Will improved neuroradiology facilities debunk the reported rarity of intracranial aneurysms in Sub-Saharan Africa?
- Department of Neurosurgery, Memfys Hospital, Enugu, Nigeria.
- Department of Radiology, Memfys Hospital and University of Nigeria, Enugu, Nigeria.
- Department of Neurology, Memfys Hospital, Enugu, Nigeria.
- Department of Neurology, University of Nigeria and Memfys Hospital, Enugu, Nigeria.
Samuel Chukwunonyerem Ohaegbulam, Department of Neurosurgery, Memfys Hospital, Enugu, Nigeria.
DOI:10.25259/SNI_136_2023Copyright: © 2023 Surgical Neurology International This is an open-access article distributed under the terms of the Creative Commons Attribution-Non Commercial-Share Alike 4.0 License, which allows others to remix, transform, and build upon the work non-commercially, as long as the author is credited and the new creations are licensed under the identical terms.
How to cite this article: Samuel Chukwunonyerem Ohaegbulam1, Chika Anele Ndubuisi1, Okwunodulu Okwuoma1, Wilfred Mezue1, Enyereibe Chuks Ajare2, Bibiana Oti3, Sunday Achebe1, Francis Campbell1, Donald Ogolo1, Birinus Ezeala-Adikaibe4. Will improved neuroradiology facilities debunk the reported rarity of intracranial aneurysms in Sub-Saharan Africa?. 31-Mar-2023;14:113
How to cite this URL: Samuel Chukwunonyerem Ohaegbulam1, Chika Anele Ndubuisi1, Okwunodulu Okwuoma1, Wilfred Mezue1, Enyereibe Chuks Ajare2, Bibiana Oti3, Sunday Achebe1, Francis Campbell1, Donald Ogolo1, Birinus Ezeala-Adikaibe4. Will improved neuroradiology facilities debunk the reported rarity of intracranial aneurysms in Sub-Saharan Africa?. 31-Mar-2023;14:113. Available from: https://surgicalneurologyint.com/surgicalint-articles/12229/
Background: Intracranial aneurysms (IAN) are rare in the Sub-Saharan Africa unlike other parts of the world. The debate is whether the low frequency might be apparent because of the scarcity of advanced neuroimaging services, or real. This study investigated if improved imaging facilities would debunk the rarity of IAN in our subregion.
Methods: This is a retrospective cohort study of prospectively recorded data of patients with subarachnoid hemorrhage (SAH) and IAN managed over 19 years (2003–2021), at the study center with a catchment population of over 47 million. The center witnessed progressive improvements in neuroimaging facilities: 2-Slice, 8-slice, and 64-slice computed tomography (CT) and 0.35T, 1.5T magnetic resonance imaging (MRI) during the period.
Results: There were 241 cases of SAH, but only 166 aneurysms were confirmed in 158 patients. Between 2003 and 2008, only 27 IAN patients (4.5 IAN/year) were diagnosed. After introduction of CT angiography/magnetic resonance angiography MRA using 8-slice CT/0.35T magnetic resonance imaging (MRI), between 2009 and 2014, the frequency of IAN increased to 8/year. Between 2015 and 2018 after installation of a 64-slice CT in 2014, the IAN remained the same (8/year). MRI 1.5T was added in 2018, the frequency doubled to 17 cases/year. The females were more (67.7%), the mean age was 46.3 years, but peak incidence was the sixth decade. Internal carotid artery aneurysms including posterior communicating artery were the most common (43%) followed by ACA with anterior communicating artery (24%) and middle cerebral artery (20%). Multiple aneurysms were seen in ten patients.
Conclusion: Improved neuroimaging between 2003 and 2021 did not debunk the rarity of IAN in our region.
Keywords: Africa, Geographical neurosurgery, Intracranial aneurysm epidemiology, Subarachnoid hemorrhage
Sub-Saharan Africa has consistently recorded low intracranial aneurysm (IAN) frequencies prompting some reporters to argue that IAN are rare.[
Mortality and morbidity from aneurysmal subarachnoid hemorrhage (aSAH) remain high despite immense research work and improvements in diagnostic and therapeutic capabilities. Each year, approximately 1 in 10,000 North Americans suffer aSAH, and despite recent advances, morbidity and mortality remain high as about 50% of aSAH patients die from the first hemorrhage or later complications.[
There is documented geographical variation in the incidence and frequency of IANs. The incidence rate of aneurysmal SAH in developed countries varies from 1% to 5% of the population. A low incidence has been reported from some parts of Asia and Africa.[
Studies such as ours are important and needed to better understand the epidemiologic, clinical, and economic burden of cerebral aneurysms in Africa at national and regional levels. The study of the epidemiology of IANs may identify populations with a high or low risk of developing IANs and therefore facilitate the identification of genetic or acquired factors that might be responsible and thus drive prevention strategies.
