Chiari & Aerobic Exercise

March 20, 2006 - Many people with the diagnosis of Chiari wonder if it is OK to perform aerobic exercise and, if so, how much. It's a very good question and one that I believe has a straightforward answer in most cases. As a decompressed Chiari patient who runs marathons, it was one of my first questions after surgery. I did not ask the question prior to surgery because by the time I got my diagnosis I could barely walk.

To answer this question, it is important to understand how cerebrospinal fluid dynamics work and what causes hindbrain compression. The skull and the spinal canal are filled with a clear fluid known as cerebrospinal fluid (CSF). CSF bathes the brain and the spinal cord. The fluid forms in the skull and drains into the spinal canal. The drainage of cerebrospinal fluid from the skull to the spinal canal does not take place at a constant rate, rather it pulses with each heart beat. Here's how it works.

When the heart contracts, blood is sent to the head and the many blood vessels in the brain swell or increase in volume. Since the volume of the skull is fixed, the increase in blood vessel volume is compensated for by an equal volume of CSF being forced out of the skull and down into the spinal canal. When the heart relaxes, blood leaves the brain to return to the heart and the blood vessels in the brain decrease in volume. With the brain blood vessel volume decrease, CSF is pulled back up into the skull. Thus, the CSF pulses back and forth between the skull and the spinal canal at the foramen magnum (large opening at the base of the skull). Because of gravity, slightly more CSF is forced down into the spinal canal during heart contraction than what returns when the heart relaxes. In this fashion, CSF drains from the skull in a stepwise mechanism.

In Chiari, the cerebellar tonsils occupy space at the foramen magnum that is not usually occupied and, in turn, can restrict the passing of CSF. Cine MRI is often used to determine if CSF flow restriction is present. Cine MRI is a special MRI scanning technique that allows the radiologist to see the actual flow of CSF at and around the foramen magnum. When calibrated, Cine MRI can even measure the CSF flow rate. When CSF is significantly restricted or blocked at the foramen magnum, the tonsils are sometimes observed to pulse by Cine MRI with each beat of the heart. Basically, when the tonsils are restricting CSF from leaving the skull, compression builds in the hindbrain (cerebellum, brain stem and lower cranial nerves) and it becomes subjected to a compression wave with each heart beat.

During aerobic exercise, the heart beats faster and with more force. When the cerebellar tonsils are blocking CSF flow at the foramen magnum, more frequent and forceful waves of compression are experienced by the hindbrain, symptoms are exacerbated and progression of Chiari syndrome is accelerated.

Whether or not one should participate in aerobic exercise then depends on the status of his/her CSF flow at the foramen magnum. Prior to decompression, one should not partake in aerobic exercise if Cine MRI reveals restricted CSF flow at the foramen magnum. If CSF flow is not restricted as determined by Cine MRI, symptoms should be your guide. If aerobic exercise exacerbates symptoms like making headache worse or increasing nausea, then aerobic exercise should not be undertaken. Cine MRI is not always the best tool for determining if CSF flow is significantly blocked in any one individual. Change in symptomatology is probably a more sensitive indicator.

Turning to the post operative patient, aerobic exercise should be safe after surgical recovery assuming CSF flow is properly restored. Obviously, one should not go out and run a mile 2 months after surgery but light aerobic exercise such as brisk walking or moderate bike riding can actually be beneficial shortly after recovery. Again, symptom exacerbation should be your guide.

So how did I run a marathon after my decompression? First, I did not run the marathon until 6 years after surgery. I gradually recovered and used a step wise approach. I began by walking outside the very first day I returned home from the hospital. I only walked about 200 yards very slowly and with the aid of my wife but it was a start. I very gradually increased the distance each day until I was independently walking 2 miles a day about 5 weeks after surgery. I walked daily for the first year. About one year after surgery, I returned to my doctors for an evaluation which included both anatomical MRI as well as Cine MRI. The results confirmed that CSF flow was normal. At the beginning of the second year, I began to ride my bike locally in the neighborhood about 3 to 5 miles a day. After a few weeks, I took my bike to the bike trail and increased my riding to 10 miles. In another month or two, I was able to take a 25 mile ride on the trail every weekend. At the beginning of the third year, I joined the local fitness center and began using the tread mill. Again, I started jogging at a very slow pace and for a short distance. Within about a year, I was able to run 3 miles a day. I maintained this average distance for a couple of years testing my ability to run harder and faster from time to time. After a couple of years, I was able to press forward in a very significant way and in the summer of 2005 I increased my weekly distance from about 20 miles to over 40 miles in 3 months so that by the fall I was ready to run a full marathon.

Along the way, when I increased my level of exertion significantly, symptoms would sometimes flare up. Sometimes it was hard to differentiate whether it was a set back or a return of symptoms. It always turned out to be a set back. The key was to back off a little for a while and then attempt to increase activity but at slower rate.

There can always be complicating factors depending on the patient's individual case and level of fitness. If you want to participate in aerobic exercise regardless of the phase of the disease (pre- or post decompression) discuss matters with your physician first, confirm that CSF flow is unrestricted, be very attentive to signs and symptoms, and increase activity at a slow but steady rate.

Ed. Note: The opinions expressed above are solely those of the author. They do not represent the opinions of the editor, publisher, or this publication. Mr. D'Alonzo is not a medical doctor and does not give medical advice. Anyone with a medical problem is strongly encouraged to seek professional medical care.