1. Poster: eP- 149

2. Disclosure
No Disclosure

3. Flow Diverter (FD) Stent Treatment for Blood Blister-like Aneurysms (BBAs)
Satya Patro, MD (Interventional Neuroradiology fellow)
Daniela Iancu, MD
Taleb Al Mansoori, MD
Cheemun Lum, MD
Howard Lesiuk, MD
The Ottawa Hospital, University of Ottawa, Ottawa, Canada

4. Introduction
Blood blister-like aneurysms (BBAs) are small and irregularly shaped aneurysms with a broad base, commonly located at the non-branching sites of intracranial arteries
Relatively rare lesions, comprising <2% of all intracranial aneurysms.
Commonly present with subarachnoid hemorrhage and demonstrated on DSA
Histopathology: abrupt loss of both intima and media with dome surrounded by adventitia and thrombus
Extremely fragile and thin walled

5. Introduction No optimal treatment
Routine surgical clipping and endovascular coiling with or without stenting are associated with very high morbidity and mortality
Endovascular treatment has high risk of peri-procedural and post- procedural rupture and hemorrhage
Parent artery sacrifice is a safe alternative; however associated with poor outcome

6. Introduction
Flow Diverter (FD) stents are special kind of intracranial stents, have been used for complex, wide neck and fusiform aneurysms
It acts by reconstructing the vessel wall and diverting the blood flow away from the aneurysm, thus resulting in thrombosis and occlusion of the aneurysm
SILK stent (Balt Extrusion, Montmorency, France) was introduced in early 2007, is a self-expanding FD made of a braided multi alloy cylindrical mesh

7. Purpose
Here we report single neurointervention center experience on the endovascular treatment by implantation of SILK flow diverter stents (Balt Extrusion, Montmorency, France) of 7 patients with subarachnoid hemorrhage secondary to ruptured BBAs

8. Materials & Methods
Retrospective study approved by our institution REB
Duration of Study: July’ 2012 to Oct’ 2015
Patients with SAH secondary to BBAs
Initial and follow-up clinical data, technical results, and angiographic findings of the patients were assessed
All patients underwent CT head/CTA head and neck

9. Materials & Methods Endovascular procedure: General anesthesia
Right groin femoral access
Systemic anticoagulation with IV heparin to maintain ACT>250
DSA with 3-D reconstruction
7F Balt long sheath and 6F FargoMax ((Balt Extrusion, Montmorency, France) guiding catheter placed in target artery
Stent delivery microcatheter (Vasco 21; Balt) over a inch (Traxcess, MicroVention) for placement of the stent
SILK FD stent deployed in the parent artery covering the aneurysm
Dyna CTA for evaluating the apposition of the stent with vessel wall
Balloon angioplasty (Scepter C- 4 x 10 mm, MicroVention) if needed

10. Materials & Methods Antiplatelet therapy:
Dual antiplatelet therapy started 6-12 hours prior to procedure with a loading dose of ASA (650 mg) and Plavix (300 mg)
Post procedure ASA (81 mg) and Plavix (75 mg) daily for 3 months
Thereafter, ASA (81 mg) life long
Follow-up:
Imaging-
Baseline MRI/CE MRA next day after the procedure
3 month DSA and MRI/CE MRA
1 year DSA and MRI/CE MRA
Thereafter, yearly MRI/CE MRA
Aneurysm class (I- complete occlusion, II- neck remnant and III- sac remnant) and degree of In-stent stenosis
Clinical follow-up-
30 and 90 days modified Rankin scale (mRS)

11. Results 7 cases of subarachnoid hemorrhage from ruptured BBAs
Age range: years (mean years)
Male:Female - 2:5
Mean Fisher grade of SAH: 4 (range: 1-4)
Mean Hunt & Hess score: 2.1 (range: 0-5)
Location of BBAs:
Dorsal supraclinoid ICA- 4
Paraophthalmic ICA-1
Basilar trunk- 2
Mean size of aneurysms: 2.6 x 2 mm (range mm)

12. Results
All patients had loading dose of ASA (650 mg) and Plavix (300 mg) 12 hours prior to procedure
Number of FD stents: Single FD- 6
Double FD- 1 (aneurysm continued to grow after 1st FD stenting, so, treated with 2nd FD)
Technical success in all cases
Immediate aneurysm occlusion: Complete occlusion- 2
Persistent filling- 5
Peri-procedural Complications:
Intra-procedural vessel perforation- 1
Non-occlusive in-stent thrombus resolved with ReoPro bolus- 1
No complications- 5

13. Results No re-rupture Immediate outcome:
1 patient died of intra-procedural vessel perforation and lobar hematoma
1 patient died of severe vasospasm and stroke
1 patient died of large hematoma secondary to EVD placement
4 patients recovered and discharged
Follow-up: Died- 3
Lost to f/u- 1
Angio and clinical f/u- 3
Follow-up period in surviving patients: months (mean months)
All follow-up patients have complete aneurysm occlusion on latest DSA/MRI
Clinical follow-up: 3 patients (good outcome- 2 and moderate outcome- 1)

