Etiology and characteristics of non-aneurysmal thunderclap headache presenting to an acute setting

To describe the characteristics and causes of non-aneurysmal thunderclap headache (TCH) and compare serious from benign underlying causes.

Retrospective cohort study of consecutive adult patients with TCH presenting to a tertiary care academic medical center between 2010 and 2020. Aneurysmal subarachnoid hemorrhage cases were excluded. Cases were categorized into serious or benign; serious TCH was defined as any condition in which delayed diagnosis and treatment could result in neurological disability or death. Risk factors for serious TCH were analyzed. We adhere to standardized guidelines for reporting observational studies.

A total of 932 patients presented with TCH. After exclusion of 393 patients with aneurysmal-type subarachnoid hemorrhage, 539 were included in the analysis. One-half (n = 275, 51.0 %) had a serious cause. Median age was 51 years, 69.0 % were female. Most frequent diagnoses were intracranial hemorrhage (n = 102, 18.9 %), reversible cerebral vasoconstriction syndrome (n = 97, 18.0 %), and idiopathic TCH (n = 102, 38.6 %). A multivariable logistic regression model for prediction of serious TCH included age, hypertension, migraines, recurrent TCH, level of consciousness and other clinical exam findings, and achieved an AUROC of 0.732. This score had a sensitivity of 79.9 % (95 % CI 73.5-83.5 %) for the identification of serious TCH. A 0.5-point increase in the risk score was associated with a 73 % increase in the odds of serious TCH (odds ratio 1.73, 95 % CI 1.53-1.95, p < 0.001).

Our study describes the relative frequency of presentation and etiologies among patients with TCH This score can aide clinicians in recognising patients with potentially serious cause of TCH, for whom additional imaging and neurological consultation is necessary.