Thunderclap headache Last edited and medically reviewed by Alaric Steinmetz on 09.02.2024 Synonyms primäre Donnerschlagkopfschmerzen, Thunderclap headache Thunderclap headache refers to a sudden-onset headache of the greatest severity[^1].EtiologyThunderclap headache is the hallmark symptom of aneurysmal subarachnoid hemorrhage. The following conditions may cause thunderclap headache:Subarachnoid hemorrhageCerebral venous sinus thrombosisColloid cystPituitary apoplexyIschemic stroke