Intracranial Arterial Calcification in Black Africans with Acute Ischaemic Stroke

Abstract

Background: Intracranial arterial calcification (IAC), a recognized marker of atherosclerosis on cranial computed tomography (CT), is an independent risk factor for ischaemic stroke. This study aimed to determine the prevalence, distribution, severity, and associations of IAC in adults with acute ischaemic stroke (AIS) at the University College Hospital, Ibadan, Nigeria.

Methods: Cranial CT images of 130 consecutive adults who presented with AIS were acquired on a 64-slice multi-detector Toshiba Aquilion scanner and evaluated for IAC in bone window on Vitrea® software using a semi-quantitative scoring method for extent, thickness, and length of calcifications in the large intracranial arteries. Associations of IAC with clinical and laboratory data were determined by statistical analysis at p < 0.05.

Results: There were 71 males (54.6%), and the mean age of all patients was 63.0 ± 13.2 years. Hypertension was the most common risk factor (83.1%). IAC was found in 121 patients (93.1%), predominantly in the carotid siphon (86.1%) followed by the intracranial vertebral arteries (9.3%), middle cerebral arteries (2.4%), basilar artery (1.2%), and the anterior cerebral arteries (1%). The burden of IAC ranged from mild (17.4%) to moderate (52.1%) to severe (30.6%). Age (p < 0.001), diastolic blood pressure (p = 0.037), and alcohol use (0.046) were significantly different among the patients with mild, moderate, and severe degrees of IAC. IAC was associated with age (p < 0.001), hypertension (p = 0.03), diabetes mellitus (p = 0.02), hyperlipidaemia (p = 0.04), and alcohol use (p < 0.001) but not with sex (p = 0.35).

Conclusions: The burden of IAC is very high among native African patients with AIS and preferentially involves proximal inflow arteries. Therefore, the role of large vessel atherosclerosis in ischaemic stroke in native Africans should be explored in future multinational, multimodality studies.

Keywords: Carotid siphon; Computed tomography; Intracranial atherosclerotic disease; Nigeria; Vascular calcification.

Fig. 1.

Schematic diagrams showing grading of extent, thickness, and length of intracranial arterial calcifications on cranial computed tomography (CT). Hatched areas show calcifications. Crosses show electronic calipers.

Fig. 2.

Axial (a, b) and coronal reformatted (c, d) cranial computed tomography bone window images showing grades 1–4 of extent of intracranial arterial calcifications, respectively. The arrow in a shows a dot of calcification (grade 1) in the left cavernous internal carotid artery (ICA); the arrow in b shows a crescentic calcification (grade 2) in the left vertebral artery; the curved arrow in c shows a semi-circular calcification (grade 3) in the right cavernous ICA; and the arrow in d shows a fairly circular calcification (grade 4) in the right cavernous ICA.

Fig. 3.

Distribution of intracranial arterial calcification in the arterial segments. ICA, internal carotid artery; MCA, middle cerebral artery; ACA, anterior cerebral artery; VA, vertebral artery; BA, basilar artery.

Fig. 4.

Severity of intracranial arterial calcification (IAC) in the arterial segments. ICA, internal carotid artery; MCA, middle cerebral artery; ACA, anterior cerebral artery; VA, vertebral artery; BA, basilar artery.