The patient is a 47 year old female who was referred after attempted coil embolization at an outside hospital

The aneurysm is seen here and involves the origin of the PICA on the left side

The PICA vessel comes directly out of the base of the aneurysm on the inferior aspect.

This made it unfavorable for stent coiling and affected the clipping strategy.

Given its high location, it was approach via a Retrosigmoid (craniotomy).

Here is a still from the video which will be seen later as well indicating the direction of flow in the PICA

as well as the pertinent anatomy.

Here is the post clipping CT angiogram as well as reconstructions of the CTA and a CT showing the craniotomy

The patient was discharged with no new deficits on postoperative day number 2.

Here's the opening, you can see the sigmoid sinus at the top right of the screen.

Initially a dural opening is made, inferiorly.

towards the foramen magnum. Inferior is to the left of the screen.

This allows for the procedure to be performed without a lumbar drain.

The first step is to open the arachnoid in the direction of the Cisterna Magna and obtain CSF drainage.

Again, we go inferior to the cerebellum to obtain CSF.

And continuing the dural opening. Now the dura is being opened towards the Sigmoid sinus.

And then reflected. You can see just how relaxed the cerebellum is. No lumbar drain was used.

Now additional dural openings will be made here.

You can see that this is clearly a Retrosigmoid approach, not a Far lateral approach.

There's no drilling of the occipital condyle involved and there is no C1 laminectomy.

The opening is larger than would be used for a microvascular decompression of the 5th cranial nerve.

Now the arachnoid is sharply opened.

To reveal the lower cranial nerves as well as the 7/8 nerve complex.

And we can see the lower medulla here.

As well, we get a glance of the vertebral artery on the left side underneath the cranial nerves.

And now we can see the left PICA vessel.

Further opening of the arachnoid is performed.

Again the cerebellum is under no tension. Seeing the lower cranial nerves here.

In the center of the view

And there is no sign of the aneurysm at this point.

So the strategy will be to use the vertebral artery and the PICA vessel

to find the aneurysm

A temporary clip can be placed, which was just shown. This ensures that should there be an rupture

that we have proximal control.

Now, opening the arachnoid over the 7/8 nerve complex.

Again, we will use the vertebral artery and the PICA vessel to trace our way back to the aneurysm dome.

Here we can see the lower cranial nerves.

Cranial nerves 9, 10, and 11

And the distal PICA is seen there, with the origin of the PICA vessel right behind it.

Note that the origin of the PICA is larger than the distal PICA.

In one of the still images, in the diagram I've created, you can see the direction of flow within the PICA vessel.

So now dissecting between the lower cranial nerves.

We can see the flocculus under the scissors there and we can see the Choroid plexus

of the Foramen of Luschka

The aneurysm is going to be buried directly behind the lower cranial nerves.

Now looking for the PICA origin to the left of the screen.

will be able to trace that back to the junction of the vertebral artery and the aneurysm dome.

We can see the distal vertebral artery as it dives away.

towards the center of the screen. It dives into the depth of the operative cavity.

Again, Choroid plexus of the Foramen of Luschka which will continue to be dissected.

That's the distal PICA just adjacent to the scissors and behind it is the proximal PICA.

as it goes towards the right of the screen

and then flows towards the top of the screen and then flows back down as it supplies the lower aspect of the cerebellar hemisphere.

Again, clearly this is demonstrated a Retrosigmoid approach.

The orientation is significantly different than what would be expected for a far lateral approach for clipping of a PICA aneurysm.

Now we can see the aneurysm dome, we just saw a glimpse of it there behind the lower cranial nerves.

We can also see it behind the PICA and visualize the PICA as it wraps around to become the distal PICA vessel.

This will require aneurysm clipping between the lower cranial nerves.

And this will involve dissection. There's the aneurysm dome right there.

We can see that the clip direction will want to be oriented parallel to the vertebral artery.

along the course of the vertebral artery as it goes towards the depth. This will allow us to capture

the neck of the aneurysm while preserving the origin of the PICA which is coming off to the left.

That's the origin of the PICA where it exits the aneurysm dome.

So that will need to be preserved. We cannot eliminate that portion of the aneurysm along the bottom.

There's the plane where the aneurysm clip will have to be placed.

And there's the aneurysm. It is going to be separated away from the brainstem.

lifted up gently so that we can identify the plane in which the aneurysm clip will be placed.

And there it is, it has been separated from the brainstem.

Again, here is the still image that shows the aneurysm, the direction of flow within the PICA vessel and the lower cranial nerves.

So now, just to be sure that we can place a clip into the space.

A 12 mm permanent clip will be used. A temporary clip is placed proximally on the vertebral artery to soften the aneurysm.

and to facilitate clipping.

And now the straight aneurysm clip is placed. The orientation of the aneurysm clip will go parallel to that of the vertebral artery.

After the clip is placed, inspecting to make sure the blades of the aneurysm clip are placed all the way across the aneurysm dome.

To the left is the origin of the PICA vessel, so we cannot clip that aspect.

Here's where we have to preserve a small remnant just to the left of the clip

to allow the PICA vessel to fill.

We can see that the clip blades are all the way across not touching the brainstem.

Now the temporary clip is removed.

Doppler indicates good flow within the PICA vessel

You can see that the clip is all the way across the aneurysm.

And in between the lower cranial nerves.

Indocyanine Green shows excellent flow in the PICA vessel following clipping

Now a small pledgit will be placed to prevent pulsation

from the aneurysm clip against the lower cranial nerves.

and we can see the 7/8 nerve complex and the Flocculus underneath the Rhoton dissector

We can see the 5th cranial nerve at the top of the screen.

Some papaverine is placed to reduce vasospasm.

And then the delicot cottonoids are removed.