Intracranial aneurysms: occur in around 3% of the population* The number of incidentally discovered aneurysms is increasing Owing to the rising availability of brain imaging Rupture of intracranial aneurysms results in aneurysmal subarachnoid haemorrhage (a subset of stroke), that has high case fatality and morbidity, and occurs at a relatively young age compared with other types of stroke. The decision whether to treat in patients with unruptured aneurysms, is often not straightforward. Preventive treatment (Clipping or Coiling) of intracranial aneurysms carries a risk of treatment-related fatality and morbidity of up to 5%. Neurosurgical treatment has a higher risk of complications as compared to endovascular treatment. whereas, The risk of rupture after endovascular treatment is slightly higher as compared to surgery, with annual rupture rates of 0·2%. (according to a large systematic review) Therefore, The risks of treatment have to be balanced carefully against the risk of rupture. However, prediction of the risk of rupture is difficult. Although, many prognostic factors for aneurysm rupture have been proposed, for example : Age, Sex, Hypertension, Cigarette smoking, History of subarachnoid haemorrhage, Aneurysm size, Aneurysm site, Number of aneurysms. However, Estimation of absolute risk of aneurysm rupture in a patient based on combination of risk factors is complex and a clinical risk score for aneurysm rupture was not exist at that period of time (2013). Therefore, this study was conducted to establish predictors of aneurysm rupture in patients with unruptured intracranial aneurysms.

1. Presenter: Dr. Shahanur Rahman

2. Development of the PHASES score
for prediction of risk of
rupture of intracranial aneurysms:
a pooled analysis of six prospective cohort studies
Lancet Neurol 2014; 13: 59–66
Published Online: November 27, 2013

4. Introduction
Intracranial aneurysms:
• occur in around 3% of the population*
The number of incidentally discovered aneurysms
is increasing
Owing to the rising availability of brain imaging
* Vlak MH, Algra A, Brandenburg R, Rinkel GJ. Prevalence of unruptured
intracranial aneurysms, with emphasis on sex, age, comorbidity, country, and time
period: a systematic review and meta-analysis. Lancet Neurol 2011; 10: 626–36.

5. Rupture of intracranial aneurysms
• results in aneurysmal subarachnoid
haemorrhage (a subset of stroke),
• that has high case fatality and morbidity, and
• occurs at a relatively young age compared
with other types of stroke.

6. • The decision whether to treat in patients with
unruptured aneurysms,
is often not straightforward.
• Preventive treatment (Clipping or Coiling) of
intracranial aneurysms carries a risk of
treatment-related fatality and
morbidity of up to 5%.

7. • Neurosurgical treatment has a higher risk of
complications as compared to endovascular
treatment.
whereas,
• The risk of rupture after endovascular
treatment is slightly higher as compared to
surgery, with annual rupture rates of 0·2%.
(according to a large systematic review)

8. Therefore,
• The risks of treatment have to be balanced
carefully against the risk of rupture.
However,
• prediction of the risk of rupture is difficult.

9. • Although, many prognostic factors for aneurysm
rupture have been proposed, for example :
Age,
Sex,
Hypertension,
Cigarette smoking,
History of subarachnoid haemorrhage,
Aneurysm size,
Aneurysm site,
Number of aneurysms.

10. • However, Estimation of absolute risk of
aneurysm rupture in a patient based on
combination of risk factors is complex and a
clinical risk score for aneurysm rupture was
not exist at that period of time (2013).
• Therefore, this study was conducted to
establish predictors of aneurysm rupture in
patients with unruptured intracranial
aneurysms.

11. AIM
• The aim of this study was
to establish predictors of aneurysm rupture in
patients with unruptured intracranial
aneurysms and
to provide a risk prediction chart that allows
physicians to easily determine the 5-year risk
of aneurysm rupture (on the basis of a set of
routinely assessed patient and aneurysm
characteristics).

12. Methods
They did a systematic review and pooled
analysis of individual patient data
from 8382 participants
in six prospective cohort studies
with subarachnoid haemorrhage as outcome.

13. They classified the location of the aneurysm as the
• internal carotid artery,
• middle cerebral artery,
• anterior cerebral arteries (including
 the anterior cerebral artery,
 anterior communicating artery, and
 pericallosal artery),
• posterior communicating artery,
• posterior circulation (including
 the vertebral artery,
 basilar artery,
 Cerebellar arteries, and
 posterior cerebral artery).

14. • When a patient had multiple aneurysms
(while analysing rupture risk per patient),
the largest of these aneurysms
were included in the study.

15. • In the study model they found that the largest amount
of prognostic information was contained in six
predictors:
1. Age,
2. History of hypertension,
3. history of subarachnoid haemorrhage,
4. aneurysm size,
5. aneurysm location, and
6. geographical region (which were included as
independent predictors of aneurysm rupture).
Although,
• Sex, smoking, and presence of multiple aneurysms
were excluded from the model, because of their
limited predictive value (p>0·20).

16. • A risk prediction chart was generated on the
basis of the combination of risk factor levels
and the corresponding risk of 5-year
aneurysm rupture.
• All subgroups with an estimated 5-year risk
greater than 15% were categorised as very
high risk (>15%)

17. • Finally, A simple risk score, PHASES,
o P- Population location
o H- Hypertention
o A- Age of patient
o S- Size of aneurysm
o E- Earlier SAH
o S- Site of aneurysm
• is presented in a table,
• which can be used in combination with a graph to
obtain approximate predictions of aneurysm
rupture for individual patients.

