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 Table of Contents  
ORIGINAL ARTICLE
Year : 2020  |  Volume : 1  |  Issue : 2  |  Page : 97-102

B-mode ultrasonographic findings of carotid artery in stroke


1 Department of Radiology, Jos University Teaching Hospital, Jos, Nigeria
2 Department of Radiology, Federal Medical Center, Keffi, Nigeria

Date of Submission21-Jun-2020
Date of Decision13-Jul-2020
Date of Acceptance17-Oct-2020
Date of Web Publication30-Nov-2020

Correspondence Address:
Anthony Epga Gabkwet
Department of Radiology, Jos University Teaching Hospital, Jos
Nigeria
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/JRMT.JRMT_17_20

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  Abstract 


Background: Stroke is a major medical disorder caused by an abrupt interruption of blood supply to the brain resulting in loss of neurological function. B-mode ultrasonography is a readily available test that is employed to visualize the extracranial carotid arteries implicated as a major source of emboli to cerebral arteries. Aim and Objective: We aimed to evaluate the pattern of carotid artery disease using B-mode ultrasonography in adults with computed tomography scan-confirmed stroke in Jos University Teaching Hospital. Materials and Methods: This is a cross-sectional study conducted at the Radiology Department of Jos University Teaching Hospital. The study population was made up of 120 consenting stroke patients where a structured questionnaire was used to obtain relevant information. A GE Medical System Logiq 5 Expert with 10 MHz linear probe was used to examine the extracranial carotid arteries from their origin to the angle of the mandible. Results: One hundred and twenty patients were recruited comprising 63 males (52.5%) and 57 females (47.5%). Three-fifth of the patients 72 (60.0%) had intima–media thickness of >0.9 mm seen in the right common and internal carotid arteries in 56 (46.7%) and 65 (54.2) patients, respectively, and left common and internal carotid arteries in 69 (57.5%) and 66 (55.0%) patients, respectively. Plaques were seen in 58 (48.0%) patients. Eleven (19%) had smooth-surfaced plaques while 33 (57.0%) had irregular/ulcerated surfaced plaques which were unilateral in 21 (36.0%) and bilateral in 12 (21.0%) patients. Mixed (smooth and irregular/ulcerated) and bilateral were seen in 14 (24.0%) patients. Conclusion: Carotid artery diseases are a significant finding in stroke patients. These findings showed the importance of B-mode ultrasonographic examination of the extracranial carotid arteries as key in predicting patients at risk of stroke development.

Keywords: B-mode ultrasonography, intima–media thickness, plaques, stroke


How to cite this article:
Gabkwet AE, Gwom PM, Igoh EO, Taiwo Y, Salaam A, Danjem S. B-mode ultrasonographic findings of carotid artery in stroke. J Radiat Med Trop 2020;1:97-102

How to cite this URL:
Gabkwet AE, Gwom PM, Igoh EO, Taiwo Y, Salaam A, Danjem S. B-mode ultrasonographic findings of carotid artery in stroke. J Radiat Med Trop [serial online] 2020 [cited 2021 Aug 4];1:97-102. Available from: http://www.jrmt.org/text.asp?2020/1/2/97/301895




  Introduction Top


Stroke is an injury to the central nervous system that is characteristically abrupt in onset and is due to a vascular insult.[1] The term is reflective of damage to the brain secondary to ischemia or hemorrhage.[2] Pathological studies indicate that 80%–85% of strokes are due to cerebral infarction, and atherosclerotic disease of the carotid arteries outside the cranial cavity has long been recognized as the most common source of emboli that travel to the brain causing stroke.[2],[3] High-degree internal carotid artery (ICA) stenosis is the most well-known risk factor for the development of cerebrovascular events.[2]

In Nigeria, stroke accounts for 0.9%–4% of all hospital admissions and 2.8%–4.5% of total deaths.[4],[5],[6] Studies among Nigerians and other populations in developed countries have shown hypertension as the most dominant predisposing factor for stroke.[7],[8],[9],[10] A recent study in Nigeria revealed hypertension as a risk factor in 82.5% of stroke patients which is strongly related to both systolic and diastolic blood pressure.[9],[11] The incidence of stroke in Africa is on the increase.[4],[12] Five decades ago, this disease was thought to be rare among use Sub-saharan Africans, but recent findings showed strong evidence of an emerging epidemic of stroke in developing countries probably due to social and economic restructuring over the last few decades.

