Headache red flags and secondary headache

Also known as Secondary headache · Thunderclap headache · SNOOP criteria

GP-fellowship guide to headache red flags and secondary headache: the SNOOP framework and beyond, thunderclap headache SAH workup (CT sensitivity by timing, LP xanthochromia), giant cell arteritis in over-50s (ESR/CRP, temporal artery biopsy, steroid before biopsy to prevent blindness), idiopathic intracranial hypertension (Friedman criteria, papilloedema risk profile), cerebral venous sinus thrombosis, medication-overuse headache, carbon monoxide exposure, cervicogenic headache, and acute angle closure overlap.

high6 referencesUpdated 22 Aug 20264 min readVerification in progress

Practise this topic

Key points

The Ottawa Subarachnoid Haemorrhage Rule identified clinical variables that achieved 100% sensitivity (95% CI 97.1–100%) for detecting SAH in neurologically intact patients across 1999 patients.^[1]
Modern multislice CT has 99.6% sensitivity for aneurysmal SAH at 48 hours after headache onset and 100% at 24 hours — extending the window for CT-only rule-out beyond the traditional six-hour threshold.^[2]
Giant cell arteritis is treated as a medical emergency due to potential sudden irreversible visual loss — start high-dose steroids immediately before temporal artery biopsy or ultrasound.^[3]
Idiopathic intracranial hypertension diagnostic criteria were revised by Friedman et al to incorporate neuroimaging abnormalities and distinguish papilloedema from non-papilloedema forms.^[4]

Overview

Headache is one of the most common presentations in general practice, and the vast majority are primary headaches (migraine, tension-type, cluster). The GP's task is to identify the minority that are secondary — caused by something dangerous — using the SNOOP framework and beyond.^[1]

References6Show

[1]Masuhr F, Mehraein S, Einhäupl K Cerebral venous and sinus thrombosis. J Neurol, 2004.PMID 14999484
[2]Perry JJ, Stiell IG, Sivilotti ML, Bullard MJ, Lee JS, et al. High risk clinical characteristics for subarachnoid haemorrhage in patients with acute headache: prospective cohort study. BMJ, 2010.PMID 21030443
[3]Friedman DI, Liu GT, Digre KB Revised diagnostic criteria for the pseudotumor cerebri syndrome in adults and children. Neurology, 2013.PMID 23966248
[4]Waller A, Jawad AM CRP and ESR in giant cell arteritis. J R Coll Physicians Edinb, 2017.PMID 29465111
[5]Vincent A, Pearson S, Pickering JW, Weaver J, Toney L, et al. Sensitivity of modern multislice CT for subarachnoid haemorrhage at incremental timepoints after headache onset: a 10-year analysis. Emerg Med J, 2022.PMID 34819306
[6]Pouncey AL, Yeldham G, Magan T, Lucenteforte E, Jaffer U, Virgili G Halo sign on temporal artery ultrasound versus temporal artery biopsy for giant cell arteritis. Cochrane Database Syst Rev, 2024.PMID 38323659