Your doctor has just ordered a test called
an EMG. EMG stands for Electromyogram which loosely translated means
electrical testing of muscles but in fact has come to mean electrical
testing of nerves and muscles. The EMG is performed by a specialist,
the Electromyographer, who is usually a Neurologist or a Physiatrist.
Parts of the test (the nerve conductions) may be performed by a
specially trained technician. It is an in-office procedure and does
not require hospitalization. On average, an EMG takes anywhere between
30 minutes and 2 hours, depending on how extensive a testing your
doctor orders on you. It can be done at any time during the day
and, with few exceptions, does not require any special preparation.
Sometimes EMGs are thought to be a treatment
of some sort, or a type of acupuncture. This is not true; an EMG
is only a test, much like an EKG or an X-ray are tests and not treatments.
What are some problems for which EMGs are
EMGs are usually ordered when patients are having problems with
their muscles or nerves. They test the nerves and muscles of the
bodys extremities, looking for a problem in either one of
these areas. An EMG may be ordered to see if you have a pinched
nerve in the back or the neck. If you have tingling or numbness
in your arms or legs, an EMG may show if you have a nerve entrapment
somewhere or a nerve injury. Weakness of the muscles or fatigue
(tiredness) may be indicative of nerve or muscle disease and require
an EMG. There are many other medical problems that might suggest
the need for an EMG. If you have any doubts as to why you need this
test, ask your doctor.
What happens during an EMG?
During this test, you will be lying on an examination table,
next to an EMG machine (which looks like a desktop or laptop computer).
The test consists of two parts, though at times one may be done
without the other. The first part is called Nerve Conduction Studies.
In this part some brief electrical shocks are delivered to your
arm or leg in an effort to determine how fast or slowly your nerves
are conducting the electrical current and therefore in what state
of health or disease they may be. You see, a nerve works something
like an electrical wire. If you want to see if the wire is functioning
properly, the easiest thing to do is to run electricity through
it. If there are any problems along its length, you will know it
by a failure of the current to go through. To do this, the doctor
will attach small recording electrodes to the surface of one part
of your limb, and will touch your skin at another point with a pair
of electrodes delivering the shock. When this happens, you will
feel a tingling sensation that may or may not be painful. Between
the brief shocks you will not feel pain. As there are several nerves
in each extremity which need to be tested, the procedure is repeated
3 or 4 times or more per extremity studied. The amount of current
delivered is always kept at a safe level. Patients wearing pacemakers
or other electrical devices need not worry since this current will
rarely interfere with such devices. During the nerve conduction
study, the doctor or the technician performing the study will occasionally
be pausing to make calculations and measurements.
The second part of the test is called Needle
Examination and as the name implies, involves some needle sticking.
The needles used are thin, fine and about one and a quarter inches
long. This part tests the muscle to see if there has been any damage
to it as a result of the nerve problem or if the disease involves
the muscle itself rather than the nerve. Usually 5 to 6 muscles
are sampled in one extremity, but occasionally, if you have problems
in more than one area, additional muscles may need to be studied.
The needle is usually inserted in the relaxed muscle and moved inside
gently in order to record the muscle activity. When this is done,
you will be able to hear the sound of the muscle activity amplified
by the EMG machine; it will sound something like radio static. The
painful part of this section is when the needle is first inserted
through the skin since all of the pain receptors are located in
this area. Once inside the muscle, the sensation is usually perceived
as discomfort or pressure rather than pain. During the needle exam,
no electrical shocks are delivered. Also, since the needle probe
is used here only as a recording device, no injections are given
through the needle into the muscle. On the average, a muscle can
be sampled in 2 to 5 minutes though this may vary with the type
of problem being investigated.
How long does an EMG take?
The nerve conduction part of the test usually takes longer than
the needle exam because one needs to make calculations and measurements
during it. On average, if one extremity is studied, the nerve conductions
take anywhere between 15 and 30 minutes. The needle exam for one
extremity usually takes 15 to 20 minutes. You can count on being
in the examination room for about one hour if only one extremity
is requested; longer if more extremities need to be tested.
What kind of preparations are necessary
for an EMG?
Few preparations are needed on the day you have an EMG. You
do not need to fast, or eat any particular kinds of food before
the test. You can drive yourself to and from the test, so you do
not need to bring a friend or a relative with you, any more than
you would say if you went to the dentist. You can count on resuming
your regular activity after the test is completed. As for clothing,
it is not as much what you wear as it is what you dont wear.
Since in a great majority of cases the low back and buttocks area
may need to be studied or in cases of neck problems, the back of
the neck and shoulder areas studied, it is best not to wear clothes
which will interfere with access to these areas.
With few exceptions, you may continue taking
medication prescribed by your physician as ordered without this
interfering with the EMG. However, if you are taking a blood thinner,
you should notify the Lab where your EMG is being done, since in
that case the needle part of the test may cause bleeding inside
the muscle. Also if you are on any medication for Myasthenia Gravis
such as Mestinon or other, your medication may interfere with the
test, so you should also notify the Lab. If you have any doubts
about other medications you are taking, it is best to check with
the Lab to be on the safe side.
Can I ask for some pain medication?
Different labs have different policies about pain medication.
Some physicians may recommend you take two Aspirins or Tylenols
before the test. Others may mail you a prescription drug to take
an hour before the test. Sometimes you may be given an injection
prior to the test. It is common however, that no sedation is given
in any form since in most instances, patients wish to return to
work or other regular activity after the test is completed. Another
reason for not giving sedation is that you should always have someone
accompany you to drive you home after receiving sedation and this
is not always easy to arrange.
How soon will I find out the results?
Though the physician performing the test has a general idea
of what the findings are during the test, the full results are only
arrived at after more calculations and measurements are performed
after the end of the test. The results are therefore usually not
ready until later that day or even the next in complicated cases.
They are usually not released directly to the patient. Instead they
will be conveyed to the referring physician since he or she has
to assess the results in light of the patients other findings.
How much will an EMG cost?
As a rule the more areas you need studied, the more the test
will cost. However costs may vary from one physician to another
and is different in different states. It is always best to inquire
about cost with your physician.
Most insurance policies cover EMGs, though
frequently the coverage is not 100% and the primary care or insurance
physician will have to OK it before it can be ordered. It is best
to have your doctors office find out what kind of coverage
you have for an EMG.