1. Surgical Decision Making for the Treatment of Intracranial Aneurysms

2. In cerebral aneurysm treatment outcome can still be improved and there are several strategies to do this, including :
(1) early diagnosis, that is, identification of aneurysms before they rupture (2) aneurysm repair, and in particular who should undergo aneurysm repair, timing of repair, and technique of aneurysm occlusion (3) intensive care

3. There are two important goals in the treatment of patients with intracranial aneurysms :
The first is complete, permanent occlusion of the aneurysm.
The second goal is optimal preservation or restoration of the patient’s neurological function.

4. The focus of the present chapter is on surgical decision making, highlighting the following aspects:
1. Natural history and treatment risk of unruptured aneurysms
2. Treatment of the ruptured aneurysm, including timing of surgery and management of the poor-grade patient or patients who present with intracerebral hemorrhage (ICH), intraventricular hemorrhage (IVH), or hydrocephalus
3. Appropriate use of endovascular or surgical techniques to occlude the aneurysm

5. DECISION MAKING The Status of the Patient and Aneurysm Natural History
Choosing the treatment modality that is safest and mostefficient for each individual patient is associated with a variety of factors such as:
whether the aneurysm is ,intact or ruptured, aneurysm size and location, the patient’s age and medical condition, and associated factors such as ICH, IVH,hydrocephalus and clinical grade after aneurysm rupture.

6. Neuroradiologic Evaluation
computed tomography (CT)
a variety of magnetic resonance imaging (MRI) sequences,
computed tomographic angiography (CTA),
magnetic resonance angiography (MRA),
cerebral angiography,
three-dimensional (3D) rotational angiography.

7. The following features need to be evaluated:
the aneurysm’s parent vessel;
(2) aneurysm size, shape, and relationship to parent and adjacent arteries;
(3) the presence and location of vasospasm;
(4) adjacent vessel displacement consistent with mass effect;
(5) the presence of other aneurysms or vascular abnormalities.

8. THE UNRUPTURED ANEURYSM
The frequency of discovery appears to be increasing, perhaps related to increased availability of highresolution MRI
The prevalence of unruptured intracranial aneurysms (UIAs) has been estimated to range from 1% to as high as 9%
it is estimated that 1 in 200 to 400 will rupture

11. Efficacy of Surgical Treatment for Unruptured Intracranial Aneurysms
There are few studies that document the success rate of UIA surgery
even when a surgeon believes the operative result is satisfactory, vessel occlusion or aneurysm remnants may be found on 5% of postoperative angiograms
more than 90% of aneurysms undergoing surgical clip occlusion are completely obliterated at surgery
the annual risk of stroke was 1.06%, which is greater than that in the general population
4% of patients were disabled and 1% died

12. Factors That Are Associated with Surgical Outcome
Increased aneurysm size is the most important factor associated with surgical complications and poor outcome
aneurysm size greater than 25 mm has a fourfold increased risk compared with a 5-mm aneurysm
clip occlusion was achieved in 85% of lesions greater than 10 mm and 93% of lesions less than 10 mm. However, less than 60% of giant aneurysms could be occluded by a clip
Aneurysm location is another risk factor for poor outcome.
Repair of unruptured posterior circulation aneurysms is associated with increased surgical risk

14. after aneurysm size and location, patient age is the next most important risk factor of poor outcome
Other factors:
aneurysm orientation, wide aneurysm neck, atherosclerosis, calcification in the aneurysm neck, ischemic cerebrovascular disease, and medical conditions such as diabetes mellitus

15. Which Patient with an Unruptured Intracranial Aneurysm Should Be Treated?

20. following patients with UIAs should be treated: those with
SAH from another aneurysm
(2) symptomatic aneurysm
(3) aneurysms of more than 7 to 10 mm in nearly all patients with a life expectancy of 12 or more years
(4) aneurysms of more than 5 mm if the patient is young or middle-aged

21. Small, incidental UIAs (<5 mm in diameter) should be managed conservatively in most cases;
the exception is when there is a positive family history.
In addition, patients who smoke and are hypertensive may be considered for treatment when the aneurysm is small.
When aneurysm occlusion is not recommended, patients should be counseled about risk factors and serial imaging (CTA or MRA) should be used (every 6 months) to follow the aneurysm
an increase in size or a morphology change appears to represent an indication for treatment
a 1-mm change in diameter represents a doubling of the aneurysm volume

22. THE RUPTURED ANEURYSM
The age-adjusted annual incidence of SAH varies in different countries and is between 2.0 and 22.5 cases per 100,000 population
Epidemiologic studies demonstrate that 60% of these patients die or are severely disabled.

23. Aneurysm Rebleeding 70 to 90 % of patients who rebleed die.
rebleeding is the most treatable cause to avoid poor outcomes
Untreated, between 20% and 30% of aneurysms rerupture within the first 30 days and then at a rate of approximately 3% to 5% per year.
The risk of rebleeding is greatest on day 1 and perhaps in the first 6 hours after SAH
Rates between 4% and 15% are described for the first 24 hours.

