Table 4

Secondary headaches presenting to the emergency department

CauseClinical features
 Subarachnoid haemorrhageNuchal 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 thrombosisHeadache (can be thunderclap), visual obscurations, papilloedema, focal signs, seizures. Increased risk with the combined contraceptive pill or other prothrombotic risk factors (eg, pregnancy)
 MeningitisFever/septic features, nuchal rigidity, nausea/vomiting, altered awareness, rash, photophobia
 EncephalitisAs above, but also focal neurological deficit, confusion, seizures
 Sinusitis/mastoiditisFever/septic features, sinus tenderness, altered hearing, nasal or aural discharge
 AbscessFever/septic features, focal neurological signs, altered awareness, papilloedema
 Acute angle-closure glaucomaRed eye, large oval pupil, unilateral visual disturbance
 Giant cell arteritisAge >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 hypertensionTypically young women with high body mass index, visual obscurations/blurring, papilloedema and tinnitus
 Colloid cyst of the third ventricleHeadache, gait disturbance, drop attacks
 Low-pressure headacheHeadache improved lying down, may be exacerbated by the valsalva manoeuvre
 Space-occupying lesion with pressure effectsHeadache (new, worsening, change in phenotype) may have associated lateralising features or seizure