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July2007 Vol.44 Issue:      2 Table of Contents
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Saccular Intracranial Aneurysm Coiling: Experience in Department of Neurology, Ain-Shams University

Hany Zakieldine

Department of Neurology, Ain Shams University



ABSTRACT

Background: Subarachnoid hemorrhage is a devastating type of stroke associated with 45% case fatality and 30% long-term dependency in survivors. Ruptured aneurysms should be treated early (within 24 to 72 hours) because the risk of subsequent rupture is high. Options for treatment include surgical clipping and endovascular coilings which is less invasive. Endovascular coiling has been proven to be effective and safer than clipping in most ruptured and unruptured intracranial aneurysms. Methods: We performed endovascular coiling for ruptured saccular aneurysm (presenting with acute subarachnoid hemorrhage, Hunt and Hess grade I-IV) and for asymptomatic aneurysms (≥7 mm in the anterior circulation or ≤ 7 mm in the posterior circulation in patients < 60 y old or with personal or family history of subarachnoid hemorrhage). All patients underwent clinical assessment together with Hunt and Hess scale (H&H scale) and modified Rankin Scale (mRS) upon discharge. Patients also performed CT scan brain +/- CSF analysis. Then six vessels digital subtraction cerebral angiography (DSA) was done followed by endovascular coiling of the aneurysm. Follow up by mRS and MRA brain or DSA was done after 6 months and then yearly till 5 years. Results: We included our first 60 saccular aneurysms (57 patients with 60 aneurysms) for whom endovascular coiling was done. Fifty seven of our patients (95%) had ruptured aneurysm while 3 (5%) had unruptured aneurysms (asymptomatic). Fifty five aneurysms (91.7%) were small (< 10 mm) and only 5 (8.3%) were between 11-15 mm. Thirty three (55%) had narrow neck while 27 (45%) had a wide neck. We succeeded to achieve total occlusion of the aneurysm in 49/60 cases (81.6%), neck remnant was left in 6 cases (10%), incomplete occlusion was done in two cases (3.3%). In 3 cases (5%) we failed to occlude the aneurysm. Balloon remodling and coiling was used in 6 patients (10%) while self-expandable stent and coiling was used in two patient (3.3%). We faced 3 clinical complications (5%) that resulted in neurologic deficit. During long-term follow up (mean 31 +/-20.4 months) for the surviving patients, none of the treated aneurysms suffered from rebleeding. MRA or angiography follow up for up to 5 years revealed persistent total occlusion in 37/42 patients (88%), stable neck remnant in 3/42 patients (7.1%) for whom no further treatment was required and major aneurysm recurrence in 2/42 patients (4.7%). Conclusion: Endovascular coiling is a less invasive alternative to surgical clipping. For patients in good  as well as poor clinical condition with ruptured or unruptured aneurysms of either the anterior or posterior circulation, there is firm evidence that if the aneurysm is considered suitable for surgical clipping and endovascular treatment, coiling is associated with a better outcome.

(Egypt J. Neurol. Psychiat. Neurosurg., 2007, 44(2): 751-769)

 




INTRODUCTION

 

Although subarachnoid hemorrhage (SAH) comprises only 1% to 7% of all strokes, the loss of productive life years in the general population from SAH is comparable to that of cerebral infarction because of the relatively young age of onset and poor outcome in SAH1,2. Aneurysmal subarachnoid hemorrhage has a 30-day mortality rate of 45 percent. An estimated 30 percent of survivors will have moderate-to-severe disability3. However, unlike other stroke subtypes, the incidence of SAH did not significantly change over the last decades1,2,3. In the most recent overview of 14 longitudinal and 23 case-control studies of risk factors for SAH published in English from 1966 through March 2005, it was concluded that smoking, hypertension, and excessive alcohol are the most important risk factors for SAH4. There is also evidence that genetic factors play an important role in the pathogenesis of SAH5.

Intracranial aneurysms are common lesions; autopsy studies indicate prevalence in the adult population between 1 and 5 percent, which translates to 10 million to 12 million persons in the United States. Fortunately, most aneurysms are small, and an estimated 50 to 80 percent of all aneurysms do not rupture during the course of a person’s life time6. The estimated incidence of subarachnoid hemorrhage from a ruptured intracranial aneurysm in the United States is 1 case per 10,000 persons, yielding approximately 27,000 new cases of subarachnoid hemorrhage each year7.

During endovascular occlusion with the use of detachable coils (coiling), a microcatheter is advanced into the aneurysm, and detachable coils of various sizes and shapes are deployed to stop blood from filling the aneurysm (Fig. 1).

 

 

Fig. (1): Endovascular occlusion of an aneurysm of the posterior communicating artery with guglielmi detachable coils.

Coiling had been introduced as an experimental procedure for patients who were not good candidates for surgery. After almost a decade of increased use and evaluation, endovascular coiling has proved to be a safe and durable alternative to the traditional neurosurgical treatment of craniotomy and clip ligation (clipping)7. Coiling has now surpassed clipping as the primary method of treatment for intracranial aneurysms in some centers. Since the Guglielmi detachable coil for the treatment of intracranial aneurysms was approved in 1995 by the Food and Drug Administration (FDA), an estimated 150,000 patients have been treated with this device9.

This is an observational study to report the results of our first 60 saccular aneurysms (57 patients with 60 aneurysms) for whom endovascular coiling was performed.

