The value of cross-sectional imaging in evaluation of stroke patients

Yunusa Dahiru; H Umar Umar; U Usman Aminu; T Sa'ad Suleiman; Philip Oluleke Ibinaiye; MC Dahiru Aminu; Yusuf Hadiza

doi:10.4103/JRMT.JRMT_31_20

ORIGINAL ARTICLE

Year : 2021 | Volume : 2 | Issue : 1 | Page : 36-39

The value of cross-sectional imaging in evaluation of stroke patients

Yunusa Dahiru¹, H Umar Umar², U Usman Aminu³, T Sa'ad Suleiman⁴, Philip Oluleke Ibinaiye⁴, MC Dahiru Aminu⁵, Yusuf Hadiza⁶
¹ Department of Radiology and Imaging, Federal Medical Centre, Yola, Nigeria
² Department of Radiology, University of Maiduguri Teaching Hospital, Maiduguri, Nigeria
³ Department of Radiology, Federal Teaching Hospital, Gombe, Nigeria
⁴ Department of Radiology, Ahmadu Bello University Teaching Hospital, Zaria, Nigeria
⁵ Department of Histopathology, Federal Medical Centre, Yola, Nigeria
⁶ Department of Chemical Pathology, Federal Medical Centre, Yola, Nigeria

Date of Submission	07-Aug-2020
Date of Decision	24-Aug-2020
Date of Acceptance	17-Oct-2020
Date of Web Publication	22-Jun-2021

Correspondence Address:
Yunusa Dahiru
Department of Radiology and Imaging, Federal Medical Centre, Yola
Nigeria

Source of Support: None, Conflict of Interest: None

DOI: 10.4103/JRMT.JRMT_31_20

Abstract

Background: Due to poor availability of functional cross-sectional imaging in the developing countries, cerebrovascular accident (CVA) and its management has continued to be a major health problem. The need for cross-sectional imaging such as computed tomography (CT) of the brain for the exclusion of stroke mimics and for therapeutic decision cannot be overemphasized. Materials and Methods: This was a prospective case study conducted at the Federal Teaching Hospital, Gombe, from June 2016 to December 2016. One hundred and thirty patients who presented with clinical features and provisional diagnosis of CVA (also known as stroke) and were referred to the radiology department for brain CT were consecutively selected. A total of 111 had CT scan features of acute stroke, 6 had brain atrophy, 8 had intracranial space-occupying lesions, and 5 were normal brain scan. Data were analyzed using SPSS version 16.0 package. P ≤ 0.05 and a confidence interval of 95% were adapted for the statistical analysis. All comparisons of variables were done applying kappa statistical analysis. Results: There were 81 (62%) males and 49 (38%) females aged 18–80 years (mean ± standard deviation of 57.49 ± 13.47 years). About 15% (19) of the patients had a diagnosis other than stroke (stroke mimics). One hundred and eleven (85%) had a stroke, of which 94 (84.7%) were ischemic stroke, while the remaining 17 (15.3%) were hemorrhagic stroke. This study also found a discordance between clinical and CT diagnosis of stroke and stroke subtypes; κ = 0.289. Conclusion: The clinical diagnosis of stroke and stroke subtypes may not be reliable without neuroimaging, and the need for CT scan for proper evaluation of stroke patients is well justified.

Keywords: Brain computed tomography, stroke, stroke mimics

How to cite this article:
Dahiru Y, Umar H U, Aminu U U, Suleiman T S, Ibinaiye PO, Dahiru Aminu M C, Hadiza Y. The value of cross-sectional imaging in evaluation of stroke patients. J Radiat Med Trop 2021;2:36-9

How to cite this URL:
Dahiru Y, Umar H U, Aminu U U, Suleiman T S, Ibinaiye PO, Dahiru Aminu M C, Hadiza Y. The value of cross-sectional imaging in evaluation of stroke patients. J Radiat Med Trop [serial online] 2021 [cited 2023 Jun 4];2:36-9. Available from: http://www.jrmt.org/text.asp?2021/2/1/36/319111

Introduction

Cerebrovascular accident (CVA) or stroke occurs when the blood supply to the brain is disturbed in some ways. As a result, brain cells are starved of oxygen, causing some cells to die and leaving others damaged. According to the World Health Organization (WHO), stroke or CVA has been defined as a syndrome of rapidly developing clinical symptoms and signs of focal or global loss of cerebral functions lasting 24 h or longer or resulting in the individual demise traceable only to vascular pathology.^[1] CVA definition has been recently updated to include neuroimaging or pathological evidence of stroke before diagnosing CVA.^[2] Neuroimaging is required for the diagnosis of stroke and stroke subtypes and for the exclusion of stroke mimics.