Ultrasound imaging plays an important role in early detection of carotid atherosclerotic disease, and the technique allows for determination of the severity of carotid stenosis by evaluating the extent of atherosclerotic changes and echo patterns within the vessel.[2] The use of this test allows for a wide range of measurements of parameters on the extracranial carotid arteries which include intima–media thickness (IMT), presence of plaques and morphology, arterial diameter, and blood flow velocity.

According to the Guidelines for Noninvasive Vascular Laboratory Testing by the American Society of Echocardiography, Vascular Medicine, and Biology, the goal of noninvasive ultrasound testing for carotid disease is to distinguish normal from diseased vessels, to classify a wide range of disease states, to assess the cerebral collateral circulation, and to do so safely and cost-effectively.[1],[13] The primary aim is to identify patients who are at risk for stroke and who may require specific treatment. A secondary aim is to document patients with progressive or recurrent disease and is known to be at risk.

B-mode ultrasound scan in combination with Doppler flow velocity is the main tool used for evaluating the severity of carotid artery diseases and its availability and accessibility makes it the first-line imaging modality.

This study aims to establish the relationship between diseases of carotid arteries with the development of stroke in our environment.


  Materials and Methods Top


General Electric Medical System Logiq 5 Expert machine with a 10 MHz linear probe was used to examine the extracranial carotid arteries of the patients from their origin in the chest and neck to the angle of the mandible.[11],[14]

Transverse and longitudinal scan of the common carotid artery (CCA) from their origin to as high as the two major branches behind the angle of the mandible using B-mode grayscale was carried out after properly positioning and exposure of the neck.[1],[15] The walls of the arteries were then examined, and the IMT is measured as the distance between two echogenic lines with echo-lucency between them and values >0.9 mm are termed abnormal. Other abnormalities (e.g., plaques) were then measured in three dimensions and recorded. In this study, the plaque surface was grouped into smooth and irregular/ulcerated surfaced.

The degree of stenosis was assessed using the North American Symptomatic Carotid Endarterectomy Trial (NASCET) criteria for calculating the degree of stenosis (% stenosis = y − x/y × 100), where y = Distal normal caliber and x = Diameter of narrowest point.

Study population

The study population comprised both male and female adult stroke patients confirmed using brain computed tomography (CT) scan who are aged 18 years and above at the Jos University Teaching Hospital.

Sample size estimation

Using the formula: N = Z2P (I − P)/d2

where

N = The desired sample size

Z = The standard normal deviation usually set at 1.96 which corresponds to 95% confidence level

P = The proportion in the target population estimated to have a particular characteristic

The proportion of stroke in Nigeria is estimated to be <4% (i.e., 0.04)[3]

d = Degree of accuracy desired, set at 0.05

N

= Z2P (1 − p)/d2

= (1.96)2 (0.04) (1.0 − 0.04)/(0.05)2

= 3.8416 × 0.04 × 0.96/0.0025

= 0.14751744/0.0025

= 59

The sample size was increased to 120 to increase the sensitivity of the study.

Sampling technique

Eligible participants were recruited consecutively after a brain CT scan-confirmed stroke until the sample size of 120 was reached.

Data collection

The procedure was explained to all participants or their relations, and written consent was obtained from each of them before carrying out the procedure.

A structured questionnaire was used to obtain relevant data such as age, sex, weight, height, and family history of high blood pressure or diabetes, etc.

Inclusion criteria

  1. Patients diagnosed with stroke using brain CT and who consented by signing the consent form themselves or by relations before clinical and ultrasound evaluation
  2. Both genders aged 18 and above who were diagnosed with stroke.


Exclusion criteria

  1. Patients who did not give consent.


Ethical consideration

Approval was obtained from the Research and Ethical Committee of Jos University Teaching Hospital.

Statistical analysis

The data obtained from the structured questionnaire were imputed into a computer to generate a computerized database for subsequent analysis and processing using Epi Info version 3.5.1 CDC Atlanta, USA, 2008.

Statistical parameters such as Chi-square were used to compare differences in nominal variables and P value (0.05 or less was considered statistically significant). The results were then presented in the form of tables and charts as appropriate.


  Results Top


A total of 120 participants who met the inclusion criteria and consented to the study were recruited.

There were 63 males (52.5%) and 57 females (47.5%), with an age range of 31–95 years. The mean ages for male and female participants were 56.2 ± 12.3 and 55.3 ± 14.4, respectively.

One hundred and one (84.2%) patients were hypertensive, 29 (24.2%) were diabetic, 32 (26.7%) take alcohol, 11 (9.2%) smoke cigarette, 26 (21.7%) had a family history of stroke, 64 (53.3%) had a family history of hypertension, and 34 (28.3%) had a family history of diabetes. No significant statistical association was found between risk factors and gender of the patients except cigarette smoking with P = 0.007 [Table 1].
Table 1: Relationship between risk factors and sex of participants

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Hypertension was the most common risk factor in the study, and the age group 60–69 years accounts for the highest percentage of 35.6%.

