Older versions of the ICD called it "combined vocal and multiple motor tic disorder [de la Tourette]".Genetic studies indicate that tic disorders cover a spectrum that is not recognized by the clear-cut distinctions in the current diagnostic framework. Since 2008, studies have suggested that Tourettes is not a unitary condition with a distinct mechanism, as described in the existing classification systems. Instead, the studies suggest that subtypes should be recognized to distinguish "pure TS" from TS that is accompanied by attention deficit hyperactivity disorder (ADHD), obsessive–compulsive disorder (OCD) or other disorders, similar to the way that subtypes have been established for other conditions, such as type 1 and type 2 diabetes. Elucidation of these subtypes awaits fuller understanding of the genetic and other causes of tic disorders. Characteristics
Tics
Tics are movements or sounds that take place "intermittently and unpredictably out of a background of normal motor activity", having the appearance of "normal behaviors gone wrong". The tics associated with Tourettes wax and wane; they change in number, frequency, severity, anatomical location, and complexity; each person experiences a unique pattern of fluctuation in their severity and frequency. Tics may also occur in "bouts of bouts", which also vary among people. The variation in tic severity may occur over hours, days, or weeks. Tics may increase when someone is experiencing stress, fatigue, anxiety, or illness, or when engaged in relaxing activities like watching TV.
Tourettes is at the more severe end of the spectrum of tic disorders; its diagnosis requires multiple motor tics and at least one vocal tic to be present for more than a year. Tics are sudden, repetitive, nonrhythmic movements that involve discrete muscle groups, while vocal (phonic) tics involve laryngeal, pharyngeal, oral, nasal or respiratory muscles to produce sounds. The tics must not be explained by other medical conditions or substance use.Other conditions on the spectrum include persistent (chronic) motor or vocal tics, in which one type of tic (motor or vocal, but not both) has been present for more than a year; and provisional tic disorder, in which motor or vocal tics have been present for less than one year. The fifth edition of the DSM replaced what had been called transient tic disorder with provisional tic disorder, recognizing that "transient" can only be defined in retrospect. Some experts believe that TS and persistent (chronic) motor or vocal tic disorder should be considered the same condition, because vocal tics are also motor tics in the sense that they are muscular contractions of nasal or respiratory muscles.Tourette syndrome is defined only slightly differently by the WHO; in its ICD-11, the International Statistical Classification of Diseases and Related Health Problems, Tourette syndrome is classified as a disease of the nervous system and a neurodevelopmental disorder, and only one motor tic is required for diagnosis.