Baseline white matter hyperintensities affect the course of cognitive function after small vessel disease-related stroke: A prospective observational study.

BACKGROUND: Cognitive impairment is a common sequel of recent small subcortical infarction (RSSI) and might be negatively affected by pre-existing cerebral small vessel disease (SVD). We investigated whether the course of cognitive function in patients with RSSI is influenced by the severity of white matter hyperintensities (WMH), an important imaging feature of SVD.

METHODS: Patients with MRI-proven single RSSI were tested neuropsychologically concerning global cognition, processing speed, attention and set-shifting. Deep and periventricular WMH severity was assessed using the Fazekas-scale, and total WMH lesion volume was calculated from T1-weighted MRI images. We compared baseline function and course of cognition 15 months after the acute event in patients with absent, mild and moderate to severe WMH.

RESULTS: The study cohort comprised 82 RSSI-patients (mean age: 61±10 years; 23% female). At baseline, 40% had cognitive impairment (1.5 standard deviations below standardized mean), and deficits persisted in one-third of the sample after 15 months. After age-correction, there were no significant differences in set-shifting between WMH groups at baseline. However, while patients without (deep: p<.001, periventricular: p=.067) or only mild (deep: p=.098, periventricular: p=001) WMH improved in set-shifting after 15 months, there was no improvement in patients with moderate to severe WMH (deep: p=.980, periventricular: p=.816). Baseline total WMH volume (p=.002) was the only significant predictor for attention 15 months post-stroke.

CONCLUSIONS: This longitudinal study demonstrates that pre-existing moderate to severe WMH negatively affect the restoration of cognitive function after RSSI, suggesting limited functional reserve in patients with pre-existing SVD.