Perimesencephalic Subarachnoid Hemorrhage After Thunderclap Headache in a Clinically Stable Patient: A Case Report.

Subarachnoid hemorrhage (SAH) is a serious neurological emergency with a typical presentation of a thunderclap headache. SAH is a cause of considerable morbidity and mortality, especially in aneurysmal form. Improvement or even resolution of symptoms does not exclude potentially dangerous intracranial pathology in this context, which often leads to delayed diagnosis. We describe a case of perimesencephalic SAH in a young male who experienced a thunderclap headache, after which he became clinically stable. Subsequent imaging confirmed perimesencephalic SAH, while the exclusion of a vascular lesion was established by CT angiography, digital subtraction angiography, and 3D rotational angiography. Thus, a thunderclap headache should be evaluated in every patient, irrespective of the dynamics of symptoms.