 

SUBJECTS AND METHODS

 

Subjects

Between January 2002 and December 2006, we performed endovascular coiling for 60 saccular aneurysms (57 patients with 60 aneurysms) fulfilling the following criteria:

 

 

Inclusion criteria:

*       Symptomatic, presenting with acute subarachnoid hemorrhage (Hunt and Hess grade I-IV)

*       Asymptomatic, ≥7 mm in size in the anterior circulation or < 7 mm in size in the posterior circulation in patients < 60 y old Or with personal or family history of subarachnoid hemorrhage.

 

Exclusion criteria:

Hunt and Hess Grade V (deep Coma, decerebrate posturing, moribund)

 

Methods

 

 

 

 

 

All patients underwent:

*       Clinical assessment together with Hunt and Hess scale (H&H scale) and modified Rankin Scale (mRS). This was done before coiling, after one month, 3 months, 6 months of coiling and then yearly thereafter.

*       Laboratory investigations: complete blood count, coagulation profile, liver and renal function tests, fasting and post-prandial blood sugar.

*       CT scan brain +/- CSF analysis.

*       Six vessels digital subtraction cerebral angiography followed by endovascular coiling of the aneurysm.

*       Follow up MRA brain (3D time of flight; 3TOF) or DSA was done after 6 months and then yearly till 5 years.

 
Description of the procedure

All procedures were carried out via puncture of the right or left femoral artery. With the use of a 5F diagnostic catheter both internal carotid arteries (ICAs), external carotid arteries (ECAs) and vertebral arteries (VAs) were selectively catheterized. When a saccular aneurysm was detected, a complete study of its angiographic features was done using different projections to determine its site, direction, size, dome to neck ratio (ie. narrow versus wide neck), presence of a functional branch arising from the aneurysm, presence of a daughter aneurysm arising from the primary sac and presence of vasospasm.

Wide neck aneurysm was defined as a dome to neck ratio <2:1. Vasospasm was graded as mild (less than 50% lumen reduction), moderate (50-70% lumen reduction) and severe (more than 70% lumen reduction)10. If more than one aneurysm were found, the symptomatic one was treated first. Symptomatic aneurysm was determined according to the distribution of blood in the CT scan, presence of focal vasospasm, size of the aneurysm, multi-lobed aneurysm and presence of daughter aneurysm.

After having studied the aneurysm to be treated, systemic heparinization was given and the internal carotid or vertebral artery was selectively engaged by using a proper 6F guiding catheter. Then, using the coaxial system, selective catheterization of the aneurysm was done using the microcatheter and then packing of its lumen was done using detachable platinum coils until its complete occlusion or near complete occlusion (neck remnant). Neck remnant was defined as the persistence of any portion of the original defect of the arterial wall as seen on any single projection but without opacification of the aneurysmal sac. Incomplete occlusion was defined as persistence of residual opacification in the aneurysm sac10. In cases of wide neck aneurysm, balloon assisted or stent assisted coiling was done. Placement of the balloon or stent across the aneurysm wide neck prevents coils from bulging out of the aneurysm. In presence of severe vasospasm local intra-arterial injection of vasodilator drugs (nimodipine, nitroglycerine or papaverine) was done.

 

Procedural success was defined as:

*       To succeed to achieve total or near total occlusion of the aneurysm (neck remnant).

*              Absence of complications.

 

During follow-up, the recurrence was qualified as major if it resulted in saccular opacification of the aneurysm sac and its size would theoretically permit re-treatment with coils10.  

 

RESULTS

 

Our study included our first 60 saccular aneurysms (57 patients with 60 aneurysms; three patients had two aneurysms) for whom endovascular coiling was done. They were 32 males (53%) and 28 females (47%). Their age ranged from 15 y to 82 y with a mean of 46.7±13.6 years. Risk factors included, hypertension in 34 (56%), smoking or ex-smoking in 17 (28.3%). On the other hand, diabetes mellitus was found in 8 (13%) and ischemic heart disease was found in 3 (5%) (Table 1).

Fifty seven of our patients (95%) had ruptured aneurysm causing subarachnoid hemorrhage while 3 (5%) had unruptured aneurysms (asymptomatic). Of the patients presenting with subarachnoid hemorrhage, 23 (40.3%) had mild symptoms (H & H scale I-II), 22 (38.5%) had moderate symptoms (H & H scale III) while 12 (21%) had severe symptoms (H&H scale IV). Their CT scan revealed no or small amount of subarachnoid hemorrhage (Fisher grade I-II) in 8 patients (14%), moderate amount of subarachnoid hemorrhage (Fisher grade III) in 25 patients (43.8%) and large amount of subarachnoid hemorrhage (Fisher grade IV) in 24 patients (42%) (Table 2).

The 3 patients with unruptured aneurysm that was coiled presented with subarachnoid hemorrhage and had two aneurysms, one symptomatic and the second unruptured that was more the 4 mm in size, terminal type rather than side wall. In addition, they were less than 60 years old with no life threatening diseases.

Concerning the localization of the aneurysms, 27 (45%) were anterior communicating or anterior cerebral aneurysms (ACoA/ACA), 15 (25%) were middle cerebral artery bifurcation aneurysms (MCA), 8 (13.3%) were posterior communicating aneurysms (PCoA), 4 (6.7%) were posterior inferior cerebellar aneurysms (PICA), 1 (1.7%) pericallosal aneurysm, 1 (1.7%) ICA bifurcation aneurysm, 1 (1.7%) carotido-ophthalmic aneurysm, 1 (1.7%) basilar tip aneurysm, 1 (1.7%) basilar trunk aneurysm, 1 (1.7%) posterior cerebral artery aneurysm (PCA) (table 3).

