Subarachnoid Haemorrhage

1 · Recognise

• Thunderclap headache — sudden, severe, typically peaking within 1 to 5 minutes
• Neck pain or stiffness, photophobia, nausea and vomiting
• Altered brain function: reduced consciousness, seizure, focal deficit
• Onset on exertion, coughing or during sex is common — and does not make it benign
• Ask specifically about a sentinel headache in the preceding days

Most thunderclap headaches are not SAH, but that must not stop you investigating.

2 · Senior review and analgesia

• Review by a senior clinical decision-maker — this is not a decision to make alone
• Give effective pain relief, including opioids if needed (NG228 is explicit about this)
• Document that opioid was given: it sedates and constricts pupils, and the next person doing neuro obs needs to know why
• ABCDE, GCS, pupils, BP, blood glucose
• Bloods including clotting and group & save
• ECG may mimic ischaemia — deep T-wave inversion, long QT

3 · Urgent non-contrast CT head

Refer for an urgent non-contrast CT head. Diagnostic accuracy is highest within 6 hours of symptom onset, so the clock starts at onset, not at arrival.

Diagnose SAH if the CT shows blood in the subarachnoid space.

4 · Negative CT — what next depends on the clock

CT within 6 hours of onset, reported by a radiologist, showing no SAH:

• Do not routinely offer an LP
• Think about alternative diagnoses and discuss with a senior

CT more than 6 hours after onset showing no SAH:

• Consider an LP
• Wait at least 12 hours from symptom onset before doing it — bilirubin needs time to form
• Diagnose SAH if spectrophotometry shows raised bilirubin (xanthochromia)

5 · Find the aneurysm

• Once SAH is confirmed, offer CT angiography of the head without delay
• Diagnose aneurysmal SAH if CTA shows an intracranial aneurysm and the blood pattern fits rupture
• If CTA is negative and an aneurysm is still suspected, consider DSA (or MRA if DSA contraindicated)

6 · Refer to neurosurgery

• Urgently discuss transfer with a specialist neurosurgical centre for every confirmed SAH
• Do not use a severity score in isolation to decide on or time the transfer
• Securing the aneurysm — coiling, or clipping if coiling is unsuitable — should happen at the earliest opportunity, because rebleeding risk is highest in the first 24 hours

7 · Nimodipine and supportive care

• Consider enteral nimodipine — usual regimen 60mg PO/NG every 4 hours for 21 days
• Only use IV nimodipine in a specialist setting when enteral is unsuitable
• Manage VTE risk per the NICE VTE guideline
• Continue analgesia and antiemetics; treat seizures conventionally

8 · Complications

• Any unexplained neurological deterioration → non-contrast CT head first
• Rebleeding — highest risk in the first 24 hours
• Hydrocephalus — diagnose on symptoms plus comparison with previous imaging; consider CSF drainage or diversion
• Delayed cerebral ischaemia (typically days 4–14) — ensure euvolaemia, and consider a vasopressor if symptoms persist. Any improvement may be temporary
• Do not use transcranial doppler to guide management outside research
• Hyponatraemia is common — distinguish SIADH from cerebral salt wasting rather than reflexively fluid-restricting