Editing Thunderclap headache (section)

==Causes==
Approximately 75% are attributed to "primary" headaches: headache disorder, non-specific headache, idiopathic thunderclap headache or uncertain headache disorder.<ref name=Devenney/>  The remainder are secondary to a number of conditions, including:<ref name=Schwedt/><ref name=Devenney/>
* [[Subarachnoid hemorrhage]] (10–25% of all cases of thunderclap headache)
* [[Cerebral venous sinus thrombosis]]
* [[Cervical artery dissection]]
* [[Hypertensive emergency]] (severely raised blood pressure)
* [[Spontaneous intracranial hypotension]] (unexplained low [[cerebrospinal fluid]] pressure)
* [[Stroke]] (headache occurs in about 25% of strokes but usually not thunderclap character)
* [[Retroclival hematoma]] (hematoma behind the [[clivus (anatomy)|clivus]] in the skull, usually due to physical trauma but sometimes spontaneous)
* [[Pituitary apoplexy]] (infarction or hemorrhage of the [[pituitary gland]])
* [[Colloid cyst]] of the [[third ventricle]]
* [[Meningitis]], sinusitis
* [[Reversible cerebral vasoconstriction syndrome]] (previously Call-Fleming syndrome, several subtypes)
* Primary cough headache, primary exertional headache, and primary [[sexual headache]]

The most important of the secondary causes are [[subarachnoid hemorrhage]], [[cerebral venous sinus thrombosis]], and [[Dissection (medical)|dissection]] of an artery in the neck.<ref name=Schwedt/><ref>{{Cite journal|last=Dilli|first=Esma|date=April 2014|title=Thunderclap headache|journal=Current Neurology and Neuroscience Reports|volume=14|issue=4|pages=437|doi=10.1007/s11910-014-0437-9|pmid=24643327|s2cid=37813850}}</ref>

In [[subarachnoid hemorrhage]], there may be [[syncope (medicine)|syncope]] (transient loss of consciousness), [[Convulsions|seizures]], [[meningism]] (neck pain and stiffness), visual symptoms, and [[vomiting]]. 50–70% of people with subarachnoid hemorrhage have an isolated headache without [[decreased level of consciousness]]. The headache typically persists for several days.<ref name=Schwedt/>

[[Cerebral venous sinus thrombosis]], thrombosis of the veins of the brain, usually causes a headache that reflects raised [[intracranial pressure]] and is therefore made worse by anything that makes the pressure rise further, such as [[cough]]ing. In 2–10% of cases, the headache is of thunderclap character. In most cases there are other neurological abnormalities, such as seizures and weakness of part of the body, but in 15–30% the headache is the only abnormality.<ref name=Schwedt/>

[[Carotid artery dissection]] and [[vertebral artery dissection]] (together cervical artery dissection), in which a tear forms inside the wall of the blood vessels that supply the brain, often causes pain on the affected side of the head or neck. The pain usually precedes other problems that are caused by impaired blood flow through the artery into the brain; these may include visual symptoms, weakness of part of the body, and other abnormalities depending on the vessel affected.<ref name=Schwedt/>