gms | German Medical Science

Objective: To describe the clinical and angiographic characteristics of associated aneurysms in posterior fossa arterio-venous malformations (AVM) in comparison to associated aneurysms in supratentorial AVMs.

Method: 64 patients with posterior fossa AVMs treated between 1990 and 2012 were retrospectively analyzed and compared with 387 patients carrying supratentorial AVMs. Only patients with aneurysms of the feeding arteries were regarded and aneurysm location was classified as proximal and distal, according to the classification by Redekop. Venous and intranidal aneurysms were excluded.

Results: The incidence of associated feeding artery aneurysms was 28.1% (n=18) in patients with posterior fossa AVMs and 14.2% (n=55) in patients with supratentorial AVMs. Mean aneurysm size was larger in aneurysms of posterior fossa AVMs (8.36 mm ± 5.37 mm;) compared to those sited supratentorially (4.5 mm ± 3.59 mm, p=0.00022). Rupture from associated aneurysms was found in 8 out of 18 patients (44.4%) with a posterior fossa AVMs, versus 10 out of 55 patients (18.2%) with supratentorial AVMs. Whereas ruptured and unruptured aneurysm size differed in supratentorial lesions (rupture 6.75 mm ± 2.71 mm; no rupture 4.2 mm ± 3.60 mm, p=0.022), this feature could not be found in lesions of the posterior fossa (rupture 7,83 mm ± 3.81 mm; no rupture 8.56 mm ±5.83 mm, p>0,05). Rupture of distal feeding artery aneurysms could be found in the majority of both subgroups (posterior fossa n=6, 75%; supratentorial n=8, 80%).

Conclusions: Associated aneurysms occur more frequently in posterior fossa AVMs and the incidence for aneurysm rupture is higher, compared to supratentorial lesions. Different to supratentorial feeding artery aneurysms, those of the posterior fossa do not show a difference in size between ruptured and unruptured aneurysms. In both subgroups, distally located aneurysms are responsible for the majority of aneurysmal bleedings.