C
central nervous system The collective structures
of the BRAINand SPINAL CORD, exclusive of the CRA-
NIAL NERVESandSPINAL NERVES(the cranial nerves
and the spinal nerves, along with their branches,
make up the PERIPHERAL NERVOUS SYSTEM). The cen-
tral nervous system functions as the master con-
trol center for the body, maintaining processes to
support basic survival as well as conducting com-
plex voluntary and conscious activities. The cra-
nium (skull) and spinal column (vertebrae)
enclose and protect the central nervous system.
For further discussion of the central nervous
system within the context of the structures and
functions of the nervous system, please see the
overview section “The Nervous System.”
See also COMA; CONSCIOUSNESS; SKELETON; UNCON-
SCIOUSNESS.
cerebral palsy Disturbances of motor movement
resulting from damage to the structures of the
BRAINresponsible for movement, notably the basal
ganglia. About 500,000 Americans, children and
adults, have cerebral palsy. Cerebral palsy is per-
manent though nonprogressive (does not worsen
over time). Though cerebral palsy often is congen-
ital (present at birth) and may result from GENE
MUTATION, it is not hereditary (passed from parents
to child).
Neurologists believe about 90 percent of the
damage that results in cerebral palsy occurs in
PREGNANCYduring the development of the NERVOUS
SYSTEM, sometimes long before birth. Known
causes of such damage include INFECTION, such as
RUBELLA(German MEASLES) and TOXOPLASMOSIS,in
the mother during pregnancy and interruptions of
BLOODflow to the developing fetus. These events
may disrupt critical stages of brain development.
The most vulnerable times are 3 to 20 gestational
weeks, 26 to 34 gestational weeks, and 36 to 40
gestational weeks.
About 10 percent of cerebral palsy occurs as a
result of injuries that occur during or after birth
that deprive the brain of oxygen (HYPOXIA). Other
known causes of cerebral palsy acquired in the
early postnatal period include untreated NEONATAL
JAUNDICE (JAUNDICE of the newborn), Rh factor
BLOOD TYPEincompatibility, and head injury such
as may occur in MOTOR VEHICLE ACCIDENTSor falls.
Most often the causes of cerebral palsy in an indi-
vidual remain uncertain and likely represent a
combination of circumstances (multiple factors).
Cerebral palsy has widely variable presenta-
tions. These presentations help determine the
stage of development—prenatal, perinatal, or
postnatal—in which the damage to the brain
occurs. Other conditions that often accompany
cerebral palsy include HEARING LOSS, VISION IMPAIR-
MENT, developmental disorders, LEARNING
DISORDERS, intellectual impairment, and SEIZURE
DISORDERS. These conditions reflect damage to
other structures of the brain that may have
occurred as a result of exposure to the same event
or circumstance responsible for the cerebral palsy
(especially hypoxia). Doctors classify the forms of
cerebral palsy according to the pattern of symp-
toms present. The four general classifications cur-
rently in use are spastic, athetoid (dyskinetic),
ataxic, and mixed.
Spastic cerebral palsy Spastic cerebral palsy
affects about 70 percent of those who have cere-
bral palsy and is the “classic” form first docu-
mented by English physician William Little in the
mid-1800s. In spastic cerebral palsy the affected
muscles are in a state of continuous contraction,
causing them to feel and appear stiff. Spasticity
affects motor movement and balance. Over time238