The role of carotid stenosis in vascular cognitive impairment

As the contribution of carotid stenosis to cognitive impairment still remains unclear, neuropsychological function and soft neurological signs were examined in patients aged 65 and over. Twenty-five patients with symptomatic carotid stenosis (CS) of 75% or more were compared with 25 patients with first anterior circulation stroke, 25 with peripheral vascular disease and 25 healthy controls. All patients were assessed using CAMCOG (Cambridge Cognitive Examination), tests examining frontal lobe function (Behavioural Dyscontrol Scale [BDYS], Trail-Making Tests A and B, Controlled Word Association Test) and a scale for primitive reflexes (Frontal Release Signs Scale). Patients with symptomatic CS showed greater global impairment on CAMCOG and more severe impairment in frontal lobe function than controls. Those patients scoring less than 15 on the BDYS were more likely to have experienced transient ischemic attacks (TIA) for 5 or more years. Frontal lobe dysfunction, suicidal thinking and age were all independent predictors of global cognitive impairment. Mean number of frontal release signs was higher in patients with CS than in controls, with a higher proportion of patients showing all release signs except glabellar, paratonia and snout reflexes. The study is limited by small numbers and the absence of brain imaging, but provides some evidence for an association between severe carotid stenosis and neuropsychological impairment. The presence of clinically 'silent' cerebrovascular disease affecting frontal lobe function may be missed in routine clinical practice.