Concerning the angiographic features of the treated aneurysms, 30 (50%) were less than 5 mm in size, 25 (41.7%) were between 5-10 mm. Hence, 91.7% of our aneurysms were small ones and only 5 (8.3%) were between 11-15 mm. Thirty three (55%) had a narrow neck while 27 (45%) had a wide neck. Branch arising from the neck or aneurysm sac was seen in 10 cases (16.6%). Vasospasm during angiography before coiling was detected in 14 cases (23.3%; mild in 2 cases, moderate in 4 and severe in 8 cases). Vasospasm was treated with local intra-arterial injection of vasodilator drugs and did not prevent access and treatment of the aneurysm (table 3).

We succeeded to achieve total occlusion of the aneurysm in 49/60 cases (81.7%), neck remnant was left in 6 cases (10%), incomplete occlusion was done in two cases (3.3%). Among 3 of those where a neck remnant was left and one of the two cases with incomplete occlusion, this was done intentionally to preserve an important branch arising from the neck. The remaining 3 cases with a left neck remnant were done early during our work when soft balloon or stent for remodling was not available. In 3 cases (5%) we failed to occlude the aneurysm. All 3 were tiny aneurysm (2 mm) and it was not possible to catheterize the aneurysm in two of them while the third was a diffuse ectasia of the upper MCA branch with no neck.  Balloon remodling and coiling was used in 6 patients (10%) while self-expandable stent and coiling was used in two patient (3.3%) (Table 4).

We faced 3 clinical complications (5%) that resulted in neurologic deficit. Two were due to thromboembolic complications and one was due to branch occlusion. One of the thromboembolic complications was due to the use of biologically active coils that are more thrombogenic. We faced no procedural related mortality (Table 5).

Delayed ischemia and cerebral infarction secondary to vasospasm (procedural unrelated) occurred in 10 patients (16.7%). Hydrocephalic changes necessitating ventriculo-peritoneal shunt insertion occurred in 8 patients (13.3%).

The outcome upon discharge from hospital was good (mRS 0-2) in 44 patients (73.3%), faire (mRS 3) in 5 patients (8.3%) and poor (mRS 4) in 2 patients (3.3%). On the other hand 9 patients (15%) died due to the complications of the subarachnoid hemorrhage (Table 6). Statistically significant correlation was found between the clinical severity of subarachnoid hemorrhage (Hunt and Hess scale), occurrence of delayed cerebral ischemia secondary to vasospasm (procedural unrelated), occurrence of hydrocephalus necessitating ventriculo-peritoneal shunting and the outcome upon discharge (p<0.001). Eighty six percent of patients presenting with mild subarachnoid hemorrhage (H&H scale I-II) and eighty one percent of those with moderate subarachnoid hemorrhage (H&H scale III) had good outcome. In contrast, only 25% of patients presenting with severe subarachnoid hemorrhage (H & H scale IV) had good outcome. On the other hand, there was no correlation between the age (<50 y versus >50 y), the amount of blood on CT scan (Fisher grade), the aneurysm site, the dome/ neck ratio, and the final outcome (Table 7). Concerning the 3 patients that we failed to occlude their aneurysm, 2 of them died from the complications of their initial subarachnoid hemorrhage despite that one of them performed surgical wrapping of the aneurysm. The third patient was followed for 6 months with no rebleeding.

During long-term follow up (mean 31 +/-20.4 months, minimum of 6 months and maximum of 72 months) of the surviving 51 patients, drop out were 6 patients (6/51 patients, 11.7%). In addition, 3 patients refused to do follow-up MRA or angiography, two of them were 73 and 82 years old. None of the treated aneurysms suffered from rebleeding. MRA or angiography follow up for up to 5 years revealed persistent total occlusion in 37/42 patients (88%), stable neck remnant in 3/42 patients (7.1%) for whom no further treatment was required and major aneurysm recurrence in 2/42 patients (4.7%). Of the small aneurysms (<10 mm) with narrow neck, only one patient (1/22 patients, 4.5%) developed major aneurysm recurrence. In this patient, only partial aneurysm coiling could be achieved immediately after coiling since she had a Rt MCA trifurcation aneurysm with two of the MCA branches were arising from the aneurysm sac itself. Therefore, partial coiling was done to preserve the flow in these branches. A second session was done for this patient 6 months later where only a neck remnant was left and the latter remained stable thereafter. Of the small aneurysms (<10 mm) with wide neck, two patients (2/16 patients, 12.5%) developed a stable neck remnant for which no further treatment was required. Of the large aneurysms (>10 mm), one patient (1/4 patients, 25%) developed a stable neck remnant for which no further treatment was required. On the other hand, one patient (1/4 patients, 25%) developed major aneurysm recurrence and a second session of embolization is being prepared for her. In this patient only partial aneurysm coiling was done during the first session of coiling (Table 8). Statistically significant correlation was found between major aneurismal recurrence and immediate angiographic results after coiling (i.e. total or near total vesus incomplete occlusion) (p<0.001). On the other hand, there was no correlation between major aneurismal recurrence and aneurysm site, size and dome/neck ratio (Table 9).

Two of our patients were particularly interesting. The first was a female patient 18 years old who developed acute subarachnoid hemorrhage (H & H II) secondary to a wide neck Lt posterior cerebral artery (PCA) aneurysm measuring 8 x 5 mm. Mass effect from this aneurysm resulted in Rt sided ataxic hemiparesis and a complete Lt oculomotor nerve palsy. A self expandable flexible stent was placed in front of the aneurysm neck then through the mesh of the stent a microcatheter was advanced into the aneurysm and coiling was performed. The presence of the stent prevented bulging of the coils out from the aneurysm and dense packing could be achieved. Owing to stopping the pulsetile flow in the aneurysm after filling its lumen followed by its fibrosis and shrinkage, the mass effect gradually improved over the next 3 months (Fig. 2). The second patient was a 20 years old female who developed acute subarachnoid hemorrhage (H&H II) secondary to a wide neck Rt middle cerebral artery (MCA) trifurcation aneurysm measuring 7 x 5 mm. Two of the three MCA trifurcation branches were arising from the aneurysm neck. Hence balloon remodling was done to protect these branches during coiling of the aneurysm. This technique allowed us to achieve dense packing of the aneurysm with preservation of the MCA branches (Fig. 3).


