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For further information, see CMDT Part 26-14: Movement Disorders
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Essentials of Diagnosis
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Multiple motor and phonic tics
Symptoms begin before age 18 years
Tics occur frequently for at least 1 year
Tics vary in number, frequency, and nature over time
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General Considerations
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The diagnosis of the disorder is often delayed for years, the tics being interpreted as psychiatric illness or some other form of abnormal movement
Patients are thus often subjected to unnecessary treatment before the disorder is recognized
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Tics are noted first in childhood, generally between the ages of 2 and 15
Genetic studies are ongoing
Gene association studies have extensively investigated dopamine and serotonin system genes, but there have been no consistent results
Genome-wide association studies have implicated several genetic loci on Slit and Trk-like 1 (SLITRK1) and histidine decarboxylase (HDC) genes; however, larger study cohorts are needed to confirm this
Whole genome/exome sequencing has identified several novel pathogenic variants in various genes in patients with Tourette syndrome but more studies are needed to reveal the exact underlying mechanisms
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Motor tics
Initial manifestation in 80% of cases
Most commonly involve the face, head, and shoulders, with movements such as sniffing, blinking, frowning, shoulder shrugging, and head thrusting
Phonic tics
Initial symptoms in 20% of cases
Commonly consist of grunts, barks, hisses, throat clearing, coughs, verbal utterances including coprolalia (obscene speech)
A combination of different motor and phonic tics ultimately develop in all patients
Echolalia (repetition of the speech of others)
Echopraxia (imitation of others' movements)
Palilalia (repetition of words or phrases)
Some tics may be self-mutilating in nature
Obsessive-compulsive disorder (OCD) and attention deficit hyperactivity disorder are commonly associated and may be more disabling than the tics themselves
In addition to OCD, psychiatric disturbances may occur because of the associated cosmetic and social embarrassment
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Differential Diagnosis
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Diagnostic Procedures
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α-Adrenergic agonists are first-line therapies because of favorable side-effect profile compared with typical antipsychotics
Clonidine (start 0.05 mg orally at bedtime, titrating to 0.3–0.4 mg orally daily, divided three to four times per day)
Guanfacine (start 0.5 mg orally at bedtime, titrating to a maximum of 3–4 mg orally daily, divided two times per day)
Atypical antipsychotic risperidone (1–6 mg daily orally) is more effective than placebo in controlling tics and more effective than pimozide in improving symptoms of comorbid OCD and may be tried before the typical antipsychotic agents
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