14. Results Summary Table: 1 57 F 2 4 Rt ICA 2.5 x 1.9 4 x 20 4.5 x 25 3
Sl No.
Age
(years)
Sex
H & H
Fisher grade
Location
Size (mm)
SILK stent (mm)
No of stents
Aneurysm class
Complications
Follow up (months)
30 days
mRS  1
 57  F  2  4
 Rt ICA
 2.5 x 1.9
 4 x 20
4.5 x 25  3
 None  5 1
 63  M
 BA
 1.9 x 1.7
 3 x 25 6
 1.2 x 1.1
 3.5 x 15
 24 3
 52
 Lt ICA
 3.4 x 2.8
 Vessel perforation  -
 3.7 x 2.4
 2.5 x 25
 Lost to f/u  6
 48
 3.7 x 2.2
 4 x 30 6   7
 67
 2.3 x 2
 Non-occlusive thrombus resolved with ReoPro bolus  0

15. Results Summary Table (Follow-up): Sl. No. Immediate DSA
Aneurysm class
Latest DSA
(months)
Latest MRI
Latest clinic (months)
mRS 1
1 month  3  1 5  5 2
7 days  - -
 6 (Dead) 3
 8 days
 24 23  4 4
 3 days
 Lost to f/u 6
1 day 7
 6 days  0

16. Case- 1: 57 year-old-female with Fisher grade- 4 SAH from a ruptured right supraclinoid ICA blister aneurysm
Growth of aneurysm on f/u
Pre FD stenting
Post FD stenting
Single FD stent
1 month f/u DSA with no residual/recurrence
Post 2nd FD stenting
Double FD stents
1 month f/u DSA

17. Post FD stenting Dyna CTA
Case- 2: 63 year-old-male with Fisher grade- 4 SAH from a ruptured Basilar trunk blister aneurysm
Pre FD stenting
Pre FD stenting
Post FD stenting
Post FD stenting
Post FD stenting
Post FD stenting Dyna CTA
EVD related ICH

18. 24 months f/u with no residual/recurrence
Case- 3: 57 year-old-male with Fisher grade- 4 SAH from a ruptured right paraophthalmic ICA blister aneurysm
24 months f/u with no residual/recurrence
Pre FD stenting
Post FD stenting

19. Case- 4: 52 year-old-female with Fisher grade- 4 SAH from a ruptured left supraclinoid ICA blister aneurysm
Vessel perforation with contrast extravasation
Pre FD stenting
Post FD stenting with class- I result
Initial CT with left frontal bleed
Later CT with increased bleed

20. Post FD stenting with no residual
Case- 5: 52 year-old-female with Fisher grade- 4 SAH from a ruptured distal basilar trunk blister aneurysm
Post FD stenting with no residual
Pre FD stenting
Pre FD stenting
Pre FD stenting

21. Case- 6: 48 year-old-female with Fisher grade- 4 SAH from a ruptured right supraclinoid ICA ruptured blister aneurysm
Pre FD stenting
Post FD stenting
Single FD stent
Diffuse brain edema

22. Discussion
BBAs are actually pseudoaneurysms, formed by dissection of arterial wall
Typically surrounded by adventitia and thrombus
Common location BBAs is the dorsal aspect of the supraclinoid ICA; however, can arise from BA, middle cerebral artery (MCA), anterior cerebral artery, anterior communicating artery, basilar artery, and posterior inferior cerebellar artery
Microsurgical techniques such as clipping, wrapping and trapping of parent artery are associated with higher complication rate due to the extremely fragile nature of these BBAs
Various endovascular techniques have been used in the past like coiling with or without stenting and multiple overlapping stents are associated with high regrowth and rebleeding

23. Discussion
Target site of treatment should be endoluminal reconstruction with flow diversion rather than the aneurysm sac
Flow diverter stents are relatively newer endovascular devices typically used to treat giant/wide neck, dissecting/fusiform, or very small intracranial aneurysms
Lower porosity and higher metal coverage ratios of these stents gives much higher flow diversion capacities than conventional self-expandable intracranial stents
Treatment of BBAs by placing FD stents in the affected parent artery is an effective and safe strategy
This results in stagnation and gradual thrombosis of the aneurysm, thus occlusion of the aneurysms
Multiple cases reports and small case series have shown promising results with good outcome and acceptable risks

24. Discussion
The present study highlights the technical challenges, angiographic and clinical outcome of FD stenting for BBAs
All procedures were technically successful
The periprocedural complication was low with only one patient (14%) had vessel perforation away from the target vessel due to difficulties from pre existing vasospasm. Two other patients died due to causes unrelated to procedure.
The surviving patients showed good clinical and angiographic outcome
Limitations of the study: Small sample size
Lack of control group for comparison
Lack of long term angio and clinical follow up

25. Conclusion
The use of endovascular treatment for BBAs is still debated because of limited experience; however the results of this study and various other published literature indicate that implantation of FD stents is a feasible alternative approach for treatment of these dangerous aneurysms