Tourette Syndrome

Tourette syndrome is a complex debilitating neurological disorder that arises during childhood or adolescence mostly affecting people under the age of 21. The syndrome, first described by Georges Gilles de la [Page 1672]Tourette in 1885, is estimated to affect approximately 1 to 2 percent of the population. The disorder affects males more than females with an approximate ratio of five to one.

This chronic idiopathic syndrome is characterized by repeated involuntary movements of the body and face known as tics. Tics are believed to result from dysfunction in the cortical and subcortical regions, the thalamus, frontal cortex, and basal ganglia. Tics are relatively common, affecting 12 to 24 percent of school-age children. Tics are defined as either simple or complex. The former presents with shoulder shrugging, frequent eye blinking, tongue clicking, and sniffing. Complex tics present with frequent jumping, vocal outbursts such as inappropriate swearing, and echolalia (repetition of phrase or sound just heard). As the disease progresses, symptoms of coprolalia also arise, where the patient presents with unprovoked obscene outbursts. Patients may present with various other disorders, for example, psychological disorders such as obsessive-compulsive disorder and attention deficit hyperactivity disorder. Patients may also present with symptoms of anxiety, depression, learning disability, and sleep disturbance.

Although the disease has no known etiology, it is suggested that the condition may be inherited. There is a prominent familial occurrence of Tourette syndrome. About 10 percent of patients have a family history of the same condition. In some cases, tics may not be inherited; these cases are identified as “sporadic” Tourette syndrome.

Pathophysiology of the disease may involve structural and functional disturbances of the basal ganglia. Reduced caudate nucleus volumes may be a good candidate marker for abnormality in the basal ganglia in persons with the syndrome. Pathophysiology may also include a dysfunction in the processing of dopamine, a neurotransmitter in the brain.

It is suggested that the spectrum of behavior can be explained on the basis of a gene causing an imbalance of the mesencephalic-mesolimbic dopamine pathways, resulting in disinhibition of the limbic system. Involvement of dopaminergic systems in the basal ganglia have been suspected to be of etiological importance because of the efficacy of dopamine D2 receptor antagonists in ameliorating some symptoms and the exacerbation of symptoms by dopamimetic agents.

Smaller lenticular nucleus volumes may be an additional marker for the presence of comorbid obses-sive-compulsive disorder and for the persistence of tic symptoms into adulthood. The syndrome may also be caused by frameshift mutations in the SLITRK1 (SLIT and NTRK-like family, member 1) gene on chromosome 13. Genetic factors are also implicated in twin studies, which show that the ratio of concordance in monozygotic versus dizygotic twin pairs is approximately five to one.

There are no specific medical or screening tests that can be used in diagnosing this disease. Diagnosis includes presence of multiple vocal tics many times a day with an onset before 18 years of age. Tourette syndrome cannot be treated; however, there are treatments available for alleviating symptoms. Various types of therapy have been employed including psychotherapy and cognitive behavioral therapy. The support of family and friends has also been known to help many patients. The only consistent useful medication is the dopamine D2 receptor antagonists, haloperidol (antipsychotic drug), but its use is associated with side effects in approximately 50 percent of the patients treated. Other proven treatments for tics include clonidine and noradrenalin reuptake inhibitors. Relaxation techniques such as yoga have also been suggested as a method for alleviating symptoms.

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