24. A variety of factors are associated with increased risk of rebleeding, including:
premorbid hypertension,
poor clinical grade,
increased admission blood pressure,
abnormal hemostatic parameters,
ICH or IVH,
greater radiographic severity of SAH,
larger aneurysm size (>10 mm),
posterior circulation aneurysms.

25. Some studies suggest that ventricular drainage may be associated with rebleeding;
however, when preoperative ventriculostomy is followed by early treatment of the ruptured aneurysm, the rebleeding risk is not increased by the ventriculostomy
it seems reasonable to keep systolic blood pressure less than 160 mm Hg using short-acting titratable agents until the aneurysm is occluded.
Aneurysm rebleeding may be reduced by antifibrinolytic administration

26. Timing of Aneurysm Obliteration
Early surgery eradicates the risk of rebleeding and appears to be associated with improved outcome.
70.9% of patients undergoing surgery between 0 and 3 days after aneurysm rupture experienced a good recovery,
62.9% of patients enjoyed a similar outcome if surgery was performed after 14 days.
Outcome was worse among patients who had surgery between days 4 and 10.
patients who present 4 days after SAH should have surgery delayed until 2 weeks.

27. The Poor-Grade Patient
Between 20% and 40% of patients admitted to a hospital after SAH are in poor clinical condition (Hunt and Hess grades IV and V).
favorable outcomes (i.e., independence) may be observed in 50% to 60% of poor-grade patients.
up to 15% of the patients die before reaching the hospital and 30% die within the first 48 hours of aneurysm rupture.
Some poor-grade patients may benefit from a decompressive craniectomy.
“Routine” EVD use in grade IV and V patients is advocated.

31. Intracerebral Hemorrhage
ICH increases mortality after SAH
Infusion CT scan, or CTA obtained immediately after the head CT scan, is useful in unstable patients
During surgery for aneurysmal ICH, large bone flaps are preferable to prevent brain herniation and strangulation, and provide easy access to the hemorrhage
During closure, lobectomy, ventriculostomy, or dural augmentation without bone replacement may be necessary if cerebral swelling persists

32. Acute Intraventricular Hemorrhage and Hydrocephalus
Acute hydrocephalus and IVH often are observed after aneurysm rupture, particularly in poor-grade patients and those with thick subarachnoid blood on CT.
increased ICP also is seen in as many as 50% of good-grade patients.
Chronic or delayed hydrocephalus is observed in about 25% to 30% of those patients who survive aneurysm rupture.
Half the patients with acute hydrocephalus require a ventriculoperitoneal shunt.

33. Factors associated with hydrocephalus:
older age,
increased ventricular size, and IVH at admission,
poor clinical grade,
hypertension,
alcoholism,
female sex,
increased aneurysm size,
ruptured anterior communicating artery aneurysm,
pneumonia,
Meningitis.

34. The rate of shunt dependency is associated with:
a worse clinical grade,
a higher Fisher CT grade,
IVH or ICH,
Repeat SAH,
anterior communicating artery aneurysms,
Increased third ventricular diameter at the time of EVD removal,
Perioperative ventriculostomy,
failures of the EVD,
Hemicraniectomy.

35. The need for a permanent shunt can be reduced by:
use of an EVD, including long tunneled catheters,
serial lumbar punctures,
lamina terminalis fenestration at craniotomy.

36. Ruptured Aneurysms and Early Vasospasm
Vasospasm is associated with poor outcome.
between 10% and 15% of patients will have angiographic evidence of vasospasm within 48 hours of aneurysm rupture.
Aneurysm obliteration can followed by immediate angioplasty for patients with symptomatic vasospasm

37. Surgical Complications After Open Microsurgery for Ruptured Aneurysms
Surgical complications, such as intraoperative aneurysm rupture, major vessel occlusions, cerebral contusion, or ICH, are associated with about 10% of the long-term morbidity and mortality after SAH.
several series suggest that surgical complications after SAH are primarily associated with aneurysm location,size, and morphology.
large or giant aneurysms, aneurysms with atherosclerotic necks, or aneurysms located at the basilar bifurcation or anterior communicating artery are more frequently associated with surgical complications.

38. Which Aneurysm Can Be Successfully Occluded Using Endosaccular Techniques?
Coil embolization is the most frequent endovascular technique.
in the Analysis of Treatment by Endovascular Approach 98% of aneurysms were treated with coils.
morphologic results are good in small aneurysms with small necks

41. microsurgery still remains a preferable primary therapy for some aneurysms located on:
superior cerebellar artery,
P1 segment of the posterior cerebral artery,
distal anteroinferior cerebellar artery,
Posteroinferior cerebellar artery
MCA