Webster's New World Medical Dictionary

myeloencephalitis
See 
encephalomyelitis.
myelofibrosis
Spontaneous scarring (fibrosis)
of the bone marrow that disrupts the normal pro-
duction of blood cells, leading to severe anemia and
enlargement of the spleen and liver. Myelofibrosis
usually begins slowly and worsens over time. It can
be associated with a variety of diseases, primarily
myeloproliferative (preleukemic) disorders. Also
known as agnogenic myeloid metaplasia.
myelogenous
See 
myeloid.
myelogram
An X-ray test of the spinal cord and
the bones of the spine. A myelogram is used to detect
impingement of the spinal cord by bone, disc, or
other tissues.
myeloid
Referring to myelocytes, a type of white
blood cell. Also known as myelogenous.
myeloma
See 
multiple myeloma.
myelomeningocele
See 
meningomyelocele.
myeloproliferative disorder
One of the malig-
nant diseases leading to overproduction of certain
bone marrow cells, including those that give rise to
the red blood cells, the granulocytes, and the blood
platelets. The myeloproliferative disorders include
chronic myelogenous leukemia, chronic idiopathic
myelofibrosis, essential thrombocythemia, chronic
neutrophilic leukemia, chronic eosinophilic
leukemia, and polycythemia vera.
myocardial infarction
See 
heart attack.
myocardial infarction, acute
See 
acute
myocardial infarction.
myocarditis
Inflammation of the heart muscle.
Inflammation of heart muscle can be caused by
viruses, medications, parasites, or underlying dis-
eases. Treatment depends on the cause.
myocardium
The heart muscle.
myoclonic twitch
A rapid, involuntary muscle
contraction, particularly near the eye. Myoclonic
twitches resemble and may be mistaken for tics.
Like tics, they tend to occur more often when the
person is under stress; unlike tics, they are not pre-
ceded by any sensation and they cannot be delayed.