Mineralizing Microangiopathy Presenting as Pediatric Stroke: A Case Report

Abstract

Introduction

Mineralizing angiopathy is a rare cause of pediatric stroke and has not previously been described in a Nordic European country. This case highlights the diagnostic value of CT imaging and the potential underdiagnosis of this condition in high-income countries.

Case Presentation

An 11-month-old previously healthy boy presented with acute left-sided hemiparesis, with a pediatric National Institutes of Health Stroke (pedNIHSS) score of nine. Initial CT revealed bilateral basal ganglia calcifications and tortuous internal carotid arteries. MRI confirmed an acute infarction in the right basal ganglia. The diagnosis of mineralizing angiopathy was made based on the neuroimaging findings, with sagittal CT views visualizing calcifications following the contours of deep perforating vessels. An extensive stroke workup, including cardiac and metabolic evaluations, was unremarkable. The patient received supportive care, was discharged with a pedNIHSS of five, and is under neurological follow-up.

Conclusion

Mineralizing angiopathy may be underrecognized in pediatric stroke, particularly in settings where MRI is preferred over CT. Early CT imaging can aid diagnosis. Longitudinal follow-up may offer novel insights into the pathophysiology of vascular calcifications.

Introduction

Pediatric stroke is often a devastating event with significant rates of mortality and long-term disability [1–4]. Nearly half of pediatric strokes are ischemic [5], with mineralizing angiopathy representing a particularly rare etiology [6]. Mineralizing angiopathy, also called mineralizing lenticulostriate vasculopathy, is diagnosed based on characteristic imaging findings, notably calcifications along the lenticulostriate arteries observed on head CT scans [6]. The underlying pathophysiology of these vascular calcifications remains unknown [6]. To date, most reported cases have originated from middle-income countries in Asia, particularly India. To our knowledge, this is the first documented case of mineralizing angiopathy in a Nordic European population.

Case Presentation

An 11-month-old boy who had no previous comorbidities or history of infection and reached normal developmental milestones for his age was admitted to the hospital due to acute-onset left-sided hemiparesis. On the morning of admission, the boy suddenly fell toward his left side whilst playing and was unable to stand up. His parents noted weakness on his left side and a left-sided facial droop and contacted emergency service. Upon arrival, paramedics confirmed the presence of a left-sided hemiparesis and the patient was urgently transported to Oslo University Hospital (OUH) with the suspicion of a stroke. Physical examination revealed a pediatric National Institutes of Health Stroke score (pedNIHSS) of nine, with two points for facial palsy, four points for motor function of the left arm, and three points for motor function of the left leg. Blood glucose was 5.8 mmol/L on admission, temperature 36.9°C, and heart rate of 144 bpm.

Noncontrast CT showed bilateral basal ganglia calcifications (Fig. 1a), more prominent on the right side (Fig. 1b), while CT angiography demonstrated pronounced tortuosity of the internal carotid arteries bilaterally, with no evidence of other vascular abnormalities (Fig. 2). The noncontrast CT and CT angiography confirmed the absence of hemorrhage and excluded the presence of a large- or medium-vessel occlusion. Together with the clinical examination, these findings raised suspicion of a lacunar stroke. This was confirmed on MRI, which showed an acute infarction in the right basal ganglia on DWI, with a corresponding FLAIR mismatch consistent with the acute phase (Fig. 3a). On the T2-weighted images, an older infarct was suspected in the same region, although small perivascular spaces could not be ruled out as an alternative explanation (Fig. 3b). SWI filtered-phase imaging revealed a minimally hyperintense focus in the right basal ganglia, without definite evidence of calcification (Fig. 4).

Fig. 1.

a NECT reveals bilateral punctate calcifications in the basal ganglia, more pronounced on the right side. b NECT in the sagittal plane showing the calcification previously seen in the axial plane. The sagittal plane demonstrates the calcification formed to and following the course of the deep performant vessel – the lenticulostriate vessel.

Fig. 2.

CTA demonstrates tortuosity of the internal carotid arteries bilaterally, with no other significant abnormalities. Demonstrated in coronal view (a) and axial view (b).

Fig. 3.

a Upper row: acute ischemic infarction in the right basal ganglia region, characterized by restricted diffusion with high signal on the b1000 map and low signal on the ADC map. As expected, it remains undetectable on FLAIR in the acute phase. b Lower row: the left image (SWI) shows prominent veins in the infarcted region due to increased oxygen extraction. The middle image (DWI b1000 map) depicts the extent of the infarction in the coronal plane. The right image (T2) suggests a possible older infarction or, alternatively, small perivascular spaces.

Fig. 4.

SWI filtered phase shows only a minimally hyperintense focus in the same location and no definite evidence of calcification.

Antiplatelet therapy was initiated with a single dose of acetylsalicylic acid 150 mg followed by a daily dose of 37.5 mg (3.4 mg/kg). A comprehensive stroke workup including a hypercoagulable and rheumatic panel, electrocardiogram, echocardiogram, renal ultrasound, metabolic screening, lumbar puncture, and genetic testing for small vessel disease was all negative. Based on the typical findings on NCCT, together with the exclusion of alternative etiologies following an extensive diagnostic workup, the diagnosis of mineralizing angiopathy was made. The patient showed improvement during his hospital stay and had a pedNIHSS score of five at discharge, with one point for facial palsy, two points each for both left arm and leg motor function. He was transferred to an outpatient rehabilitation unit for physical and occupational therapy.

