Spastic diplegia, the disorder first
described by Dr. Little in the 1860s, is only one of several disorders
called cerebral palsy. Today doctors classify cerebral palsy into four
broad categories -- spastic, athetoid, ataxic, and mixed forms --
according to the type of movement disturbance.
Spastic cerebral palsy. In this form of cerebral palsy, which affects
70 to 80 percent of patients, the muscles are stiffly and permanently
contracted. Doctors will often describe which type of spastic cerebral
palsy a patient has based on which limbs are affected. The names given
to these types combine a Latin description of affected limbs with the
term plegia or paresis, meaning paralyzed or weak. The four commonly
diagnosed types of spastic cerebral palsy are illustrated in the
figure.
When both legs are affected by spasticity, they may turn in and cross
at the knees. As these individuals walk, their legs move awkwardly and
stiffly and nearly touch at the knees. This causes a characteristic
walking rhythm, known as the scissors gait.
Individuals with spastic hemiparesis
may also experience hemiparetic tremors, in which uncontrollable
shaking affects the limbs on one side of the body. If these tremors
are severe, they can seriously impair movement.
Athetoid, or dyskinetic, cerebral palsy. This form of cerebral palsy
is characterized by uncontrolled, slow, writhing movements. These
abnormal movements usually affect the hands, feet, arms, or legs and,
in some cases, the muscles of the face and tongue, causing grimacing
or drooling. The movements often increase during periods of emotional
stress and disappear during sleep. Patients may also have problems
coordinating the muscle movements needed for speech, a condition known
as dysarthria. Athetoid cerebral palsy affects about 10 to 20 percent
of patients.
Ataxic cerebral palsy. This rare form affects the sense of balance and
depth perception. Affected persons often have poor coordination; walk
unsteadily with a wide-based gait, placing their feet unusually far
apart; and experience difficulty when attempting quick or precise
movements, such as writing or buttoning a shirt. They may also have
intention tremor. In this form of tremor, beginning a voluntary
movement, such as reaching for a book, causes a trembling that affects
the body part being used and that worsens as the individual gets
nearer to the desired object. The ataxic form affects an estimated 5
to 10 percent of cerebral palsy patients.
Mixed forms. It is common for patients to have symptoms of more than
one of the previous three forms. The most common mixed form includes
spasticity and athetoid movements but other combinations are also
possible.
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