About a month ago, my family doctor sent me for a head ct because I
was having headaches.  The radiologist's report indicates that there
is an "ill-defined, small hypodense area in the white matter of the
right frontal lobe of uncertain etiology.  If clinically indicated,
MRI of the head may be useful for further evaluation."  My family
doctor said it was imperative that I have an MRI immediately.  She
said the the hypodense area might indicate MS.  I decided to get a
second opinion before proceeding with the MRI.  The second doctor
stated that small hypodense areas are very common and the cause
generally can't be identified without doing a brain biopsy which is
not warranted when the only symptom is headache.  The second doctor
did not believe any further testing was indicated so long as I did not
have any symptoms of neurological impairment.  I've read that CT scans
are notorious for detecting all kinds of things that are totally
benigne and that they often lead to a lot of unnecessary patient
anxiety and follow-up testing.  I also understand that the use of CT
scans when the only symptom is headache is questionable.  I am
positively terrified of having an MRI.  I am extremely claustrophobic,
and I have had some very traumatic and frightening experiences with
medical tests.  I understand that MRI's also have a high rate of false
positives.  I would hate to endure a bunch of invasive follow-up tests
just to learn that everything is fine.  The second doctor I consulted
said that a diagnosis of MS should not even be considered absent
symptoms of neurological impairment.  How likely is it that the
hypodense area is a serious threat to my health?  What are the
possible reasons for the hypodense area?  Are there any non-invasive
tests, other than an MRI, that might be useful?  I understand there
are some simple, non-invasive, tests that can tell a lot about a
person's neurological health when administered by a skilled person. 
Also, I am breastfeeding a baby at this time, and I have receiving
conflicting advice about the safety of contrast dye while
breastfeeding.

Thanks for your question.  The hypodense area in the frontal lobe that
you describe on CT could be due to several diseases, including MS.  As
your 1st doctor suggested, MRI is more useful (sensitive) to
demonstrate MS lesions, which are usually located around the
ventricles of the brain (the open areas near the core of the brain
containing cerebrospinal fluid).  Other common locations include the
corpus callosum (structure that connects the two hemispheres of the
brain), deep white matter structures and basal ganglia (generally
involved in movement).  To make a diagnosis of MS, one must see two
lesions in the brain or spinal cord on MRI imaging, or the patient
must have had two seperate episodes of symptoms.  The lesions are
initially poorly defined (have fuzzy borders), but later become more
localized.  CT scans can miss about 50% of lesions, even with high
doses of contrast agent.

Symptoms typically include numbness, weakness or visual problems.
Sensory symptoms may include paresthesias, burning, tightness,
diminished sensation, and so on.  Less commonly, symptoms may include
vertigo (room spinning), problems with walking, sexual dysfunction,
among others.  Headache is not commonly seen as a symptom of MS, but
can be a symptom of other brain abnormalities.  They can also be
caused by stress, tension, caffeine withdrawal, medications,
migraines, and a host of other things.  A neurologist could better
evaluate the cause of your headaches if they persist.

As was commented on, open MRI is an open if you are claustrophobic. 
The resolution of these images is not quite as good as with a standard
MRI, however they are not that bad.  An MRI of the spinal cord should
be included as well, since MS may cause problems there as well. 
Another option may be to take an anti-anxiety medication just prior to
the scan (such as Ativan) - this is commonly done for claustrophobic
patients such as yourself.

Other things that a hypodense frontal area on CT scan could be
artifact (something that's not really present), blood (usually
hyperintense on CT), and numerous inflamatory conditions.  A spinal
tap is sometimes performed so that cerebrospinal fluid can be analyzed
for proteins typically found in MS patients.  Since you are a
breastfeeding mom, you are still in the age range where MS is a
possibility.  The likelihood of MS in someone over about the age of 40
starts to diminish.  MS is also more common in women, as with other
auto-immune diseases.  A long list of diseases that can look like MS
can be found at this site:
http://www.mult-sclerosis.org/differentialdiagnosis.html

The contrast agent used with MRI (Gadolinium) has not been shown to
harm breastfeeding babies.  It is possible that a child may rarely
have an allergic reaction to the contrast.  Also, one group found that
less than 0.04% of injected contrast agent is excreted into
breastmilk.  Here's a link to the paper:   [a discussion of this paper
is found at the link below]
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10924585&dopt=Abstract
The full paper is here:
http://radiology.rsnajnls.org/cgi/content/full/216/2/555

Breastfeeding is sometimes stopped for 24 hours following the
administration of Gadolinium contrast.  An easy-to-read editorial on
the topic (and discussion of the above paper) is found here:
http://radiology.rsnajnls.org/cgi/content/full/216/2/325

The decision to have an MRI performed is ultimately up to you.  If you
can tolerate it, the scan may set your mind at ease that nothing is
wrong; It may also allow you to get treatment early if there is some
type of disease - brain disease treated early generally responds
better than when it is allowed to advance prior to intervention.

More detailed information can be found at these websites:

http://www.neurohaven.com/ms1.htm
http://www.nationalmssociety.org/
http://www.intelihealth.com/IH/ihtIH/WSIHW000/8320/8320.html  [Harvard
Med site]
http://directory.google.com/Top/Health/Conditions_and_Diseases/Neurological_Disorders/Demyelinating_Diseases/Multiple_Sclerosis/

I hope this was helpful.  Feel free to ask for clarification.

   -welte-ga.

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Request for Answer Clarification by councelor-ga on 11 Oct 2003 21:16 PDT

Thank you very much for your answer.  It did clarify some things for
me.  I understand that people occasionally do have fatal allergic
reactions to the contrast dye.  I don't want to die of an allergic
reaction, even a rare one.  Is there any way to test for an allergy
ahead of time?  For example, by adminstering a small amount of the dye
prior to the MRI to see if the person has an allergic reaction?

---

Clarification of Answer by welte-ga on 11 Oct 2003 23:05 PDT

See clarification above.

I don't know if the MRI is necessary or not, but in regards to
claustrophobia, there is a newer type of MRI called an open MRI, in
which you don't have to be placed into a tube or tunnel - it just has
an arm which goes over you and has been great for people with
claustrophobia, as well as younger children.  If you determine with
your doctors that you do need an MRI, see if this is available in your
area.

The rate of allergic reactions to gadolinium is about 1/20,000 people.
 The rate of serious reactions is estimated to be 1/350,000 to
1/450,000.  The less severe reactions are typically limited to hives
and resolve within one day of administration.  The gadolinium used as
contrast in MRI scans is different from the iodine-based contrast used
in CT scans, which has a higher rate of serious allergic reactions. 
I'm not familiar with persons being pre-tested for sensitivity to
gadolinium, perhaps because the adverse reaction rate is so low.

More details can be found in the following paper, which is
unfortunately not available for free online.  The abstract is given at
the site below:
http://www3.interscience.wiley.com/cgi-bin/abstract/72514140/ABSTRACT

Some other information is also available in this abstract:
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=8130951&dopt=Abstract

      -welte-ga

Just a bit of constructive feedback for welte-ga.  Your answer was
very helpful and you are right about my age.  I am 39 which means I am
still barely within the age range when MS is typically diagnosed. 
However, you cannot assume that all nursing moms are under 40.  Some
women have babies after 40 (becoming increasingly more common these
days) and even after fifty (generally only with medical assistance but
it happens).  Just thought I would throw that out.  Thanks again for
your input.