White matter lesions predominantly located in deep white matter represent embolic etiology rather than small vessel disease

Abstract

AbstractBackgroundIndividuals with cerebral small vessel disease (CSVD) usually have both periventricular and deep white matter hyperintensities (dpWMH). However, we often encounter individuals whose WMH lesions are mainly located in the corticomedullary or deep white matter with minimal periventricular WMHs (dWMH). We aimed to determine if the dWMH pattern could be attributed to embolic etiologies.MethodsWe retrospectively recruited participants who had undergone comprehensive dementia evaluation, agitated saline contrast echocardiography, and brain MRI. The participants were classified into two groups according to WMH distributions, the dWMH (WMHs in deep and corticomedullary area, with minimal periventricular WMHs) and the dpWMH (mainly periventricular WMHs with or without deep WMHs) groups. We hypothesized that dWMH is more likely associated with embolism, whereas dpWMH with CSVD. We compared the clinical characteristics, WMH distributions, and the positive rate of agitated saline study between the two groups.ResultsOf the 90 participants, 27 fulfilled the dWMH criteria and 12 met the dpWMH criteria. The dWMH group was younger (62.2±7.5 vs 78.9±7.3, p<0.001), and had a lower prevalence of hypertension (29.6% vs. 75%, p = 0.008), DM (3.7% vs. 25%, p = 0.043), and hyperlipidemia (33.3% vs. 83.3%, p = 0.043) than the dpWMH group. Regarding deep white matter lesions, the number of small lesions (<3 mm) was higher in the dWMH (10.9±9.7) than the dpWMH (3.1±6.4) group (p = 0.008), and WMHs were predominantly distributed in border‐zones of major cerebral arteries and corticomedullary areas.Most importantly, the positive rate of agitated saline was higher in the dWMH than the dpWMH group (81.5% vs. 33.3%, p = 0.003).ConclusionsThe dWMH group with younger age, fewer cardiovascular risk factors showed more border‐zone distributions, and higher positivity of agitated saline test than dpWMH group, indicating that WMH distributions mainly in the corticomedullary or deep area with minimal periventricular WMH lesions suggest embolic etiologies.