A computerised and manual search on PubMed of published work was done to identify studies about the pathogenesis of Tourette's syndrome and its treatment, with particular focus on original reports published over the past 5 years. Selection criteria included a judgment about novelty and importance of studies and their relevance to the well-informed general medical doctor. In the case of treatment studies, only those interventions whose efficacy has been supported by at least one randomised,
SeminarTourette's syndrome
Section snippets
Symptoms and natural history
The cardinal features of Tourette's syndrome are motor and phonic tics that wax and wane in severity.2 Motor tics usually begin between the ages of 3 and 8 years, with transient periods of intense eye blinking or some other facial tic. Phonic tics, such as repetitive bouts of sniffing or throat clearing, can begin as early as 3 years of age, but typically they follow the onset of motor tics by several years.3 In uncomplicated cases, severity of motor and phonic tics peaks early in the second
Epidemiology and genetics
Once thought to be a rare disorder,12 the prevalence of Tourette's syndrome is presently estimated to be between 31 and 157 cases per 1000 in children aged 13ā14-years.13 Frequency of the disorder varies by age, sex, source of sample, and method of assessment. For example, studies on direct classroom observation and that use multiple informants consistently yield substantially higher prevalence estimates than do other assessment methods. Many patients identified with these techniques have mild
Neural substrates of habit formation and tics
Habits are assembled routines that link sensory cues with motor action. Ideas at present have suggested neural substrates of habit formation are crucial for a better understanding of Tourette's syndrome38, 39, 40, 41, 42 (Figure 3, Figure 4, Figure 5).
Neuroscientists who are interested in learning and habit formation have focused on the motor, sensorimotor, association, inhibitory, and limbic (motivational and threat detection) neural circuits that course through the basal ganglia.39, 40, 41, 42
Developmental models
Future progress in elucidation of the pathogenesis and treatment of Tourette's syndrome could be greatly accelerated with development of animal models. Thus far, the use of psychomotor stimulants, direct dopamine receptor agonists, behavioural stress sensitisation conditioning paradigms, and immune-based challenges to induce different levels of stereotypy in rats and other species seem to offer the greatest promise in modelling key components of the disorder's phenotype.48, 58, 59, 60
If tics,
Assessment and diagnosis
Clinical examination of a child with tics should include an assessment of the child or adolescent as a whole not merely as someone with tics.62, 63 During the examination, the full range of difficulties and competencies should be charted: the clinician, family, and child must collaborate to reconstruct the child's history, tic symptoms (onset, progression, waxing and waning, and factors that have worsened or ameliorated tic status), and present functioning. An important question is the extent
Treatment
Multimodal treatment for Tourette's syndrome is usually indicated.69 As noted above, this approach includes educational and supportive interventions appropriate for any chronic disease. Panel 2 outlines possible protective factors for the disorder. The various manifestations of the disorder are best treated in the context of a long-term relationship with a clinician who can help the patient, family, and school deal with the changing manifestations of the disorder through the years. Because
Future prospects
Present ideas about Tourette's syndrome have been shaped by advances in the neurosciences and our emerging understanding of the role of the basal ganglia in learning and habit formation. Although evidence that the same mechanisms have a role in habit formation and tics is circumstantial, progress has set the stage for a major advance in our understanding of this disorder. Continued success in these areas will lead to molecular insights into functioning of neural networks, complexities of
Search strategy and selection criteria
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