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October2013 Vol.50 Issue:      4 Table of Contents
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Relationship between Common Carotid Artery Intima Media Thickness and Post-Stroke Cognitive Impairment

Sami El-Shazli, KaramSelim, Tarek Goda

Department of Neurology, Zagazig University; Egypt



ABSTRACT

Background: Common carotid artery intima-media thickness (CCA-IMT) has been associated with different cerebrovascular diseases, but its association with vascular cognitive impairment has not been clarified. Objective: The purpose of this study was to investigate whether CCA-IMT is associated with cognitive impairment 6 months after an acute ischemic stroke. Methods: A total of 50 patients (32 males, 18 females) with a mean age 46.48±12.46, prospectively collected from neurology critical care unit in Zagazig university hospitals, with the first ever ischemic stroke, underwent brain imaging and carotid ultrasonography during hospitalization. Patients’ cognitive performance was assessed using the Mini-Mental State Examination (MMSE) during hospitalization and six months later. Results: CCA-IMT was significantly associated with cognitive impairment. Older age, hypertension, were also independently associated with post-stroke cognitive impairment. Conclusion: CCA-IMT was independently associated with cognitive impairment 6 months after an acute ischemic stroke. It might help in screening of stroke patients at risk of cognitive impairment. [Egypt J Neurol Psychiat Neurosurg.  2013; 50(4): 431-435]

Key Words: carotid intima media thickness, stroke, cognitive impairment.

Correspondence to Tarek Gouda, Neurology Department, Zagazig University; Egypt Tel.: +201115606539    e-mail: t-gouda@hotmail.com.




INTRODUCTION

 

Common carotid artery intima media thickness (CCA-IMT) is a recently identified vascular risk factor and is considered an early marker of carotid atherosclerosis.1 CCA-IMT was weakly associated with cognitive performance in the general population, but this association has not been studied in stroke patients who had increased risk of cognitive impairment. Vascular risk factors and any kind of cerebrovascular disease are the only necessary conditions for cognitive impairment of vascular origin.2

 

Aim of the Work

Our aim is to study the relationship between common carotid artery intima media thickness and post stroke cognitive impairment six months after acute ischemic stroke.

 

PATIENTS AND METHODS

 

This study was done in neurology department, Zagazig university hospitals, during period from January 2012 to January 2013. It included 50 patients (32 males, 18 females).Their ages ranged from 24 to 75

 

with a mean age (46.48±12.46). Patients were prospectively collected from neurology critical care unit. Inclusion criteria were; patients with the first ever acute ischemic stroke and patients admitted to neurology critical care unit.

Exclusion criteria were; patients with concomitant Alzheimer’s disease, neurological diseases that potentially affect cognition (as Parkinson’s disease), patients with severe medical illness (as terminal cancer, hepatic or renal failure), patients with residual aphasia and those with recurrent strokes within six months post stroke to avoid confounding effects of multiple strokes3, and illiterate patients.

All patients were subjected to;(a)full history taking, stressing on vascular risk factors, (b)general and neurological examination,(c) laboratory assessment including ECG, complete blood count (CBC), liver and kidney function tests, lipid profile, chest x-ray and urine analysis, (d) brain imaging (at least one CT or MRI brain within three days of admission), (e) carotid ultrasonography during the first week of hospitalization. Measurement of intima media thickness was made on the wall of the common carotid artery, 1.5 cm proximal to the bifurcation, at a point free of plaques. Echogenic density of plaques was also recorded. Left and right common carotid arteries, bifurcation and internal carotid will be examined for the presence of plaques. Degree of carotid stenosis will be categorized in three groups (<40%, 40-70%, ≥ 70%), (f) assessment of cognition by Mini-Mental State Examination (MMSE) during hospitalization and 6 months post stroke. Scores below 24 will be considered to be indicative of cognitive impairment4, and (g) demographic data, past medical history and vascular risk factors were recorded on admission. Education level was coded, according to the educational system in Egypt as 1-6, 7-12 and more than 12 years of studying. Classification of the characteristics of the ischemic lesion, as regards size, location and side, was based on the clinical features of the presenting stroke and the brain imaging findings. The study was approved by the local ethics committee.

 

Statistical Analysis

Statistical analysis was done by statistical package of social sciences (SPSS), version 10.Relation between different variables was done by using qui square, correlation coefficient, and multivariatelogistic regression .Test is significant when P value is < 0.05.

 

RESULTS

 

Among our 50 patients, 28 patients were hypertensive. Half of hypertensive patients were cognitively impaired and 50% were cognitively normal. This difference was statistically significant (P=0.007) (Table 1).

