Gilles de la Tourette syndrome is a disorder of the nervous system that causes a person to make repeated and uncontrolled (involuntary) movements and sounds (vocalizations) called tics. The disorder is commonly called Tourette syndrome.

Tourette syndrome is named for Georges Gilles de la Tourette, who first described this disorder in 1885. There is strong evidence that Tourette syndrome is passed down through families, although the gene has not yet been found.

The syndrome may be linked to problems in certain areas of the brain, and the chemical substances (dopamine, serotonin, and norepinephrine) that help nerve cells talk to one another.

Tourette syndrome can be either severe or mild. About 10% of Americans have a mild form. Many people with very mild tics may not be aware of them and never seek medical help.

Tourette syndrome is four times as likely to occur in boys as in girls.

Most people first notice symptoms of Tourette syndrome during childhood, between ages 7 and 10.

The most common first symptom is a facial tic. Other tics may follow. A tic is a sudden, rapid, repeated movement or voice sound (vocalization). Tics can include:

• Arm thrusting
• Eye blinking
• Jumping
• Kicking
• Repeated throat clearing or sniffing
• Shoulder shrugging

Tics may occur many times a day, but they tend to improve or get worse at different times. The tics may change with time.

Contrary to popular belief, use of curse words or other inappropriate words or phrases (coprolalia) occurs in only a small number of patients.

Many patients say that the tics are not totally out of their control (involuntary), but that "things just would not feel right" if they did not do them. This is what makes Tourette syndrome different from obsessive-compulsive disorder (OCD) -- people with OCD feel as though they have to do the behaviors.

There are no lab tests to diagnose Tourette syndrome. However, a health care provider should do an examination to rule out other causes of these symptoms.

To be diagnosed with Tourette syndrome, a person must:

• Have had many motor tics and one or more vocal tics at some time, although not necessarily at the same time.
• Have tics that occur many times a day, nearly every day or on-and-off, for a period of more than 1 year. During this period there must not be a tic-free period of more than 3 months in a row.
• Have started the tics before age 18.