Functional MRI Study of Working Memory Impairment in Patients with Symptomatic Carotid Artery Disease

The neuropsychological tests in patients with internal carotid artery (ICA) demonstrated cognitive deficits associated with frontal lobe dysfunction, but the pathophysiological mechanism of memory impairment is not fully understood. This study evaluated relationship between degree of ICA stenosis and frontal activations induced by working memory (WM) task using fMRI. The fMRI data of 21 patients with unilateral ICA stenosis (left/right, 11/10) and 21 controls were analyzed. In comparison with controls, ICA patients demonstrated significant activations in middle frontal gyrus (MFG) bilaterally, particularly in left MFG. In right ICA stenosis, there was slightly less MFG activation than that of controls. Importantly, lower MFG activity was associated with higher stenosis of ipsilateral ICA. For left ICA stenosis, weaker activation in left MFG was negatively correlated with degree of stenosis. Similarly, for right ICA stenosis, there was a significant negative correlation between right ICA stenosis and weaker activation of right MFG. Cognitive impairments in ICA stenosis were associated with frontal lobe dysfunctions. Left ICA stenosis had worse WM impairments than right ICA stenosis, which was affected by the degree of stenosis.