How Does the Brain Recover?

by Guy McKhann, M.D.

September 14, 2010

On April 15th of this year, I was getting ready for the research meeting I have every Thursday. I had arrived a bit early, so I started down the hall to visit my wife’s office. Suddenly I veered off to the right, hitting the wall, and thought to myself, “I can’t be that clumsy.” When I tried to continue, I couldn’t maintain my balance, falling to my right. I went into my wife’s office and put my head down, though I didn’t experience a headache or dizziness.

One of the younger neurologists, with whom I was supposed to meet, came running in. I remember saying, “Rebecca [Dr. Rebecca Gottesman, one of Johns Hopkins’ best stroke neurologists], just leave me alone for a minute or two, I will be perfectly all right.” The next thing I knew Rebecca and my wife had loaded me in a wheelchair and taken me to the emergency room, where five or six my fellow neurologists were waiting for me. The time from the episode to my being in the brain scanner was less than 30 minutes.

I have always preached to medical students and residents that lack of blood supply to the brain, a stroke, occurs suddenly, usually with no warning. Guess what? That’s exactly what happened. Secondly, modern brain imaging techniques make it possible to determine what happened. In my case a small artery that supplies the right side of my cerebellum had suddenly become blocked. Without going into details, the mechanism appeared to be a small embolus (blood clot). After looking at the scan, Dr. Amy Bastian, an expert on the mechanisms of movement, came to see me and gave me super news: “Guy, I have seen many patients like you, and they almost all get markedly better.”

I spent a few days in the hospital, took medications to keep my blood from clotting, and started a vigorous physical therapy program to improve my balance. Now, almost five months later, I am, indeed, markedly improved. I am not ready to play tennis yet, but am back at work, walking around, and not noticeably impaired.

How did I get better? What has my brain been doing? The article “The Brain at Work” by Anita Slomski in Proto magazine addresses some of these questions. I also have picked the brains of Amy Bastian, mentioned above, and Dr. John Krakauer, a recent recruit to Hopkins and a neurologist interested in recovery from stroke. I had a second imaging study of my brain, and the area of damage in my cerebellum is still there, meaning something else has to have taken over. Exactly what and how is not clear.

One possibility is that other circuits within the cerebellum have become more active, bypassing the damaged pathways. If you think of the brain as a telephone circuit, it would be as if calls from Europe to Baltimore, which normally pass through New York, are now directed through Chicago—a longer, and possibly less efficient, pathway.

Another possibility is that I am using entirely different brain mechanisms, activating circuits from the cerebral cortex that are usually involved in voluntary movements. Supporting that idea is the fact that initially I had to consciously think of what I was doing. If I wanted to stop walking, or turn to the right or left, I had to think about how I was going to do that. Only after time did my balancing mechanisms start to become automatic. If you watched the U.S. Open, you saw examples of this. A tennis player doesn’t have time to think about where and how he is going to hit the return of serve, or a shot directly at her near the net. It is an automatic response developed by many repetitions. As he or she gets tired, those automatic mechanisms start to break down, and the player start mishitting shots.

Whatever the mechanisms are, they are undoubtedly fragile. If I get too tired, or get the flu, as I did last month, my balance deteriorates markedly, only to return as I got proper rest. I like wine, but a glass or two makes me wobble all over the place. I am afraid that non-alcoholic beers have become my imbibitions of choice

This field of “restorative neurology,” the mechanism of recovery, is set to explode in coming years. The newer forms of brain imaging will not only tell us the nature of the damage, but also what the brain is doing during recovery. I am lucky; I got better. But suppose I didn’t—what would it have meant my brain did not do? Are there things I could be doing, or should not be doing, that would promote recovery? These will be answerable questions.

The fact that my stroke happened to me on “tax day” may be related to the unseen influence of the IRS, “rewarding me” for my prompt filing of my taxes, usually some time in June.