In Africa, stroke accounts for 0.9%–4% of all hospital admissions and 2.8%–4.5% of total deaths.^[3] The incidence of stroke in Africa is on the increase.^[4],[5] The current prevalence of stroke in Nigeria is 1.14 per 1000, while the 30-day case fatality rate is as high as 40%.^[6] The factors that determine outcome following stroke include the stroke subtype, patient bio-profile (age and gender), disease severity, physiological parameters (blood pressure on admission, blood glucose, and level of consciousness), and presence of complication.^[7],[8]

Brain computed tomography (CT) has been shown to be the first imaging tool for diagnosis of cerebral hemorrhage and infarct and to rule out other brain lesions that may mimic stroke, such as tumors, extradural hematomas, and abscesses.^[9] In addition, CT is the most suitable for critically ill patients, it is fast, relatively available, and has fewer restriction when compared to MRI.

Clinicians usually rely on clinical evaluation in the diagnosis and in classifying stroke into its subtypes, using the WHO criteria or the Siriraj stroke score.^{[10],[11],[12]} However, the sensitivity and specificity of both scores are as low as 35%–63%, according to the validation studies using brain CT scans as the gold standard.^[13],[14] Furthermore, stroke scores do not exclude cerebral abscesses or tumors mimicking stroke, and they also do not distinguish subarachnoid hemorrhage (SAH) from intracerebral hemorrhage (ICH).^[15]

Oyinloye et al.^[16] studied stroke in young adults. They reported that, out of the 60 cases of clinically suspected stroke patients, 10 (16.7%) had SAH following brain imaging.

This study aimed to emphasize the importance of cross-sectional imaging in the management of stroke patients, especially in an environment that is ravaged with poverty and insurgency.

Materials and Methods

This was a prospective case study conducted between June 2016 and December 2016. The patients were recruited using a continuous consecutive sampling technique following the stated inclusion criteria. The study was carried out at the Federal Teaching Hospital (FTH), Gombe, the capital of Gombe State, located in the northeastern part of Nigeria. The study population consisted of 130 clinically suspected stroke patients who were referred from the accident and emergency unit or medical wards to the radiology department for brain CT.

Inclusion criteria include patients with clinically suspected stroke and patients 18 years and above, and for patients who had more than one CT scan, only the first CT scan was used for the analysis, while exclusion criteria were patients with a history of head injury in the past 6 months, patients on anticoagulant drugs, and patients presenting with a history of stroke of more than 2-week duration.

One hundred and thirty consenting patients with clinical features of stroke who were referred from the emergency or neurology unit to the radiology department for cranial CT scan and fulfilled the inclusion criteria for this study were recruited consecutively. The relevant clinical information was retrieved from the patient or patient's relatives, CT request form, and patient's folder. This included age, sex, clinical diagnosis, duration of symptoms, and history of previous systemic arterial hypertension (previous or current treatment of hypertension).

Philips Brilliance (16 slices) 1622, 2010 CT Machine was used in the study. The patient was placed supine on the scanner table with head resting on the head support and positioning aided by the external alignment lights. The patient was then moved into the gantry and the table was raised to bring the scan reference point to the level of external auditory meatus (EAM).

A lateral skull scanogram was obtained, from 5 cm below to 12 cm above the baseline. Subsequently, noncontrast 5-mm thick axial contiguous sections were acquired from the foramen magnum to the superior border of the petrous bone, parallel to the orbitomeatal baseline using the scanogram as a reference image. Further 10-mm thick contiguous sections were done from the superior border of the petrous bone to the skull vertex. Fifty milliliter of nonionic (iohexol) contrast medium (350 mg/mL) was administered via an antecubital vein and given only when ICH was ruled out; postcontrast images are then acquired. The images were automatically reformatted into sagittal and coronal sections. The images obtained were reviewed by two consultant radiologists independently. Discrepancies in interpretation between two observers were resolved by consensus.

Informed written consent was obtained from each patient or the caregivers before enlistment into the study. An approval to carry out the study was obtained from the Ethical Committee of the FTH, Gombe.

Results

Demographic characteristic of the study population

A total of 130 patients referred to the radiology department with clinical features of stroke were consecutively selected for this study, 81 (62%) were males and 49 (38%) were females [Figure 1]. One hundred and eleven (85%) had CT scan features of a stroke, while 19 (15%) have no features of stroke [Figure 2] Among those that had no features of stroke; eight had intracranial space-occupying lesions, six had brain atrophy, and five were normal study.

