QUESTION: I recently had knee-replacement surgery and I just don’t feel like myself. I’m a retired school principal and I used to have an excellent memory. Now I struggle to remember the simplest things—even my husband’s name. I am slowly getting better, but it has been very frustrating and frightening. My doctor said I could be suffering a side effect from the anesthetic or the operation. Is this a common problem after surgery?
ANSWER: Doctors have long assumed that patients return to normal once the anesthetic wears off. But in recent years, a growing body of research suggests that some people experience lingering cognitive impairment after being wheeled out of the operating room.
“We now know that between 10 and 20 percent of patients will have problems at the time they are discharged from hospital,” says Dr. Beverley Orser, an anesthesiologist at Sunnybrook Health Sciences Centre.
“And one in 10 of those affected will still have problems three to six months later. What happens at the one-year mark is still debated,” she says, adding that some may never fully recover.
The cognitive impairment seems to affect memory, word-finding and attention as well as certain “executive functions” of the brain such as decision-making and problem-solving.
In some patients, the effects can be very subtle. They may not feel mentally impaired, although family members may notice a difference in their memory or behaviour.
Experts believe the anesthetic drugs used to induce an unconscious state—so patients don’t feel pain or remember the surgery—may be partly responsible for the cognitive changes.
But the biggest contributor to the mental deficits, known as post-operative cognitive dysfunction (POCD), might be the operation itself.
“Surgery is not a natural thing and the body goes into a high state of alert,” says Dr. Roderic Eckenhoff, vice-chair of research in the department of anesthesiology and critical care at the University of Pennsylvania in Philadelphia.
In particular, he adds, the immune system unleashes a cascade of cells that produce an inflammatory response, which continues to ramp up in intensity several days after the operation.
The brains of older patients and those with complex medical conditions appear to be especially vulnerable to this inflammatory assault.
“For people with existing mild cognitive impairment, the surgery may be tipping them over the edge,” says Dr. Orser, who is also chair of the department of anesthesia at the University of Toronto and co-chair of Sunnybrook’s Perioperative Brain Health Centre.
Researchers are looking for ways to reduce the risks of POCD. For instance, they are studying whether certain drugs that are given to surgical patients may have fewer negative effects than others. As well, in some cases, a local nerve block can be used to ease pain without the need for a full anesthetic.
“With a nerve block, you recover faster from the anesthetic because you get less of the drug,” says Dr. Stephen Choi, a Sunnybrook anesthesiologist and an assistant professor at the University of Toronto.
Even so, it’s not clear that the use of a nerve block actually protects the brain from cognitive impairment. The powerful effects of post-surgical inflammation may simply overwhelm the brains of some patients.
Researchers agree that there are gaps in their knowledge of POCD and they can’t identify with certainty which patients will run into problems. Although seniors tend to be at an elevated risk of post-surgery memory lapses, some do just fine.
To better understand the condition, Dr. Choi is leading a study in which patients’ mental faculties are assessed both before and after surgery using tablet-based card games which are less time-consuming and labour intensive than traditional cognitive tests.
So, what are patients and health-care providers supposed to do while researchers probe for solutions?
Good post-operative nursing care is probably the best prevention strategy for all patients, says Dr. Eckenhoff. That means making sure patients resume a normal routine as soon as possible. “If they use glasses or hearing aids, they should get them back quickly so they can reorient themselves,” he says.
Returning to a natural sleep cycle is also critically important, he adds. “Poor sleep hygiene is thought to translate to a greater degree of inflammation of the brain.”
Dr. Choi says patients should at least be aware they might feel off kilter after an operation.
But he stresses that the risk of possible cognitive impairment is not a good enough reason to forgo an operation.
After all, the goal of most surgeries is to improve a patient’s quality of life or even extend life. Those benefits will likely outweigh any possible memory deficits—whether short or long term.
Sunnybrook’s Patient Navigation Advisor provides advice and answers questions from patients and their families. This article was originally published on Sunnybrook’s Your Health Matters, and it is reprinted on Healthy Debate with permission. Follow Paul on Twitter @epaultaylor.
If you have a question about your doctor, hospital or how to navigate the health care system, email AskPaul@Sunnybrook.ca
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Recently had major surgery – was in hospital two weeks before abd one week after. Definitely the lack of sleep due to hospital setting, pain, discomfort, nightly nurse checks, blood draws – can disorient anyone!! The side effects of not only anaesthetics but of the pain meds, narcotic, anti nauseantS, antibiotics etc also contribute!! Perhaps offering more quiet at night, brain stimulation in day with activities or books etc, minimize disruption to a normal daily activities may help!
Thanks Paul. I enjoyed reading this.
I am trying to reconcile two comments in this article: a) Dr. Orser’s statement that “…between 10 and 20 percent of patients will have problems [cognitive impairment] at the time they are discharged from hospital,” and “… one in 10 of those affected will still have problems three to six months later.” and b) Dr Choi’s comment that “… the risk of possible cognitive impairment is not a good enough reason to forgo an operation. After all, the goal of most surgeries is to improve a patient’s quality of life….”
Boy, a 20% risk of cognitive impairment, with 10% of those continuing on for 3-6 months sounds like a pretty big negative hit on quality of life to me, and might make me delay a hip or knee joint replacement until my pain is really, really bad.
I always assumed that if i had a spinal anesthetic (instead of a general) for my knee replacement that the impact on my cognition would be less. It sounds like you are saying that assumption is wrong….
One thing to keep in mind is that hospitals are now discharging people earlier
than they did years ago.
That trend might partly explain why the numbers look high at time of
discharge. Within a few days, many would likely return to a normal state.
(I recently had surgery to repair a broken elbow. For the procedure, I was put under a full anaesthetic and I was discharged from hospital the same day. I noticed no impairment but some of the changes are so subtle that they are only picked up with cognitive tests. )
Also, 10 per cent of the 10 per cent affected (going on the low side of the estimate)
is just one per cent of all patients at the 3 to 6 month point.
So, it’s not a big number in a relative sense, but when you consider how many people get surgery each year it’s still significant.
There are risks with any medical procedure or treatments and as the last line from this excellent article reads “those benefits will likely outweigh any possible memory deficits.” Medicine like all applied sciences is not an exact entity and no one should be under the false belief it is. It’s all a personal decision as to undergoing surgery and thankfully our fantastic physicians and research teams are trying to make all medical procedures safer and more effective for everyone.