Educational draft · awaiting clinical reviewUse Rapid for revision, not patient-care decisions. Check current national and local guidance and the BNF or BNFC before acting.
2 min synopsisUK scopeSources checked 13 Sept 2026Clinical review pending
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Deterioration has several treatable causes
A new focal deficit, reduced consciousness or sudden severe headache after subarachnoid haemorrhage may represent rebleeding, hydrocephalus, delayed cerebral ischaemia, seizure, infection or metabolic disturbance; labelling it vasospasm can miss immediate surgical disease.
Action: Repeat ABC assessment and structured neurology, obtain urgent non-contrast CT first, and involve the specialist neurovascular team while additional angiographic, perfusion, EEG and laboratory tests follow the leading cause.
Synopsis
Differentiate delayed cerebral ischaemia, acute or chronic hydrocephalus and recurrent aneurysmal bleeding after subarachnoid haemorrhage, then choose urgent investigation and cause-specific treatment.
Rebleeding is most dangerous early, particularly while the culprit aneurysm is unsecured; prevention depends on securing the lesion at the earliest opportunity.
Delayed cerebral ischaemia is a clinical syndrome of new deficit or reduced consciousness after excluding rebleeding, hydrocephalus, seizures and systemic or metabolic causes; angiographic vasospasm may be present without clinical ischaemia.
Hydrocephalus may be acute or chronic and is diagnosed from symptoms and signs plus comparison of current with previous brain imaging, not ventricular size alone.
Key red flags
Abrupt severe recurrent headache, collapse or rapid loss of consciousness suggests rebleeding, especially before the culprit aneurysm has been secured.
Progressive drowsiness, headache, vomiting, abducens palsy or worsening gait with enlarging ventricles suggests symptomatic hydrocephalus and needs urgent neurosurgical review.
A new focal deficit or fall in consciousness several days after SAH can indicate delayed cerebral ischaemia, but rebleeding and hydrocephalus must be excluded first.
Seizure, fever, hypoxia, hypotension, hyponatraemia and sedative accumulation can mimic or amplify cerebral ischaemia; bedside physiology and blood tests run alongside imaging.
Temporary improvement with a vasopressor or CSF drainage does not establish durable cause control and requires continued observation and imaging.
Rebleeding pattern
A sudden return of maximal headache, collapse, abrupt GCS fall or new blood burden on CT is recurrent haemorrhage until the specialist team proves another cause.
Delayed cerebral ischaemia
New focal neurology or a sustained consciousness decline days after SAH, unexplained by CT, seizures, sodium, fever, oxygenation or sedation, supports the clinical DCI syndrome.
Acute hydrocephalus
Drowsiness, headache, vomiting, gaze or abducens change and progressive ventricular enlargement suggest impaired CSF flow requiring urgent drainage assessment.
Reasoning priorities
01
Urgent non-contrast CT head
Identify rebleeding, acute hydrocephalus, haematoma, swelling and established infarction when neurology worsens.
New blood or enlarging ventricles directs immediate source control or CSF diversion; a scan without either preserves DCI, seizure and systemic causes.
Worked reasoning
Worked case: post-SAH deteriorationNew deficit or falling consciousness after SAH
A patient develops new focal neurology, reduced alertness, severe recurrent headache or another unexplained neurological change.
Reassess airway, breathing, circulation, glucose, temperature, oxygenation, blood pressure, pupils, GCS components and focal findings, and activate the specialist neurovascular team.
Obtain urgent non-contrast CT as the first diagnostic investigation to look for new blood, hydrocephalus, haematoma, swelling or infarction while checking sodium, infection, medicines and seizure clues.
If rebleeding is present, resuscitate and reassess culprit occlusion for immediate source control; if symptomatic acute hydrocephalus is present, obtain urgent neurosurgical CSF-drainage or diversion assessment.
If CT does not explain the decline, investigate DCI with specialist vascular or perfusion imaging and seizure with EEG as indicated, then treat confirmed or strongly suspected causes without waiting for irreversible infarction.
Document neurological response to every intervention and repeat imaging or escalation when improvement is absent, transient or discordant with the proposed diagnosis.
Key medicines
NimodipineUse the specialist subarachnoid-haemorrhage protocol and current product information; NICE recommends considering enteral administration and reserving intravenous treatment for specialist settings when enteral use is unsuitable.Monitor arterial pressure and cerebral perfusion, review missed or reduced doses with the specialist team, and do not describe it as a treatment that simply dilates every spastic artery.
Vasopressor therapyTitrate in a neurocritical-care setting to clinical response and safe haemodynamic endpoints after euvolaemia is established; NICE does not specify one universal drug or pressure target.Benefit may be temporary; monitor cardiac ischaemia, arrhythmia, pulmonary oedema and the risk from unsecured aneurysm or other bleeding, and avoid prophylactic hypertension.
National guidance is shown before implementation-dependent detail. Typical adult dose examples remain subject to patient factors, contraindications and the live BNF or specialist protocol. Source check completed 13 Sept 2026; clinical approval remains outstanding.
NICE NG228 aneurysmal subarachnoid haemorrhage recommendationsNICE guideline NG228, published 23 November 2022; recommendations and rationale sections 1.1.16–1.3.6 read 13 September 2026. Applies to people with confirmed or suspected aneurysmal subarachnoid haemorrhage in England; UK nations decide applicability separately. Chapter-specific use: rebleeding, delayed cerebral ischaemia and hydrocephalus.
2026 ESO–EANS–ESMINT aneurysmal subarachnoid haemorrhage guidelineJoint European professional guideline published 7 May 2026; PICO 3a–3b on coiling, clipping and adjunctive endovascular devices, PICO 4 on DCI prevention, PICO 5a–5b on DCI rescue, PICO 6 on monitoring and PICO 7 on hydrocephalus read 13 September 2026. Evidence population is predominantly adults with acute saccular aSAH; NICE remains the UK practice anchor. Chapter-specific use: rebleeding, delayed cerebral ischaemia and hydrocephalus.
NICE NG228 evidence review E: monitoring for raised ICP and vasospasmFinal NICE evidence review E, November 2022; monitoring modalities and committee conclusions read 13 September 2026. Supports the recommendation against TCD-guided clinical management outside research and the CT-first deterioration pathway.
NICE NG228 evidence review H: managing hydrocephalusFinal NICE evidence review H, November 2022; acute and chronic hydrocephalus drainage evidence and committee discussion read 13 September 2026. Applies to hydrocephalus after aneurysmal SAH; device operations require local neurosurgical protocol.