Discussion

In this paper, we present the first case of a child with ischemic stroke caused by calcifications in the lenticulostriate arteries, a condition known as mineralizing angiopathy, in a Nordic European population. The diagnosis was made following a comprehensive diagnostic workup, which adhered to and surpassed international guidelines [7].

Previous reports, primarily from Asian countries, have described infants and toddlers who developed basal ganglia infarction after minor head trauma, with CT evidence of calcifications along the lenticulostriate arteries [8]. The clinical and radiological features in our case are consistent with these earlier descriptions, but this is, to our knowledge, the first reported occurrence in a Northern European population. The reasons for this apparent geographic disparity in prevalence are unclear. However, it is possible that mineralizing angiopathy is underreported in high-income countries, where international guidelines recommend MRI for evaluating suspected pediatric stroke [7]. MRI is generally less sensitive than CT for detecting calcifications [9]. However, a recent study demonstrated that basal ganglia calcifications can be visualized on SWI filtered-phase imaging and correspond to findings on head CT [10]. In contrast, we did not observe such correspondence in our case. It is also possible that this underreported pathology is also less actively screened for and thus geographically underdiagnosed. As a result, mineralizing angiopathy may be underdiagnosed in these settings.

The pathophysiology of mineralizing angiopathy remains largely unknown [6]. Based on more general knowledge of vascular calcifications, and considering the size of the arteries involved, one may speculate that the underlying process resembles arteriolosclerosis rather than atherosclerosis as the latter typically affects larger vessels [11, 12]. Arteriolosclerosis is characterized by medial sclerosis and intimal thickening, and more often than not does not cause complete occlusion. This may explain why infarction caused by mineralizing angiopathy is often preceded by a traumatic event.

Most patients presenting with stroke due to mineralizing angiopathy report a preceding minor head trauma, occurring hours before the stroke onset [8], such as falling out of bed or while walking. The exact mechanism linking trauma to subsequent ischemia in areas of the mineralized lenticulostriate arteries is not fully understood. It is hypothesized that the anatomical angle and rigidity of the arterial walls make these arteries particularly susceptible to shear forces from even minor head trauma, potentially leading to thrombotic events [6, 13, 14]. In cases where stroke onset occurs several hours after the traumatic event, impaired arterial contractility and local inflammation have been proposed as additional contributing mechanisms [15].

In our case report, there was no known history of trauma preceding the stroke. However, identifying such trauma can be challenging in younger children and the nature of the trauma might be unmemorable. Anemia has also been associated with strokes ascribed to mineralizing angiopathy, as was the case in our patient.

From a clinical perspective, since mineralizing angiopathy affects the deep perforating branches of the middle cerebral artery, patients typically present with lacunar stroke syndromes. Although no randomized clinical trial on intravenous thrombolysis (IVT) in children has been completed, it is hypothesized that IVT in children might be even more efficacious due to less adherent fibrin structures [7]. A recent retrospective study of 26 children, aged 1.1–17 years, treated with IVT at a dose of 0.9 mg/kg, reported no cases of intracranial hemorrhage [7]. In our patient, there were early signs of infarction on the NCCT and we therefore refrained from IVT. There was a DWI-FLAIR mismatch, but to our knowledge, the use of tissue-based imaging windows, rather than time-based windows for IVT in young children, has not been explored. The use of IVT in mineralizing microangiopathy is also not documented.

Following the success of endovascular treatment in adults, thrombectomy has been performed in pediatric cases [16]. However, lowest age in the cohort was 5 years, and such treatment is not feasible for the lenticulostriate arteries and is reserved for large-vessel occlusions.

In conclusion, we present the first documented case of mineralizing angiopathy in a Nordic European country, in a Caucasian toddler. Mineralizing angiopathy is a rare condition that may be underdiagnosed in high-income countries due to the preferential use of MRI over CT. Over time, the study of this condition may provide valuable insights into the mechanisms underlying vascular calcifications. The CARE Checklist has been completed by the authors for this case report, attached as online supplementary material (for all online suppl. material, see https://doi.org/10.1159/000549988).

Acknowledgments

ChatGPT was used to improve the written English and enhance the readability of the article.

Statement of Ethics

Written informed consent for the publication of medical case details and images was obtained from the parents of the patient. A retrospective review of patient data did not require ethical approval, in accordance with national guidelines.

Conflict of Interest Statement

The authors have no conflicts of interest to declare.

Funding Sources

This study was not supported by any sponsor or funder.

Author Contributions

Gisle Berg Helland: visualization and writing – first draft and review and editing. Gunnthorunn Gunnarsdottir: clinical investigation and writing – review and editing. Piotr Sowa: clinical investigation, visualization, and writing – review and editing. Rajiv Advani: conceptualization, clinical investigation, supervision, and writing – review and editing.

Funding Statement

This study was not supported by any sponsor or funder.

Data Availability Statement

Relevant data generated or analyzed during this study are included in the article. For further inquiries, please contact the corresponding author.