Secondary headaches presenting to the emergency department
| Cause | Clinical features |
|---|---|
| Vascular | |
| Subarachnoid haemorrhage | Nuchal rigidity, thunderclap headache, altered consciousness, nausea/vomiting, possibly focal neurological deficit (vasospasm, infarction) |
| Arterial dissection (carotid or vertebral artery) | Neck pain, focal neurological deficit if associated stroke |
| Venous sinus thrombosis | Headache (can be thunderclap), visual obscurations, papilloedema, focal signs, seizures. Increased risk with the combined contraceptive pill or other prothrombotic risk factors (eg, pregnancy) |
| Infective | |
| Meningitis | Fever/septic features, nuchal rigidity, nausea/vomiting, altered awareness, rash, photophobia |
| Encephalitis | As above, but also focal neurological deficit, confusion, seizures |
| Sinusitis/mastoiditis | Fever/septic features, sinus tenderness, altered hearing, nasal or aural discharge |
| Abscess | Fever/septic features, focal neurological signs, altered awareness, papilloedema |
| Ophthalmological | |
| Acute angle-closure glaucoma | Red eye, large oval pupil, unilateral visual disturbance |
| Inflammatory | |
| Giant cell arteritis | Age >50 years, unilateral visual loss, general malaise, weight loss, scalp tenderness, jaw claudication, raised erythrocyte sedimentation rate/serum C reactive protein) |
| Altered cerebrospinal fluid dynamics | |
| Idiopathic intracranial hypertension | Typically young women with high body mass index, visual obscurations/blurring, papilloedema and tinnitus |
| Colloid cyst of the third ventricle | Headache, gait disturbance, drop attacks |
| Low-pressure headache | Headache improved lying down, may be exacerbated by the valsalva manoeuvre |
| Space-occupying lesion with pressure effects | Headache (new, worsening, change in phenotype) may have associated lateralising features or seizure |