[Idiopathic thunderclap headache: reversible vasospasm of the Arteria basilaris].

Thunderclap headache describes a rare headache syndrome characterized by abrupt-onset severe headache mimicking subarachnoidal bleeding, which has to be excluded by adequate diagnostic procedures such as digital subtraction angiography. The pathophysiology is still not clear but there are an increasing number of reports which describe some kind of vasospasm of the intracranial arteries during the headache episode. Here we describe a patient with a thunderclap headache and a mid-basilar narrowing due to a reversible vasospasm.