Incidence and outcome of sudden severe headache in the emergency department

To assess the incidence, diagnostic yield, discharge diagnoses, and outcome of patients admitted to a district teaching hospital with sudden onset severe headache, and to evaluate the diagnostic processes for subarachnoid hemorrhage (SAH) and if this has changed over the past years.

Headache is a common presentation in the emergency department, yet there are limited data on patients presenting with sudden onset severe headache, a subgroup of headache that may indicate subarachnoid hemorrhage.

This was a single-center, retrospective observational cohort study conducted at Nordland Hospital Trust. We reviewed the medical records of every patient presenting with sudden onset severe headache at our hospital between January 2008 and December 2020. Data collected included headache characteristics, associated symptoms, radiological findings, lumbar puncture/cerebrospinal fluid results, treatments, discharge diagnoses, complications, and follow-up information. Rehospitalization or death associated with the headache was monitored until April 2022.

A total of 588 patients, with a mean age of 42.5 ± (SD = 17.9) years (362/588, 61.6% female, 226/588, 38.4% male), were included. These patients represented 0.4% of all hospital emergency admissions and 4.5% of neurological department admissions. Thunderclap headache was observed in 49.7% (292/588) of cases. Of the total cohort, 119/588 (20.2%) had a certain secondary headache. Half of these, 58/588 (9.9%), were diagnosed with a SAH, including 38/588 (6.5%) with an aneurysmal SAH. Most patients, 338/588 (57.5%), received a nonspecific headache diagnosis, 50/588 (8.5%) were diagnosed with migraine, and 50/588 (8.5%) had other primary headache disorders. Among the 205/588 (34.9%) patients scanned within 6 hours of symptom onset, two with a negative computed tomography later turned out to have a perimesencephalic hemorrhage. Twenty-four patients, 24/588 (4.1%), were diagnosed with a central nervous system infection. Additional diagnoses included other infections, ischemic stroke, and more uncommon secondary headaches. Appointed follow-up was recorded for 106/588 (18.0%) of all patients. No deaths or readmissions attributed to overlooked subarachnoid hemorrhage were recorded by the final review in 2022.

SAH suspected headaches represent only a small proportion of hospital admissions. At least two in 10 will have a secondary headache, and one in 10 will have an SAH, of which two-thirds are attributed to an aneurysmal rupture. These findings underscore the importance of thorough diagnostic evaluation of sudden onset severe headache and clinical vigilance in emergency settings. However, the majority of patients are discharged with a nonspecific headache diagnosis. One must suspect that most of these have a primary headache disorder. Few receive follow-up, and the individual and societal cost of this should be evaluated in future studies.