Anterior clinoidectomy

Facilitates access to parasellar and suprasellar regions.

Variations

• Extradural Anterior Clinoidectomy - (for short/normal-sized clinoid or distant aneurysms)
• Intradural Anterior Clinoidectomy - (preferred for aneurysms adjacent to clinoid or long/fused clinoid)

Techniques for Extradural Anterior Clinoidectomy

• Optic canal unroofing w/ diamond
• Peel dura from ACP.
• Use high-speed drill for coring out ACP
• Remove optic strut

Techniques for Intradural Anterior Clinoidectomy

(A) Extradural bone exposure (schematic) includes a frontotemporal craniotomy (hatched area 1) along with resection of the sphenoid ridge, posterior orbital roof, and medial floor of the superior orbital fissure (SOF) (hatched area 2). Intradural bone removal includes resection of the remaining medial sphenoid wing and drilling of the anterior clinoid process (ACP) and optic strut (OS) (area 3). (B) Clinoid dural opening (schematic). The dashed lines represent the dural incisions used during intradural anterior clinoidectomy. The incision is extended through the falciform ligament and optic nerve (ON) ensheathment to decompress and mobilize the ON as needed. (C) Exposure following intradural ACP removal and drilling of the OS (schematic). Aneurysms arising from the clinoidal segment (ClinSeg) and ophthalmic segment (OphSeg) of the internal carotid artery (ICA) are well accessed through this approach. (D) Operative view—clinoidal segment. Opening of the carotid-oculomotor membrane (COM) between the clinoidal segment and the oculomotor nerve (III) provides excellent exposure of the anterior genu of the cavernous ICA segment. DR, Dural ring; OphArt, ophthalmic artery; PComArt, posterior communicating artery.

A) An incision is made in the dura overlying the anterior clinoid as shown by the dash line. B) A diamond 3mm bit drill is used to unroof the optic canal and cavitate the anterior clinoid. c) The anterior clinoid is removed and d) the distal dural ring is opened. e) The distal dural ring is dissected superiorly and medially, which allows more of the optic strut to be removed. Additional dissection laterally and inferiorly mobilizes the carotid artery.  

Surgical Considerations

• Check for sphenoid or ethmoidal sinus extensions into optic strut/ACP.
• Seal any openings with temporalis fascia, fat, or hydroxyapatite bone cement; aim for watertight dural closure.
• If frontal sinus opened, prevent CSF leak by removing mucosa.