Reversible cerebral vasoconstriction syndrome associated with hyperosmolar hyperglycaemic state: A case report and literature review.

Reversible cerebral vasoconstriction syndrome (RCVS) is an uncommon disorder characterised by thunderclap headache and self-resolving angiographic vasospasm in the presence or absence of neurological deficit. We present the first case of RCVS likely precipitated by a complex array of confounding factors including a hyperosmolar hyperglycaemic state (HHS), induction chemotherapy with cyclophosphamide, non-Hodgkin's lymphoma, pancytopenia and previous blood transfusions. However, the clinical presentation in this case of altered conscious state followed by thunderclap headache was highly suggestive of HHS being the crucial inciting factor. This report of RCVS associated with HHS lends unique insight into key underlying pathophysiological mechanisms, and warns of the need to maintain a high index of suspicion for this elusive condition given the dynamic and transient nature of its clinical and radiological features.