18. To calculate the PHASES risk
score for an individual, the
number of points associated
with each indicator can be
added up to obtain the total
risk score.
For example, a 55-year-old
North American man with h/o
hypertension, previous SAH,
and a medium-sized (8 mm)
posterior circulation aneurysm
will have a risk score of
0+0+1+1+3+4=9 points.

19. The number in each cell refers to the predicted risk (%)
for aneurysm rupture within the next 5 years.

20. The number in each cell refers to the predicted risk (%)
for aneurysm rupture within the next 5 years.

21. In the first risk charts:
• The study populations from North America and
European countries (other than Finland),
 the predicted 5-year absolute risk of aneurysm rupture
ranged from 0·25%
 in individuals younger than 70 years
 without vascular risk factors and
 with a small sized (<7 mm) internal carotid artery
aneurysm
 to more than 15%
 in individuals aged 70 years or older
 with hypertension,
 a history of subarachnoid haemorrhage, and
 a posterior circulation aneurysm of giant size (>20 mm).

22. • By comparison with populations from North
America and European countries (other than
Finland),
Japanese people a 2·8-times increased risk,
and
Finnish people had a 3·6-times increased risk
of aneurysm rupture.
• The mean observed 1-year risk of aneurysm
rupture was 1·4% and the 5-year risk was
3·4%.

23. Finally, They made a Predicted
Probability graph plotting 5 yrs
Risk of rupture against PHASES
risk score, from which we can
calculate the 5-year risk of
rupture would be 4.3% for the
previous mentioned patient
who had PHASES score 9.

24. Interpretation of Chart/Graph
5yr cumulative rupture risk:
≤ 2 points: 0.4%
3 points: 0.7%
4 points: 0.9%
5 points: 1.3%
6 points: 1.7%
7 points: 2.4%
8 points: 3.2%
9 points: 4.3%
10 points: 5.3%
11 points: 7.2%
≥ 12 points: 17.8%

25. Although, this study has some limitations.
However, important strength of this study are:
• First, The large number of patients with an
unruptured intracranial aneurysm from which
the model was derived.
• Second, the natural history of the studies took
place in several different countries, improving
external validity.
• Third, all included studies were prospective
cohort studies with careful follow-up.

26. • Fourth, the predictors in their model are well
defined, easily measured clinical variables.
• Fifth, patients with previous subarachnoid
haemorrhage from another aneurysm and
patients with incidentally found aneurysms
both were included.
• Therefore, the risk chart seems to have broad
applicability in prediction of aneurysm rupture
in various populations.

27. Limitations of this study:
• First, in patients with multiple aneurysms
they used only the characteristics of the
largest unruptured aneurysm in the analysis.
• Second, some values were missing in their
database and to predict missing values
Regression imputation method was used.
• Third, although this model has been validated
internally, it has not yet been validated
externally in another population.

28. • Fourth, different imaging modalities were used
to assess the initial aneurysm characteristics and
different methods of measuring aneurysm size
were used across studies.
• Fifth, instances of subarachnoid haemorrhage
might have been missed or the aneurysm listed
as the cause of the haemorrhage might have
been incorrect and the overall risk of rupture
might be higher if haemorrhages have been
missed.
• Sixth, a potential for selection bias exists in this
study. These types of selection bias definitely
affected the calculation of the risk of rupture.

29. CONCLUSION
• This PHASES risk score and Prediction chart is
based on easily available predictors, which
could support Neurosurgeons in their
 assessment of the risk of rupture of aneurysm
and
 serve as a valuable aid in determining the
clinical decision to whether a patient needs a
preventive measure (clipping / coiling) or not.

31. PHASES Score for the Management of
Intracranial Aneurysm (2017)

32. • Results:
• PHASES scores of immediately treated UIA patients were
significantly higher than follow-up UIA group (5 versus 2).
• Patients diagnosed with UIA and PHASES score of >3 were
more likely to be treated, and
• The score ≤3 was predictive for observation.
• Odds of being diagnosed with an aSAH were associated
with PHASES score of >3 (UIA, 4 vs aSAH, 5).
• Scores of stable UIA patients were significantly lower than
high risk of rupture group (2 versus 5).
• Stable UIA outcome prediction by PHASES score was ≤3.
• Conclusion: PHASES score of ≤3 is associated with a low
but not negligible likelihood of aneurysm rupture.

33. INDIA
2003:
• The incidence of intracranial arterial aneurysms from
various parts of India varies from 0.75 to 10.3%.*
• North-west Indian population in the present study had
an incidence of 1%.*
• Due to the wide variations in published reports, it is
not possible to conclusively support the observations
that Asian and African countries have a lower incidence
of aneurysms as compared to their European
counterparts.*
 *Kapoor K, Kak V K. Incidence of intracranial aneurysms in northwest
Indian population. Neurol India 2003;51:22-6

34. INDIA
2015
• The annual incidence of aneurysmal SAH
between 6 to 16/100,000 population,*
• About 76,500-204,100 new cases occur in India
each year.*
 Ambekar S. Need for brain aneurysm treatment registry of India: How
effectively are we treating intracranial aneurysms in India?. Neurol India
2015;63:290