In general, 48 (40%) patients had normal IMT while 72 (60%) had abnormal IMT.

Among the patients with abnormal IMT, 56 (46.7%) and 69 (57.5%) had abnormal IMT on the right CCA and left CCA, respectively, while 65 (54.2%) and 66 (55.0%) had abnormal IMT on the right ICA and left ICA, respectively [Table 2]a and [Table 2]b.


Click here to view


Varying sizes of brain infarcts were noted among the patients with abnormal IMT. Large-sized brain infarcts (>3 cm) were seen in 46 (63.9%), 22 (30.6%) with medium-sized infarcts (1.5–3 cm), and 4 (5.6%) with small-sized infarcts (<1.5 cm).

Sixty-two (52%) patients recruited had no plaque while 58 (48%) had plaques on the carotid artery. 11(19%) demonstrating smooth surfaced plaques,33(57%) patients had irregular/ulcerated surfaced plaques and 14(24%) had both smooth and irregular/ulcerated plaques [Table 3] [Table 3].
Table 3: Relationship of plaque surface and frequency at side of location

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Atherosclerotic plaques were seen in all age groups. However, the prevalence increases progressively with increase in age and peaks at 50–69 years (69.8%), with a significant statistical association (P = 0.004) noted [Table 4].
Table 4: Relationship of plaque location with age distribution

Click here to view


The degree of percentage stenosis was compared with the size of brain infarcts, and the majority of the patients with carotid artery stenosis had large-sized brain infarcts.

No patient had stenosis >70%, near occlusion, or total occlusion [Table 5].
Table 5: Relationship between percentage stenosis and size of infarct

Click here to view



  Discussion Top


A significant percentage of all acute strokes are caused by cerebral ischemia, usually resulting from thrombotic or embolic occlusion of a cerebral artery, and the remaining 20% are caused by intracerebral or subarachnoid hemorrhage.[4],[17],[18] B-mode ultrasonography plays a critical role in early detection of carotid atherosclerotic disease. Its high specificity makes it very helpful for ruling out vascular abnormalities that could increase the risk of developing a stroke. Characterization of atheromatous plaque and estimation of carotid stenosis using high-resolution ultrasound has been termed the biggest advantage of this modality.[19]

This study observed that the prevalence of stroke increases with age and peaks at about the seventh decade (32.5%) with a sudden decline afterward. The sudden decline after the seventh decade could be explained by the relatively smaller number of participants seen within that age group. This finding is comparable with that reported by Desolu and Wahabwho documented a prevalence of 33.7% in patients between 60 and 69 years in a 2011 study in Southwestern Nigeria.[20] This is also consistent with findings in previous studies that have identified increasing age as a strong risk factor for stroke, even though stroke occurs 10–15 years earlier in patients in sub-Saharan Africa compared with patients in developed countries.[8],[17] The age of occurrence is even younger for hemorrhagic stroke compared with ischemic stroke.[21] This could be as a result of the history of long-standing and uncontrolled hypertension that is becoming common among young adults who usually are not aware that they are hypertensive.[22]

Several risk factors for stroke were observed in this study, however, hypertension was the most important risk factor regardless of age and sex. Hypertension is the most significant risk factor for stroke worldwide and remains a consistent and powerful predictor for stroke.[23]

It is a factor in nearly 70% of strokes for people of all ages and gender. Most patients in this study were known hypertensive on treatment, but compliance with treatment was doubtful in some cases.

The prevalence of hypertension in our study was found to be 84.2%, and this is similar to findings recorded in studies in different parts of Nigerian[3],[20],[24],[25] and other parts of the world. Desolu and Wahab reported a prevalence of 82.5% in Southwestern Nigeria while Chukwuemeka and Christianreported a prevalence of 87% in Southeastern Nigeria.[20],[24] Ignorance of common risk factors and noncompliance with therapy could be the reason for the high incidence of hypertension in stroke. On the other hand, a lower prevalence of 45.1% and 32.2% was reported in Baghdad and Jordan, respectively.[2],[26]

IMT is considered as a surrogate marker for atherosclerotic disease not only in the cerebrovascular system but in the whole arterial system. It is the only sonographic parameter recommended by the American Heart Association to be used routinely when screening for cardiovascular risk.[1],[16]

