Description

Tourette syndrome (TS) is a childhood-onset neurobehavioral disorder characterized by the presence of multiple motor and at least one phonic tic.

• Tics are sudden, brief, repetitive, stereotyped motor movements (motor tics) or sounds (phonic tics) produced by moving air through the nose, mouth, or throat.
• Patients can suppress their tics, but this often causes inner tension that eventually results in more forceful tics.
• System(s) affected: nervous

Epidemiology

Incidence

• Average age of onset: 7 years with greatest tic severity between 10 and 12 years (1)
• Male > female (3:1); heterogeneous disorder, but non-Hispanic whites (2:1) compared with Hispanics and/or blacks

Prevalence
0.77% overall in children (1.06% in boys, 0.25% in girls)

Etiology and Pathophysiology

Abnormalities of dopamine neurotransmission and receptor hypersensitivity, most likely in the ventral striatum, play a primary role in the pathophysiology; may involve dysfunction of basal ganglia–thalamocortical circuits, likely involving decreased inhibitory output from the basal ganglia, which results in an imbalance of inhibition and excitation in the motor cortex

• Thought to result from a complex interaction between social, environmental, and multiple genetic abnormalities
• Controversial pediatric autoimmune neuropsychiatric disorder associated with streptococcal infection (PANDAS); TS/OCD cases linked to immunologic response to previous group A β-hemolytic Streptococcus (GABHS)

Genetics

• Predisposition: frequent familial history of tic disorders and OCD
• Recent studies suggest polygenic inheritance with evidence for a locus on chromosome 17q; sequence variants in SLITRK1 gene on chromosome 13q also are associated with TS.

Risk Factors

• Risk of TS among relatives: 9.8–15%
• Low birth weight, maternal stress, nausea/vomiting in 1st trimester, maternal smoking (2)

Commonly Associated Conditions

• OCD (28–67%), ADHD (50–60%), conduct disorder, learning disabilities (23%)
• Depression/anxiety including phobias, panic attacks, and stuttering; increased risk of contemplating suicide (1)
• Impairments of visual perception, sleep disorders, restless leg syndrome, and migraine headaches
• Cardiometabolic disorders, especially obesity, circulatory system diseases, type 2 diabetes (50%) (3)