Far lateral trans-condylar approach to V3 and V4 segments of the vertebral artery - surgical steps

This material is accepted for publication in Operative Neurosurgery journal and is under production. More details will come soon.

A far lateral craniotomy is simulated revealing 
the V4 segment of the vertebral artery:

Model. 1 The far lateral approach right side. A hockey stick incision was made from C4 to occipital bone on the middline and then curved to the mastoid tip. The muscles are then detached from the occipital bone (here the attachments are left on the bone for reperesentative purposes). The C2 lamina and C1 venous plexus and fat tissue are exposed. The dissection plane between close to the semispinalis capits m. and away from the C1 posterior arch of atlas is the safest for the vertebral artery.

Model. 2 The musculocutaneous flap is fully retracted and the dissection is close to the semispinalis capits m. and away from the C1 posterior arch of atlas is the safest to avoid injury the the vertebral artery.
Correctly the vertebral artery (V3 segment) embedded within the venous plexus is visible.

Model. 3 The subperiosteal exposure of the C1 posterior arch leaves the venous plexus around the vertebral artery intact and avoids any excessive venous bleeding.

Model. 4 The vertebral artery is exposed as the fat tissue surrounding it is removed. 
In this specimen a degenerative occipital joint hypertrophy is presented.

Model. 5 The occipital condyle is drilled (<50%) and a standard far lateral craniotomy is done.

Model.6  This is a 3D models combined from macrophotography and micro 3D model of the CPA generated from microscope images.
The craniotomy was extended to the mastoid emissary vein. 
The dura was opened and the vertebral artery V4 (intradural segment) is presented. 
The anatomy of the cerebellopontine angle is presented.
The nerves - IX, X, XI entering the jugular foramen are presented. 
The VII/ VIII nerve complex entering the IAC (internal accoustic canal) are visualised.
The Tuebingen line is indicated as a mark of the position of the IAC.

Model. 7 In neutral position, the vertical and horizontal portions of the V3 segment of the vertebral artery are perpendicular. After the head is rotated to contralateral side and extended (as required by the anterolateral approach) both segments are stretched and run parallel, only separated by the groove of the posterior arch of the atlas.