Tourette syndrome

• Simple tics, which are sudden, brief and repetitive and involve a limited number of muscle groups
• Complex tics, which are distinct, coordinated patterns of movements involving several muscle groups

Tics involving movement (motor tics) — often facial tics, such as blinking — usually begin before vocal tics do. But the spectrum of tics that people experience is diverse, and there's no typical case.

Causes

The exact cause of Tourette syndrome isn't known, and there's no known way to prevent it. Tourette is a complex syndrome, likely caused by a combination of genetic and environmental factors. Theories about the causes of Tourette include:

• Genetics. Tourette syndrome may be an inherited disorder. The specific genes involved in Tourette syndrome are still being defined, although one genetic mutation has been identified as a rare cause of Tourette syndrome.
• Brain abnormalities. Certain chemicals in the brain that transmit nerve impulses (neurotransmitters) may play a role, including dopamine and serotonin.

Risk factors

Having a family history of Tourette syndrome or other tic disorders may increase the risk of developing Tourette syndrome.

Complications

People with Tourette syndrome have a normal life span and often lead a healthy, active life. However, having Tourette syndrome may increase the risk of learning, behavioral and social challenges, which can mar self-image.

In addition, having Tourette syndrome means you're likely to have other related conditions, such as:

• Attention-deficit/hyperactivity disorder (ADHD)
• Obsessive-compulsive disorder
• Learning disabilities
• Sleep disorders
• Depression
• Anxiety disorders

Diagnosis

There's no specific test that can diagnose Tourette syndrome. Instead, doctors must rely on the history of the person's symptoms to diagnose the disorder.

The Diagnostic and Statistical Manual of Mental Disorders (DSM) determines the criteria for a diagnosis of Tourette syndrome. Published by the American Psychiatric Association, the DSM is used by mental health professionals to diagnose certain conditions and by insurance companies to reimburse for treatment.

The criteria to diagnose Tourette syndrome include:

• Both motor tics and vocal tics must be present, although not necessarily at the same time.
• Tics occur several times a day, nearly every day or intermittently, for more than a year. There must not be a break in tics for more than a three-month period.
• The onset of tics occurs before age 18.
• Tics aren't caused by medications, other substances or another medical condition.

Diagnosis of Tourette syndrome may be delayed because families and even doctors are sometimes unfamiliar with the symptoms or the symptoms may mimic other problems. Eye blinking may be initially associated with vision problems, for instance, while sniffing may be attributed to allergies.

Because tics and movement problems can be the result of other serious health conditions, your doctor may suggest having tests to rule out other problems. These tests include blood tests or neuroimaging studies, such as magnetic resonance imaging (MRI).

References

http://www.mayoclinic.org/diseases-conditions/tourette-syndrome/home/ovc-20163623

https://www.hse.ie/eng/health/az/T/Tourette's-syndrome/Causes-of-Tourette's-syndrome.html

http://www.webmd.com/brain/tourette-syndrome-nord

http://www.nhs.uk/Conditions/Tourette-syndrome/Pages/Introduction.aspx