Catecholamine-Induced Reversible Cerebral Vasoconstriction Syndrome: An Overlooked Cause of Thunderclap Headache.

Reversible cerebral vasoconstriction syndrome (RCVS) is a rare but important cause of thunderclap headache. It is often under-recognized, as the presentation can be variable, and early imaging can be normal. RCVS may be precipitated by catecholaminergic surges, including those from pheochromocytoma. We describe a 35-year-old female patient who presented with recurrent thunderclap headaches, later complicated by acute confusion and transient dysphasia. Initial investigations were unremarkable, but subsequent magnetic resonance imaging (MRI) revealed a transient parieto-occipital lesion and vascular irregularities, prompting consideration of RCVS. Her evolving clinical picture eventually led to the discovery of a large adrenal mass, which was confirmed via biochemical testing as a catecholamine-secreting pheochromocytoma. Surgical resection following appropriate alpha- and beta-blockade resulted in complete symptom resolution and biochemical normalization. This case highlights the diagnostic complexity of RCVS secondary to pheochromocytoma, where the absence of typical imaging features and systemic symptoms delayed diagnosis. Early involvement of the multidisciplinary team can be useful in unraveling complex presentations associated with rare secondary causes of headaches. Pheochromocytoma should be considered a potential trigger for RCVS, particularly in patients with unexplained recurrent headaches and systemic symptoms, as early diagnosis and treatment can lead to symptom resolution and prevent serious complications.