Regarding age, 28 patients were below 60 years, 21.4% of them were cognitively impaired and 78.6% were cognitively normal. On the other hand, 22 patients were above 60 years, 50% of them were cognitively impaired and 50% were cognitively normal. This difference was statistically significant. (P=0.034) (Table 1)

Regarding CCA- IMT among our 50 patients, 26 patients had IMT <1mm,11.5% of them were cognitively impaired and 88.5 % were cognitively normal, whereas 24 patients had IMT>1mm, 41.7% of them were cognitively impaired and 58.3% were cognitively intact. This difference was also statistically significant (P=0.001) (Table 1).

No statistically significant difference between those who are cognitively impaired and cognitively normal as regard sex, diabetes mellitus, atrial fibrillation, hyperlipidemia, site and size of lesion and degree of carotid stenosis (Table 1).

               Intact cognitive function had CCA-IMT with mean of 1.06±519, while patients with cognitive impairment having CCA-IMT with mean of 1.21±37, so CCA IMT has statistically significant effect in development of cognitive impairment (Table 2).

Multiple logistic regression analysis was done between increased CCA-IMT, hypertension  and old age (>60 year) in order to define the most probable risk factor involved in development of cognitive impairment (Table 3).


 

Table 1. General characteristics of patients in relation to cognitive state.

 

P-value

Cognitively not impaired

Cognitively impaired

 

 

NS

0.034*

 

22(78.6%)

11(50%)

 

6(21.4%)

11(50%)

Age

< 60years(n=28)

>60years(n=22)

 

NS

NS

 

23(71.9%)

10(55.6%)

 

9(28.1%)

8(44.4%)

Sex

Males      (n=32

Females  (n=18)

0.007*

NS

NS

NS

 

14(50%)

9(50%)

19(73.1%)

10(62.4%)

 

14(50%)

9(50%)

7(26.9%)

6(37.6%)

Vascular risk factors:

Hypertension(n=28)

Diabetesmellitus(n=18) 

Hyperlipidemia(n=26)

Atrial fibrillation(n=16)

 

NS

NS

NS

NS

 

18(75%)

13(56.5%)

2(100%)

0(0%)

 

6(25%)

10(43.5%)

0(0%)

1(100%)

Site of lesion:

Cortical (n=24)

Subcortical(n=23)

Brainstem(n=2)

Cerebellar(n=1)

 

NS

NS

 

13(61.9%)

18(62.1%)

 

8(38.1%)

11(37.9%)

Side of lesion:

Right sided(n=21)

Left sided (n=29)

 

NS

NS

NS

 

2(33.3%)

6(75%)

1(33.3%)

 

4(66.7%)

2(25%)

2(66.7%)

Degree of stenosis:

<40%(n=6)

40-69%(n=8)

>70%(N=3)

NS non significant,

*Significant at p<0.05

 

Table 2. Correlation between common carotid IMT and cognitive impairment.

 

 

MMSE ≤24

MMSE >24

t

P

IMT (mm±SD)

1.21±0.37

1.06±0.519

1.057

0.001*

MMSE Mini-Mental State Examination, IMT intima media thickness

 

Table 3. Multivariate logistic regression analysis.

 

 

Odds Ratios  (95% CI)

P-value

Increased IMT (>1mm)

7.242 ( 1.580-33.201)

0.011

Old age (>60 year)

1.780  (0.396 -8.003)

0.452

Increased IMT (>1mm)

7.835  (1.739 -35.300)

0.007*

Hypertension

3.906  (0.825 -18.486)

0.086

IMT intima media thickness

 


Discussion

 

In our study, stroke patients who had increased CCA-IMT values were at higher risk to be cognitively impaired 6 months after their first ischemic stroke.

In a longitudinal population-based study, CCA-IMT was associated with cognitive impairment in the baseline evaluation of non-stroke patients5, but no association was found 4 years later.6On the contrary, retinopathy, as a marker of microvascular disease, was significantly associated with progressive cognitive decline in this population. Wong and colleagues7have also proposed cerebral atherosclerosis as the possible mediating mechanism to explain the association between retinopathy and progressive cognitive decline in non-stroke patients.

Auperin and colleagues8,studying a smaller cohort of non-stroke patients, reported that increased CCA-IMT was associated with compromised cognitive performance in a subgroup of male patients with carotid atherosclerotic plaques. However, prevalence of both cognitive impairment and increased CCA-IMT values in these populations were notably low, in contrast to our findings. However, the higher prevalence of CCA-IMT and cognitive decline found in our study is not surprising since we are dealing with a stroke population.

In our study older age ,hypertension and increased intima media thickness (> 1 mm) was independently associated with cognitive impairment, and this was in accordance with the findings of other works.9,10 Cognitive performance was not associated with the side of lesion, in contrast with reports which claim that the dominant hemisphere is more often affected in demented stroke patients.9,11Atrial fibrillation, diabetes mellitus and dyslipidemia and the degree of carotid stenosis was not associated with post stroke cognitive impairment and this was in agreement with Talleli and colleagues.12

Among our stroke patients, those with increased CCA-IMT values seem to be more vulnerable to post stroke cognitive impairment. This association was independent of the known confounding factors, as age and infarct site. Thickening of the wall of the small penetrating arteries and arterioles may cause narrowing of the lumen lead to hypoperfusion and consequently to ischemic injuries. This atherosclerotic process in the brain is probably the cause of diffuse white matter lesions (WMLs), which, together with ischemic lesions from an acute stroke, are responsible for declining cognition.