Table 1. Baseline characteristics and medical history.

  

 

No

%

Male

32

5353

Female

28

47

Age

mean 46.7±13.6 y

 

Hypertension

34

5655

Smoking

17

28.3

Diabetes Mellitus

8

1313

Ischemic Heart Disease

3

55

 

Table 2. Presentation and severity of clinical picture and CT scan.

 

 

No

%

Ruptured aneurysm (SAH)

57

95

Asymptomatic

3

5

Severity of SAH

       Hunt & Hess Scale I-II

       Hunt & Hess Scale III

       Hunt & Hess Scale IV

 

23

22

12

 

40.3

38.5

21

CT scan grading

       Fisher grade I-II

       Fisher grade III

       Fisher grade IV

 

8

25

24

 

14

43.8

42

 

Table 3. Angiographic characteristics of the aneurysms.

 

 

No

%

Localization of aneurysms

       ACoA/ACA

       MCA

       PCoA

       PICA

       Pericallosal

       ICA bifurcation

      Carotido-ophthalmic

      Basilar tip

      Basilar trunk

      PCA

 

27

15

8

4

1

1

1

1

1

1

 

45

25

13.3

6.7

1.7

1.7

1.7

1.7

1.7

1.7

Size of aneurysms

      Less than 5 mm

      5-10 mm

      More than 10 mm

 

30

25

5

 

50

41.7

8.3

Size of neck of aneurysm (dome/neck ratio)

      Narrow neck

      Wide neck

 

33

27

 

55

45

Branch arising from neck or sac

10

16.6

Vasospasm during initial angiography

14

23.3

Table 4. Procedural details and success.

 

 

No

%

Total occlusion

49

81.7

Neck remnant

6

10

Incomplete occlusion

2

3.3

Failed coiling

3

5

Balloon remodling

6

10

Self-expandable stent

2

3.3

 

Table 5. Complications.

 

 

No

%

Thromboembolic complications

2

3.3

Branch occlusion

1

1.6

Procedural related mortality

0

0

 

Table 6. Outcome upon discharge.

 

 

No

%

mRS 0-2

44

73.3

mRS 3

5

8.3

mRS 4

2

3.3

Death

9

15

 

Table 7. Factors related to the outcome upon discharge.

 

Variables

P value

Significance

Age (<50 vs >50 y)

0.394

NS

H&H scale

<0.001

S

Fisher CT scan grade

0.771

NS

Aneurysm site

0.496

NS

Dome/ neck ratio

0.808

NS

Delayed cerebral ischemia secondary to vasospasm (procedural unrelated)

<0.001

S

Hydrocephalic necessitating ventriculo-peritoneal shunting

<0.001

S

 

Table 8. Long-term follow-up.

 

 

No

%

Rebleeding

0

0

Persistent total occlusion

37

88

Stable neck remnant

3

7.1

Major aneurysm recurrence

2

4.7

 

Table 9. Factors related to major aneurysm recurrence.

 

Variables

P value

Significance

Aneurysm site

0.6

NS

Aneurysm size

0.08

NS

Dome/ neck ratio

0.33

NS

Immediate angiographic results

<0.001

S

 

 

A

B

C

D

 

Fig. (2): (A) CT scan showing the Lt PCA aneurysm compressing the midbrain. (B) Digital subtraction angiography showing the Lt PCA wide neck aneurysm. (C) Digital subtraction angiography after stent supported coiling of the aneurysm resulting in its total occlusion. (D) Self expandable stent and coil mass.

A

B

C

D

E

F

Fig. (3): (a and b) Wide neck Rt MCA trifurcation aneurysm with two of the MCA branches arising from the neck. (c and d) Balloon placed in one of the upper MCA branches protecting the MCA trifurcation while coiling is performed. (e and f) After coiling of the aneurysm resulting in its total occlusion.


DISCUSSION

 

For ruptured aneurysms, early treatment within 24 to 72 hours has been recommended because the risk of subsequent rupture is high, with approximately 20% risk of rerupture in the first 2 weeks after subarachnoid hemorrhage11. Each additional rupture substantially increases the risk of mortality and morbidity. Treatment has also been recommended for most of the unruptured aneurysms, although there is uncertainty about treatment of some small aneurysms <7 mm because their risk of rupture appears low12.

All ruptured aneurysms in patients with Hunt and Hess grades I to IV are treated early. There is debate about how to treat patients with the most severe grade, Hunt and Hess grade V. The historically high incidence of poor outcome despite treatment has prompted the suggestion of conservative management unless clinical improvement occurs. However, recent evidence supports the use of aggressive therapy for most of these patients, including placement of a ventricular drain and securing the aneurysm by clipping or coiling13. 

In 1991, Guido Guglielmi was the first to describe the technique of occluding aneurysms from an endovascular approach with electrolytic detachable platinum coils, termed Guglielmi detachable coils (GDCs) thereby excluding it from the circulation14,15. As clinical experience with this technique has increased and coil design has improved, coil embolization has been used with increasing frequency even in patients who could be treated by conventional surgical clipping16,17. Furthermore, some centers are treating patients with surgical clipping only if they cannot be treated primarily by endovascular coil embolization therapy18.

