Tourette Syndrome Health Article

Definition

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 and 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, and/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 and 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 and 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 and 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.

SIMPLE MOTOR TICS

• blinking eyes
• jerking head
• shrugging shoulders
• facial grimacing
• rolling eyes up
• squinting
• smacking lips
• jaw snapping

SIMPLE VOCAL TICS

• throat clearing
• yelping
• sniffing
• tongue clicking
• grunting
• coughing
• spitting
• humming
• whistling

COMPLEX MOTOR TICS

• jumping
• touching other people or things
• smelling
• twirling about
• thrusting of arms, groin, or torso
• pinching
• fiddling with clothing
• self-injurious actions including hitting or biting oneself (rare)

COMPLEX VOCAL TICS

• uttering words or phrases out of context
• repeating words or sounds
• stuttering
• repeating others' words (echolalia)
• repeating one's own last word or sound (palilalia)
• talking to oneself
• muttering
• vocalizing socially unacceptable words (a rare tic called coprolalia)