Unruptured aneurysm producing thunderclap headache treated with endovascular coil embolization.

The abrupt onset of acute, high-intensity headache, unlike any experienced before, can be an urgent medical condition, which requires attention. A 32-year-old female patient developed thunderclap headache attacks had applied with increasing intensity and frequency since 1 week. She had visited the emergency department several times, and cranial computed tomography findings were normal. On the last presentation, neurological examination showed complete oculomotor nerve palsy on the left. Brain magnetic resonance imaging together with intracranial brain angiography revealed left posterior communicating aneurysm compressing the ipsilateral oculomotor nerve, with no evidence of subarachnoid hemorrhage. The patient was treated with endovascular balloon-assisted coil embolization of the aneurysm under digital subtraction angiography. As a result, the headache resolved soon after the intervention. Furthermore, complete ptosis recovered by the third month. Although thunderclap headache has rarely been attributed to an enlarging unruptured cerebral aneurysm, early recognition and treatment are rather important as it may indicate a high risk of rupture.