Magnetic Resonance Imaging (MRI)
What is magnetic resonance imaging (MRI)? Magnetic resonance imaging (MRI) is a scanning procedure that uses strong magnets and radiofrequency…Read more
Aneurysm diagnosis may be with CT, CTA, MRI, MRA, or DSA. DSA is required for endovascular treatment and may be a separate diagnostic procedure prior to aneurysm treatment or performed immediately prior to definitive treatment under the same general anaesthetic.
Consultation with a neurointerventional specialist is essential for referring clinicians to obtain a full understanding of the risk of treatment versus the risk of rupture if untreated. This risk-benefit equation will vary from patient to patient and aneurysm to aneurysm and so the discussion is important.
Renal function must be tested prior to contrast administration–U&E, including eGFR estimation. Contrast dosage can be quite high for this procedure particularly if the aneurysm is large or hard to access.
Clotting function must be assessed prior to the procedure if the patient is on anticoagulant therapy, or has clinical risk factors for abnormal clotting function. Warfarin or heparin therapy will need to be ceased (3 days or 24 hours respectively) before treatment. Premedication discussed and arranged e.g. aspirin 100 or 150mg per day for 7 days prior to treatment in elective cases, sometimes combined aspirin with clopidogrel 75mg per day if more complicated treatment is anticipated.
Medical assessment for fitness for general anaesthesia needs to be undertaken in all cases.
Contraindications may not apply to emergency treatment for a ruptured aneurysm where there is a high risk of death without urgent treatment:
The treatment options for most unruptured intracranial aneurysms are continued observation, neurosurgical clipping, and endovascular coiling.
Neurosurgical clipping involves a craniotomy, dissection in the subarachnoid space, brain retraction, occasional temporary clipping arresting blood flow to the brain, and final placement of one or more metal clips across the base of the aneurysm. When successful, the aneurysm is completely excluded from the lumen of the parent artery, and there is no narrowing or occlusion of branch vessels – either perforating branches which can be hard to identify, or larger branches. As the skull is opened and brain manipulated, there is a risk of post operative seizures, which often require a period on anticonvulsant medications, and not being permitted to drive.
Coil treatment involves an angiogram, with the patient under general anaesthetic. A microcatheter is then navigated into the aneurysm from the femoral arterial access. Once in position, one or more coils are placed into the aneurysm body, continuing until the aneurysm is fully packed and no longer filling with contrast when it is injected, indicating effective cessation of blood flow into the aneurysm. There is no brain retraction, and if no subarachnoid haemorrhage, no increased risk of seizures. The coils are very soft platinum, to minimise the chance of aneurysm perforation and rupture, and to allow them to fill all of the often irregular shapes that aneurysms may take. However, because they are soft, they can become compacted over time, and follow up investigations are necessary to confirm complete persistent “cure” of the aneurysm. This may be with MRI or DSA.
ISAT showed a lower chance of poor outcome (stroke, death, disability) when patients with ruptured intracranial aneurysms were randomised to treatment with endovascular coiling rather then clipping. This was despite a higher chance of recurrent or residual aneurysm in the patients treated with coiling, and the benefit was not lost over prolonged follow up.
Such robust evidence of benefit from randomised controlled trials does not exist for treatment of unruptured aneurysms. In general, endovascular intervention is likely to be more easily tolerated, with lower procedural risks than are associated with surgery, but at the cost of a greater chance of incomplete aneurysm obliteration and increased likelihood of the need for further endovascular treatments due to aneurysm recurrence. The individual patient needs to have specific consultations with surgeons and neurointerventionists to assess patient factors (age, clinical condition, rupture, other illnesses), aneurysm factors (site and risk of rupture, and aneurysm geometry) to determine the best treatment and weigh the risks versus the benefits if treatment is undertaken.
National Institute of Neurological Disorders and Stroke – USA
eMedicineHealth – Practical Guide to Health
Please refer to the references below for some further information on natural history, diagnosis, and treatment options for intracranial aneurysms.
Page last modified on 31/8/2017.
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