CCA-IMT is associated both with stroke13,14 and WMLs15,16 and thus has been qualified as a marker of cerebral atherosclerosis. Cerebral atherosclerosis may be more extended or severe in stroke patients with increased CCA-IMT values, a condition that could provide additional risk for post-stroke cognitive impairment. Furthermore, increased CCA-IMT values have been associated with the atherosclerotic process in other vascular regions.17

Measurements of CCA-IMT are relatively simple, safe, inexpensive, precise and reproducible.18 The identification of carotid plaques in the ultrasonography may present quantification problems of certain parameters, as length or texture, which may play an important role. The overall evidence so far suggests that separate evaluation of both plaques and CCA-IMT might provide better information to determine risk of vascular disease.17

 

Conclusion

In this study, CCA-IMT, measured soon after an acute ischemic stroke, was independently associated with cognitive impairment 6months later. Among stroke patients who are already at risk of cognitive impairment, those with increased CCA-IMT values seem to be even more vulnerable. Further studies with more detailed assessment of cognition could help to clarify whether CCA-IMT could be used as an additional tool for screening stroke patients at risk of cognitive impairment.

 

[Disclosure: Authors report no conflict of interest]

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6.        Knopman D, Boland LL, Mosley T, Howard G, Liao D, Szklo M. Cardiovascular risk factors and cognitive decline in middle-aged adults. Neurology. 2001; 56(1): 42-8.

7.        Wong TY, Klein R, Sharrett AR, Nieto FJ, Boland LL. Retinal microvascular abnormalities and cognitive impairment in middle-aged persons: the Atherosclerosis Risk in Communities Study. Stroke. 2002; 33(6): 1487-92.

8.        Auperin A, Berr C, Bonithon-Kopp C, Touboul PJ, Ruelland I, Ducimetiere P. Ultrasonographic assessment of carotid wall characteristics and cognitive functions in a community sample of 59- to 71-year-olds. The EVA Study Group. Stroke. 1996; 27(8): 1290-5.

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13.     Touboul PJ, Elbaz A, Koller C, Lucas C, Adrai V, Chedru F, et al. Common carotid artery intima-media thicknes and infarction: the Etude du ProfilGenetique de l’Infarctus Cerebral (GENIC) case control study. The GENIC Investigators. Circulation. 2000; 102(3): 313-8.

14.     Cupini LM, Pasqualetti P, Diomedi M, Vernieri F, Silvestrini M. Carotid artery intima-media thickness and lacunar versus nonlacunar infarcts. Stroke. 2002; 33(3): 689-94.

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الملخص العربى

 

العلاقة بين سمك الطبقة الداخلية والوسطى للشريان السباتي الرئيسي والتدهور الذهني

الذي يعقب الجلطة الدماغية

 

من المعروف أن سمك طبقات الشريان السباتي يرتبط بالعديد من الأمراض الوعائية الدماغية. وكان الغرض من هذه الدراسة هو دراسة العلاقة بين سمك طبقات الشريان السباتي والتدهور الذهني الذي يعقب الجلطة الدماغية. وقد أجريت الدراسة على خمسين مريضا (32 ذكور، 18 إناث) بعد ثبوت إصابتهم بالجلطة الدماغية، تم تجميعهم من العناية المركزة لقسم طب المخ والأعصاب بمستشفيات جامعة الزقازيق، في الفترة بين يناير 2012 إلى يناير 2013 وقد تراوحت أعمارهم بين 24-75 سنه. وقد تم إخضاع جميع المرضى للتصوير بالموجات فوق الصوتية للشريان السباتي الرئيسي أثناء تنويمهم بالمستشفى. وتم أيضا تقييم الحالة الذهنية باستخدام مقياس الحالة الذهنية المصغر أثناء تنويمهم بالمستشفى وبعد ستة شهور من حدوث الجلطة. وقد وجد أن زيادة سمك الطبقة الداخلية والوسطى للشريان السباتي الرئيسي وارتفاع ضغط الدم الشرياني وتقدم السن يرتبط بالتدهور الذهني الذي يعقب الجلطة الدماغية ارتباطا ذو دلاله احصائيه. قد استخلصت الدراسة أن زيادة سمك طبقات الشريان السباتي الرئيسي يمكن ان يستخدم في  التنبؤ بالمرضى الأكثر تعرضا للتدهور الذهني الذي يعقب الجلطة.

 

 



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