The key symptom of<unk>  is recurrent thunderclap headaches, which over 95% of patients experience. In two-thirds of cases, it is the only symptom. These headaches are typically bilateral, very severe and peak in intensity within a minute. They may last from minutes to days, and may be accompanied by nausea, photophobia, phonophobia or vomiting. Some patients experience only one headache, but on average there are four attacks over a period of one to four weeks. A milder, residual headache persists between severe attacks for half of patients. 1–17% of patients experience seizures. 8–43% of patients show neurologic problems, especially visual disturbances, but also hemiplegia, ataxia, dysarthria, aphasia, and numbness. These neurologic issues typically disappear within minutes or a few hours; more persistent symptoms may indicate a stroke. Posterior<unk>  encephalopathy syndrome is present in a small minority of patients. This condition features the unique property that the patient's cerebral arteries can spontaneously constrict and relax back and forth over a period of time without intervention and without clinical findings. Vasospasm is common post subarachnoid hemorrhage and cerebral aneurysm, but in<unk>  only 25% of patients have symptoms post subarachnoid hemorrhage.
Reversible cerebral vasoconstriction syndrome
Cerebral hyperperfusion syndrome
Brain fag syndrome
Intracranial hypertension syndrome
Cerebral vasospasm
Thrombotic storm
Posterior cerebral artery syndrome
Middle cerebral artery syndrome