Tic disorders are defined in the Diagnostic and Statistical Manual of Mental Disorders

Diagnostic and Statistical Manual of Mental Disorders

The Diagnostic and Statistical Manual of Mental Disorders is published by the American Psychiatric Association and provides a common language and standard criteria for the classification of mental disorders...

 (DSM) based on type (motor or phonic) and duration of tic

Tic

A tic is a sudden, repetitive, nonrhythmic, stereotyped motor movement or vocalization involving discrete muscle groups. Tics can be invisible to the observer, such as abdominal tensing or toe crunching. Common motor and phonic tics are, respectively, eye blinking and throat clearing...

s (sudden, rapid, nonrhythmic, stereotyped, involuntary movements). Tic disorders are defined similarly by the World Health Organization

World Health Organization

The World Health Organization is a specialized agency of the United Nations that acts as a coordinating authority on international public health. Established on 7 April 1948, with headquarters in Geneva, Switzerland, the agency inherited the mandate and resources of its predecessor, the Health...

 (ICD-10 codes).

Classification

Tic disorders are classified 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
  Tourette syndrome
  Tourette syndrome is an inherited neuropsychiatric disorder with onset in childhood, characterized by multiple physical tics and at least one vocal tic; these tics characteristically wax and wane...
  
  

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

Prevalence

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.

As many as 1 in 100 people may experience some form of tic disorder, usually before the onset of puberty. 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 significant amount of investigative work indicates genetic linkage of the various tic disorders, further study is needed to confirm the relationship.

Treatment

Treatment of tic disorders, although not usually necessary, is similar to treatment of Tourette syndrome

Treatment of Tourette syndrome

Tourette syndrome is an inherited neuropsychiatric disorder with onset in childhood, characterized by the presence of motor and phonic tics...

. Tics should be distinguished from other causes of tourettism

Tourettism

Tourettism refers to the presence of Tourette-like symptoms in the absence of Tourette syndrome, as the result of other diseases or conditions, known as "secondary causes"....

.