|
Ray D’Alonzo, Ph.D., is a visiting professor in the
Chemistry Department of the University of Massachusetts Amherst and a
retired R&D Manager of Procter & Gamble where he worked for over 31 years.
He has led research programs in bone metabolism, infectious disease,
respiratory disease, arthritis, and nutrition and has published scientific
papers on a wide variety of topics from the chemical composition of fats and
oils to the pharmacoeconomics of osteoporosis. Dr. D’Alonzo is the
recipient of the Chancellor’s Medal from the University of Massachusetts,
Amherst, in part, for his contributions to the development of new
pharmaceutical agents. As both a patient and scientist, he has made a
personal effort to increase the awareness of Chiari in the health care
sector and to assist others afflicted with the syndrome. He has published
the story of his personal struggle with Chiari in a book,
Contents Under Pressure, with 100% of royalties going towards Chiari
education, awareness, and research programs.
June 30th, 2010 --
I often decide
on what to write about in this column by reading patient posts from various
on-line support groups. Recently, I noticed a number of posts by people
seeking information on what appears on the surface to be a simple question
but actually is not. That question is, “Does Chiari progress?” This
question is not only difficult to answer for Chiari but when you think about
it, also difficult to answer for a number of other diseases and medical
conditions as well.
What makes this
question difficult to answer in the case of Chiari is that there can be a
lot of variation between patients. There are differences between groups
like children and adults as well as differences between individuals. In
children, natural growth can change the anatomy of the malformation for
better or for worse. In adults, aging, trauma, medications, diseases that
affect the spine like arthritis and osteoporosis, and even events like child
birth can result in permanent or transient anatomical changes that can
affect symptoms.
Another
important consideration is the phase of the condition. When answering this
question, it is important to be specific. Asking if the condition will
progress in patients with herniated tonsils but who have no symptoms is an
entirely different question than asking if progression will occur in
patients already experiencing symptoms.
Definitions are
also important to consider particularly in patients without symptoms.
People with herniated tonsils and no symptoms may never become symptomatic
and thus should probably never be labeled as Chiari patients in the first
place. This has to do with definitions. At present, there is a tendency to
define Chiari on the basis of the length of herniation. Unfortunately, the
length of herniation does not correlate well with symptom severity. Symptom
severity depends in part as to whether or not the herniated tonsils impede
the drainage of cerebrospinal fluid from the skull. Whether or not the
tonsils impede flow depends on the overall shape of the tonsils and other
factors and not the length of the tonsils alone. Some people can have
significant herniation lengths but still have sufficient space at the base
of the skull to permit normal drainage and they can remain that way for the
rest of their natural life. While little data exists on the natural history
and progression of Chiari, the evidence that does exists seems to suggest
that most people with tonsil herniations will never become symptomatic.
Ideally, we would like a definition of the disease and diagnostic measure of
the condition such that symptomatic progression is highly predictable but
that doesn't exist at present.
There only
exists in the medical literature a couple of studies on the natural history
of Chiari1,2. In all cases, the studies are too small and too
short in observation time to make firm conclusions. Also, these studies
followed patients who were asymptomatic and whose malformations were found
incidentally following head MRIs taken for other reasons. These studies
show that about 10-15% of these patients will progress to a symptomatic
state requiring surgical decompression.
Unfortunately,
most people who ask about the progression of Chiari are those with existing
symptoms and no published studies on the natural history and progression of
Chiari in patients with existing symptoms exist. It is extremely important
to recognize that the progression of symptoms in asymptomatic and
symptomatic patients can not be assumed to be similar. In fact, anecdotal
observations suggests that it is very different and that symptom severity
more frequently increases in symptomatic patients. However, this anecdotal
observation is clouded by the fact that the severity of symptoms in
symptomatic patients is often masked by treatment with drugs. And, herein
lies a major problem and concern. Symptomatic patients being treated with
drugs are at risk of long term drug side effects as well as silent
progression of the disease that can lead to further neurological damage
including syringomyelia.