Endovascular treatment, a less stressful alternative to clipping has been proven to be effective in preventing rebleeding after subarachnoid hemorrhage due to aneurismal rupture. Accumulating clinical experience confirms that early and midterm results after endovascular repair can be very good19,20,21 although it does not appear to be cheaper than surgery at the present time22. Overall procedural morbidity and mortality rates for coiling have been reported as 3.7 to 5.3 percent and 1.1 to 1.5 percent, respectively19,21,23,24.

Overall clinical outcome of endovascular treatment was related to the immediate postprocedural angiographic result, which in turn was related to microcatheter stability, aneurysm geometry and aneurysm neck diameter25.

Several retrospective comparative studies comparing aneurysm coiling to clipping16,17,26 suggest that despite its attendant risks, treating most ruptured and unruptured intracranial aneurysms with detachable coils appears to be safer than clipping, at least during the perioperative period. It was concluded that for patients in good clinical condition with ruptured aneurysms of either the anterior or posterior circulation, there is firm evidence that if the aneurysm is considered suitable for surgical clipping and endovascular treatment, coiling is associated with a better outcome. For patients in poor clinical grade, there is no reliable randomized evidence comparing the risks and benefits of coiling versus clipping. Because coiling is less invasive than surgery, also in patients with poor clinical condition, coiling seems the preferred option27.  More robust data favoring the safety of coiling over clipping for aneurysms presenting with subarachnoid hemorrhage came from a large, multicenter prospective study conducted in England. In the International Subarachnoid Aneurysm Trial (ISAT) 28, 2143 primarily good-grade patients presenting with a ruptured aneurysm (mostly small <10mm and located in the anterior circulation) were prospectively randomly assigned to either clipping or coiling. Recruitment into the trial was stopped, since the relative risk (22.6 percent) and the absolute risk (6.9 percent) of dependency and death in the group assigned to coiling was clearly reduced as compared with that in the group assigned to clipping. These observations were upheld in the one-year follow-up report on the patients who had been recruited and treated before the trial was stopped. At 1 year there was no difference in fatality rates between the 2 treatment groups, but for combined death and dependent rates there was an absolute risk reduction of 7.4% associated with coiling, which was significant. This survival advantage of endovascular related to surgical therapy was maintained up to 7 years. This emphasizes that late events, in particular late aneurysm rebleeding leading to death or dependency, are uncommon and are unlikely to reverse the early benefit of endovascular treatment. The endovascular group also had a lower incidence of epilepsy, and a low incidence of rebleeding (0.2% per patient year with follow up from 1 to 8 years), but the latter was higher than the surgical group (7 patients in the endovascular group versus 2 patients in the surgical group)29. Since endovascular treatment has been accepted by most to be the preferred treatment modality for basilar artery aneurysms, which are relatively uncommon and difficult to repair surgically30, the main impact of ISAT has been a steady increase in the use of endovascular coils in the management of anterior circulation aneurysms, depending on the availability of endovascular expertise at individual centers.

In addition, patients with aneurysms in the anterior communicating/ anterior cerebral artery, there is a greater expectation that they will have cognitive impairment and subtle personality changes after surgical clipping. This is because the surgical techniques used to access the area of the anterior communicating artery might require resection or retraction of frontal lobe structures. A case-matched study of MRI changes and cognitive outcomes after clipping and coiling showed local damage or encephalomalacia exclusively after neurosurgery and more small infarcts in the vascular territory of the aneurysm in the surgical group. There was a trend towards poorer cognitive outcome in the surgical group. They concluded that endovascular treatment may cause less structural brain damage than surgery and have a more favorable cognitive outcome31.

Nevertheless, it is not feasible to perform a coiling procedure for some aneurysms (5 to 10% of cases)19,20,32 because of unusual tortuosity of the vessels which renders access difficult or because the anatomical characteristics  of the aneurysm do not permit the coils to sit safely inside (e.g. very wide neck). Recent technologic advances, including coils that are better able to conform in aneurysms with atypical morphology, remodling balloons33, and flexible intracranial self expandable stents, which were introduced in 2002 have markedly reduced the number of aneurysms that cannot be approached with the detachable coil procedure34.

The concern of endovascular coiling remains incomplete aneurysm obliteration (more common in large, complex and wide-neck aneurysms) associated with remnant growth or aneurysm recanalization due to coil compaction that might lead to rebleeding in a small number of patients10,20. The rates of major recanalization appear to be in the range of 9 to 34% with follow up ranged from 3-5 years10,20,21,24,35,36,37,38,39. Vigilant follow-up angiography or MRA is needed to detect aneurysms that recanalize10, since re-coiling may be indicated and is safe38.

Variables determined to be significant predictors of aneurysm recanalization includes aneurysm size > or = 10 mm, dome to neck ratio,  incomplete initial occlusion after coiling and duration of follow up10,20,21,35,36. Darwish et al36 reported that stable occlusion was achieved in 100% of small and medium sized aneurysms while Sluzewski et al21 reported that recanalization of the aneurysm occurred mainly in aneurysms larger than 15 mm. In the ISAT  trial29 where 90% of aneurysms were small (<10mm) follow-up angiography at 1 year showed that 92% of aneurysms were  completely occluded (66%) or had a neck remnant (26%) while only 8% were incompletely occluded with aneurysm filling. Interestingly, in the surgical group, 82% of the aneurysms were completely occluded, 12% had a neck remnant while 6% were incompletely occluded with aneurysm filling.

