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VIDEO SECTION.OPERATIVE NUANCES: STEP BY STEP
Year : 2021  |  Volume : 69  |  Issue : 5  |  Page : 1184-1195

Paraclinoid Segment Aneurysms of the Internal Carotid Artery: Surgical Clipping


1 Department of Neurosurgery, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow, Uttar Pradesh, India
2 Department of Radiology, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow, Uttar Pradesh, India

Date of Submission09-Jul-2021
Date of Decision23-Sep-2021
Date of Acceptance27-Sep-2021
Date of Web Publication30-Oct-2021

Correspondence Address:
Dr. Sanjay Behari
Department of Neurosurgery, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow - 226 014, Uttar Pradesh
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0028-3886.329547

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 » Abstract 


Background: Paraclinoid segment aneurysms arise from the internal carotid artery (ICA) between the distal dural ring and the origin of the posterior communicating (PComm) artery.
Objective: This pictorial study presents videos showing clipping of paraclinoid segment aneurysms.
Materials and Methods: The various subtypes of these aneurysms, the nuances in the technique of clinoidectomy, and methods of proximal control are presented.
Results: Cavernous ICA is designated as C4, clinoidal segment (between the proximal and distal dural rings) as C5, and supraclinoid segment (between the distal dural ring up to the PComm artery as C6 segment. The techniques used for clipping various aneurysms are based upon their subtypes and location. In the first case, in a giant superior hypophyseal artery aneurysm directed toward the suprasellar region, an intradural clinoidectomy helped in accessing the neck of the aneurysm encroaching into the clinoidal segment of ICA. In the second case, concurrent bilateral “kissing” paraclinoid segment aneurysms were clipped using a unilateral approach. In the third case, clipping of a dissecting paraclinoid segment aneurysm is demonstrated.
Conclusions: Surgery still represents the most definitive form of treatment. It may also be used to evacuate an intracerebral hematoma, with an extremely tortuous proximal vessel or in an aneurysm with complex anatomy, with blister aneurysms, or following aneurysm regrowth following a failed endovascular procedure. Assessing the three-dimensional anatomy of various segments of ICA is an important step.


Keywords: Anatomy, carotico-ophthalmic aneurysm, extradural clinoidectomy, internal carotid artery, intradural clinoidectomy, paraclinoid aneurysm, subarachnoid hemorrhage
Key Message: This pictorial study presents the videos of operative steps of clipping of various types of paraclinoid segment internal carotid artery aneurysms with a short description of the anatomical nuances involved in the technique of clinoidectomy.


How to cite this article:
Behari S, Dikshit P, Singh S, Singh G, Singh V, Phadke RV, Bhaisora KS. Paraclinoid Segment Aneurysms of the Internal Carotid Artery: Surgical Clipping. Neurol India 2021;69:1184-95

How to cite this URL:
Behari S, Dikshit P, Singh S, Singh G, Singh V, Phadke RV, Bhaisora KS. Paraclinoid Segment Aneurysms of the Internal Carotid Artery: Surgical Clipping. Neurol India [serial online] 2021 [cited 2021 Dec 3];69:1184-95. Available from: https://www.neurologyindia.com/text.asp?2021/69/5/1184/329547




Paraclinoid segment aneurysms arise in the segment of the internal carotid artery (ICA) between the distal dural ring and posterior communicating artery.[1],[2],[3],[4],[5] In this article, surgical videos related to clipping of various types of paraclinoid segment aneurysms are depicted. In the first two cases, proximal control of the internal carotid artery was taken in the neck prior to starting the craniotomy.


 » Clipping of a Giant Superior Hypophyseal Artery Aneurysm (Operative Video 1) Top


Video link: https://youtu.be/Gr5eTlSnM7U



Video timeline with audio transcript:

0:04–0:23

A 53-year-old lady presented with bilateral temporal field defects. Her plain and contrast-enhanced computed tomography (CT) scans showed the laminar pattern of contrast enhancement of the suprasellar aneurysm indicative of both an intact flow and partial thrombosis within its lumen [Figure 1]a and [Figure 1]b. Her T1- and T2-weighted axial magnetic resonance imaging (MRI) scans showed the suprasellar, giant aneurysm with a variegated appearance within its lumen indicative of persistent flow with partial thrombosis.
Figure 1: Case 1: A 53-year old lady presented with bitemporal field defect. (a) Plain; and, (b) Contrast-enhanced computed tomographic (CT) scan show the laminar pattern of contrast enhancement of the suprasellar aneurysm indicative of both an intact flow and partial thrombosis within its lumen; (c) Magnetic resonance angiography; and, (d) Three-dimensional CT angiogram show the giant right-sided superior hypophyseal artery aneurysm pointing towards the suprasellar cistern. (e) Antero-posterior; and, (f) Lateral right-sided internal carotid artery (ICA) angiogram shows a giant superior hypophyseal artery aneurysm. (g) Lateral image of left carotid angiogram does not show any filling of the aneurysm; (h) Left carotid angiogram with right-sided (ipsilateral to the side of aneurysm) compression shows a good cross-flow indicating that the right internal carotid artery (ICA) is filling through a patent anterior communicating artery from the left side

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0:24–0:32

The magnetic resonance angiography [Figure 1]c and three-dimensional CT angiogram [Figure 1]d showed the giant right-sided superior hypophyseal artery aneurysm pointing toward the suprasellar cistern.

0:33–0:42

The anteroposterior [Figure 1]e and lateral right-sided internal carotid artery (ICA) angiogram [Figure 1]f showed a giant superior hypophyseal artery aneurysm.

0:43–0:58

Lateral image of the left carotid angiogram does not show any filling of the aneurysm [Figure 1]g. The left carotid angiogram with right-sided (ipsilateral to the side of aneurysm) compression showed a good cross-flow, indicating that the right internal carotid artery (ICA) was filling through a patent anterior communicating artery from the left side [Figure 1]h. The right vertebral angiogram showed a slight filling of the anterior circulation through the patent posterior communicating artery.

