|
TOURETTE SYNDROME |
|
Tourette syndrome
(TS) is an inherited neurological disorder that
typically appears in |
|
childhood. The main
features of TS are repeated movements and
vocalizations called tics. |
|
TS can also be
associated with behavioral and developmental
problems. |
|
|
|
Description |
|
Tourette syndrome is
a variable disorder with onset in childhood.
Though symptoms can |
|
appear anywhere
between the ages of two and 18, typical onset is
around age six or seven. |
|
Tics, which may be
motor or vocal, tend to wax & wane (increase and
decrease) in severity |
|
over time. Facial
tics, such as rapid blinking or mouth twitches,
are the most common initial |
|
sign of TS. Other
early symptoms include involuntary sounds such as
throat clearing and |
|
sniffing, or tics of
the limbs. Symptoms usually intensify during
teenage years and diminish in |
|
late adolescence or
early adulthood. Patients may also develop
co-occurring behavioral |
|
disorders, namely
obsessive-compulsive disorder (OCD), attention
deficit hyperactivity |
|
disorder (ADHD) or
attention deficit disorder (ADD), poor impulse
control, &/or sleep disorders. |
|
Though some children
have learning disabilities, intelligence is not
impaired. TS is not |
|
degenerative and
life span is normal. |
|
|
|
Tourette syndrome is
classified by the Diagnostic and Statistical
Manual of Mental Disorders, |
|
Fourth Edition Text
Revision (DSM-IV-TR) as a "Tic Disorder." The
International Classification |
|
of Disease and
Related Health Problems, Tenth Revision (ICD-10)
calls TS a "combined vocal |
|
and multiple motor
tic disorder (de la Tourette's syndrome)." A
French neurologist, Jean Marc |
|
Itard, described the
first known case of Tourette syndrome in the 1825.
He had recorded the |
|
ticcing and cursing
behavior of an aristocratic woman, Madame de
Dampierre. The disorder is |
|
named for another
French physician, Georges Gilles de la Tourette,
who reported a series |
|
of cases in 1885,
the primary example of which was the marquise.
Tourette syndrome may |
|
also be referred to
as Gilles de la Tourette syndrome (GTS). |
|
|
|
Demographics |
|
Tourette syndrome
occurs worldwide, in people of all racial and
ethnic groups. It is thought |
|
that approximately
200,000 people in the United States have TS. About
three-quarters of |
|
patients are males.
Once thought to be a rare disorder, TS is one of
the most common |
|
genetic conditions.
Recent estimates of prevalence suggest that TS
occurs in one in 1,000 |
|
to one in 100 male
children. One report indicated that prevalence may
be as high as 25% in |
|
children in special
education classes. |
|
|
|
Causes and
Symptoms |
|
Genetic factors are
believed to play a major role in the development
of TS. Several |
|
chromosomal regions
have been identified as possible locations of
genes that confer |
|
susceptibility to
TS. Some family studies have indicated that TS is
inherited in an autosomal |
|
dominant manner. In
an autosomal dominant condition, an individual has
a 50% chance to |
|
pass the gene to his
or her children. Not everyone who inherits a TS
gene will show |
|
symptoms.
Approximately 70% of females and 99% of males with
a TS gene will express
|
|
symptoms. An
individual who inherits the TS gene may develop
TS, a milder tic disorder, |
|
obsessive-compulsive
disorder (OCD) without any tics, or no signs of
TS. The gender of a |
|
person influences
the expression (the disease symptoms and severity)
of the TS gene; |
|
males are more
likely to have TS or tics and females are more
likely to have OCD. |
|
Approximately one in
ten children who inherit the TS gene from a parent
will show symptoms |
|
that are severe
enough to warrant medical treatment. |
|
|
|
Non-genetic factors
are also believed to contribute to the development
of TS. In about |
|
10-15% of cases, TS
is not genetic. Certain stressful processes during
gestation (pregnancy) |
|
or at the time of
birth may increase the chance for a person to
develop TS. For example, |
|
it is known that
when both twins have TS, the twin who weighed less
at birth tends to have
|
|
more severe tics.
Other non-genetic factors that may predispose a
person to TS include: |
|
severe psychological
trauma, recurrent daily stresses, extreme
emotional excitement, |
|
PANDAS (pediatric
autoimmune neuropsychiatric disorder with
streptococcal infection), drug |
|
abuse, and certain
co-existing medical or psychiatric conditions. In
PANDAS, children |
|
experience an abrupt
onset of TS symptoms and/or obsessive-compulsive
symptoms following |
|
a strep throat
infection. |
|
|
|
It is thought that
TS is the result of abnormal metabolism of a
neurotransmitter (a chemical |
|
in the brain that
carries signals from one nerve cell to another)
called dopamine and possibly |
|
of other
neurotransmitters including serotonin and
norepinephrine. As of December 2003, |
|
the exact mechanisms
by which the TS gene or genes lead to disease
symptoms were
|
|
unresolved. It is
hoped that locating the gene or genes responsible
for TS will improve |
|
understanding of how
TS develops and eventually will lead to more
effective treatments. |
|
|
|
Tics seen in
patients with TS can range in intensity,
frequency, duration, type & complexity. |
|
Although there is
wide range of severity observed in TS, the
majority of cases are mild. |
|
A minority of
patients has symptoms that are severe enough to
interfere with daily |
|
functioning. In the
most severe cases, patients experience numerous
debilitating tics during |
|
all waking hours.
Tics usually occur in "bouts" with many tics over
a short interval of time. |
|
Many patients
experience waxing and waning (fluctuations in
severity) of their tics over the |
|
course of weeks or
months. Tics can be made worse by stress or
fatigue & tend to improve |
|
when the individual
is absorbed in an activity or task that requires
concentration. Although
|
|
the tics associated
with TS are involuntary (not deliberate), people
with TS can sometimes |
|
control their tics
for a period of time ranging from minutes to
hours. However the tic must |
|
eventually be
expressed and will come out. Coprolalia, a
sensationalized type of tic in which |
|
people make obscene
or socially inappropriate comments, is present in
less than 15% of TS |
|
patients. |
|
|
|
Tics are classified
as either simple or complex. Simple tics are
sudden, repetitive movements |
|
that involve a
limited number of muscle groups. Simple motor tics
are fast & without purpose. |
|
They can cause both
emotional and physical pain (such as head jerking
or jaw snapping). |
|
Simple vocal tics
are meaningless sounds or noises. Complex tics are
coordinated patterns of |
|
stepwise movements
that involve multiple muscle groups. Complex motor
tics appear slower |
|
and more deliberate
than simple motor tics. Complex vocal tics involve
meaningful words, |
|
phrases or
sentences. |
|
|
