A “thunderclap” headache is exactly what it sounds like and just as nasty. In 2014, Devenney et al. reported one hundred nineteen causes other than the only usual suspect (subarachnoid haemorrhage). Yikes!
Thunderclap headaches are a “genus” not a “species.” Pathologies are often part of larger, more diverse groups than we know.
We often make the same mistake with critters! For instance, the anglerfish is not just one mean-looking species, but a family of hundreds (hat tip to Cara Santa Maria, who talked about this on a recent episode of The Skeptics Guide to the Universe).
Thunderclap headaches are one of my own chronic pain demons — indeed, probably my single worst symptom. The specific cause remains undiagnosed. A neurologist once overconfidently asserted that we’d already eliminated the “only possible serious cause” of my symptoms. O rly? 🤔 Please see Devenney et al.!
My huge guide to headaches describes several other primary headaches — migraine, cluster, exertional, hypnic, and so on — plus a whole bunch of secondary headaches.