In the series reported by Raymond et al10 that included 383 aneurysms followed by angiography for up to 3 years, complete occlusion was achieved in 35.9% of lesions while residual neck was left in 46.3 % and residual aneurysm was left in 13.8 % (incomplete occlusion). In 4% of the lesions they failed to occlude the aneurysm. Major recurrences were found in 20.7% of lesions at a mean of 16.49±15.93 months. Almost half (49.4%) of major recurrences were re-treated with coils. Age, sex, and aneurismal location had no significant influence on recurrences. The most significant predictors of a recurrence for the entire group were treatment of ruptured aneurysm in contrast to unruptured ones (P=0.013), size of the aneurysm (P<0.001), width of the neck of the aneurysm (P<0.001), suboptimal initial angiographic result (neck remnant or incomplete occlusion; P<0.001), and length of follow-up period (P=0.003). There were strong correlations between aneurismal dimensions and recurrence. Aneurysms ≥10 mm in diameter and with necks wider than 4 mm had a significantly higher risk of recurrences (P<0.001). Major recurrence was observed in 10.9 % of aneurysms measuring 3 to 9 mm (221 patients) and in 34.4% of aneurysms measuring ≥10 mm (160 patients) (p<0.001). Similarly, major recurrence was observed in 13.3 % of aneurysms with narrow neck (≤ 4 mm) (249 patients) and in 34.8% of aneurysms with wide neck (>4 mm) (132 patients) (p<0.001). Lesions that were completely occluded with coils, without a residual neck, had a significantly lower risk of developing a recurrence (P<0.001).

Despite this aneurysm recurrence seen in some patients after endovascular therapy, the risk of hemorrhage from a coiled aneurysm is still very small; two large studies documented a risk of 0.8% and 1.2% percent, with a mean follow-up of 31.32 and 47.7 months10,40. Therefore, the magnitude of this risk is not sufficient to undermine the initial benefits of endovascular management of patients with ruptured aneurysms, which continue for at least 7 years as demonstrated by the ISAT trial29. In addition, since risk of rebleeding seems to be low, any recommendation to re-treat the aneurysm need to be weighted carefully against the risks of further treatment, particularly in old patients29.

On the other hand, although surgery claims to exclude aneurysms completely from the circulation, rates of aneurysm residuals after clipping are not negligible, ranging from 3.8% to 8%41,42. Long-term studies have documented a certain small risk of aneurysm regrowth (1.5-3.9%), and hemorrhage (0.26-1.4%) following surgical clipping43,44,45. Considering all aneurysms (completely occluded and those with remnants), Feuerberg et al41 reported a rate of rupture of 0.8% per year after surgical clipping, all from aneurysms that were originally incompletely treated.

Promising solution to the problem of recurrence after coiling is the advent of biologically active coils (coated coil system). Originally, coils were composed of inert metals that induced thrombosis by interrupting normal flow through the aneurysm.   Biologically active coils are covered with a bioabsorbable polymeric material (polyglycolic acid/lactide copolymer, PGLA). They were developed to accelerate intra-aneurismal clot organization and fibrosis through enhancement of cell proliferation (Matrix coil)46. Another new type of coil, the HydroCoil, have a layer of hydrogel polymer surrounding a platinum metallic core. The hydrogel polymer expands soon after making contact with blood. The expanded hydrogel polymer provides increased volumetric filling compared with bare metal coils and offers a more biocompatible surface for endothelial growth47,48. Another potential solution to recanalization is a new flexible, self-expandable nitinol stent. This intracranial stent is placed within the artery from which the aneurysm arises opposite to the aneurysm neck49,50.

Concerning the results of biologically active coils (Matrix) and expanding coils (HydroCoils), Ding et al51 reported a direct comparison of bare platinum coils, Matrix coils, and HydroCoils in a single animal model. They concluded that in the rabbit model, the use of HydroCoils results in improved long-term occlusion rates compared with Matrix and platinum coils. The Matrix group showed an increase in inflammation and coil compaction compared with HydroCoils and platinum coils.

The HydroCoil for Endovascular Aneurysm Occlusion (HEAL) study that included 191 cerebral aneurysms treated with HydroCoil Embolic System (HES) reported an initial occlusion result of "complete" or "near-complete"  in 91.8% of aneurysms48. Periprocedural thromboembolic events occurred in 8.1% of aneurysms treated with neurologic deficits related to thromboemboli occurring in 2.1% of aneurysms treated. Intraprocedural aneurysm perforations occurred in 2.8% of previously ruptured aneurysms, and in 0% of previously unruptured aneurysms.  Hence, the overall safety profile of HydroCoils appears acceptable48. Of those patients, 135 aneurysms that included a number of large, giant, and previously recurrent aneurysms were followed up for 3-6 months. When HES represented > or = 75% of coil length used, the recurrence rate was 0 (0%) of 18, whereas with <75% length of HES, the recurrence rate was 16 (23%) of 71 (P = .035). When the final coil deposited was a HES coil, the recurrence rate was 6 (11%) of 53, whereas when the final coil was platinum, the recurrence rate was 10 (29%) of 34 (P=.047). Therefore, although the overall recurrence rates for small and large aneurysms in HEAL were no lower than published rates for aneurysms treated with platinum coils, patients treated in HEAL had a reduced recurrence rate when greater than 75% of the coil length used to treat an aneurysm was HES and when the final coil was HES53. On the other hand, Berenstein et al53 reported that using the HES no recanalization occurred in 23 aneurysms with small size (<10 mm)/small neck (<4 mm).

The results of the biologically active coils (Matrix) are still unclear. Some reported that the incidence of recanalization was not different in aneurysms treated with PGLA-coated coils as compared to that seen with bare platinum coil54. However, others reported worse recanalization rates with PGLA-coated coils with overall recanalization rate of 57%55.