Figure 1: Pie chart showing sex distribution of the study population

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Figure 2: Bar chart showing computed tomography findings of the study population

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Comparison between clinical diagnosis of stroke subtypes and computed tomography subtypes

Comparison between clinical diagnosis and CT diagnosis of stroke subtypes was made using kappa statistics, as shown in [Table 1]. The kappa value was 0.289 signifying poor agreement between clinical diagnosis and CT diagnosis of stroke subtypes P < 0.002. The sensitivity and specificity of clinical diagnosis of ischemic stroke were 91.5% and 42.9%, respectively, whereas the sensitivity and specificity of clinical diagnosis of hemorrhagic stroke were 35.3% and 88.7%, respectively. The clinical diagnosis has a positive predictive accuracy (PPA) of 88.7% for ischemic stroke and 35.3% for hemorrhagic stroke.

Table 1: Diagnostic comparison of stroke subtypes by computed tomography scan and clinical diagnosis

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Discussion

This study shows that there was a male preponderance over a female with regard to the incidence of stroke. This finding is similar to that of Geofery et al.^[17] who reported 1.7:1 male-to-female ratio in the Gombe, Northeast Nigeria. This higher male preponderance was also reported in other studies; Bwala^[18] reported a 2.5:1 male-to-female ratio in Maiduguri, Northeastern Nigeria, and Eze et al.^[19] reported 4:1 male-to-female ratio in Southeastern Nigeria.

The increased incidence of stroke in males compared to females might be due to increased risk factors of stroke in males such as hypertension, diabetes mellitus, smoking, and excess alcohol consumption. More so, the male gender is a nonmodifiable risk factor for stroke.

The advancement in the management of acute stroke stipulates differentiating ischemic from hemorrhagic stroke as the first step in the management of acute stroke. CT scan is the gold standard imaging modality for achieving this. CT scan is the most suitable for critically ill patients, it is fast, relatively available, and has fewer restriction when compared to MRI. CT angiography, with or without perfusion studies, rapidly provides visualization of the blood flow and vascular occlusions, as well as assesses for salvageable brain tissue.

The study further shows that clinical diagnosis of stroke subtypes is by far less accurate in comparison to CT diagnosis. The sensitivity and specificity of clinical diagnosis for ischemic stroke when compared with CT diagnosis were 91.5% and 42.9%, respectively, while the sensitivity and specificity for hemorrhagic stroke were 35.3% and 88.7%, respectively. The PPA for clinical diagnosis of both the subtypes further validates the nonreliability of clinical diagnosis of stroke. This finding is in conformity with a study conducted by Badam et al.^[20] They reported from their findings that clinical diagnosis is not accurate in differentiating ischemic from hemorrhagic stroke.

Ogun et al.^[21] also highlighted the need for cranial CT in patients with stroke, as the clinical diagnosis demonstrated only 50% accuracy in diagnosing hemorrhagic stroke and 58% in diagnosing ischemic stroke when compared with the CT findings of the same patients. In a similar prospective study conducted by Jehangir et al.,^[22] they compared clinical diagnosis with CT findings in ascertaining stroke subtypes, and they found out that of 25 clinically suspected hemorrhagic stroke, only 13 had hemorrhage on CT scan showing 52% accuracy of clinical diagnosis, while the rest 12 (48%) had infarction. In the same study, of the 43 clinically suspected ischemic stroke, only 25 proved to have infarction on CT scan reflecting a clinical accuracy of 58.6%.

The clinical differentiation between hemorrhagic and ischemic lesions has proved problematic because small hematomas may cause symptoms and signs that are identical to those caused by infarcts, while large infarcts might present with features identical to hematoma.

In previous studies, some authors have reported intracranial space-occupying lesion as the most common stroke mimic,^[23] while some studies have reported cerebral atrophy as the most common stroke mimic.^[21],[22] In this study space-occupying lesion was the most common, accounting for about 42% of all the stroke mimics.

Conclusion

This study has highlighted the value of CT in making an accurate diagnosis of stroke and stroke subtypes. It also emphasizes the poor sensitivity and specificity of clinical diagnosis of stroke, hence discouraging strong reliance on it. Since the treatment protocols for stroke subtypes differ, we recommend that secondary and tertiary institutions in Nigeria should at least have a functional CT machine and the examination should not only be accessible to stroke patients but should be prompt and affordable.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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