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), as follows:
* 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:
* 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:
* 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

A large, community-based study suggested that over 19% of school-age children have tic disorders. 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. (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. (Swerdlow, 2005 and Black)

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

References

* Black, Kevin J. Tourette Syndrome and Other Tic Disorders.
* DSM-IV-TR codes
*Evidente, GH. "Is it a tic or Tourette's? Clues for differentiating simple from more complex tic disorders." PostGraduate Medicine Online. October 2000 108:5.
* Kurlan R, McDermott MP, Deeley C, et al. Prevalence of tics in schoolchildren and association with placement in special education. Neurology. 2001 Oct 23;57(8):1383-8. PMID 11673576
* National Institutes of Health (NIH). Tourette Syndrome Fact Sheet Accessed 23 Mar 2005.
* Swerdlow, NR. Tourette Syndrome: Current Controversies and the Battlefield Landscape. Curr Neurol Neurosci Rep. 2005, 5:329-331. PMID 16131414
* World Health Organization International Statistical Classification of Diseases and Related Health Problems, 10th Revision, Version for 2006
*The Tourette Syndrome Classification Study Group. Definitions and classification of tic disorders. Arch Neurol. 1993 Oct;50(10):1013-6. PMID 8215958 Full text.