Assertion: stroke's symptom | /r/HasProperty | severe headache
Facets:
value: with no known cause
type: OTHER
value: very
type: DEGREE
Source sentences:
text: When caused by a ruptured aneurysm, symptoms can include: A very severe headache that starts suddenly (Some people describe it like a "thunderclap.")
text: Symptoms, which usually develop suddenly and without warning, include: severe headache with no known cause