Surgical Anatomy of the Paraclinoid Region: Lessons From Many Masters

Issam A. Awad, MD, MSc, FACS, MA (hon)Professor of Neurosurgery

Northwestern University

Evanston Northwestern Health

Evanston, Illinois

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The Paraclinoid Region:Fundamentals for Every Surgeon

The anatomic facts: Rhoton’s Canon Implications for paraclinoid aneurysms

Implications for surgical approach Maximalist versus minimalist strategies

A personal philosophy

The Anatomic Facts: Rhoton’s Canon

Segments of the internal carotid artery (ICA) Unique anatomic features of the C5-6

segments of the ICA The oculomotor triangle

Relations to the optic nerve Anatomy as

the surgeon’s safeguard

The Anatomic Facts: Rhoton’s Canon

Segments of the ICA Fisher Berenstein and

Lasjaunias Bouthillier and van

Loveren

The Anatomic Facts: Rhoton’s Canon

Unique anatomic features of the C5-6 segments of ICA

The Anatomic Facts: Rhoton’s Canon

Unique anatomic features of the C5-6 segments of ICA Hemodynamic

stresses Imaging limitations Dural relationships Bony relationships The subarachnoid

space

The Anatomic Facts: Rhoton’s Canon

Unique anatomic features of the C5-6 segments of ICA Hemodynamic

stresses Imaging limitations Dural relationships Bony relationships The subarachnoid

space

The Anatomic Facts: Rhoton’s Canon

Unique anatomic features of the C5-6 segments of ICA Hemodynamic

stresses Imaging limitations Dural relationships Bony relationships The subarachnoid

space

Imaging The Paraclinoid Region

Kobayashi: Cisternographic Guidance

Gonzales, Zabramski and Spetzler: Optic Strut as Reference

The Anatomic Facts: Rhoton’s Canon

The oculomotor triangle The interclinoid

ligament The tentorial edge

(anterior petroclinoid ligament)

The posterior petroclinoid ligament

Relations to Cr. Ns. III, IV and VI

The Anatomic Facts: Rhoton’s Canon

The oculomotor triangle The interclinoid

ligament The tentorial edge

(anterior petroclinoid ligament)

The posterior petroclinoid ligament

Relations to Cr. Ns. III, IV and VI

The Anatomic Facts: Rhoton’s Canon

Relations to the optic nerve The anterior clinoid

process The falciform

ligament The optic strut The distal ring The proximal ring

The Anatomic Facts: Rhoton’s Canon

Anatomy as the surgeon’s safeguard Ease of approach Vascular control Maximize safety Maximize exposure,

maneuverability Maximize

effectiveness

Implications for Paraclinoid Aneurysms

The ophthalmic aneurysm

The superior hypophyseal aneurysm (extradural versus carotid cave)

The ventral paraclinoid aneurysm (transitional versus intradural)

Ophthalmic Aneurysm

Optic nerve canal decompression + clinoidectomy

Endovascular adjuncts Proximal control Suction

decompression Intraoperative

angiography

Ophthalmic Aneurysm

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Ophthalmic Aneurysm

IO Angio

IO Angio

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Superior Hypophyseal Aneurysm

Ventral Paraclinoid Aneurysm

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Ventral Paraclinoid Aneurysm

Clip Intradural Portion, Coil Extradural Portion

Maximalist vs. Minimalist Strategies

Adaptation of conventional approaches Maximalist skull base approaches

Minimalist (keyhole, endoscopic assisted or controlled)

Focused strategies

A Personal Philosphy: Balancing What is “Safe” and What is “Feasible”

Proximal control Intradural versus extradural

consideration Endovascular adjuncts

Endovascular treatments Future challenges and opportunities

-- surgical, endovascular