Headache is a common presentation to ED and Subarachnoid Haemorrhage (SAH) is the diagnosis we never want to miss. However, working out who needs a scan can be difficult as 50% of patients presenting with a subarachnoid have no neurological deficit.

• ‘Thunder Clap’ headache peak of pain within 5min is a RED-FLAG
  • Although, most patients with ‘Thunder Clap’ don’t have SAH, this should not deter emergent investigation
• Patients may present more subtlety the following should make you consider the diagnosis:
  • neck pain or stiffness (limited or painful neck flexion on examination)
  • photophobia
  • nausea and vomiting
  • new symptoms or signs of altered brain function (such as reduced consciousness, seizure or focal neurological deficit)
• Always be suspicious if the patient has communication difficulties.

NICE Investigation Algorithm

NICE SAH guidance