So, one
question that emerges is, “If progression is likely more common in
symptomatic patients then why do so many doctors tell patients that Chiari
doesn't progress or rarely progresses?”. Well, like the last question, it
depends, It depends on the specialty of the doctor, the doctor's personal
experience with Chiari, the manner in which doctors manage risk, the
doctor's communication style with patients, and even the doctor's approach
to managing his/her practice as a business.
When it comes
to Chiari there is a distinct difference between neurologists and
neurosurgeons. Neurologists primarily treat patients with either drugs or
physical therapy, not surgery. Chiari doesn't respond well to drug
treatment. As a result, Chiari patients end up at the neurosurgeon's office
and neurologists see less of them and therefore don't take the initiative to
learn more about the disease.
Many
neurologists have also been trained in the trenches as opposed to the class
room when it comes to Chiari and in this training environment have been
taught incorrectly that Chiari is not a real disease but an asymptomatic
malformation of the brain that is actually a variant of normal.
Consequently, they believe that patients with herniated tonsils that
complain about symptoms not explained by other diseases are suffering from
depression or mood disorders. They tell these patients that Chiari really
isn't responsible for their complaints and often prescribe pain medications
or antidepressants. Another possibility is that they will misdiagnose them
with diseases like fibromyalgia and refer them to a different specialist or
treatment with medications like Lyrica. Actually, in many cases, they may
be right but in certain cases they may be wrong.
When it comes
to neurosurgeons, the spectrum of response is considerably wider. Some
respond like the neurologists above but not as many. Others do a more
thorough work up that includes diagnostic tests such as Cine MRI and a
complete MRI of the spine. When these neurosurgeons arrive at a diagnosis
of symptomatic Chiari on the basis of clinical findings and Cine MRI, their
recommendation regarding decompression surgery can vary. Many will prefer
to wait and observe for a period of time. Why? Because decompression
surgery has a relatively high failure rate. Only about 20% will experience
a significant improvement while about 50 to 60% will not experience
improvement. The remaining fraction of about 20% will continue to worsen.
Also, even in symptomatic patients, progression is variable. Many will not
grow worse and a small fraction may improve with time. As a result, many
neurosurgeons take a wait and see approach even with patients chomping at
the bit so to speak for surgical treatment. And, importantly, when they
recommend surgery they stress that they can not promise improvement with
their goal or definition of success being an outcome where no further
progression will occur.
So, where does
all of this net out? For patients without symptoms who learn they have
Chiari as a result of tonsil herniation being discovered incidentally, the
scant data in the literature suggests that most of them will not progress to
a symptomatic stage. For patients who are symptomatic, it is important
first of all to get a complete work up that includes Cine MRI and an MRI of
the full spine. Those who do not get a Cine MRI and full spine MRI and who
walk away without a clear diagnosis for the cause of their symptoms should
not be satisfied and should continue to seek other opinions until a clear
diagnosis is reached. For those who receive a diagnosis of symptomatic
Chiari and whose symptoms interfere with their normal standard of living,
decompression surgery should be considered. For those whose symptoms are
mild to moderate, there is a distinct probability, although impossible to
quantify, that their symptoms may worsen. For these individuals, a wait and
see approach may be warranted taking care not to cloud the picture going
forward with too much drug treatment. Keep in mind that an increase in the
use of medication to manage symptoms is often a sign of worsen disease.
Chiari varies
greatly across individuals. The anatomy of each patient's malformation is
different. Patients also vary in their underlying health condition.
Symptom progression can occur but it is not possible to predict to what
extent it will occur or how fast. Current evidence which is inadequate
suggests that symptomatic patients are more likely to worsen than
asymptomatic patients. Finally, the decision to proceed with decompression
surgery depends on several factors including but not limited to the
severity of symptoms, objective evidence that cerebrospional fluid drainage
is impeded, the clinician's confidence that symptoms can not be attributed
to other diseases or conditions, and the patient's overall health status.
1J
Neurosurg Pediatr. 2008 Sep;2(3):179-87.
2Neurosurgery. 2001 Sep;49(3):637-40
-- Ray
D'Alonzo
** If you
would like to share your comments, thoughts, or ideas with Ray,
please send them to dalonzo.rp@gmail.com.
Due to the volume and nature of email received, individual responses are not
possible. **
[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.]
Return To Home
Read Past Ray's
Corner Articles
|