Description

• A childhood-onset neurobehavioral disorder characterized by the presence of multiple motor and at least 1 phonic tic (see “Physical Exam”):
  • Tics are sudden, brief, repetitive, stereotyped motor movements (motor tics) or sounds (phonic tics) produced by moving air through the nose, mouth, or throat.
  • Tics tend to occur in bouts.
  • Tics can be simple or complex:
    • Motor tics precede vocal tics.
    • Simple tics precede complex tics.
  • Tics often are preceded by sensory symptoms, especially a compulsion to move.
  • Patients are able to suppress their tics, but voluntary suppression is associated with an inner tension that results in more forceful tics when suppression ceases.
• System(s) affected: Nervous

Epidemiology

• Predominant age:
  • Average age of onset: 7 years (3–8 years).
  • Tic severity is greatest at ages 7–12 years:
    • 96% present by age 11
  • Of children with Tourette syndrome (TS), 50% will experience complete resolution of symptoms by age 18 (based on self-reporting).
• Predominant sex: Male > Female (3:1)
• Predominant race/ethnicity: Clinically heterogeneous disorder, but non-Hispanic whites 2:1 compared with Hispanics and/or blacks

Prevalence
Estimated at 3:1,000 in children ages 6–17 years

Risk Factors

• Risk of TS among relatives: 9.8–15%.
• First-degree relatives of individuals with TS have a 10–100-fold increased risk of developing TS.

• Predisposition: Frequent familial history of tic disorders and obsessive–compulsive disorder (OCD)
• Precise pattern of transmission and genetic origin unknown. 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.
• Higher concordance in monozygotic compared with dizygotic twins; wide range of phenotypes

Pathophysiology

Abnormalities of dopamine neurotransmission and receptor hypersensitivity, most likely in the ventral striatum, play a primary role in the pathophysiology.

Etiology

• Abnormality of basal ganglia development
• Mechanism uncertain; 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
• Controversial pediatric autoimmune neuropsychiatric disorder association with Streptococcus (PANDAS) (1):
  • TS/OCD cases linked to immunologic response to previous group A β-hemolytic streptococcal infection (GABHS)
  • Thought to be linked to 10% of all TS cases
  • 5 criteria:
    • Presence of tic disorder and/or OCD
    • Prepubertal onset of neuropsychosis
    • History of sudden onset of symptoms and/or episodic course, with abrupt symptom exacerbation, interspersed with periods of partial/complete remission
    • Evidence of a temporal association between onset/exacerbation of symptoms and a prior streptococcal infection
    • Adventitious movements during symptom exacerbation (e.g., motor hyperactivity)

Commonly Associated Conditions

• ADHD and OCD are most common.
• Depression and anxiety are also concerns due to disruptive behavior problems that can lead to social difficulties and learning disorders.
• Impairments of visual perception, sleep disorders, restless leg syndrome, and migraine headaches are higher than in the general population.