0:59–1:31

The schematics of the surgical technique are illustrated in [Figure 2]. a: A right-sided pterional craniotomy and a frontotemporal approach is adopted. The aneurysm (*) has a broad neck and is lifting up the optic nerve (II). The proximal aspect of its neck is not visible as it is covered by both the optic nerve (II) and the anterior clinoid process (ACP). b: After an intradural clinoidectomy, the distal dural ring (DDR) and the carotid collar (CC) covering the clinoidal segment of the internal carotid artery (ICA) are exposed. The excision of these fascial layers exposes the clinoidal ICA proximally curving laterally toward the cavernous sinus. The ophthalmic artery (arrow) is visible just distal to the DDR. The drilling of the planum sphenoidale (PS) that forms the roof of the optic foramen exposes the distal 8–10 mm of the optic nerve (E II) covered by the falciform ligament. The mobilized optic nerve may be gently displaced medially to access proximal and distal aspects of the broad neck of the medially directed aneurysm (*) and clipped. No attempt is made to mobilize the fundus of this giant aneurysm as it is surrounded by perforators to the hypothalamus. ACA: Anterior cerebral artery; MCA: Middle cerebral artery; E II: Exposed distal part of the optic nerve within the optic foramen; #: Exposed and drilled planum sphenoidale bone after reflecting the dura overlying it; L: Membrane of Liliequist.
Figure 2: Case 1: Schematic illustrations of the surgical technique: (a) A right-sided pterional craniotomy and a fronto-temporal approach is adopted. The aneurysm (*) has a broad neck and is lifting up the optic nerve (II). The proximal aspect of its neck is not visible as it is covered by both the optic nerve (II) and the anterior clinoid process (ACP). (b) After an intradural clinoidectomy, the distal dural ring (DDR), the carotid collar (CC) covering the clinoidal segment of the internal carotid artery (ICA) are exposed. The excision of these fascial layers exposes the clinoidal ICA proximally curving laterally towards the cavernous sinus. The ophthalmic artery (arrow) is visible just distal to the DDR. The drilling of the planum sphenoidale (PS) that forms the roof of the optic foramen exposes the distal 8-10mm of optic nerve (E II) covered by the falciform ligament. The mobilized optic nerve may be gently displaced medially to access proximal and distal aspects of the broad neck of the medially directed aneurysm (*) and clipped. No attempt is made to mobilize the fundus of this giant aneurysm as it is surrounded by perforators to the hypothalamus. ACA: Anterior cerebral artery; MCA: Middle cerebral artery; E II: Exposed distal part of the optic nerve within the optic foramen; #: Exposed and drilled planum sphenoidale bone after reflecting the dura overlying it; L: Membrane of Liliequist

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1:32–1:39

A right-sided fronto-temporal craniotomy was performed [Figure 3]a. The Sylvian fissure was opened by dissecting the arachnoid on the aspect of the superficial middle cerebral vein toward the frontal lobe. A trans-Sylvian approach was adopted by an adequate dissection of the arachnoid over the Sylvian fissure [Figure 3]b. This prevented an excessive retraction of the frontal lobe during the subfrontal approach.
Figure 3: Case 1: (a) A right-sided fronto-temporal craniotomy is performed. (b) The Sylvian fissure is opened by dissecting the arachnoid on the aspect of superficial middle cerebral vein towards the frontal lobe. (c) The opening of the arachnoid exposes the planum sphenoidale (#), optic nerve (2), internal carotid artery (ICA), and the subarachnoid part of the oculomotor nerve (III) entering the cavernous sinus (CS). CS: Cavernous sinus; P Comm A: Posterior communicating artery; *: Aneurysm. (d) Further retraction of the frontal lobe exposes the giant aneurysm (*). The aneurysm (*) has a wide neck arising from the internal carotid artery (ICA) and its fundus is directed towards the suprasellar region. The proximal aspect of its neck cannot be seen as it is hidden by the optic nerve (II). (e) The dura over the planum sphenoidale (#) and anterior clinoid is incised and reflected downwards. This maneuver protects the optic nerve from injury during drilling of the roof of optic foramen. The lateral wall of cavernous sinus (CS) is also seen. II: Optic nerve; ICA: Internal carotid artery. Reflecting the dura exposes the planum sphenoidale (#) over the optic foramen. Drilling this portion of the bone helps to expose and mobilize additional 6-8 millimeters of the optic nerve (II). ICA: Internal carotid artery; CS: Cavernous sinus; *: Aneurysm. This disconnects the anterior root of the anterior clinoid process (ACP). II: Optic nerve; ICA: Internal carotid artery; CS: Cavernous sinus. (f) The planum sphenoidale (#) has been drilled, exposing the falciform ligament (arrow) covering the distal 6-8 mm of the optic nerve within the optic foramen. The remnant of anterior clinoid process (ACP) is also seen. This represents the optic strut or the posterior root of the ACP, the small piece of bone separating the optic foramen from the superior orbital fissure. ICA: Internal carotid artery; CS: Cavernous sinus

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1:40–2:08

The frontal lobe retraction exposed the optic nerve, the ICA, and the planum sphenoidale [Figure 3]c. An arachnoid covering was seen over these structures. The opening of the arachnoid exposed the planum sphenoidale (#), optic nerve (2), internal carotid artery (ICA), and the subarachnoid part of the oculomotor nerve (III) entering the cavernous sinus (CS). CS: Cavernous sinus; P Comm A: Posterior communicating artery; *: Aneurysm.

2:09–2:21

Further retraction of the frontal lobe exposed the giant aneurysm (*) [Figure 3]d. The aneurysm had a wide neck arising from the ICA and its fundus was directed toward the suprasellar region. The proximal aspect of its neck could not be seen as it was hidden by the optic nerve (II).

2:22–3:20

The dura over the planum sphenoidale (#) and the anterior clinoid was incised and reflected downward [Figure 3]e. This maneuver protected the optic nerve from injury during drilling of the roof of the optic foramen. The lateral wall of cavernous sinus (CS) is also seen. II: Optic nerve; ICA: Internal carotid artery; *: Aneurysm. Drilling this portion of the planum sphenoidale helped to expose and mobilize an additional 6–8 mm of the optic nerve (II). The anterior clinoid process was then disconnected from the planum sphenoidale. This disconnected the anterior strut of the anterior clinoid process (ACP). The planum sphenoidale (#) drilling exposed the falciform ligament covering the optic nerve within the optic foramen.

3:21–3:54

The remnant of the anterior clinoid process (ACP) was also seen [Figure 3]f. This represented the optic strut or the posterior root of the ACP, the small piece of bone separating the optic foramen from the superior orbital fissure [ICA: Internal carotid artery; CS: Cavernous sinus].

