SUBARACHNOID HEMORRHAGE
Brain aneurysm diagnosis
Created 20.11.2019 , last update 07.04.2022
- in each SAH patient, it is necessary to search for its source by examining the arterial circulation
- CT angiography (as part of the initial CT scan) is the primary diagnostic method for aneurysm detection; in case of negative findings, DSA is usually performed
- in isolated perimesencephalic SAH (PMSAH), the cost-effectiveness of subsequent DSA is questionable [Kalra, 2015]
- a potential source of bleeding in the spinal cord should be excluded when SAH is localized to the posterior fossa
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CT Angiography
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MRI and MR Angiography
- the time-of-flight (TOF) method is used in intracranial MRA; 3T scanners have a higher sensitivity
- sensitivity 85-100% for aneurysm > 5mm [Sailer, 2013]
- sensitivity decreases with aneurysms < 5mm (56%)
- MRA is a suitable method for screening and follow-up (but compared to CTA and DSA, MRA is less sensitive for detection of small changes in the aneurysm size)
- MRI + MRA can detect thrombosed aneurysms that DSA may miss and can help to assess the extent of thrombosis)
Digital Subtraction Angiography (DSA)
Technique
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Images assessment
- seek aneurysm(s) or other sources of bleeding
- assess the type and localization of the aneurysm (shape and size of the sac, type, and width of the neck, vascular geometry, and relationship to the parent artery and surrounding branches)
- exclude multiple aneurysms and other concomitant vascular malformations
- with multiple aneurysms (present in up to 15% of cases), estimate the one which was the probable source of the current bleeding
- localization of blood and the shape of the aneurysm can help
- GRE sequence can be helpful in SAHs with negative CT (small or old SAH)
- GRE sequence can be helpful in SAHs with negative CT (small or old SAH)
- the most frequent findings among ruptured aneurysms are:
- multilobular aneurysm
- sac with irregular contour
- aneurysm with a daughter sac
- localization of blood and the shape of the aneurysm can help
- assess the overall intracranial vascular status:
- the presence of vasospasms
- the patency of the Circle of Willis (is the collateral circulation sufficient if feeding artery occlusion is required?)
- the general condition of the intracranial circulation (sclerotic changes and stenoses in the access route and feeding artery)
- if feeding artery occlusion is considered, add functional tests
- Matas test – manual compression of the artery with simultaneous injection of the contralateral ICA or ipsilateral vertebral artery to assess the functionality of the collateral circulation
- Balloon Test Occlusion (BTO) is more reliable because manual external compression is usually inadequate
- should not be performed in acute SAH as heparinization during the procedure is required
- Matas test – manual compression of the artery with simultaneous injection of the contralateral ICA or ipsilateral vertebral artery to assess the functionality of the collateral circulation
Further procedures after negative initial examination
Non-perimesencephalic SAH
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