UpToDate: Internal carotid artery segments

Internal carotid artery segments

The course of the internal carotid artery (ICA) and its segment classifications were reviewed by means of a new and freely available interactive 3D model of the artery and the skull base, based on human neuroimages, that can be freely downloaded at the Public Repository of the University of Barcelona ( http://diposit.ub.edu/dspace/handle/2445/112442 ) and runs under Adobe Acrobat Reader in Mac and Windows computers and Windows 10 tablets. The 3D-PDF allows zoom, rotation, selective visualization of structures, and a predefined sequence view. Illustrative images of the different classifications were obtained 1).

In 1938 Fischer, described five internal carotid artery segments in the opposite direction to the blood flow 2).

These segments were based on the angiographic course of the intracranial ICA rather than its arterial branches or anatomic compartments. Subsequent attempts to apply modern nomenclature to these numerical segments failed to recognize Fischer’s original intent of describing patterns of arterial displacement by tumors and, therefore, resulted in a nomenclature that was anatomically inaccurate. Fischer’s system was further limited, because segments were numbered opposite the direction of blood flow and the extracranial ICA was excluded 3).


Gibo et al. in 1981 studied the microsurgical anatomy of the supraclinoid portion of the internal carotid artery (ICA) in 50 adult cadaver cerebral hemispheres using X 3 to X 40 magnification. The ICA was divided into four parts: the C1 or cervical portion; the C2 or petrous portion; the C3 or cavernous portion; and the C4 or supraclinoid portion.

The C4 portion was divided into three segments based on the origin of its major branches: the ophthalmic segment extended from the origin of the ophthalmic artery to the origin of the posterior communicating artery (PCoA); the communicating segment extended from the origin of the PCoA to the origin of the anterior choroidal artery (AChA); and the choroidal segment extended from the origin of the AChA to the bifurcation of the carotid artery. Each segment gave off a series of perforating branches with a relatively constant site of termination. The perforating branches arising from the ophthalmic segment passed to the optic nerve and chiasminfundibulum, and the floor of the third ventricle. The perforating branches arising from the communicating segment passed to the optic tract and the floor of the third ventricle. The perforating branches arises from the choroidal segment passed upward and entered the brain through the anterior perforated substance. The anatomy of the ophthalmic, posterior communicating, anterior choroidal, and superior hypophyseal branches of the C4 portion was also examined. Gibo-Rothon (J Neurosurg 55:560-574, 1981) follow the blood flow, incorporated the cervical and petrous portions, and divided the subarachnoid course-supraclinoid-in ophthalmic, communicating, and choroidal segments, enhancing transcranial microscopic approaches 4).


see Bouthillier classification.

Bouthillier et al. described in 1996 a seven segment internal carotid artery (ICA) classification system. It remains the most widely used system for describing ICA segments.


The Kassam’s group (2014), with an endoscopic endonasal perspective, introduces the “paraclival segment,” including the “lacerum segment” and part of the intracavernous ICA, and details surgical landmarks to minimize the risk of injury 5).

see also Carotid Siphon

AC: anterior clinoid process; ICA: internal carotid artery; LT: lamina terminalis; ON: optic nerve; OlN; olfactory nerve; SW: sphenoid wing; TS: tuberculum sellae; A1: A1 segment of the Anterior Cerebral Artery; A2: A2 segment of the Anterior Cerebral Artery; M1: M1 segment of the Middle Cerebral Artery

Endoscopic classification

Based on anatomic correlations, the ICA may be described as 6 distinct segments:

(1) parapharyngeal (common carotid artery bifurcation to carotid canal)

(2) petrous (carotid canal to posterolateral aspect of foramen lacerum)

(3) paraclival (posterolateral foramen lacerum to the superomedial aspect of the petrous apex)

(4) parasellar (superomedial petrous apex to the proximal dural ring)

(5) paraclinoid (from the proximal to the distal dural rings)

(6) intradural (distal ring to ICA bifurcation).

Corresponding surgical landmarks included the Eustachian tube, the fossa of Rosenmüller, and levator veli palatini for the parapharyngeal segment; the vidian canal and V3 for the petrous segment; the fibrocartilage of foramen lacerumforamen rotundummaxillary strut, lingular process of the sphenoid bone, and paraclival protuberance for the paraclival segment; the sellar floor and petrous apex for the parasellar segment; and the medial and lateral opticocarotid and lateral tubercular recesses, as well as the distal osseous arch of the carotid sulcus for the paraclinoid segment 6).

see Intracavernous internal carotid artery.

References

1)

Melé MV, Puigdellívol-Sánchez A, Mavar-Haramija M, Juanes-Méndez JA, Román LS, De Notaris M, Catapano G, Prats-Galino A. Review of the main surgical and angiographic-oriented classifications of the course of the internal carotid artery through a novel interactive 3D model. Neurosurg Rev. 2018 Jul 26. doi: 10.1007/s10143-018-1012-7. [Epub ahead of print] Review. PubMed PMID: 30051302.
2)

Fischer E. Die Lageabweichungen der vorderen hirnarterie im gefässbild. Zentralbl Neurochir. 1938;3:300–313.
3)

Bouthillier A, van Loveren HR, Keller JT. Segments of the internal carotid artery: a new classification. Neurosurgery. 1996 Mar;38(3):425-32; discussion 432-3. PubMed PMID: 8837792.
4)

Gibo H, Lenkey C, Rhoton AL Jr. Microsurgical anatomy of the supraclinoid portion of the internal carotid artery. J Neurosurg. 1981 Oct;55(4):560-74. PubMed PMID: 7277004.
5) , 6)

Labib MA, Prevedello DM, Carrau R, Kerr EE, Naudy C, Abou Al-Shaar H, Corsten M, Kassam A. A road map to the internal carotid artery in expanded endoscopic endonasal approaches to the ventral cranial base. Neurosurgery. 2014 Sep;10 Suppl 3:448-71. doi: 10.1227/NEU.0000000000000362. PubMed PMID: 24717685.

Leave a Comment

This site uses Akismet to reduce spam. Learn how your comment data is processed.