Abstract text (incl. figure legends and references)

Introduction: Thunderclap headache (TCH) is an hiperacute and severe headache, which needs a comprehensive differential diagnosis. Primary TCH has been reported rarely, associated to cough, sexual intercourse. We report a case of a patient otherwise healthy, with recurrent episodes of Primary TCH triggered by micturition.

Case presentation: A 55 years old woman was admitted in the ER because of episodes which fulfilled TCH clinical criteria, associated to micturition. These episodes started spontaneously, in the absence of arterial hypertension or any previous medical illness and occurred several times during the day, lasting for up to ten minutes, starting upon micturition. Her physical exam was normal. Her brain CT scan, CTA and MRA were normal. At first, she was treated with anxiolytics, antidepressants, with no improvement. Her blood lab tests were unremarkable. Normal urinary metanephrines and abdominal CTscan excluded urinary bladder pheochromocytoma. She was treated with nimodipine and her situation improved visibly since the first day after starting therapy.

Discussion: The causes of such disorder, are still not well understood, but the typical clinical history of the patient and all negative tests for other causes of TCH, including urinary bladder pheochromocytoma are the main clues to the right diagnosis and treatment. Treatment was based on similar cases in the literature.

Conclusions: Primary TCH triggered by micturition is a challenging and rare diagnosis. Nimodipine seems to be a good treatment option for this rare type of primary TCH.