Tics are sudden, rapid, non-rhytmic, repetitive, motor movements or vocalizations. The mean age of onset is approximately 5 years old.
Tourette's syndrome is the most common form of tic disorder.
There is a strong genetic component showing a 10- to 100-fold increase in the rates of tics and Tourette's syndrome among first-degree relatives of Tourette's syndrome patients.
Simple motor tics are restricted to a single or a few muscle groups and last less than a fraction of a second.
Complex motor tics involve larger muscle groups, usually last longer and appear purposeful and goal-directed.


  • Mean age of onset is approximately 5 years
  • There is a strong genetic component showing a 10- to 100- fold increase in the rates of tics & Tourette's syndrome (TS) among 1st-degree relatives of Tourette's syndrome patients



  • Sudden, rapid, non-rhythmic, repetitive, motor movements or vocalizations


Primary Causes of Tic Disorders

Inherited Tic Disorders

  • Tourette’s syndrome (TS)
  • Huntington’s disease
  • Primary dystonia
  • Neuroacanthosis

Sporadic Tics

  • Transient motor or phonic tics (<1 year duration)
  • Chronic motor or phonic tics (>1 year duration)
  • Adult-onset (recurrent tics)
  • Tourette's syndrome

Secondary Causes of Tic Disorders

Primary Neurologic Disorders

  • Head trauma
  • Stroke
  • Encephalitis
  • Carbon monoxide poisoning
  • Neurosyphilis
  • Sydenham’s chorea
  • Hypoglycemia
  • Down syndrome
  • Tuberous sclerosis
  • Fragile X syndrome
  • Klinefelter’s syndrome
  • Chromosomal disorders
  • XYY karyotype
  • Duchenne’s disease
  • Hallervorden-Spatz disease
  • Creutzfeldt-Jakob disease

Primary Neuropsychiatric Disorders

  • Mental retardation
  • Schizophrenia
  • Asperger’s syndrome/autism

Drugs Which May Induce or Worsen Tics

  • Stimulants (eg Methylphenidate, Amphetamines, Pemoline)
  • Cocaine
  • Antipsychotics
  • Antidepressants
  • Anticonvulsants
  • Antihistamines
  • Lithium
  • Opioids & opioid withdrawal
  • Levodopa

Other movement disorders that need to be ruled out:

  • Eg myoclonic movements, torsion dystonia, chorea, stereotypies
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