Microsurgical Clipping of Ruptured Posterior Fossa Aneurysms in the Semi-Sitting Position

Posterior fossa aneurysms, especially ruptured ones, are challenging to treat due to their deep location, complex anatomy, and proximity to the brainstem, and lower cranial nerves. The semi-sitting position, though historically controversial due to concerns over venous air embolism, may offer distinct advantages. The aim of this study was to evaluate the safety and efficacy of the semi-sitting position for the clipping of ruptured posterior fossa aneurysms.

We retrospectively reviewed 39 consecutive patients with ruptured posterior circulation aneurysms treated with microsurgical clipping in the semi-sitting position between 1990 and 2023. Data included clinical presentation, surgical technique, intraoperative and postoperative complications, and functional outcomes measured by the Glasgow Outcome Scale at discharge and at 6 months.

Complete aneurysm occlusion was achieved in 92% (36/39). The most common aneurysm location was the posterior inferior cerebellar artery (79%). Intraoperative rupture occurred in 8% (3/39), and new neurological deficits attributable to surgery were seen in 13% (5/39). Venous air embolism was detected in 20% (3/15) of patients monitored with transesophageal echocardiography, though no cases required abortion of the procedure or resulted in serious complications. Surgical mortality was 0%, and 84% (21/25) of surviving patients achieved a Glasgow Outcome Scale >3 at 6 months.

Microsurgical clipping of ruptured posterior fossa aneurysms in the semi-sitting position is safe and effective when performed with appropriate monitoring. Close collaboration with the anesthesiology team is essential to ensure patient safety. Our findings reinforce the continued relevance of the semi-sitting position in posterior fossa aneurysm surgery.