**2. Techniques of clipping**

Despite the technical skills and expertise of the surgeon revest a pivotal role, aneurysms surgery is often associated with a high risk of intraoperative rupture because of the fragility of the aneurysm and surgical manipulation. For this reason, vascular control is a pivotal concept that the neurosurgeon must respect during aneurysms surgery. Vascular control means the exposition of the afferent and efferent arteries, which move blood to the aneurysm in anterograde and retrograde direction, respectively. Vascular control is mandatory to allow the application of temporary clip on the afferent artery and eventually on efferent arteries in case of difficult aneurysm dissection or intraoperative rupture. Permanent clipping means the application of a definitive clip on the neck of the aneurysm to arrest the blood flow into the dome [12].

## **2.1 Temporary clipping**

Temporary clipping is the application of the clip to the vessels that move the blood flow into the aneurysm. Thus, temporary clipping is usually referred to the apposition of the temporary clip on the afferent vessels in order to stop the anterograde blood flow. However, since the blood could flow into the aneurysm retrogradely through the efferent vessels, it could be needed the application of temporary clip on these vessels in case of persisting bleeding [12, 15]. Therefore, proximal control is referred to the exposition of the afferent vessels, distal control of the efferent vessels [12]. The application of temporary clip is useful in case of complex aneurysm, to facilitate the dissection without risk of bleeding. Moreover, arresting the flow, temporary clipping led the aneurysm to soften, allowing an easier dissection for the visualization of the parent vessels [16].

Temporary clipping is also a savage maneuver in case of aneurysm rupture because it stops the blood flow into the aneurysm, facilitating the dissection of the parent vessels and the neck, allowing the application of the permanent clip [15, 17].

*Clipping Strategies and Intraoperative Tools to Detect Aneurysm Obliteration and Cerebral… DOI: http://dx.doi.org/10.5772/intechopen.110774*

Aneurysms with a single afferent vessel, or with multiple afferent and efferent vessels, could be classified. For this reason, different vessels should be exposed during the surgery considering aneurysm location:

	- Proximal control: sphenoidal segment of MCA (tract M1)
	- Distal control: post-bifurcation segments (tract M2–M3)
	- Proximal control: precommunicating segment of anterior cerebral artery (tract A1) of both sides
	- Distal control: postcommunicating segments of anterior cerebral artery (tract A2) of both sides
	- Proximal control: precallosal (tract A3) or supracallosal (tract A4) segments of anterior cerebral artery, in relation to aneurysm location
	- Distal control: supracallosal (tract A4) or postcallosal (tract A5) segments of anterior cerebral artery, in relation to aneurysm location
	- Proximal control: ophthalmic segments (tract C6) of internal carotid artery (ICA). Ophthalmic segments begins from the distal dural ring and end at the origin of PCoA.
	- Distal control: communicating segments (tract C7) of ICA, PCoA. Communicating segments begins from the origin of PCoA and ends at ICA bifurcation.
	- Proximal control: clinoidal segments (tract C5, which is the tract between the proximal and the distal dural ring) and ophthalmic segments (tract C6) of ICA, exposed through anterior clinoidectomy.
	- Distal control: supraclinoidal segments (tract C6-ophtalmic and C7-communicating) of ICA, OphA and PCoA.
	- Proximal control: basilar artery (BA)
	- Distal control: precommunicating segment (tract P1) of posterior cerebral artery (PCA), superior cerebellar artery (SCA)
	- Proximal control: vertebral artery (VA), anterior medullary segment (trac p1), lateral medullary segments (tract p2), tonsillomedullary segment (tract p3), or telovelotonsillar segments (tract p4) of PICA, in relation to aneurysm location

○ Distal control: anterior medullary segment (trac p1), lateral medullary segments (tract p2), tonsillomedullary segment (tract p3), or telovelotonsillar segments (tract p4) of PICA, in relation to aneurysm location
