When you visit your General Practitioner (PCP) with your medical
complaints related to CMT, usually, you will be referred to a
Neurologist(nerve doctor). The common complaints are numbness, pins
& needles (in a stocking and glove pattern), frequent tripping,
ankle sprains, and loss of balance.
The Neurologist will do a complete medical history paying particular
attention to your family history, if it is available. Family members ,who
have similar symptoms to yours, may be asked to come in to see the
Neurologist as well.
Then, you will be examined : the Neurologist
will observe: how you walk , whether you have high arches and other foot
or hand deformities, whether your hands and/or legs are thin compared to
the rest of your body .
Your skin will be pricked very lightly with a pin or other sharp
object, up and down your legs and arms to determine if you feel the touch
as sharp, dull, or not at all.
A piece of cotton, or kleenex may be used in the same way as the pin,
to find out if you feel soft touch.
A tuning fork, that is vibrating, will be used on specific bony
prominences (your elbows, wrists, hips, the outside of your knees,
ankles, fingers & toes). You will be asked if you feel the vibration
as well as when the vibration starts and also when it stops.
Your reflexes will be tested : your feet (Plantar or
Babinski)will be tested with a dull object that is run from your
heels, up the middle of the soles of your feet and across the balls of
your feet quickly; your ankles (Achilles),your knees
(Patellar), your wrists (Brachioradialis), and your elbows
(Biceps) are tested with a “reflex hammer”; and your abdomen
(Abdominal))is tested by running an object quickly and lightly
across the skin of your abdomen. These tests are done to find out if your
reflexes are normal . The Plantar or Babinski reflex causes your toes to
automatically curl if it is normal. It is only abnormal, when the brain or
spinal cord are involved, so the results of testing this reflex are
important in the diagnosis of CMT to help rule out diseases in the
brain.
In CMT Type I : the ankle,
knee, wrist, elbow reflexes are often absent.; in CMT type II
the reflexes are sometimes slow, but usually not absent
.
You will have your toes and fingers moved up and down by the doctor,
while your eyes are closed, to find out if you know which direction they
are being moved This tests for your ability to know where your body parts
are, without looking at them. (Proprioception)
Another test of your sense of where your body is in space, is standing
with your feet right together and eyes closed, if you automatically sway
or fall more than you do with your eyes open, then Romberg’s sign
is positive, which means you have difficulty knowing where parts of your
body are and that you are having problems with balance.
Once the physical examination is complete, the doctor often will ask
you to have an EMG(electromyography)done
. There are two parts to this test:
The first part tests your different
nerves for their ability to carry messages to the muscles,and the speed
(NCV-nerve conduction velocity) at which the messages are carried .
This test uses pads (electrodes) (like a heart ECG) , attached at
specific points along the muscle, a very small electric shock is applied
to measure the speed at which the shock travels to the muscle, causing the
muscle to contract. This test is done on both motor nerves
(MNCV)and sensory nerves (SNCV) In CMT Type I nerve
conduction speed is slowed. In CMT Type II the nerve
conduction speed is often normal or only mildly slowed. If you have
a muscle disease, the nerve conduction speed remains normal.
The second
part, tests the ability of your muscles to respond to
electrical impulses supplied by the nerves. This is the uncomfortable
part. Very thin needles (like those used for acupuncture) are inserted
into each muscle, and the activity of the muscle is recorded on an
oscilloscope (like a TV screen). The muscle activity produces a wave form,
which shows normal and abnormal muscle activity. The results of this will
show the condition of your muscles, whether you have a muscle disease or a
nerve disease, and the areas of your body that are involved. This part of
the test also helps the Neurologist to rule-out diseases of the muscles,
brain or spinal cord and to diagnose CMT.
After the EMG is done, you may be
asked to have Blood tests and Urine
tests, especially if there is no family history. These tests
are vital to the diagnosis, because they will eliminate other
treatable causes of your problem. For example: diabetes, vitamin B12
deficiency, heavy metal poisoning (eg.lead), nutritional deficiencies and
alcoholism etc. There are many disease which mimic CMT, which always need
to be ruled out.
A Muscle and Nerve biopsy, is the
next thing the doctor may want done. A small piece of muscle and diseased
nerve is removed and then examined under a microscope, and can lead to a
more definite diagnosis. Some CMTers experience slow healing ability and
this should be taken into consideration before a biopsy is done. The area
where the biopsy has been done, may take a long time to heal, and may be
quite painful. Discussing this with your doctor prior to the test is
important!
If the doctor has found an indication
of a demyelinating disease on your EMG (the covering of the
nerve:Myelin Sheath) is not intact, (imagine an electric cord with
the plastic cover having nicks in it), or there is a suspicion that you
may have Pressure Palsies, or evidence that the disease was
transmitted in a genetic X-Linked pattern by family history, you may be
asked to have DNA testing done.
The DNA testing which is commercially
available is limited to variants of CMT Type I and HNPP
(Hereditary Neuropathy with Liability to Pressure Palsies) and
X-linked CMT. There are several DNA Blood tests in the experimental
research stages for CMT Type II which should be available to all of us
within the next few years. Therefore, DNA testing can be used to
either diagnose specific types of CMT, or to rule those specific types
out, at this time .
Once the doctor has put all of this
information together, he can then diagnose CMT, because of the known
characteristics of the disease. Depending on the severity of your symptoms
and family history, often the physician can tell you if you have CMT
before completing all of the tests.
Make sure you ask questions of the doctor, and find out why certain
tests are necessary, get all of your questions answered...it is your
body!
