Abstract
Carotid endarterectomy (CEA) is a surgical procedure to remove atherosclerotic plaque from the carotid arteries. It has become a routine surgical procedure for the prevention of stroke in patients with severe occlusive disease. The main aim of this thesis was to investigate the possible beneficial function of CEA on cognitive
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functioning and on perceived health. Several potentially confounding factors on task performance, such as mood and nonspecific effects from practice and surgery, were taken into account.
Before CEA, patients performed significantly worse than healthy control subjects on tests of attention, verbal and visual memory, psychomotor speed, and executive functioning, even if preoperative mood was taken into account. Patients with vascular disease of their legs performed very similarly. Simple motor skills and visuospatial performance (in both vascular groups) were not affected. Within the group with carotid artery disease, patients classified according to the presence and type of previous clinical symptoms or to the severity of the stenosis of the contralateral carotid artery only slightly differed from each other. Accordingly, the findings do not clearly support the necessity of a distinction of subgroups in investigating the cognitive effects of CEA.
Patients undergoing vascular surgery of their lower limbs were included as control subjects to control for the nonspecific effects of practice and surgery. Improvements up to one year postoperatively were demonstrated in a number of cognitive functions, but patients after CEA did not improve móre than patients after vascular surgery of the lower limbs. A specific effect of CEA on cognitive functioning could thus not be demonstrated. Furthermore, CEA was not more beneficial to cognitive functions mediated by the hemisphere ipsilateral to the operated side than to those of the contralateral hemisphere. This further supports the observation that the preoperative cognitive impairments cannot be reversed by CEA.
Within the CEA group, it was also investigated whether perioperative emboli accounted for cognitive decline after surgery. Emboli are particles from the atherosclerotic plaque that have come loose and block smaller arteries located further down. Intraoperative and immediate postoperative emboli were indeed detected in a large majority of patients, most often after the surgical phase of clamp release, but the total number per patient was generally low. This finding, and the relatively large postoperative interval of three months, may explain why a significant association between embolic load and cognitive change following surgery was not shown.
Patients did not report a change in cognitive functioning in daily life either, although they did notice small improvements in several physical and mental health aspects. This latter outcome possibly reflects a postoperative decrease in anxiety due to the knowledge of the reduced stroke risk and relief after uncomplicated surgery. The findings of this thesis thus indicate that prevention of future complications, like stroke, remains as the basis for the decision to perform CEA.
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