Stroke in Sub-Saharan Africa: What We Know And Why We Should Know More

Globally, stroke is one of the leading causes of death and chronic disability. About 70% of all stroke deaths and 87% of stroke-related disability cases occur in low- and middle-income countries (LMICs), including the majority of Sub-Saharan Africa (SSA).[1] Analysing the data of the Global Burden Disease study, the worldwide incidence and mortality of stroke are likely to decrease, but the area of SSA has demonstrated an increasing trend.[2]

The most common cause of ischemic stroke in SSA is cerebral small vessel disease (CSVD) (42%), followed by large vessel atherosclerotic disease (17%), cardioembolism (11%), and an undetermined cause (30%).[1] The burden of CSVD may be explained by the effect of undiagnosed and uncontrolled risk factors (e.g. hypertension, dyslipidemia, or hyperglycemia), which can favour the arteriolosclerotic process of deep perforating arteries.[1]

Within the group of strokes due to other determined causes, haematologic disorders represent a relevant part, especially in SSA, where a high incidence of sickle cell disease (SCD) exists.[4] This pathology is responsible for a certain percentage of stroke cases in both pediatric and adult populations. According to the American Society of Hematology (ASH) guidelines for SCD, annual transcranial Doppler ultrasound (TCD) monitoring is recommended as a well-established primary stroke prevention strategy.[3] Considering the time-averaged mean of the maximum velocity of a non-imaging TCD, two measurements >200 cm/s or a single measurement >220 cm/s in the distal internal carotid artery or proximal middle cerebral artery is associated with a greater risk of stroke. That risk can be lowered by regular monthly blood transfusions for at least 1 year.[3]

However, access to stroke care in SSA is often limited, and a large part of these populations can’t afford the stroke care that is available and recommended by the international guidelines[1], including, for example, blood transfusion therapy or chelation therapy for SCD. Behind this background, countries such as Nigeria, Uganda, Angola, and the Democratic Republic of Congo aimed at developing and testing alternative therapy options that might be accessible to a large part of the affected population. In several clinical studies, they successfully demonstrated that hydroxyurea therapy is effective and safe for children with SCD and abnormal TCD measurements.[4-8] Consequently, this alternative option has been included in the 2020 ASH guidelines.[3]

In summary, the majority of stroke cases in the world occur in LMICs, but, at the same time, these patients are often underrepresented in the principal international trials, which recommend interventions that are not always affordable for all.[9] The above-mentioned African studies represent a brilliant example of the great utility of data from SSA, considering the limited resources of these areas, and suggesting widely affordable strategies as an effective therapy. Nowadays, the real challenge for researchers should be proposing new diagnostic, therapeutic, and prevention options, from which everyone can benefit, regardless of their economic level. This could effectively help improve stroke assistance worldwide, allowing as many people as possible to receive the best evidence-based stroke care.

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 References:

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