DearCustomer If your mother was given a general anaesthesia (vs a spinal block) which I am sure she was, it was more likely the combination of anaesthetic agents and drugs that linger and may cause confusion for up to 6-8 weeks, especially in the elderly, but the effect will wear off eventually. This is much more like that the morphine causing her symptoms.
Hope this helps.
DearCustomer What I've learned from medscape is that there is little difference in post surgical confusion with spinal block vs general anaesthesia. There's much more in this article that we need, but it addresses what statement I've just made: http://www.medscape.com/viewarticle/406246. and the American Society of Anesthesia describes post surgical confusion in the elderly in this article at
http://www.asahq.org/clinical/geriatrics/posto.htm which states that only 10% of the postsurgical cases of cognitive declilne do not recover by 3 mths. So, back to my original estimate of 6-8 weeks, this seems like a reasonable expected recovery time for your mother post surgically.