| . |
|
Diagnosing Multiple Sclerosis: There is no laboratory test, symptom, or physical finding which, when
present or positive, always means a person has MS. In addition, some
of the symptoms of MS could also be caused by other diseases.
Consequently, the diagnosis of MS must be made by a careful process
which demonstrates findings that are consistent with MS, and that also
rules out other causes.
The basic "rule" for diagnosing MS relies on two criteria:
1.There must have been two attacks at least one month apart. An
attack, also known as an exacerbation, flare, or relapse, is a
sudden appearance of or worsening of an MS symptom or
symptoms which lasts at least 24 hours.
1.There must be more than one area of damage to central nervous
system myelin—the sheath that surrounds and protects nerve
fibers. The damage to myelin must have occurred at more than
one point in time and not have been caused by any other disease
that can cause demyelination or similar neurologic symptoms.
MRI Is Preferred Method of Imaging the Brain
MRI (magnetic resonance imaging) is currently the preferred method of
imaging the brain to detect the presence of plaques or scarring caused
by MS. It is better at detecting plaques than CT scanning. Often brains
that appear to be normal on CT scans will be shown to have plaques
on MRI.
Still, the diagnosis of MS cannot be made solely on the basis of MRI.
There are other diseases that cause lesions—areas of damage—in the
brain that look like those caused by MS. There are also spots found in
healthy individuals, particularly in older persons, that are not related to
any ongoing disease process.
On the other hand, a normal MRI does not absolutely rule out a
diagnosis of MS. About 5% of patients who are confirmed to have
MS on the basis of other criteria, do not show any lesions in the brain
on MRI. These people may have lesions in the spinal cord or may have
lesions which cannot be detected by MRI.
Clinical Exam Includes History and Tests of Function
Other symptoms of MS will be evaluated during the clinical
examination conducted by a physician. This covers an extensive review
of mental, emotional, and language functions, movement and
coordination, vision, balance, and the functions of the five senses. Sex,
birthplace, family history, and age of the person when symptoms first
began are also taken into consideration.
Sometimes, Other Tests Are Needed
It is not usually necessary to do all diagnostic tests for every patient. If,
however, a clear-cut diagnosis cannot be made based on the tests
above, additional tests may be ordered. These include tests of evoked
potentials, cerebrospinal fluid, and blood.
Evoked potential tests are electrical diagnostic studies which can show
if there is a slowing of messages in the various parts of the brain. They
often provide evidence of scarring along nerve pathways that is not
apparent on a neurologic exam. Cerebrospinal fluid, usually taken by a
spinal tap, is tested for levels of certain immune system proteins and for
the presence of oligoclonal bands. These bands indicate an abnormal
autoimmune response within the central nervous system, meaning the
body is producing an immune response against itself. Oligoclonal bands
are found in the spinal fluid of about 90-95% of people with MS, but
since they are present in other diseases as well cannot be relied on as
positive proof of MS. They may also take some years to develop.
While there is no definitive blood test for MS, blood tests can rule out
other causes for various neurologic symptoms. Some other conditions
that cause symptoms similar to those of MS are Lyme disease, a group
of diseases known as collagen-vascular diseases, certain rare
hereditary disorders, and AIDS.
National Multiple Sclerosis Society Can Provide Referrals If
some, but not all of the test results suggest MS, and other causes for
these results have been ruled out, a physician may diagnose "probable
MS" and repeat testing at a future date.
The National MS Society does not require people to have a definite
diagnosis before offering support, information, and services. Chapters
of the National MS Society can also provide referrals to area
physicians who have experience diagnosing and treating MS.
RELATED TOPICS:
CEREBROSPINAL FLUID (CSF)
CLINICS/COMPREHENSIVE CARE CENTERS
DIAGNOSIS OF DEMYELINATING DISEASES
EVOKED POTENTIALS (EP)
MAGNETIC RESONANCE IMAGING (MRI)
SYMPTOMS
SOURCE: NMSS Information Resource Center and Library.
Compendium of Multiple Sclerosis Information (CMSI). ã 1997,
National Multiple Sclerosis Society. Rev. 10/97 |
|
