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Updated: May 5, 2026
Microsurgical Clip Obliteration of Middle Cerebral Aneurysm Using Intraoperative Flow Assessment
Published on: September 25, 2009
Bypass surgery for complex middle cerebral artery aneurysms: impact of the exact location in the MCA tree
Leena Kivipelto1, Mika Niemelä, Torstein Meling
1Department of Neurosurgery, Helsinki University Hospital, Helsinki, Finland; and.
Insights
This study shows bypass and parent vessel occlusion effectively treat complex middle cerebral artery (MCA) aneurysms when other methods fail. The technique offers a 100% obliteration rate with acceptable risks for challenging MCA aneurysm cases.
Area of Science:
- Neurosurgery
- Vascular Neurology
- Cerebrovascular Surgery
Background:
- Complex middle cerebral artery (MCA) aneurysms often require advanced treatment strategies.
- Conventional surgical or endovascular techniques may not be feasible for certain MCA aneurysms.
- Bypass with parent artery sacrifice is an alternative approach for complex MCA aneurysms.
Observation:
- 24 patients with complex MCA aneurysms treated with bypass and parent artery sacrifice were reviewed.
- Aneurysms varied in location (M1, bifurcation, distal) and type (saccular, fusiform), with a mean diameter of 30 mm.
- Extracranial-intracranial and intracranial-intracranial bypasses were performed, along with various parent artery occlusion techniques.
Findings:
- The study achieved a 100% aneurysm obliteration rate with no recanalization during a mean 27-month follow-up.
- A 4% mortality rate and 6% permanent morbidity rate were observed, with most deficits linked to M1 aneurysms.
- 88% of patients achieved a good outcome (Glasgow Outcome Scale score of 4 or 5).
Implications:
- Bypass combined with parent vessel occlusion is a viable treatment for complex MCA aneurysms when standard methods are unsuitable.
- Aneurysm location is critical for planning bypass type and vessel occlusion site.
- Partial trapping may be preferable to total trapping for M1 aneurysms to mitigate flow alteration risks.
Object:
The object of this study was to describe the authors' institutional experience in the treatment of complex middle cerebral artery (MCA) aneurysms necessitating bypass and vessel sacrifice.
Methods:
Cases in which patients with MCA aneurysms were treated with a combination of bypass and parent artery sacrifice were reviewed retrospectively.
Results:
The authors identified 24 patients (mean age 46 years) who were treated with bypass and parent artery sacrifice. The aneurysms were located in the M1 segment in 7 patients, MCA bifurcation in 8, and more distally in 9. The mean aneurysm diameter was 30 mm (range 7-60 mm, median 26 mm). There were 8 saccular and 16 fusiform aneurysms. Twenty-one extracranial-intracranial and 4 intracranial-intracranial bypasses were performed. Partial or total trapping (only) of the parent artery was performed in 17 cases, trapping with resection of aneurysm in 3, and aneurysm clipping with sacrifice of an M2 branch in 4. The mean follow-up period was 27 months. The aneurysm obliteration rate was 100%. No recanalization of the aneurysms was detected during follow-up. There was 1 perioperative death (4% mortality rate) and 6 cerebrovascular accidents, causing permanent morbidity in 5 patients. The median modified Rankin Scale score of patients with an M1 aneurysm increased from 0 preoperatively to 2 at latest follow-up, while the score was unchanged in other patients. Most of the permanent deficits were associated with M1 aneurysms. Twenty-one patients (88%) had good outcome as defined by a Glasgow Outcome Scale score of 4 or 5.
Conclusions:
Bypass in combination with parent vessel occlusion is a useful technique with acceptable frequencies of morbidity and mortality for complex MCA aneurysms when conventional surgical or endovascular techniques are not feasible. The location of the aneurysm should be considered when planning the type of bypass and the site of vessel occlusion. Flow alteration by partial trapping may be preferable to total trapping for the M1 aneurysms.
