HI Thank for asking to HCM I can understand your worry, look dementia can be considered age related right now until and unless proved, it could be due to surgery but the chances of this is very unlikely because the surgical team taking extra care for blood supply towards the brain and they left no chance for mistake, I would advise you to first consult the physician for clinical examination that will confirm the nature of dementia because she has not being diagnosed for dementia by physician, so this will not considered as clinical diagnosis, it is just your idea and that couldnbe wrong, so better to consult the physician, as long as the swelling of leg is concern her hemodynamic system has to be monitored the possibility of heart failure need to be ruled out, take care of your mother bye.