[Figure 4]a. The coring of the ACP from within its bony shell was done using a 3–4-mm diamond drill. This was helpful in drilling out the posterior strut of the anterior clinoid process *(ACP), thereby mobilizing the ACP [#: Drilled planum sphenoidale; II: Optic nerve; ICA: Internal carotid artery; CS: Cavernous sinus] [Figure 4]b. The mobilized shell of the anterior clinoid process was gently dissected off from the carotid collar, the fascial layer covering the clinoidal segment of ICA [#: Drilled planum sphenoidale; II: Optic nerve; ICA: Internal carotid artery; CS: Cavernous sinus] [Figure 4]c.
Figure 4: Case 1: (a) The coring the anterior clinoid process (ACP) from within its bony shell is done using a 3-4mm diamond drill. This is helpful in drilling out the posterior strut of anterior clinoid process (ACP). #: Drilled planum sphenoidale; II: Optic nerve; ICA: Internal carotid artery; CS: Cavernous sinus. (b) The last portion of the posterior root (optic strut) of the anterior clinoid process (ACP) is being drilled, thereby mobilizing the ACP. #: Drilled planum sphenoidale; II: Optic nerve; ICA: Internal carotid artery; CS: Cavernous sinus. (c) The mobilized shell of anterior clinoid process (ACP) is gently dissected off from the carotid collar (CC), the fascial layer covering the clinoidal segment of internal carotid artery. #: Drilled planum sphenoidale; II: Optic nerve; ICA: Internal carotid artery; CS: Cavernous sinus. D: Removal of the anterior clinoid process by drilling its anterior strut (the portion between the planum sphenoidale (#) and anterior clinoid process; and, also its posterior strut (the core of the anterior clinoid process) exposes the distal dural ring (DDR), the proximal dural ring and the carotid collar [CC; the fascia covering the proximal clinoidal segment of the internal carotid artery (ICA)], as the internal carotid artery (ICA) curves laterally to enter the cavernous sinus (CS). The junction of distal cavernous sinus dura and the thickened proximal aspect of the carotid collar forms the proximal dural ring. The drilling of the planum sphenoidale (#) over the roof of optic foramen has exposed the distal part of optic nerve (II). The latter may gently be mobilized medially to access the proximal aspect of neck of the aneurysm. (e) The distal dural ring and carotid collar (CC) are gently lifted off from the clinoidal segment of internal carotid artery (ICA) and excised until the proximal dural ring that is located at the junction of carotid collar with the dural covering of the cavernous sinus (CS). This helps in exposing the proximal aspect of neck of the aneurysm arising from the internal carotid artery (ICA). II: optic nerve. (f) After excising of the carotid collar (CC), the clinoidal segment of internal carotid artery (ICA) is exposed (arrow)

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3:55–4:34

Removal of the anterior clinoid process by drilling its anterior strut (the portion between the planum sphenoidale (#) and anterior clinoid process, and its posterior strut (the core of the anterior clinoid process) exposed the distal dural ring (DDR), the proximal dural ring and the carotid collar [CC; the fascia covering the proximal clinoidal segment of the internal carotid artery (ICA)] as the ICA curves laterally toward the cavernous sinus [Figure 4]d. The drilling of the planum sphenoidale (#) over the roof of optic foramen exposed the distal part of the optic nerve (II). The latter could then be gently mobilized medially to access the proximal aspect of the neck of the aneurysm. The distal dural ring and the carotid collar (CC) could then be gently lifted off from the clinoidal segment of ICA and excised until the proximal dural ring that was located at the junction of carotid collar with the dural covering of the cavernous sinus (CS). This helped in exposing the proximal aspect of the neck of the aneurysm arising from the internal carotid artery [ICA] (II: Optic nerve) [Figure 4]e. After excising the carotid collar (CC), the clinoidal segment of the internal carotid artery (ICA) was exposed [arrow] [Figure 4]f.

4:35–4:57

It was then possible to insinuate the dissector along the proximal aspect of the neck of the aneurysm (*) in order to define it [Figure 5]a. The drilling of the planum sphenoidale (#) over the optic nerve (II) helps to gently mobilize the latter in order to access the proximal part of the neck of the aneurysm.
Figure 5: Case 1: (a) A dissector is insinuated along the proximal aspect of neck of the aneurysm (*). The drilling of the planum sphenoidale (#) over the optic nerve (II) helps to gently mobilize the latter in order to access the proximal part of neck of the aneurysm. (b) The clip is applied over the neck of aneurysm (*) while ensuring that the lumen of internal carotid artery (ICA) is patent. The posterior communicating artery (P Comm A) and cavernous sinus (CS) are also seen. II: Optic nerve; CS: Cavernous sinus. (c) A second clip is placed over the neck of aneurysm (*) just proximal to the previous clip. #: Planum sphenoidale; II: Optic nerve; ICA: Internal carotid artery; CS: Cavernous sinus; P Comm A: Posterior communicating artery; III: Subarachnoid part of the oculomotor nerve entering the cavernous sinus (CS). (d) The fundus of the aneurysm (*) is opened using microscissors to remove the clot (arrow). The deflation of the fundus of the aneurysm relieves pressure over the optic nerve (II) and chiasma. ICA: Internal carotid artery; CS: Cavernous sinus. (e) The relaxed frontal and temporal lobes are seen after surgery. (f) The postoperative angiogram showing the patent internal carotid artery (ICA), ophthalmic artery and two clips applied to secure the aneurysm. The patient made an uneventful recovery with complete resolution of the bitemporal field defect

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4:58–5:19

A 20-mm straight Yasargil clip was applied over the neck of the aneurysm (*) while ensuring that the lumen of the internal carotid artery (ICA) remained patent. No attempt was made to mobilize the fundus of the giant aneurysm from the suprasellar cistern so that the perforators of ICA to the hypothalamus that were wrapped around ICA were not disturbed [Figure 5]b. The posterior communicating artery (P Comm A) and the cavernous sinus (CS) are also seen [II: Optic nerve].

5:20–5:39

A second clip was then placed over the neck of the aneurysm (*) just proximal to the previous clip. This ensured that in case the aneurysm was not completely secured using the distal clip, a portion of the neck of the aneurysm still remained accessible, the site at which a more proximal clip might have been applied [#: Planum sphenoidale; II: Optic nerve; ICA: Internal carotid artery; CS: Cavernous sinus; P Comm A: Posterior communicating artery; III: Subarachnoid part of the oculomotor nerve entering the cavernous sinus (CS)] [Figure 5]c.

5:40–6:19

The fundus of the aneurysm (*) was opened using microscissors, its lumen aspirated [Figure 5]d, and the clot within removed [arrow] [Figure 5]e in order to deflate it. The deflation of the fundus of the aneurysm relieved pressure over the optic nerve (II) and chiasma. Following the operative procedure, the relaxed frontal and temporal lobes could be well-visualized [Figure 5]e.

6:20–6:34

The postoperative angiogram showed the patent internal carotid artery (ICA), ophthalmic artery, and two clips applied to secure the aneurysm [Figure 5]f. The patient made an uneventful recovery with complete resolution of the bitemporal field defect.


