Narrow-Neck Aneurysms

Abstract

The definition of the narrow-neck aneurysm in the literature is described. As the easiest to be treated endovascularly among all eight types of aneurysms, the narrow-neck aneurysm is introduced along with a discussion of the most basic principles and techniques for aneurysm embolization. The topics of interest include access establishment, pre-embolization angiogram imaging, embolization view determination, microcrater selection, catheterization of the aneurysms, coil selection, and deployment. Some of the new techniques, such as 3D printing techniques, are also discussed.

Other than the procedural techniques, assessment of the embolization result is also an important topic discussed. The most commonly used Raymond-Roy occlusion classification and its relationship with the long-term embolization outcome are reviewed in detail. The predictors of long-term outcomes of embolization reported in the literature are introduced.

Case Illustration

Case 8.1 Basic Steps for Primary Coiling Embolization

Case Pearls

• 1. 3D angiogram is needed to identify the good working trajectories for embolization.

• 2. The working (embolization) views need to show the aneurysm neck and its relationship with parent vessels clearly to avoid hidden/unrecognized coil/device malposition.

• 3. Correct coil size selection is pivotal for good outcome.

• 4. Good neck framing is important to prevent neck residual and coil migration/protrusion.

• 5. The greater the framing coil percentage, the more stable the framing structure.

• 6. Usually, there is no need for any antiplatelet treatment given the small exposure of the coil to lumen.

(a, b) Two views of pre-embo 3D angiograms; carefully analyzing 3D angiogram to understand the anatomy of the aneurysm completely is required; (c, d) pre-embo 2D coiling views; the neck and interface between the aneurysm and parent vessel are clearly demonstrated; biplane is preferred over monoplane angio machine for two working views to fully monitor the progression of the embolization process under fluoroscopy; (e, f) first framing coil placement with good neck coverage, which makes neck residual less likely; (g, h) final run, no neck residual; clear final angiograms are performed, which is important for future comparison; (i, j) follow-up angiogram showing no residual with RR occlusion class 1; 6–12 months follow-up angiogram for primary coiling embolization is recommended and performed by most providers

Case 8.2 Good Neck Coverage Is the Priority of Primary Coiling

Case Pearls

• 1. Narrow neck is relatively easy to get good neck coverage and dense coil filling.

• 2. Primary coiling is often the first choice for narrow-neck aneurysm embolization.

• 3. Size of the framing coil dictates the neck coverage.

• 4. The tip of the microcatheter should be deep enough if the aneurysm size allows, even loop back to avoid microcatheter kickback/herniation and increase the chance of filling all different compartments if needed.

(a) Pre-embo 3D angiogram showing a 6 mm paraclinoid ICA aneurysm with narrow neck; (b, c) pre-embo 2D views for the best view of the neck and its relationship to parent vessels. (d) Microcatheter tip position deep in the 2/3 position (arrow); (e, f) good neck coverage is obtained; (g, h) final run post-coiling showing complete occlusion of the aneurysm; (i, j) 7 months follow-up angiogram with RR Grade I occlusion

Case 8.3 Treatment of Ruptured Multiple Aneurysms

Case Pearls

• 1. Individualize the plan for each case of multiple aneurysms based on SAH pattern, aneurysm morphology, available treatment techniques, and procedure-associated risk profiles.

• 2. Quickly secure the culprit aneurysm, and avoid perfect radiographic result. Time of the procedure is directly associated with clinical outcome.

• 3. It is acceptable to treat the culprit aneurysm only if it is convinced.

• 4. Surgical clipping is preferred by author for ruptured MCA aneurysm if SAC or FD is needed given the respective risk profiles.

(a, b) Presenting head CT showing diffuse SAH pattern with anterior interhemispheric cistern hematoma, HH Grade IV; (c) pre-embo 3D of right ICA showing long shape AComA aneurysm and right ICA angiogram showing two small blister aneurysms of right MCA (circle); (d) pre-embo 3D angiogram of right ICA showing two small blister aneurysms of right MCA; (e) given the SAH pattern supporting AComA aneurysm as the culprit of SAH and the difficulty of endovascular treatment of both left MCA aneurysms in a ruptured situation, embolization of AComA aneurysm only was planned; (f) one Smart 4×10 coil quick embolization; (g) final run post-coiling. Given the multiple aneurysms, rupture history, and small wide neck, the two left MCA aneurysms were clipped 4 months later; (h–j) 1 year (8 months for MCA aneurysm clipping) follow-up angiogram

Case 8.4 Primary Coiling of Very Distal Callosomarginal Artery Aneurysm

Case Pearls

• 1. More superficial intracranial aneurysms, such as MCA and ACA/pericallosal/callosomarginal aneurysms, are appropriate for surgical clipping given the risk profile of different treatments.

• 2. Primary coiling for narrow-neck distal aneurysm is also a good option with low risks.

• 3. Technological advancement made other options, such as FD, a good choice for distal wide-neck aneurysms.

(a) Angiogram of left ICA for follow up for previously clipped aneurysm and known untreated aneurysm. (b) High magnification angiogram showing the callosomarginal aneurysm with narrowed neck (Dome neck ratio of 2); (c) immediate post coiling (Smart coils standard, 3.5×8, soft 3×6, 2.5×4, 1×4, 1×3, Penumbra) angiogram showed RR occlusion class I; (d) one year follow up angiogram showed the aneurysm remains completely obliterated

Case 8.5 Narrow-Neck Aneurysm Treated with Flow Diverter

Case Pearls

• 1. FD stent placement is easier than primary coiling technically in some situations; it may be a better option for narrow-neck aneurysm if it is available.

• 2. Less procedure time and radiation with FD device placement than primary coiling for some cases.

• 3. Primary coiling is preferred over FD device for ruptured aneurysm given the risks associated with DAPT.

(a) Pre-embo 3D angiogram showing a paraclinoid narrow aneurysm and a small opposite wall blister aneurysm; (b) pre-embo 2D views for the best view of the neck; (c) arterial phase angiogram after PED placement; (d) late arterial phase angiogram after PED placement showing contrast stasis; (e) follow-up angiogram with complete obliteration of both aneurysms; (f) contour of PED

Case 8.6 Intrasaccular Flow Diverter for a Narrow-Neck Aneurysm

Case Pearls

• 1. ISFD embolization is simpler than primary coiling with less time and radiation in some situations.

• 2. It may be a better option for bifurcation narrow-neck aneurysm (off-label use) than primary coiling.

(a, b) Head CT and MRI for work-up of a patient being found down: SAH with interhemispheric cistern hematoma and likely a right temporal glioblastoma multiforme; (c) 3D angiogram showing AComA narrow-neck aneurysm; (d, e) pre-embo 2D views for the best view of the neck and parent vessels. (f, g) Post-WEB device placement run (inserts: un-subtracted), good neck coverage; (h, i) post-WEB device placement run (inserts: un-subtracted), showing the relationship of WEB device and parent vessel and completely obliterated/secured aneurysm