Tourette Syndrome

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Basics

Description

Tourette syndrome (TS) is a movement disorder most commonly seen in school-age children; a childhood-onset neurobehavioral disorder characterized by the presence of multiple motor and at least one 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

Incidence
  • The onset occurs before 18 years of age.
  • Predominant age
    • Average age of onset: 7 years (3 to 8 years)
    • Tic severity is greatest at ages 7 to 12 years.
      • 96% present by age 11 years
    • Of children with TS, 50% will experience complete resolution of symptoms by age 18 years (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

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.

  • Abnormality of basal ganglia development
  • Thought to result from a complex interaction between social, environmental, and multiple genetic abnormalities
  • Mechanism is 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 associated with streptococcal infection (PANDAS)
    • TS/OCD cases linked to immunologic response to previous group A β-hemolytic Streptococcus (GABHS)
    • Thought to be linked to 10% of all TS cases
    • Five 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)
Genetics
  • Predisposition: frequent familial history of tic disorders and 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

Risk Factors

  • Risk of TS among relatives: 9.8–15%
  • First-degree relatives of individuals with TS have a 10- to 100-fold increased risk of developing TS.
  • Low birth weight, maternal stress during pregnancy, severe nausea and vomiting in 1st trimester

Commonly Associated Conditions

  • OCD (28–67%)
  • ADHD (50–60%)
  • Conduct disorder
  • Depression/anxiety including phobias, panic attacks, and stuttering
  • Learning disabilities (23%)
  • Impairments of visual perception, sleep disorders, restless leg syndrome, and migraine headaches

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