 » Simultaneous Clipping of Concurrent Bilateral “Kissing” Paraclinoid Segment Superior Hypophyseal Artery Aneurysms Using a Unilateral Approach (Operative Video 2) Top


Video link: https://youtu.be/Gr5eTlSnM7U



Video timeline with audio transcript:

0:01–0:14

A 55-year-old lady presented with sudden-onset, severe headache with left-sided significant vision loss for 2 days. On examination, she was in modified Hunt and Hess Grade I with left-sided vision being finger counting close to face.

0:15–0:30

T1-weighted axial MR image showed the peri-Sylvian and suprasellar subarachnoid hemorrhage. T2-weighted MR image showed bilateral “kissing” aneurysms of the ICA located in the suprasellar cistern [Figure 6]a.
Figure 6: Case 2: (a) T2-weighted MR image showed bilateral 'kissing' aneurysms of the ICA located in the suprasellar cistern. (b) Basal CT angiogram showing bilateral, medially-directed 'kissing' superior hypophyseal aneurysms with the left-sided aneurysm being larger than the right-sided one. (c-g) Schematic illustrations of the surgical technique. (c) Using a left-sided fronto-temporal trans-Sylvian approach, the left internal carotid artery (ICA), anterior cerebral artery (ACA) and middle cerebral artery (MCA) are exposed. The left-sided superior hypophyseal artery aneurysm (*1) is arising from the ICA, has a broad neck and is pointing medially towards the suprasellar cistern, elevating the left optic nerve. The right-sided superior hypophyseal artery aneurysm (*2) is also pointing medially and is smaller than its counterpart on the left side. The proximal portion of the neck of both the aneurysms is covered by the optic nerve (II), planum sphenoidale (PS) and anterior clinoid process (ACP), on either side, respectively. The fundi of the two aneurysms (mirror aneurysms) are touching each other in the suprasellar cisterns; (d) The part of planum sphenoidale (PS) forming the roof of optic foramen as well as the left anterior clinoid process (ACP) are drilled, exposing the part of the optic nerve within the optic foramen (covered by falciform ligament; exposed optic nerve: E II) and the clinoidal segment of ICA (proximal internal carotid artery: P ICA), respectively (#: Exposed and drilled part of PS). (e) The broken lines and arrow indicate the dural incision over the planum sphenoidale and ACP to access the proximal portion of neck of the right-sided aneurysm. (f) Three fenestrated clips (taking the ICA in the fenestration) are applied to occlude the lumen of the left-sided aneurysm. The superior blades of the three clips traverse the optico-carotid plane below the left optic nerve. On the left side, working from the right side, the part of planum sphenoidale (PS) forming the roof of optic foramen as well as the left anterior clinoid process (ACP) are drilled exposing the part of the right optic nerve within the optic foramen (curved arrow). (g) The right-sided ICA (arrow) and the aneurysm (*2) are visible below the right optic nerve. Two straight clips are also applied to the neck of the right-sided aneurysm

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0:31–0:45

The basal [Figure 6]b and oblique views of the CT angiogram showed bilateral, medially directed “kissing” superior hypophyseal aneurysms with the left-sided aneurysm being larger than the right-sided one.

0:46–1:18

The schematic [Figure 6]c to f show the operative technique of simultaneously clipping of the two superior hypophyseal artery mirror aneurysms located on the left and right ICA, respectively, by using a single approach. C: Illustrations of the surgical technique. Using a left-sided frontotemporal trans-Sylvian approach, the left internal carotid artery (ICA), anterior cerebral artery (ACA), and middle cerebral artery (MCA) are exposed. The left-sided superior hypophyseal artery aneurysm (*1) is arising from the ICA, has a broad neck and is pointing medially toward the suprasellar cistern, elevating the left optic nerve. The right-sided superior hypophyseal artery aneurysm (*2) is also pointing medially and is smaller than its counterpart on the left side. The proximal portion of the neck of both the aneurysms is covered by the optic nerve (II), planum sphenoidale (PS), and anterior clinoid process (ACP) on either side. The fundi of the two aneurysms (mirror aneurysms) are touching each other in the suprasellar cisterns; D: The part of planum sphenoidale (PS) forming the roof of optic foramen as well as the left anterior clinoid process (ACP) are drilled, exposing the part of the optic nerve within the optic foramen (covered by falciform ligament; exposed optic nerve: E II) and the clinoidal segment of ICA (proximal internal carotid artery: P ICA), respectively (#: Exposed and drilled part of PS). E: The broken lines and the arrow indicate the dural incision over the planum sphenoidale and ACP to access the proximal portion of the neck of the right-sided aneurysm. F: Three fenestrated clips (taking the ICA in the fenestration are applied to occlude the lumen of the left-sided aneurysm. The superior blades of the three clips traverse the optico-carotid plane below the left optic nerve. On the left side, working from the right side, the part of planum sphenoidale (PS) forming the roof of optic foramen as well as the left anterior clinoid process (ACP) are drilled exposing the part of the right optic nerve within the optic foramen (curved arrow). G: The right-sided ICA (arrow) and the aneurysm (*2) are visible below the right optic nerve. Two straight clips are also applied to the neck of the right-sided aneurysm.

1:19–2:10

A left frontotemporal craniotomy with a wide Sylvian fissure opening was performed [Figure 7]a. The medially directed, left-sided superior hypophyseal artery aneurysm (*) arising from the left ICA could be seen with the optic nerve (II) being stretched over the fundus of the aneurysm [Figure 7]b.
Figure 7: Case 2: (a) A left fronto-temporal craniotomy with a wide Sylvian fissure opening are performed. (b) The medially directed, left-sided superior hypophyseal artery aneurysm (*), arising from the left internal carotid artery (ICA), is seen. The optic nerve (II) is stretched over the fundus of the aneurysm. (c) The dura over the planum sphenoidale (#) is incised and reflected downwards. The planum sphenoidale (#) is drilled using a diamond drill. (d) The proximal 8-millimetres of the optic nerve (II) and the clinoidal segment of the left internal carotid artery (ICA) are exposed. A large aneurysm with a wide neck, with its fundus extending on both sides of the left internal carotid artery is seen (*I/L). The fundus of contralateral (right-sided) aneurysm is directed medially, closely approximated to the left sided aneurysm (*C/L) [arrow]. The planum sphenoidale (#) over the contralateral aneurysm is also seen. The posterior communicating (PComm) artery exits from the left ICA just distal to the left ICA aneurysm. The dorsum sellae (DS) is seen lateral to the left internal carotid artery. Space is created between the fundus of left internal carotid artery aneurysm (*I/L) and the optic nerve (II; after its mobilization by drilling the planum sphenoidale over the optic foramen). (e) Proximal control was taken in the neck and distal control in the ICA just proximal to the posterior communicating artery. Three fenestrated straight clips are applied in tandem, preserving the lumen of supraclinoid segment of the left internal carotid artery (ICA) proximally, while securing the neck of the aneurysm (*I/L). The distal-most clip is proximal to the origin of posterior communicating artery from the ICA. The contralateral aneurysm (*C/L) is also seen. #: Planum sphenoidale over contralateral (right-sided) aneurysm (f) The microscope is shifted to the side of the contralateral aneurysm (*C/L) whose neck is partly hidden behind the contralateral optic nerve (C/L II) and planum sphenoidale (#). II: Left-sided optic nerve; I/L ICA: Left-sided ICA

