Published online by Cambridge University Press: 28 July 2009
Introduction: tics
Tics are brief, sudden movements (motor tics) or sounds (phonic tics) which are intermittent but may be repetitive and stereotypic (Jankovic, 2001; Singer, 2005). Transient tic disorder is the mildest and most common cause of tics. Although these tics usually resolve in childhood, some may persist and become associated with a variety of comorbid disorders such as attention deficit disorder and obsessive compulsive disorder. Tourette's syndrome (TS), considered a genetic and neurodevelopmental disorder, is the most common cause of chronic tics (Jankovic, 2001; Albin and Mink, 2006). There are many other causes of tics which are referred to as “tourettism” or secondary tics. Other causes of tics in particular include insults to the brain and basal ganglia (infection, stroke, head trauma, drugs, and neurodegenerative disorders) (Jankovic & Mejia, 2006). The currently used diagnostic criteria for definite TS formulated initially by The Tourette's Syndrome Classification Study Group (1993) include: (1) multiple motor tics; (2) at least one vocal tic (not necessarily concurrently); (3) a waxing and waning course with increasing severity over time; (4) tic symptoms for at least one year; (5) onset before age 21 years; (6) no precipitating etiologies such as illnesses or drugs; and (7) observation of tics by a medical professional (Jankovic, 2001).
Clinical features
Motor and phonic tics consist of either simple or complex movements that may be seemingly goal directed. Motor tics may be rapid (clonic), or more prolonged (Jankovic, 2001).
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