Testing the laterality hypothesis after left or right carotid endarterectomy: no ipsilateral effects on neuropsychological functioning.

Carotid endarterectomy (CEA) is performed to prevent stroke, but the possible restorative function of CEA on neuropsychological functioning has frequently been considered. Restorative effects might be clearer in functions mediated by the hemisphere ipsilateral to the operated side than in those of the contralateral hemisphere. The present study examined this hypothesis, both at group level and at individual level, in 45 right-handed male patients with CEA of either the right or the left carotid artery. Patients with a clinically presented stroke were excluded. Only tasks sensitive to hemispheric specialization were included. Preoperatively, the two patient subgroups performed significantly worse than the healthy control group in the planning of motor behavior, verbal fluency, and visual recognition. Three months after surgery, the mean performance of the patient group increased only in left-hand finger tapping. This was irrespective of the side of surgery and could be attributed to practice. In addition, the number of patients with meaningful cognitive change did not differ between the group with right-sided CEA and the group with left-sided CEA. In conclusion, ipsilateral effects on neuropsychological functioning after CEA were not demonstrated, although instruments and sample characteristics were optimal in light of hemispheric functional asymmetry.