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2:11–3:18

The dura over the planum sphenoidale (#) was incised and reflected downward and the planum sphenoidale was drilled using a diamond drill [Figure 7]c. The proximal 8 mm of the optic nerve and the clinoidal segment of the left ICA were thus exposed.

3:19–4:09

The proximal 8 mm of the optic nerve (II) and the clinoidal segment of the left internal carotid artery (ICA) were exposed [Figure 7]d. A large aneurysm with a wide neck, with its fundus extending on both sides of the left internal carotid artery, was seen (*I/L). The fundus of the contralateral (right-sided) aneurysm was directed medially, closely approximated to the left-sided aneurysm (*C/L) [arrow]. The planum sphenoidale (#) over the contralateral aneurysm was also seen. The posterior communicating (PComm) artery exited from the left ICA just distal to the left ICA aneurysm. The dorsum sellae (DS) was seen lateral to the left internal carotid artery. Space was created between the fundus of left internal carotid artery aneurysm (*I/L) and the optic nerve (II; after its mobilization by drilling the planum sphenoidale over the optic foramen).

4:10–5:03

Control of the ICA was taken in the neck and on the ICA just proximal to the posterior communicating artery. Three fenestrated straight clips were applied in tandem, preserving the lumen of supraclinoid segment of the left internal carotid artery (ICA) proximally, while securing the neck of the ipsilateral aneurysm (*I/L). The distal-most clip was proximal to the origin of the posterior communicating artery from the ICA. The small amount of hemorrhage that occurred due to a small rent that appeared in the fundus of the aneurysm during the clip application was adequately controlled by the occurrence of the collapse of the aneurysmal fundus and apposition of its walls by the clip blades. The contralateral aneurysm (*C/L) was also seen. #: Planum sphenoidale over the contralateral (right-sided) aneurysm [Figure 7]e.

5:04–5:34

The microscope was then shifted to the side of the contralateral aneurysm (*C/L) whose neck was partially hidden behind the contralateral optic nerve and planum sphenoidale [#] [Figure 7]f. The dura over the planum sphenoidale (#) covering the contralateral aneurysm (*C/L) was reflected to expose the underneath bone C/L II: Right-sided optic nerve; II: Left-sided optic nerve; I/L ICA: Left-sided ICA; ACA: Anterior cerebral artery [Figure 8]a.
Figure 8: Case 2: (a) The dura over the planum sphenoidale (#) covering the contralateral aneurysm (*C/L) is reflected to expose the underneath bone. C/L II: Right-sided optic nerve; II: Left-sided optic nerve; I/L ICA: Left-sided ICA; ACA: Anterior cerebral artery. (b) The contralateral (right-sided) planum sphenoidale (#) and anterior clinoid process are drilled, exposing the proximal portion of the right internal carotid artery (C/L ICA) and the proximal part of the neck of the contralateral aneurysm (*C/L). II C/L: Right-sided optic nerve; II: Left-sided optic nerve; ACA: Anterior cerebral artery. (c) After drilling the planum sphenoidale (#) and anterior clinoid process, a dissector is insinuated between the fundus of contralateral aneurysm (*C/L) and the reflected dura over the planum sphenoidale (#), to ensure the presence of an adequate space between these structures and the aneurysm for the insertion of the clip blade. The contralateral (right-sided) ICA from which the aneurysm is arising is also seen. II C/L: Right-sided optic nerve; II: Left-sided optic nerve; ACA: Anterior cerebral artery. (d) The first clip is applied to the neck of contralateral aneurysm. II: Left-sided optic nerve; ACA: Anterior cerebral artery. (e) The second clip is applied to the neck (arrow) of the contralateral aneurysm. The patent contralateral (right-sided) ICA and the optic nerve (C/L II) are also seen. #: Drilled planum sphenoidale. (f) After removal of the retractors, surgicel spread over the frontal and temporal lobes, is seen. Postoperatively, the patient remained in the same clinical status as that at admission. At a follow-up visit, there was no improvement of vision in the left eye visual acuity and there have been no further episodes of subarachnoid hemorrhage

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5:35–5:54

The contralateral (right-sided) planum sphenoidale (#) and anterior clinoid process were drilled to expose the proximal portion of the right internal carotid artery (C/L ICA) and the proximal part of the neck of the contralateral aneurysm (*C/L). II C/L: Right-sided optic nerve; II: Left-sided optic nerve; ACA: Anterior cerebral artery [Figure 8]b. After drilling the planum sphenoidale (#) and anterior clinoid process, a dissector was insinuated between the fundus of contralateral aneurysm (*C/L) and the reflected dura over the planum sphenoidale (#) to ensure the presence of adequate space between these structures and the aneurysm for the insertion of the clip blade [Figure 8]c. The contralateral (right-sided) ICA, from which the aneurysm was arising, was also seen. II C/L: Right-sided optic nerve; II: Left-sided optic nerve; ACA: Anterior cerebral artery.

5:55–6:27

A straight clip was applied to the neck of the contralateral aneurysm. II: Left-sided optic nerve; ACA: Anterior cerebral artery [Figure 8]d. This permitted the application of the second clip at the neck of the aneurysm while also ensuring that the parent vessel was not compromised. The patent contralateral (right-sided) ICA and the optic nerve (C/L II) were also seen. #: Drilled planum sphenoidale [Figure 8]e. Surgicel was applied to the surface of the retracted frontal lobe after removal of the frontal lobe retractor [Figure 8]f. Postoperatively, the vision in the patient remained in the same clinical status as that at admission. At the follow-up visit, there was no improvement of vision in the left eye visual acuity and there have been no further episodes of subarachnoid hemorrhage.


