects if indo can be seen pretty quickly, others say it can be a couple of weeks or more. So I can't help but wonder how many people have "tried" indomethacin but (as is also true with some CH meds like verapamil), not really had it at high enough doses for a long enough time for a fair test.  Second, I would be cautious about any data regarding hemicranias, just as we have had to be cautious about CH data.  Hemicrania wasn't recognized as a medical condition until the 1980s, and I'm going to guess that the majority of doctors don't recognize it, so it can be strongly underreported. I wonder sometimes how many cases of "intractable chronic CH" are actually misdiagnosed hemicranias.  There was a journal article in 2001 with the title "Hemicrania is not that rare." One of the authors was the great student of CH, Todd Rozen. (https://www.ncbi.nlm.nih.gov/pubmed/11577748).  Maybe current projections factor in that observation. Also, the women/men thing is highly untrustworthy in my view, because as we have seen with shifting CH "statistics" over the years, women quite often get misdiagnosed. Even though the hemicrania reports go in the opposite direction (more women than men with hemis; more men than women with CH), I just don't trust any gender-related statistics since there's no reason that I know of that there should be a prevalence in either direction, and so I tend to think it's a function of some kind of diagnostic error.

All that said, your general principle is probably correct, and maybe people should treat things as CH unless standard CH abortives don't work for them. (On the other hand, there are some "experts" who say no harm done with first trying indomethacin so hemicrania can be ruled out.)  

Edited July 6, 2019 by CHfather