In this study, abnormal IMT occurs in both CCA and ICA, with an abnormal value ranging from 47% to 69% for both carotid arteries. Okeahialam et al. in Jos North Central Nigeria describe abnormal IMT as a robust indicator of vascular risk which has shown a positive association with some emerging cardiovascular diseases.[27] It has also been shown that abnormal IMT is a power predictor of cerebrovascular and coronary complications.[28] This finding is very important for health policymakers in advancing the need for regular carotid artery evaluation in adults to determine patients who are at higher risk of developing more serious carotid pathologies that could predisposed to strike. This is comparable with the findings of Laith and Firas and Touboul and Elbazwho reported that there was a significantly higher incidence of stroke in patients with increased IMT.[2],[25]

A significant relationship between abnormal IMT with increasing age and the size of brain infarct was also observed in this study. A similar finding was documented by Laith and Firasin Baghdad where a significant association between increased IMT and stroke development was established.[2]

The presence of plaques on the carotid artery wall was the second most common abnormality noted in this study. Fifty-eight (48%) of the patients recruited had plaques which are similar with studies by Malik and Tiwari who recorded 43.7% and Sanjeev and Sarabjit who documented 41% and 37% of elder males and females, respectively. Most (54%) of the plaques were sighted on the right side similar to the findings of Sanjeev and Sarabjit who recorded 60% of plaques sighted on the right.[16],[29] This finding is, however, at variant with that recorded by Bhimeshwer and Rama and Rajesh and Priyanka who documented left carotid artery accounting for most of the plaques.[30],[31]

Half of the plaques recorded 33 (57%) have irregular/ulcerated surfaced. These findings agree with that reported by Laith and Firas in Bagdad who documented 40% and 60% for smooth and irregular/ulcerated surfaced plaques, respectively, and Malik and Tiwari in India who recorded irregular surfaced and ulcerated plaques together accounting for 53% of plaques.[2],[16]

Regarding the atheromatous plaque morphology, this study found that patients with either smooth or irregular/ulcerated surfaced plaques have large-sized infarcts, however, a higher percentage sized brain infarcts were seen in patients with irregular/ulcerated plaques which supports the suggestion that the more friable and soft plaques are, the more likely that they break off and propagates to produce symptoms more than with the firmer more fibrous and coherent plaques. Carra et al. and Malik and Tiwari reported similar findings where intraplaque hemorrhage and ulceration are considered unstable and these could progress, modified their echographic pattern from homogeneous to nonhomogeneous (78% of cases) leading to new neurological events.[16],[32] Our findings showed that progressive carotid artery plaques rise with increase in age and peak at 60–69 years with a sudden decline afterward. This finding is similar to that of Fabris et al. in Turin Italy who documented that most plaques are seen in the 45–64 years' age group.[33]

The majority of the participants in this study 62 (52%) had no stenosis while the remaining had different degrees of stenosis. This is a variant with that recorded by Noor ul and Rukhsana in Pakistan, with 56% of the patients having carotid stenosis of varying degrees.[34]

Each category above has its recommended therapeutic approach. For stenosis of <50%, medical therapy is recommended for symptomatic patients. Medical treatment is recommended for patients with 50%–69% stenosis and Color and Duplex Doppler sonography follow-up every 6 months to detect progression that may warrant surgery. The results of the NASCET showed that patients with moderate stenosis may also benefit from surgery.[13]

For stenosis of >70% and near occlusion, NASCET and the European Carotid Surgery Trial established the benefit of carotid endarterectomy in symptomatic patients.

Patients with carotid near occlusion are distinct from those with 90%–95% stenosis and have a lower risk of stroke on medical treatment and a marginal benefit from endarterectomy.[13]

A greater number of patients (57.1%) with large-sized infarct on the left have <50% stenosis while the majority on the right (61.8%) have stenosis of 50%–69%. The findings on the right carotid are similar to those reported by Malik and Tiwari in India who found that 70% of the patients with 50%–69% stenosis had large-sized brain infarct while only 25% of the patients with <50% stenosis had large-sized brain infarct on CT scan.[16]

Regarding the size of brain infarction, there was a statistically significant association between large-sized infarcts with increasing age, but no relationship was found between the sizes of the brain infarct with gender in this study.

Our findings have shown the need for further investigation of other plaque-related risk factors that may enhance stroke prevention through improved selection of surgical or medical therapy.


  Conclusion Top


This study provides important information regarding the pattern of carotid artery disease and the role of B-mode ultrasonography in detecting patients at risk of developing stroke. It also shows that large-sized brain infarct is common among patients with plaque (smooth or irregular/ulcerated).

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
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    Tables

  [Table 1], [Table 2], [Table 3], [Table 4], [Table 5]



 

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