Tic disorder

Tic disorders are defined in the Diagnostic and Statistical Manual of Mental Disorders (DSM) based on type (motor or phonic) and duration of tics (sudden, rapid, nonrhythmic, stereotyped, involuntary movements). Tic disorders are defined similarly by the World Health Organization (ICD-10 codes).

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Classification

Tic disorders are classified as follows:^[1]

• Transient tic disorder consists of multiple motor and/or phonic tics with duration of at least 4 weeks, but less than 12 months.
• Chronic tic disorder is either single or multiple motor or phonic tics, but not both, which are present for more than a year.
• Tourette's disorder is diagnosed when both motor and phonic tics are present for more than a year.
• Tic Disorder NOS is diagnosed when tics are present, but do not meet the criteria for any specific tic disorder.

Tic disorders onset in childhood (before the age of 18), and are not due to the effects of medication or another medical condition.

DSM-IV-TR diagnosis codes for the tic disorders are:^[2]

• 307.20 Tic Disorder NOS (Not Otherwise Specified)
• 307.21 Transient Tic Disorder
• 307.22 Chronic Motor or Vocal Tic Disorder
• 307.23 Tourette's Disorder

ICD10 diagnosis codes are: ^[3]

• F95.0 Transient tic disorder
• F95.1 Chronic motor or vocal tic disorder
• F95.2 Combined vocal and multiple motor tic disorder [de la Tourette]
• F95.8 Other tic disorders
• F95.9 Tic disorder, unspecified

Prevalence

A large, community-based study suggested that over 19% of school-age children have tic disorders.^[4] The children with tic disorders in that study were usually undiagnosed. (Kurlan) As many as 1 in 100 people may experience some form of tic disorder, usually before the onset of puberty. (NIH) Tourette syndrome is the more severe expression of a spectrum of tic disorders, which are thought to be due to the same genetic vulnerability. Nevertheless, most cases of Tourette syndrome are not severe. Although a good body of investigative work indicates genetic linkage of the various tic disorders, further study is needed to confirm the relationship.^[5]

Treatment

Treatment of tic disorders, although not usually necessary, is similar to treatment of Tourette syndrome. Tics should be distinguished from other causes of tourettism.

Notes

References

• Tourette Syndrome Fact Sheet. National Institutes of Health (NIH). Retrieved on 2005-03-23
• The Tourette Syndrome Classification Study Group. "Definitions and classification of tic disorders". Arch. Neurol. 50 (10): 1013-6. PMID 8215958. Retrieved on 2005-03-22