 » Clipping of a Dissecting Aneurysm of the Paraclinoid Segment of ICA (Operative Video 3) Top


Video link: https://youtu.be/Gr5eTlSnM7U



Video timeline with audio transcript:

0:00–0:08

A 17-year-old girl presented with sudden-onset left hemiparesis without any evidence of headache or neck stiffness.

0:09–0:32

A left carotid three-dimensional computed tomographic (CT) angiogram showed an irregular fusiform dilatation of the paraclinoid segment of the internal carotid artery (ICA) distal to the anterior clinoid process (ACP). There was a small sessile aneurysm also arising from the dorsal surface of this fusiform dilatation of the ICA [Figure 9]a. The distal vessels showed a distinct narrowing.
Figure 9: Case 3: Following the sudden onset hemiparesis in the young girl, (a) A left carotid three-dimensional computed tomographic (CT) angiogram showed an irregular fusiform dilatation of the paraclinoid segment of internal carotid artery (ICA) distal to the anterior clinoid process (ACP). There is a small sessile aneurysm also arising from the dorsal surface of this fusiform dilatation of the ICA. The distal vessels show a distinct narrowing. (b) Left carotid angiogram antero-posterior image; and, (c) Lateral image showed the dissection of supraclinoid internal carotid artery (ICA) with the anterior cerebral artery and the middle cerebral artery not filling from the left side. The posterior communicating and posterior cerebral arteries, however, show a good filling from the left internal carotid artery (ICA). Endovascular nimodipine was instilled into the lumen of ICA. Her hemiparesis improved. (d) The right internal carotid artery (ICA) injection showed a good flow through bilateral middle cerebral arteries and anterior cerebral arteries. (e and f) However, within six-hours of the procedure, the patient again developed hemiparesis and the DSA images of right ICA showed a recurrence of spasm of the left-sided middle cerebral artery (MCA). The patient was retaken to the angiogram suit and intra-arterial nimodipine was reinstilled. Following the second intervention, the patient improved to near-normal motor power. (g and h) The right internal carotid artery angiogram showed a good filling of bilateral middle cerebral and anterior cerebral arteries.

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Left carotid angiogram anteroposterior image [Figure 9]b and lateral image [Figure 9]c showed the dissection of supraclinoid internal carotid artery (ICA) with the anterior cerebral artery and the middle cerebral artery not filling from the left side. However, the posterior communicating and posterior cerebral arteries showed a good filling from the left internal carotid artery (ICA). In view of the presence of the dissecting aneurysm of ICA with nonvisualization of the major arterial branches of ICA, nimodipine was instilled into the lumen of ICA via the endovascular route. Following the instillation of local nimodipine via the endovascular route, her hemiparesis improved.

0:33–0:52

The right internal carotid artery (ICA) injection showed a good flow through bilateral middle cerebral arteries and anterior cerebral arteries [Figure 9]d. However, within 6 hours of the procedure, the patient again developed hemiparesis and the DSA images of the right ICA [Figure 9]e and [Figure 9]f showed a recurrence of spasm of the left-sided middle cerebral artery (MCA). The patient was retaken to the angiogram suite and intra-arterial nimodipine was re-instilled.

0:53–1:04

Following the second intervention, the patient improved to near-normal motor power. The right internal carotid artery angiogram showed a good filling of bilateral middle cerebral and anterior cerebral arteries [Figure 9]g and [Figure 9]h. Thereafter, the patient was taken up for surgery.

1:05–1:23

In [Figure 10]a,[Figure 10]b,[Figure 10]c, the surgical technique is illustrated using schematic diagrams. A: A left frontotemporal craniotomy was performed. The retraction of the frontal lobe revealed the surface of the ICA being irregular, reddish, and thin-walled due to the arterial dissection and the fusiform aneurysmal dilatation present. B: A clip was applied across the broad neck of the fusiform aneurysm. C: The abnormally looking proximal and distal internal carotid artery segments were wrapped with muscle and surgicel, and fibrin glue was applied over it in order to reinforce this part of the arterial wall.
Figure 10: The schematic diagrams showing (a) A left fronto-temporal craniotomy was performed. The retraction of the frontal lobe revealed the surface of ICA being irregular, reddish and thin-walled due to the arterial dissection and the fusiform aneurysmal dilatation present. (b) A clip was applied across the broad neck of the fusiform aneurysm. (c) The abnormally looking proximal and distal internal carotid artery segments were wrapped with muscle and surgicel, and fibrin glue was applied over them, in order to reinforce this part of the arterial wall

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1:24–1:36

During the actual surgery, a left frontotemporal craniotomy was performed [Figure 11]a. The retraction of the frontal lobe revealed the optic nerve (II) and the left internal carotid artery (ICA). The surface of the internal carotid artery was irregular, reddish and thin-walled due to the arterial dissection and the fusiform aneurysmal dilatation (*) present [Figure 11]b.
Figure 11: During the actual surgery, (a) A left fronto-temporal craniotomy is performed. (b) The retraction of the frontal lobe reveals the optic nerve (II) and the left internal carotid artery (ICA). The surface of the internal carotid artery is irregular and reddish and thin- walled due to the arterial dissection and the fusiform aneurysmal dilatation (*) present. (c) The complete exposure of the internal carotid artery (ICA), its bifurcation and anterior cerebral artery (ACA) reveal a dissecting fusiform aneurysm (*) arising from the internal carotid artery (ICA). II: Optic nerve. (d) A clip is applied across the broad neck of the fusiform aneurysm. The proximal internal artery (prox. ICA) still appeared reddish, thin walled and abnormal. Distal ICA: The part of ICA distal to the dissecting aneurysm; II: Optic nerve; ACA: Anterior cerebral artery. (e) The lumen of the clipped aneurysm is aspirated to ensure that there is no residual filling. Prox. ICA: Proximal internal artery; Distal ICA: The part of ICA distal to the dissecting aneurysm; II: Optic nerve; ACA: Anterior cerebral artery; (f) The abnormally looking proximal (Prox. ICA) and distal internal carotid artery (Distal ICA) are wrapped with muscle and surgicel, and fibrin glue is applied over them, in order to reinforce this part of the arterial wall. Prox. ICA: Proximal internal artery; Distal ICA: The part of ICA distal to the dissecting aneurysm; II: Optic nerve; ACA: Anterior cerebral artery

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1:36–2:20

The complete exposure of the internal carotid artery (ICA), its bifurcation, and anterior cerebral artery (ACA) revealed a dissecting fusiform aneurysm arising from the ICA [Figure 11]c.

