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Prevention has a different starting point

An incidental aneurysm can produce anxiety even when no bleeding has occurred. The decision is whether preventive treatment offers enough expected benefit to justify its immediate risks, or whether observation is appropriate. Both choices need a plan. Evidence about emergency treatment after a rupture cannot simply decide a preventive-treatment question. The 2022 ESO guideline primarily addresses adults with asymptomatic unruptured aneurysms and acknowledges substantial uncertainty.1

An “unruptured” label describes what has been established, rather than granting immunity from an acute problem. A sudden severe headache or new acute neurological symptoms still need urgent local assessment. Do not wait for a scheduled scan or an overseas appointment to investigate such a change.2

More than size alone

The discussion considers location, shape, neck and branch anatomy, symptoms thought to relate to the lesion, changes on comparable imaging, earlier subarachnoid bleeding, family history, smoking and hypertension. Age, overall health, expected future benefit, procedural complexity and the person's priorities also matter. A small aneurysm is not guaranteed safe, and a particular diameter does not mandate the same treatment for everyone. Growth can lead to reassessment, but does not remove the need to weigh treatment risks.1

Risk models can organize some population information, but a number generated from a limited set of factors cannot capture every lesion or patient circumstance. Ask the team to explain both uncertainty and the time horizon of any estimate they discuss.1

Monitoring is active care

Observation can include vascular imaging, comparison with earlier scans and support with modifiable health factors. The plan should say who reviews the images, what change would trigger a new discussion, and how long follow-up remains useful. Frequency depends on the aneurysm, the person and whether treatment would remain an option. A fixed schedule copied from another person's care may be unsuitable.1

Smoking cessation support and treatment of hypertension are part of the guideline's approach. A medicine needed for another health condition has a different indication from an unproven aneurysm-prevention strategy; review it with the responsible clinicians.1

If preventive treatment is considered

Ask why clipping, coiling or flow diversion fits this anatomy, what alternatives were discussed and how the team expects to assess benefit and harm. Complete closure on an image, a neurological complication and later retreatment are separate outcomes. The 2022 guideline's very low-certainty recommendations should be read alongside later evidence. A completed randomized unruptured-device comparison appeared in 2026, but it does not answer all questions about preventive treatment versus observation and we have not used its results as a treatment rule.13

A shared decision should leave you able to describe the purpose of the chosen approach and its follow-up. Ask for a written plan, time to discuss concerns and clarification of who coordinates ongoing care.

References

  1. Etminan N et al. European Stroke Journal. 2022;7: LXXXI–CVI. doi:10.1177/23969873221099736. Source ↩
  2. National Institute for Health and Care Excellence. NG228. Subarachnoid haemorrhage caused by a ruptured aneurysm: diagnosis and management. 2022. Source ↩
  3. Efficacy and safety of flow diverter therapy for unruptured intracranial aneurysms compared to conventional endovascular therapy: a multicentre, randomised, open-label trial in South Korea. EClinicalMedicine. 2026. doi:10.1016/j.eclinm.2026.104135. PMID 42598553. PubMed ↩