Results in the treatment of intracranial aneurysms at HUS are among the best in the world

The researchers examined the quality of the treatment of unruptured intracranial aneurysms. In the study, 169 consecutive patients who were treated at HUS either with microsurgery (29% of patients) or endovascular therapy (71%) between December 2022 and August 2024 were included.

Exceptionally good results in recovery

The treatment results in the study were excellent. Three months after the procedure, 98% of patients had made an excellent recovery according to the commonly used modified Rankin Scale for functional outcome (mRS rating 0-1).

Overall hospital care was effective, as the average duration of the hospitalization was only three days. It is also notable that 97% of patients who were employed before the treatment returned to work within three months.

Permanent neurological symptoms were rare: only 2% of the patients in the microsurgery group and 5% of the patients in the endovascular treatment group had them.

An experienced and centralized unit at HUS behind the quality of treatment

“If we compare our microsurgical results with other large and prestigious neurovascular centers around the world, our results seem to be exceptionally good,” says Mika Niemelä, Professor and Chair of Neurosurgery, who participated in the study.

For example, the extensive PRAEMIUM study covering several top centers in the world, reported that after microsurgical treatment, as many as 14% of patients had significant neurological disability when they were discharged. In our study, the corresponding numbers were only a fraction of this, which emphasizes not only the importance of a centralized and experienced unit but also the high standards we have in HUS for the treatment of unruptured intracranial aneurysms.

Latent findings a reason to strive to avoid ischemia completely

Although the patients’ functional outcome was excellent, the sensitive MRI diffusion-weighted images (DWI) revealed new, small ischemic lesions, i.e. changes caused by lack of oxygen or microthrombosis, in 63% of the patients. Most of these were asymptomatic, but they were associated with an increased risk of developing new transient neurological symptoms. The result shows that the traditional indicators of functional outcome, in other words the mRS, do not reveal all the effects that the treatment has on the brain.

“In the treatment of aneurysms, we must aim to avoid ischemia completely. We cannot settle for outcome indicators that do not identify latent damage caused by the treatment,” says Miikka Korja, Associate Professor in Neurosurgery.

The main author of the study, Associate Professor Rahul Raj adds:

“This is why we propose that MRI findings and return to work should be made part of the routine monitoring of quality of care. At HUS, 97% of our patients returned to work within three months. For example, in a Norwegian study, the corresponding figure was only 60%. In other words, good functional outcome alone is no longer sufficient as an indicator of the quality of treatment of unruptured intracranial aneurysms.”

Key results of the study:

• Functional outcome: 98% of the patients achieved excellent functional outcome (mRS rating 0-1) at 3 months.
• Effectiveness: The median length of hospitalization was only 3 days.
• Return to work: 97% of those employed returned to work within 3 months.
• Safety: The risk of permanent neurological symptoms was low (microsurgery 2%, endovascular therapy 5%).

 

Original publication: Raj R, Numminen J, Huhtakangas J, Nurminen V, Lehecka M, Laakso A, Kivipelto L, Niemelä M, Korja M. The Helsinki Unruptured Intracranial Aneurysm Quality of Care study: a prospective observational study. J Neurosurg. 2025 Dec 5:1-10. doi: 10.3171/2025.7.JNS25775

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