The aim of this study was to review the annual frequency of IANs seen at a major referral neurosciences hospital in South-Eastern Nigeria over a 19-year period (2003–2021) that included a period of progressive upgrade of diagnostic facilities. Have the improved diagnostic facilities and awareness led to increase in the frequency of diagnosed IANs in the center?
This is a retrospective analysis of prospectively recorded data of patients with the diagnosis of IAN seen between January 1, 2003, and December 31, 2021, at the study center. Information was obtained from clinic records, radiology (angiography, computed tomography [CT], and magnetic resonance imaging [MRI]), inpatient and operating theater database of the hospital.
The study was carried out in a private tertiary hospital established in August 2002. It was the only hospital that provided surgical management of IAN cases in the sub-region during most of the period of the study. The center had 8 consultant neurosurgeons and 30 Senior Neurosurgical Residents over the period of the study. Although located in a city with a population of about 723,000 (2006 National Census), the hospital also served as a referral center for many states, providing cerebral angiography (CA), CT angiography (CTA) and MRA services. The catchment population of mixed socio-economic status is over 47 million [
Diagnosis of aSAH was based on history, examination, lumbar puncture, carotid angiography, CTA, and/or MRA. The protocol of the hospital for aSAH included repeating the CTA 2 weeks after a negative initial angiogram. Autopsy search for IAN was not performed because of religious and cultural impediments. The demographic data, age, sex, clinical features, and anatomical location of aneurysm were recorded for analysis. Annual frequencies were calculated and matched with the growth of diagnostic facilities and specialists. The findings were compared to earlier local, regional, and international experiences. The study was not concerned with management or outcome.
Data were entered into spreadsheet and descriptive statistics estimated temporal trends. Frequency tables of variables were generated. Figures and tables were used to illustrate relevant findings.
There were 241 SAH patients of which aneurysms were responsible for 158 (65.56%), and AVM in 24 (10%), while for the rest, the cause of SAH could not be confirmed [
There was no aneurysm diagnosed in the first decade of age as the youngest patient was 13 years while the oldest was 78-years-old. The mean age was 48.23 years, the peak incidence was sixth decade, but 37.5% of the patients were 40 years or younger.
There were 166 aneurysms diagnosed in the 158 patients because of multiple aneurysms in some patients. The internal carotid artery (ICA) was the most frequent location (43%), while others were anterior communicating artery (ACoA) (23%), middle cerebral artery (MCA) (20%), and VertebroBasilar (VBA) (14%). Multiple aneurysms were seen in 10 patients (6.3%) [
The annual frequency of patients with IAN fluctuated [
The females were more (67.7%), the mean age was 46.3 years, but peak incidence was in the sixth decade.
During the period of the study, 24 cases of AVM were diagnosed giving AVM to IAN ratio of 1:6.6. Two of the patients with AVM also had multiple aneurysms, with one of them harboring four aneurysms.
The clinical presentations of IAN were diverse, but SAH predominated in 65%. Other findings were headaches (92%), 3rd nerve palsy (32), seizures (5), suspected meningitis (2), and sudden blindness (2). Two patients had polycystic kidney disease but there were no cases of Sickle cell disease, HIV, or family history of IAN in the series.
Does the study suggest low frequency of Aneurysms in Enugu?
