Patients with pre-existing cognitive impairment had a greater ischemic stroke severity than patients without.
Association between cognitive impairment and severity was not mediated by pre-existing leukoaraiosis, old vascular brain lesions, cortical and central brain atrophy.
Impaired brain ischemic tolerance in patients with prior cognitive impairment could involve other mechanisms than structural brain damage visible on conventional imaging.
We evaluated whether pre-existing brain damage may explain greater severity in cognitively-impaired patients with ischemic stroke (IS).
IS patients were retrieved from the population-based registry of Dijon, France. Pre-existing damage (leukoaraiosis, old vascular brain lesions, cortical and central brain atrophy) was assessed on initial CT-scan. Association between prestroke cognitive status defined as no impairment, mild cognitive impairment (MCI), or dementia, and clinical severity at IS onset assessed with the NIHSS score was evaluated using ordinal regression analysis. Mediation analysis was performed to assess pre-existing brain lesions as mediators of the relationship between cognitive status and severity.
Among the 916 included patients (mean age 76.8 ± 15.0 years, 54.3% women), those with pre-existing MCI (n = 115, median NIHSS [IQR]: 6 [2-15]) or dementia (n = 147, median NIHSS: 6 [3-15]) had a greater severity than patients without (n = 654, median NIHSS: 3 [1-9]) in univariate analysis (OR=1.69; 95% CI: 1.18-2.42, p = 0.004, and OR=2.06; 95% CI: 1.49-2.84, p < 0.001, respectively). Old cortical lesion (OR=1.53, p = 0.002), central atrophy (OR=1.41, p = 0.005), cortical atrophy (OR=1.90, p < 0.001) and moderate (OR=1.41, p = 0.005) or severe (OR=1.84, p = 0.002) leukoaraiosis were also associated with greater severity. After adjustments, pre-existing MCI (OR=1.52; 95% CI: 1.03-2.26, p = 0.037) or dementia (OR=1.94; 95% CI: 1.32-2.86, p = 0.001) remained associated with higher severity at IS onset, independently of confounding factors including imaging variables. Association between cognitive impairment and severity was not mediated by pre-existing visible brain damages.
Impaired brain ischemic tolerance in IS patients with prior cognitive impairment could involve other mechanisms than pre-existing visible brain damage.Le texte complet de cet article est disponible en PDF.
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Keywords : Ischemic stroke, Mild cognitive impairment, Dementia, Severity, Imaging