Summary

The Call–Fleming syndrome (CFS) comprises acute severe recurrent (thunderclap) headaches, occasional transient or fluctuating neurological abnormalities and reversible segmental cerebral vasoconstriction. It is a benign condition with an excellent prognosis, yet because it is often clinically and radiologically similar to a number of commonly encountered conditions, diagnostic difficulties may arise, leading to inappropriate, and even potentially harmful, investigative and therapeutic approaches. Three personal cases are presented to highlight the occurrence of subarachnoid haemorrhage (SAH) as part of CFS. In two patients with a positive CT head, SAH involved the sulci in the upper cerebral convexity, an unusual location in aneurysmal SAH. SAH is not an uncommon feature of CFS, occurring in approximately 25% of reported cases, and may pose a diagnostic challenge. CFS has a relatively characteristic spectrum of features, allowing a confident diagnosis in most cases, even when atypical features such as SAH are present. Recognising the spectrum of abnormalities seen in CFS, including particularly SAH, allows a sound approach to a safe diagnosis.