Between 2003 and 2008, the study center depended exclusively on non-digital carotid angiography as there were no facilities for CTA or MRA. The annual frequency of IAN detected ranged from 1 to 8. The introduction of CTA and MRA in 2009 using 8-slice CT and 0.35T MRI did not increase the numbers significantly [
The quality of our diagnostic services improved in 2014 with the installation of a 64-slice CT scanner that provided a high standard CTA, but this did not significantly increase the IAN volumes in the subsequent 3 years as was expected. In 2018, the hospital installed 1.5T MRI that improved MRA quality from the earlier 0.35T machine. Over the 3-year period (2019–2021) there were 51 IAN cases giving an annual frequency of 17 compared to the preceding periods. There was increase in IAN numbers, but considering the large catchment population of the hospital and the fact that it was the referral center for SAH and IAN cases, the results suggest that the frequency of IAN in the sub-region is still low in comparison with international data [
Experiences in other parts of Nigeria and Africa seem to support this view. A study in Abuja, Nigeria,[
A recent scoping review of aneurysmal SAH in Africa revealed the scanty publications on this important subject that dominates neurosurgical literature.[
Interestingly, over a period of 4 years, 82 patients with spontaneous SAH were managed at hospital in Austria, serving 360,000 inhabitants, giving SAH incidence of 5.7/100,000/year. In 70 of the 82 patients (85.4%), cerebral aneurysms were detected by CTA.[
Autopsy studies have provided information on the incidence of IAs although there may be concerns about the accuracy of the results. In an autopsy study of 1000 brains in India, IANs were found in 10 (1%).[
Are IAN characteristics different?
The age distribution in our cohort showed mean age was 48.23 years but the peak incidence was in the 6th decade which is similar to global experience. Females outnumbered males by 2:1 which also is similar to reports from most studies with a few exceptions like a study from Qatar which reported a preponderance of males (68.7%).[
The anatomical distribution of aneurysms showed that ICA which included posterior communicating artery accounted for about 43%, while ACA/ACoA contributed 23% and MCA 20%. This distribution pattern was also recorded in other African studies and in Black Americans unlike Caucasian IAN patients that show dominance of MCA aneurysms,[
Racial and geographical differences in frequency of IANs
Racial differences have been reported between Māori and European populations of New Zealand in aneurysmal SAH. It was found that the incidence per 100,000 of the population for all aneurysms was 14.3 for Europeans but 25.7 for Maoris.[
Other explanations for these differences include genetic predilection and connective tissue disorders. Connective tissue defects may play a significant role in the development of IAN. Multi organ connective tissue disorders may, therefore, indicate a risk of IAN development.[
The major risk factors for IANs are hypertension, tobacco abuse and female sex.[
The uneven sex distribution of IANs suggests possible physiologic or pathologic factors in the intracranial arteries. The female preponderance is usually explained by systemic factors such as hormonal influences and intrinsic wall weakness.[
Despite massive efforts, progress so far has been modest in isolating the genetic determinants for IAN. More detailed epidemiology data might be essential for successful genome-wide association study.
Modern aneurysm management requires heavy investments in financial and human resources to equip specialist centers. Such centers must provide facilities for CTA, MRA, digital subtraction angiography, operating microscopes, vascular C-Arms, endovascular armamentarium, modern intensive care unit, high-dependency unit, and aneurysm clipping tools. The question then arises as how neurosurgical units in countries with low IAN volumes could justify such heavy investments when the healthcare budget is inadequate to even cater for more common diseases. Are the IAN numbers sufficient to produce vascular neurosurgeons? Perhaps the best option might be to identify centers with higher volumes and encourage other centers to refer their cases to those centers. High-volume hospitals have more favorable outcomes than low-volume hospitals. This effect is substantial, even for hospitals conventionally classified as high volume.[
Out of pocket payment for healthcare prevents many patients from seeking help. The absence of digital subtraction angiography (DSA) facilities might have led to missing small aneurysms. The COVID-19 pandemic might have prevented some patients from seeking healthcare. Catchment population was based on national census of 2006 and 2016 and for a hospital is not precise.
There was an increase in the number of IANs diagnosed in the study center with increasing awareness of the availability of neuroimaging facilities.
Improved diagnostic facilities led to detection of more IANs in the study center. However, the frequency rate was still far less than would be expected for the catchment population of this study, strongly suggesting that improved diagnostic neuroradiology has not debunked rarity of IANs in our subregion.
Patients’ consent not required as patients’ identities were not disclosed or compromised.
There are no conflicts of interest.
The views and opinions expressed in this article are those of the authors and do not necessarily reflect the official policy or position of the Journal or its management. The information contained in this article should not be considered to be medical advice; patients should consult their own physicians for advice as to their specific medical needs.
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