Microsurgical Clipping of a Complex PICA Aneurysm

Surgical Approach

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This segment demonstrates the surgical approach to clipping of a complex PICA Aneurysm.


  • Posterior inferior cerebellar artery
  • Complex aneurysm
  • Hypoglossal triangle
  • Hypoglossal nerve
  • Spinal accessory nerve
  • Vertebral artery
  • Intraoperative angiography

Conflict of Interest

The authors declare that they have no conflict of interest.


  1. Bonda DJ et al (2017) Intracranial bypass of posterior inferior cerebellar artery aneurysms: indications, technical aspects, and clinical outcomes. Oper Neurosurg 13(5):586–595.  https://doi.org/10.1093/ons/opx064CrossRefGoogle Scholar
  2. Rodríguez-Hernández A, Lawton MT (2011) Anatomical triangles defining surgical routes to posterior inferior cerebellar artery aneurysms. J Neurosurg 114(4):1088–1094.  https://doi.org/10.3171/2010.8.jns10759CrossRefPubMedGoogle Scholar
  3. Steiger H-J, Etminan N, Hänggi D (2015) Microsurgical brain aneurysms - illustrated concepts and cases. Springer, Berlin. ISBN 978-3-662-45679-8CrossRefGoogle Scholar

About this video

Katherine Elizabeth Wagner
Amir Reza Dehdashti
First online
26 April 2019
Online ISBN
Springer, Cham
Copyright information
© The Author(s) 2019

Video Transcript

This is a left far lateral approach. We have done a suboccipital craniotomy. We have removed the lateral rim of C1 all the way to the C1 tubercle. The left vertebral artery and an extradural facet is just below the suction on the left side here. We’re drilling a little bit of the occipital condyle is— doesn’t need to be too much, just enough to make the edge of the foramen quite smooth, and flat, and that will allow a good exposure with no obstruction of the bone into the lateral exposure of the CP angle.

Once this is done, the dural is opened in a linear fashion, as you can see with this dark line starting at the foramen magnum and going up and down and then retracted laterally. After exposure into the subarachnoid space in a caudal cranial fashion, we identify the vertebral artery. Here you have the branched of the 11th nerve here. You see the 12th nerve right under the aneurysm— is very important to completely dissect here— we are dissecting the branches of the 12th nerve that are very intimate with the back wall of the aneurysm. You can see clearly the 12th nerve here. We separate and preserve them. And once the aneurysm is dissected on the back part, then these are some branches of the 11th nerve in front that needs to be dissected.

This aneurysm is large and, therefore, we temporary clip, under burst suppression, the vertebral artery. Remember this is a dominant vert, so we cannot have this clip for a long time. Further dissection with the aneurysm flattened a little bit is performed and I use a fenestrated clip straight with the fenestration holding the PICA inside the fenestration and a clip occluding the aneurysm. We also make sure that the distal vertebral artery is not compromised.

Once the first clip is positioned, we check— confirm the patency of the distal vertebral artery, the intact hypoglossal nerve underneath, and, obviously, the PICA, which has to be patent and these are the branches of the 11th nerve on the vertebral artery. Doppler confirms patency of all vessels, including the PICA and vertebral artery.

However, we know that this one clip is not enough? This aneurysm is globulus, it’s large and has calcification at the base. Once we are sure, we add another clip on top of the first one, still with a fenestrated clip. But this time the fenestration just incorporate the calcification of the aneurysm. Because if I put a straight clip on this, the calcification was slid into the origin of the PICA. So this second clip further completes the occlusion of the aneurysm as a booster clip. And after final dissection around the dome, we add a third clip as a final booster clip to completely eliminate the flow in the aneurysm.

And as you can see here the PICA is between the first and second clip inside the fenestration of the first clip and it’s patent confirmed with the Doppler here. We check with Micro Dissector, make sure there is no perferator whatsoever of PICA involved in any of the clips. If that’s the case, then the clip will be released. However, the dissection had been already done before and we made sure of that. Monitoring of motor evoked potential, and some other sensory and brainstem evoked potential all remains stable. We always do an intraoperative angiogram for complex aneurysms. And you can see that confirms patency of the PICA with no delay, complete patency of the vertrebrobasilar junction with no flow compromise and exclusion of the aneurysm.

This patient woke up fine with a normal neurological exam, including a normal lower cranial nerve neurological function. The post-operative CAT scan does not reveal any hematoma or sign hypodensity. The patient was mobilized within a few hours after surgery and discharged on day three to home with no neurological deficit and an appropriate follow-up afterward. Thanks for your attention.