Flexible, self-expanding nitinol stent specifically designed for use in the cerebral vasculature, became available for aneurysm treatment since 2002 (e.g. Neuroform stent). Preliminary experience demonstrated that they could be deployed safely and relatively easily within the cerebral vasculature, facilitating the treatment of complex cerebral aneurysms, many of which otherwise might not have been amenable to traditional endovascular treatment strategies. In addition to providing durable parent vessel protection in wide neck aneurysms, intravascular stents theoretically offer the potential to produce flow redirection and provide an endovascular matrix for endothelization. This potential for endovascular reconstruction and flow redirection is particularly attractive with respect to the treatment of dissecting, fusiform aneurysms. In many cases, these aneurysms are not amenable to standard constructive microsurgical and endovascular embolization techniques. Endovascular stent reconstruction provides a potentially favorable constructive option for the treatment of these lesions, which typically would otherwise require deconstructive treatment consisting of either sacrifice of the parent vessel aneurismal segment or proximal occlusion to achieve flow reversal34.

A short term follow up series involving 64 patients with 74 aneurysms were treated with Neuroform stents. Initial follow-up data suggest a significant advantage of the stent-supported coil embolization of small aneurysms (<10mm) with wide necks with high rates of progressive thrombosis (68%) and very low rates of recanalization (5%) as observed at 3 to 6 months. This compares favorably with the results of coiling without stening presented by Murayama et al.20, who reported rates of progressive thrombosis of 22% and recanalization of 20% in small, wide-necked aneurysms. Delayed, severe, in-stent stenosis was observed in 3 patients (6.2%), 1 of whom was symptomatic and required angioplasty and subsequently superficial temporal artery-to-middle cerebral artery bypass surgery. Although these initial results are encouraging, longer-term follow-up will be necessary to definitively determine the effect of the stent on the durability of aneurysm embolization34.

Studies of asymptomatic unruptured intracranial aneurysms, including the randomized International Study of Unruptured Intracranial Aneurysms (ISUIA) suggest that the rupture rate across all aneurysms is 1–2% per year and that certain aneurysms are at greater rupture risk, including those with increasing diameters and in certain anatomical distributions (for example basilar tip)56. The authors report an overall mortality rate of 66% when unruptured aneurysm ruptures. Using the result of the ISUIA, incidentally discovered aneurysms in the anterior circulation less than 7 mm in size in people with no personal or family history of subarachnoid hemorrhage should be left untreated. People with remaining life expectancy of less than 20 years or so (ie those over age 60 years) should be informed that from a statistical point of view the benefits of treatment do not outweigh the risks. Third, in all other cases treatment with surgical clipping or coil embolization should be advised57,58 .

However, the management of asymptomatic aneurysms 7 mm or smaller remains a controversial issue. Clinical observations and retrospective studies demonstrated that a significant number of patients with SAH hemorrhage resulted from aneurysms smaller than 7 mm in the anterior circulation59,60,61,62. A recent study analyzing 280 ruptured aneurysms showed that 74% were smaller than 10mm, with a mean size of 7.6mm. The mean size of ruptured aneurysms in patients who were normotensive, had medically controlled hypertension, and had poorly controlled hypertension was 8.3 mm, 7.4 mm, and 6.5 mm, respectively. Furthermore, patients with a family history of SAH or who had poorly controlled hypertension were more likely to have ruptured aneurysms less than 5 mm. With respect to location, ruptured aneurysms of the anterior communicating artery were smaller on average (6.6 mm) than aneurysms in other locations59.

In a study designed to investigate the long term history of unruptured aneurysms where 181 unruptured aneurysms were followed for a median of 19.7 years (range 0.8-38.9 years), the annual incidence of rupture was 1.3%. The cumulative rate of bleeding was 10.5% at 10 years, 23% at 20 years and 30.3% at 30 years. Cigarette smoking, size of the unruptured aneurysm and age were independent predictors of subsequent aneurysm rupture. Interestingly, 70% of aneurysms that later ruptured were ≤ to 6 mm in diameter63.

In addition, among patients with small asymptomatic aneurysms (<7 mm), hypertension, relatively young age (<50 y) and posterior circulation aneurysm were significant risk factors for aneurysm rupture64.

Similarly, symptomatic aneurysms (presenting with mass effect such as cranial nerve palsy) were associated with significantly higher rates of rupture (relative risks of 2.1)65.

The morphology of the unruptured aneurysm should be also taken in consideration, especially the presence of blebs. Presence of blebs in an aneurysm was found to carry a high risk of rupture (28.3 %/year)66 .

In conclusion, several studies have shown that the decision to treat asymptomatic unruptured aneurysms should not be based on the aneurysm size alone. Many studies have attempted to identify risk factors, in addition to the size, that predict aneurismal rupture. Family history of SAH and modifiable risk factors including hypertension, smoking have been suggested to increase risk of rupture67,68.  In addition, aneurysms in certain anatomical distributions (for example, terminal aneurysms such as basilar tip and ICA aneurysms) carries a greater risk of rupture58. Furthermore, presence of mass effect or aneurysm blebs carries a high risk of rupture.