2:21–2:41

A clip was applied across the broad neck of the fusiform aneurysm [Figure 11]d. The proximal internal artery (prox. ICA) still appeared reddish, thin-walled, and abnormal.

2:42–3:06

The lumen of the clipped aneurysm was aspirated to ensure that there was no residual filling [Prox. ICA: Proximal internal artery; Distal ICA: The part of ICA distal to the dissecting aneurysm; II: Optic nerve; ACA: Anterior cerebral artery] [Figure 11]e. The abnormally looking proximal and distal internal carotid artery were wrapped with muscle and surgicel, and fibrin glue was applied over them in order to reinforce this part of the arterial wall [Figure 11]f. The postoperative period was uneventful and the young girl made an uneventful complete recovery.


 » Tips and Pearls Top


  1. In this article, the authors preferred an intradural clinoidectomy that entailed drilling of the wing of sphenoid until the superior orbital fissure, disconnecting the anterior root of anterior clinoid by drilling the planum sphenoidale over the optic foramen, and drilling the posterior root of anterior clinoid by coring the clinoid from within, leaving an outer shell of bone that may be dissected out. This removes the posterior strut, the bone between the optic and superior orbital foramen. An extradural clinoidectomy may be performed for most paraclinoid aneurysms except for the dorsally pointing caroticoopthalmic aneurysms and giant aneurysms that are lying in close proximity to the undersurface of the anterior clinoid. During the extradural clinoidectomy, division of the orbitomeningeal band, connecting the orbital fascia to the temporal dura, facilitates the dissection of the temporal dura from the cavernous sinus dura and permits a wide extradural exposure of the anterior clinoid without significant temporal lobe retraction.
  2. Adequate cerebrospinal fluid drainage ensures a good brain relaxation and helps to preserve the arachnoidal plane. In the presence of acute subarachnoid hemorrhage, where the brain is edematous and tense, cerebrospinal fluid (CSF) drainage is possible by opening multiple carotid cisterns as well as the membrane of Liliquest in the carotico-optic space (which helps to drain CSF from the prepontine and interpeduncular cisterns anterior to the brain stem).[1],[2],[3],[4],[5]
  3. In a dorsally directed aneurysm, the fundus of the aneurysm lies just below the inferior surface of the anterior clinoid process. Drilling of the planum sphenoidale circumferentially around the fundus of the aneurysm and then gently dissecting the mobilized segment of bone from the fundus of the aneurysm helps to prevent rupture of the aneurysm.[1],[4]
  4. A “blister” or sessile dorsal wall aneurysm may be extremely thin-walled and its neck may avulse from the parent vessel during the clipping process. This type of aneurysm, if being clipped, requires reinforcement with a bemsheet or cottonoid buttress, on which the clip blades may be applied.[1],[4]
  5. A part of the dorsally directed aneurysm may be adherent to the optic nerve or the subpial surface of the orbitofrontal cortex. Mobilizing the optic nerve by drilling the orbital roof helps in safely creating a plane of dissection between the optic nerve and the aneurysm. The subpial plane may be developed along the orbitofrontal cortex to facilitate frontal lobe retraction to reach the carotid and suprasellar cisterns. Drilling of the planum sphenoidale of the orbital roof should be done very gently with constant irrigation, keeping the dural layer covering the optic nerve intact in order to permit the dural layer to act as a protective layer.
  6. Constant irrigation over the aneurysm helps in maintaining the elasticity of the aneurysm, thus facilitating its dissection. A dry aneurysm wall becomes friable.
  7. The origin of the ophthalmic artery must be meticulously sought and preserved prior to clipping of the neck of the aneurysm. Within the optic canal, the ophthalmic artery lies inferolaterally to the optic nerve. The artery then crosses over, under the optic nerve, from the lateral to the medial side.
  8. After the clinoidectomy, the distal dural ring and carotid collar must be incised and the genu of the internal carotid artery (ICA) defined prior to the arterial entry into the cavernous sinus.
  9. Proximal control of the ICA must be undertaken prior to clipping of the aneurysm. The application of temporary clipping has both advantages and disadvantages. It reduces the turgor of the aneurysm and, therefore, facilitates permanent clipping, and in case the aneurysm ruptures during its dissection, a bloody field is not encountered. The disadvantage is the possibility of occurrence of a prolonged ischemia time by the temporary clipping in an already compromised cerebral circulation being supplied by the ICA. Once the temporary clip is applied, the surgeon often becomes a little hasty in performing the dissection as he is being constantly reminded of the temporary clipping ischemia time. In such a situation, if the fundus ruptures, then intermittent removal of temporary clips in order to preserve cerebral blood flow distal to the ICA no longer remains an option. Thus, meticulously defining the neck with a gentle dissection without the temporary clipping prior to the application of the permanent clips to the aneurysm is also a viable technique.
  10. If following rupture of a paraclinoid segment aneurysm, there is profuse bleeding from the site of rupture despite the temporary clipping of the ICA, either a retrograde filling from the ipsilateral middle cerebral artery (MCA), a cross filling from both anterior cerebral arteries (ACA) and contralateral MCA via a patent anterior communicating artery (A Comm A), or blood flow from the vertebrobasilar system being directed to the ipsilateral ICA through the patent posterior communicating artery (P Comm A) may be taking place.[1],[4]
  11. In the case of a large-to-giant superior hypophyseal artery aneurysm directed medially toward the suprasellar cistern, multiple fenestrated clips applied in tandem may be required to reconstruct the ICA. In this case, the positions of the anterior choroidal and posterior communicating arteries must be carefully determined prior to the application of these clips. The initial fenestrated right-angled clip must be applied toward the part of the fundus rather than directly on the neck of the aneurysm so that the clip does not occlude the lumen of the ICA.[1],[4]
  12. A straight clip applied to a giant partially thrombosed aneurysm often twists its neck, and occasionally, also the parent vessel and may often slip on the latter. With temporary clipping in place, the atheroma within the lumen of the aneurysm should be removed to collapse the aneurysm sufficiently in order to clip it.[5]
  13. In the “two clip” technique, the first clip is applied a little distally on the neck of the aneurysm. The second clip is applied more proximally. This helps the surgeon in getting access to the proximal part of the neck of the aneurysm and in applying the second clip. This maneuver helps in cases when the first clip fails to occlude the aneurysm or when the aneurysmal dome ruptures during the initial clipping and the first clip is unable to completely occlude the neck of the aneurysm resulting in hemorrhage from the aneurysm that obliterates the vision in the surgical field.[4],[6]
  14. Even after the successful clipping of the giant medially directed aneurysms, no attempt should be made to mobilize its walls. There are several lateral and medial lenticulostriate arteries, anterior communicating artery perforators, and other hypothalamic perforators draped around its wall that may be compromised with this maneuver. The clipping itself and the clot removal from its lumen will shrink the tumor and alleviate the mass effect produced by it.[4],[7],[8],[9]
  15. In dissecting aneurysms, surgery is rarely required. The aneurysmal wall, though fusiform, has to be seen to be projecting and clearly distinguishable from the ICA outer wall so that a neck is clearly observable prior to the application of the clip.
  16. When aneurysmal dissection of a blood vessel wall is encountered, the aneurysm wall is very fragile and may lack the regular blood vessel layers. The clip should be applied very gently, often with a reinforcing sheet of bemsheet or cottonoid buttress wrapped around the neck of the aneurysm prior to its clipping.
  17. Every attempt must be made to ensure that the lumen of the ICA is patent prior to clipping of the dissecting aneurysm. In case the dissection is in the form of an occluded lumen, a string or beaded-shaped lumen, a stricture, or a double-barreled lumen, clipping is not the solution.[10]
  18. In case bilateral superior hypophyseal artery aneurysms coexist, a contralateral approach to the medially directed aneurysm toward the side opposite to that of the performed craniotomy can be adopted. The aneurysm should be preferably unruptured and either superiorly or medially directed. The planum sphenoidale may have to be drilled in the case the aneurysmal neck is partially hidden underneath it or if the chiasma is prefixed in type. A giant contralateral aneurysm should not be operated using this approach.[1],[4],[5],[11],[12]
  19. The superior hypophyseal arteries are often multiple and bilateral and supply both the pituitary stalk and gland and the optic apparatus. No attempt is usually made to secure these arteries away from the clip as a unilateral compromise of some of these vessels in a clip is usually of no clinical consequence as a rich collateral arcade exists. However, during bilateral clipping of these aneurysms, pituitary and optic nerve function may occasionally be compromised due to the involvement of these vessels on both sides.
  20. A three-dimensional CT angiogram assesses the relation of the proximal aspect of the neck of the aneurysm with the optic strut (the bony landmark for the location of the distal dural ring). Therefore, it defines the need to drill the anterior clinoid process based on the location of the aneurysm proximal or distal to the optic strut and, therefore, in deciding its supraclinoidal (subarachnoid) or clinoidal (extradural) extent.[13]
  21. A balloon test occlusion (BTO) of the side of the ICA harboring the aneurysm, with crossflow from the opposite side, helps in predicting the consequences of parent vessel compromise during surgery and of the need for a bypass procedure. Sekhar et al.[14] stated that following the patients clinically and radiologically and then conducting the balloon test occlusion along with cerebral blood flow (CBF) assessment by single-photon emission computed tomography, four categories of patients emerged based on their propensity to developing ischemia: A: Low risk: Tolerated BTO, CBF: >35 mL/100 g/min; B: Moderate risk: Tolerated BTO, CBF: 15–35 mL/100 g/min; C: Severe risk: Tolerated BTO, CBF: <15–35 mL/100 g/min; D: Do not tolerate BTO and develop neurological deficits during the procedure. Categories B, C, and D require a bypass procedure.
  22. The origin of carotid cave and ventral wall aneurysms are in close proximity to each other from the medial wall of the ICA and may be difficult to distinguish from each other on angiographic images. A ventral wall aneurysm arises from the ICA just distal to and directly opposite the point of origin of the ophthalmic artery. A carotid cave aneurysm arises proximal to the ophthalmic artery near the distal dural ring and its fundus is directed into the dural outpouching that is directed extradurally toward the cavernous sinus. Due to its extra- as well as intradural location, it may bleed either in the subarachnoid or the extradural space, or both. Thus, on lateral angiograms, a ventral wall aneurysm will have a defined angiographic axillary space between the wall of the parent vessel and the margins of the aneurysm. This space will be lacking in a carotid cave aneurysm, which lies in a nearly parallel orientation and in close proximity with the ICA walls within a confined space. On anteroposterior angiographic images, the carotid cave aneurysms have a more medial projection than a ventral wall aneurysm, as the carotid cave lies at the 1–6-o'clock position medial to the ICA.[1]
  23. In the cases having a transitional paraclinoid aneurysm with a good crossflow from the contralateral side and the ability of the patient to tolerate balloon test occlusion, trapping of the ipsilateral parent vessel in the neck and proximal to the posterior communicating artery in the cranial cavity, with either a low- or a high-flow bypass is a useful surgical maneuver. However, a bypass procedure may, in certain instances, neither be able to overcome the ischemia produced in ICA territory with the parent vessel ligation nor will it be able to prevent distal thromboembolism from this region.[1]
  24. The clinoid may often be pneumatized and ethmoidal or sphenoidal air cells may get opened during the clinoidal drilling. Clinoidal pneumatization may be in the optic strut (Type I), anterior root or planum sphenoidale (Type II), or both (Type III). These openings need to be meticulously closed using autologous fat with fibrin glue in order to prevent a subsequent cerebrospinal rhinorrhea.[5]



