Surgeons in all medical specialties have long pondered how the aging brain responds to anesthesia and surgery. In many cases, among patients of all age groups, there is often a minor cognitive decline – some call it “brain fuzziness” – after surgical procedures. Recent research suggests some reasons for the phenomenon among knee replacement patients.

According to Science Daily, a University of Florida study found that 23 percent of adults, age 60 and older, who underwent a total knee replacement experienced a decline in activity in at least one region of the brain responsible for specific cognitive functions. Fifteen percent of patients declined across all brain networks the team evaluated.

The study also found that patients who were cognitively weaker before surgery – with worse working memory, slowed mental processing and evidence of brain atrophy as seen in imaging scans – demonstrated the biggest network declines after surgery.

The researchers used “resting state” functional MRI to look at patterns of blood flow in the brain while patients were lying still. Imaging data helped researchers understand how blood flow changes affected connections across brain networks that are responsible for functions such as memories of oneself and others, and the determination of what outside stimuli deserve further attention.

Participants who were not given anesthesia did not demonstrate any changes across the two brain scans, but 23 percent of participants who had knee replacement surgery showed large declines in connectivity in at least one brain network when tested 48 hours after surgery.

While this study was done with joint replacement patients, the mild cognitive decline can occur after any surgery. Fortunately, experienced surgeons have ways to reduce this condition.

 A Neurosurgeon Looks at Brain Fuzziness

Dr. Rob Dickerman, a neurosurgeon in North Texas and a member of the referral line of Texas Health Spine & Orthopedic Center, understands the challenges of surgery such as that on the spine and brain with regards to lingering effects of anesthesia.

“As we age, humans metabolize medications differently,” Dr. Dickerman said. “This is particularly true with anesthesia.

“In most cases, ‘brain fuzziness’ is a lingering effect from the anesthesia. It is interesting to note that this is seen more often among patients who have undergone cardiac surgery, where there is a lack of blood flow and oxygen to the brain. The patient will sometimes develop an ischemic event, which is not qualified as a stroke but enough of an ‘insult’ to the brain whereby the patient is not quite where they used to be mentally. Typically, this is a temporary condition, but in some cases, it can take a while for this fuzziness to go away.”

 Other Factors That Can Cause This Condition

What are some factors that can play a role in the odds of having this post-surgical cognitive decline?

“When you examine the data on all types of orthopedic surgeries, some of these patients can be morbidly obese, some have vascular diseases and some can have chronic diseases, such as diabetes. These patients are at a higher risk for this post-surgical complication because there is limited blood flow to the brain. Once the anesthetics are administered, they can accumulate and it takes longer for them to be passed out of the body.

“It is also age-related. With an older patient, they are less likely to be able to metabolize the anesthesia as quickly as a younger patient. There is a great deal of medical literature on octogenarians (80+ years), and it points to the fact that when surgical procedures are completed among this group, it’s a totally different ballgame. The way they react to anesthetics, the durability of the immune system and other factors make this group more susceptible to complications such as this cognitive decline. As the population continues to live longer, these factors will become more and more important to consider.”

 Two Things a Surgeon Can do to Prevent or Lessen Brain Fuzziness

“There are actually a couple of things we can do to help patients lessen this brain fuzziness,” Dr. Dickerman said. “Keeping the blood pressure up, making sure that the oxygen saturation and blood flow to the brain is consistent during surgery is one critical tactic. We don’t want the blood pressure so low that it depletes the oxygen flow to the brain.

“Another consideration involves choosing different anesthetics that are short acting and we can also limit the amount of gas that is being used during the surgery. Sometime we will use Propofol or Precedex, both of which rapidly enter the brain because they are lipid-soluble and then dissipate very quickly.”

As with any surgical procedure, complications can happen and it’s important for patients to discuss all the risks and benefits of surgery with their surgeon prior to undergoing a procedure. Medical science, physician expertise, and advanced technology all play a role in helping to minimize surgical complications.

If you are concerned about experiencing brain fuzziness after joint replacement, contact us to schedule an appointment.

 Physicians who are members of the referral program practice independently and are not employees or agents of THSOC.