Furthermore, aneurysms can grow in size and aneurysm growth is associated with a high risk of rupture. Increased growth rate of an unruptured aneurysm was found to be very significantly associated with later aneurysm rupture (0.95 versus 0.04 mm/y, p<0.0001) hence patients with aneurysm growth should be identified and followed up. In a study based on MRA follow up of unruptured aneurysms, 10.8% of unruptured aneurysms increased in size over a mean follow-up of 29 months. Aneurysm size of 5 mm or more, location on the MCA, multiplicity of aneurysms and family history of SAH were independent risk factor for aneurysm growth69. In another study, growth-related changes were significantly associated with also the size of the aneurysm and occurred in 2.4% of aneurysms measuring 2 to 4 mm, in 9.1% of lesions measuring 5 to 9 mm, and in 50% of lesions measuring 10 to 20 mm. These changes were more frequently found in aneurysms located at the BA bifurcation (40%) and the ICA (8.8%)70. Other trials found that cigarette smoking, hypertension and female sex to be significant independent risk factors for aneurysms growth of 1 mm or more while cigarette smoking was associated with growth of 3 mm or more67,71.

In our study, we could achieve total occlusion in 81.7% of the aneurysm while a neck remnant was left in 10%. Apart from those where a neck remnant was left or incomplete occlusion was done intentionally to preserve an important branch, our ability to achieve total aneurysm occlusion improved significantly with the availability of balloon and stent remodling techniques. We faced only 3 clinical complications (5%), and this is comparable to that published in other large case series19,21,23,24. We faced no procedural related mortality.

During long-term follow up (mean 31±20.4 months, minimum of 6 months and maximum of 72 months), we could achieve rates of persistent total occlusion similar to the large case series (i.e. 88%) while any degree of recanalization (i.e. neck remnant or major aneurysm recurrence) was observed in 11% of patients. The major factor related to aneurismal recanalization was the immediate angiographic results after coiling (i.e. total or near total and incomplete occlusion) rather than the aneurysm size. These results could be explained by the fact that the majority of our patients had small aneurysms. This emphasizes the importance of patient selection particularly in the era before the availability of the recent types of coils (i.e. the hydrocoils and biologically active coils) and the remodling techniques (i.e. flexible balloons and stents) that probably will improve the results of large aneurysm coiling. On the other hand, none of the treated aneurysms suffered from rebleeding.

In conclusion, endovascular treatment of intracranial aneurysms was initially devoted to nonsurgical patients, then was considered as an alternative option to surgical approach. However, remarkable progress over the past 15 years occurred in this technique and it has a low incidence of complications. Therefore, its accepted now that its not anymore an alternative option to surgical treatment but has rather gained the place as the first therapeutic option for ruptured and unruptured aneurysms less than 20 mm in diameter27.

 

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الملخـص العربى

 

غلق التمدد الشرياني بالمخ بإستخدام الملفات الحلزونية : خبرة قسم الأعصاب جامعة عين شمس.

 

          يعتبر نزيف ألام العنكبوتية بالمخ من أخطر أنواع الفالج فهو يؤدى الى الوفاة فى 45% من الحالات والى حدوث إعاقة دائمة فى 30% من الحالات. ويجب غلق التمدد الشرياني المسبب لهذا النزيف خلال فترة زمنية قصيرة (خلال 24-72 ساعة) حيث ان  إ حتمالات تكرار النزيف عالية. ويمكن غلق التمدد الشرياني عن طريق الجراحة او القسطرة المخية و التى أثبت أنها طريقة فعالة و أكثر امناً من الجراحة. ويتم غلق التمدد حين يكون مسبباً للنزيف (تمدد شرياني عرضى) او حتى لو لم يسبب نزيف (تمدد شرياني غير عرضى) اذا كان حجمة اكبر من 7مم بالدورة السباتية او اصغر من هذا بالدورة القاعدية. و يتم عمل كشف اكلنيكى كامل لهؤلاء المرضى مع عمل اشعة مقطعية على المخ كما ان بعض المرضى يحتاج الى عمل تحليل لسائل النخاع الشوكى. ثم يتم عمل قسطرة مخية لتشخيص وغلق التمدد. ويتم متابعة المريض اكلنيكياً مع عمل رنين على شرايين المخ.  وفى هذا البحث ننشر نتائج غلق أول 60 تمدد شريانى بالمخ. كان 57 مريضا (95%) يعانون من تمدد شرياني عرضى و 3 (5%) يعانون من تمدد شرياني غير عرضى. خمس وخمسون تمدد (91.7%) كانوا ذو حجم صغير (>10مم) و فقط 5 (8.3%) كانوا من 11-15 مم. ثلاث و ثلثون (55%) تمدد كانوا ذو رقبة ضيقة و 27 (45%) كانوا ذو رقبة واسعة. لقد نجحنا فى غلق 49 تمدد (81.6%) غلقاً تاماً و تم ترك جزء من الرقبة فى 6 (10%) حالات و تم غلق التمدد جزئيا فى حالتين (3.3%). كما اننا لم ننجح فى غلق  3 (5%) تمددات. تم استخدام البالون الساند فى 6 حالات (10%) والدعامة فى حالتين (3.3%). حدثت مضاعفات اثناء القسطرة لثلاث مرضى (5%). وفى أثناء المتابعة لمدة خمس سنوات (متوسط 31 شهر) لم يتكرر النزيف لأى من المرضى الذين تم علالجهم. كما اظهر الرنين المغناطيسى خلال تلك الفترة ان 37 تمدد (88%) ما زالوا مغلقين تماماً وان 3 تمددات (7.1%) بها جزء متبقى من الرقبة و لكنه مستقر ولا يحتاج الى تدخل وحدث ارتجاع للتمدد فى حالتين (4.7%). ولهذا فإن غلق التمدد الشرياني بالمخ باستخدام الملفات الحلزونية يمكن أن يكون بديلاً غير جراحى أكثر امناً من الجراحة  لعلاج هؤلاء المرضى.



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