The effect of white matter lesions on cognition after carotid revascularization

Cerebral white matter lesions (WML) are associated with cognitive impairment, and carotid revascularization with cognitive worsening or improvement. We assessed the relation between WML severity and changes in cognition after carotid endarterectomy or stenting.

Patients with symptomatic carotid artery stenosis, enrolled in the International Carotid Stenting Study (ISRCTN25337470), underwent detailed neuropsychological examinations (NPEs) before and after 6 months. Cognitive results were standardized into z-scores, from which a sum score was calculated. The primary outcome was the mean difference (MD) in sum score between baseline and follow-up. Changes in sum score were related to WML severity with the 'age-related white matter changes' score, assessed on baseline MRI-FLAIR. Three groups were formed based on this score.

Eighty-nine patients had both baseline MRI and NPE, of these 77 had a calculable cognitive difference score. The cognitive sum score at six months was worse than at baseline: MD, -0.21; 95% CI, -0.32 to -0.09. The change in sum score did not depend on WML load: MD for no-to-mild WML, -0.15; 95% CI, -0.39 to 0.09, for moderate WML, -0.27; 95% CI, -0.48 to -0.06; and for severe WML, -0.21; 95% CI, -0.40 to -0.04. This did not change essentially after adjustment for baseline factors.

Cognitive functioning deteriorated after carotid revascularization, regardless of baseline WML burden.