 » Conclusions Top


The technical nuances of safely clipping the different subtypes of paraclinoid segment aneurysms require an in-depth knowledge of the three-dimensional anatomy of this region and the safe corridors of approach. Surgical treatment may be preferred to endovascular treatment as it still represents the most definitive form of treatment for these entities. It may also be used to simultaneously access a coexistent intracerebral hematoma, in the presence of an extremely tortuous proximal vessel, in an aneurysm with a complex anatomy, in the presence of small blister aneurysms, or in the case of rebleed due to reformation of the aneurysm following a failed endovascular coiling or stenting procedure. The surgical procedure may also be used in conjunction with endovascular treatment to optimize care.

Acknowledgements

The authors acknowledge with deep gratitude the outstanding teaching contribution in the form of schematic diagrams in this article made by Dr. Priyadarshi Dikshit.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
 » References Top

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Bouthillier A, von Loveren HR, Keller JT. Segments of the internal carotid artery: A new classification. Neurosurgery 1996;38:425-33.  Back to cited text no. 2
    
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Singh S, Kumar A, Behari S. Fronto-temporal craniotomy with zygomatic osteotomy for a clinoidal meningioma. The role of extradural clinoidal drilling. In: SGPGI Neurosurgery, editors. The Operative Atlas of Neurosurgery. A Compendium of 120 Neuro-oncological, Case-based, Surgical Approaches. Vol. 1. 2020. p. 483-98.  Back to cited text no. 3
    
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    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8], [Figure 9], [Figure 10], [Figure 11]



 

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