Is Transcranial Extradural Is Transcranial Extradural Posterior Clinoidectomy a Posterior Clinoidectomy a

Feasible Maneuver? A Cadaver Feasible Maneuver? A Cadaver Anatomical StudyAnatomical Study

Asem Salma MDAsem Salma MD, Song Wang MD,, Song Wang MD,Mario Ammirati MD MBAMario Ammirati MD MBA

Department of Neurological Department of Neurological Surgery, Surgery,

The Ohio State University Medical The Ohio State University Medical Center, Columbus, OhioCenter, Columbus, Ohio

NASBS Presenter Disclosure SlideNASBS Presenter Disclosure Slide

Asem Salma MDAsem Salma MD

Song Wang MDSong Wang MD

Mario Ammirati MD, MBAMario Ammirati MD, MBA

Nothing To Disclose

IntroductionIntroduction

In this anatomical study, we explored the feasibility of performing a transcranial extradural posterior clinoidectomy via a subtemporal route between V2 and V3 with skeletonization of the sphenoidal part of the medial wall of the cavernous sinus. This was accomplished by integrating the surgical microscope and the endoscope.

Materials and MethodsMaterials and Methods

Cadaver characteristics and surgical Cadaver characteristics and surgical toolstools

1010 dissections were carried out in 10 fresh dissections were carried out in 10 fresh cadaver heads. Standard operating cadaver heads. Standard operating microscopes and 0 and 30° endoscopes were microscopes and 0 and 30° endoscopes were usedused . .

Surgical techniqueSurgical technique

After an extended orbitozygomatic craniotomy was After an extended orbitozygomatic craniotomy was performed a two stage dissection to remove the performed a two stage dissection to remove the posterior clinoid process was executedposterior clinoid process was executed

Stage one (microscopic stage) Stage one (microscopic stage) was conducted using an was conducted using an operating microscopeoperating microscope

the area between V2 and V3 was the area between V2 and V3 was exposedexposed

microscopic view illustrating the flattening of the floor of microscopic view illustrating the flattening of the floor of the middle cranial fossa and the widening of the foramina the middle cranial fossa and the widening of the foramina

rotundum and ovale (V2= maxillary nerve, V3= rotundum and ovale (V2= maxillary nerve, V3= mandibular nerve, mm=middle meningeal artery, mcf = mandibular nerve, mm=middle meningeal artery, mcf =

middle cranial fossamiddle cranial fossa

Microscopic view showing that the bone at the junction of the anterior one third and posterior two thirds of the distance between V2 and V3 has been drilled all the way to the sphenoid sinus cavity (V2= maxillary nerve, V3= mandibular nerve, mm=middle meningeal artery, sph.s = sphenoid sinus).

This drilling was conducted at the plane that intersects This drilling was conducted at the plane that intersects the long axis of V2 at a 45 degree anglethe long axis of V2 at a 45 degree angle

microscopic view showing that the bone underneath microscopic view showing that the bone underneath Meckel’s cave and the beginning of the lateral portion of Meckel’s cave and the beginning of the lateral portion of the carotid sulcus has been removed. (V3= mandibular the carotid sulcus has been removed. (V3= mandibular nerve, gg= gasserian ganglion, sph.s = sphenoid sinus)nerve, gg= gasserian ganglion, sph.s = sphenoid sinus)..

Stage two (endoscopic Stage two (endoscopic stage)stage) was performed using the was performed using the

endoscopeendoscope

The drilling was continued to remove the carotid sulcus, then, the endosteal layer of the dura lining the carotid sulcus was dissected from the bone (ca= carotid artery, cs = carotid sulcus, gg = gasserian ganglion, sph.s =

sphenoid sinus).

At the end of this stage, the dura reflection that forms the At the end of this stage, the dura reflection that forms the posterior part of the pituitary capsule was exposed along posterior part of the pituitary capsule was exposed along with the base of the posterior clinoid processwith the base of the posterior clinoid process

Endoscopic view showing the removal of the posterior Endoscopic view showing the removal of the posterior clinoid process (ca= carotid artery, pcp= posterior clinoid process (ca= carotid artery, pcp= posterior clinoid process, sph.s= sphenoid sinus)clinoid process, sph.s= sphenoid sinus)..

Finally, the dura was opened to confirm the Finally, the dura was opened to confirm the removal of the posterior clinoid processremoval of the posterior clinoid process..

ResultsResults::

We were able to remove the posterior clinoid process in all specimens. This study reveals the feasibility of transcranial resection of the posterior clinoid process extradurally. It also highlights a neurosurgical path that could afford an extra dural access to the posterior clinoid.

ConclusionsConclusions::

Keeping in mind the inherent limitations of any Keeping in mind the inherent limitations of any cadaver studycadaver study,,

- - This new neurosurgical maneuver could be This new neurosurgical maneuver could be incorporated into orbitozygomatic osteotomy, incorporated into orbitozygomatic osteotomy, mainly when dealing with basilar tip mainly when dealing with basilar tip aneurysms that are located posterior to the aneurysms that are located posterior to the posterior clinoid processposterior clinoid process..

- - This maneuver could decrease the risk of This maneuver could decrease the risk of third cranial nerve or posterior third cranial nerve or posterior communicating artery injuries that could communicating artery injuries that could occur when the posterior clinoid is drilled occur when the posterior clinoid is drilled intradurallyintradurally

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