Tourette Syndrome: What Is It, Symptoms, Diagnosis & Treatments
The worldwide prevalence of Tourette syndrome (TS) is estimated to be around 0.3 to 0.8 percent of all children and up to three percent of children may develop a partial (forme fruste) presentation predominantly with motor tics. The CDC has reported that three in every 1,000 school age children have the disorder. The age of onset is typically four to six years with maximum severity around 10 to 12 years. This is followed by a gradual decline in severity in adolescence. Most individuals will be free of tics, or have minimal symptoms, in adulthood. Boys are more affected than girls and a family history of either a full-blown syndrome or a partial tic disorder is often present.
Though most cases of TS are familiar, a specific gene has not been identified. The most accepted hypothesis regarding the mechanism is the dopamine hypersensitivity hypothesis. It is believed that dopamine receptors in the deeper structures of the brain, called the basal ganglia, have a higher than normal sensitivity to dopamine, an important neurotransmitter. This leads to excessive, involuntary movements. Suppressing this activity with dopamine receptor blocking agents, such as haloperidol, would expect to reduce the tics. This is indeed observed and dopamine antagonists are part of the treatment options for TS.
Tourette’s syndrome typically presents with multiple motor and vocal tics.
- The motor tics may take the form of shoulder shrugs, excessive eye blinks or other involuntary movements.
- The vocalizations may be minor in the form of sniffing but in a small percentage of patients may present as coprolalia. The tics may occur many times a day and are present on most days.
There is often a premonitory or warning sensation prior to the tics. The movement disorder maybe accompanied by psychiatric manifestations that include obsessive-compulsive disorder (OCD) and attention deficit disorder (ADD). Boys with TS are more likely to get ADHD symptoms whereas girls are more likely to present with OCD. Other psychiatric manifestations may include:
- Anxiety disorder
- Severe panic attacks
Diagnosis and Treatment
The diagnosis of TS may be made by clinical examination. However, if secondary etiologies are suspected, a MRI of the brain may be obtained. In terms of the motor tics and vocalizations the first treatment option is reassurance as the severity usually gets milder over time. Functionally disabling tics can be treated with dopamine antagonists such as risperidone, olanzapine, pimozide and haloperidol. Other medications also used include clonidine, guanfacine, reserpine and tetrabenazine. Close follow-up is required as potential side effects include drowsiness, fatigue, depression and symptoms of Parkinson’s disease such as tremor and slow movements. Particularly with the dopamine antagonists, the potential for a long-term side effect, tardive dyskinesia, should be discussed with the patient. Given the common psychiatric comorbidities of ADHD and OCD, collaboration between the patients treating neurologist and a psychiatrist may often be necessary.
The prognosis for normal occupational and social functioning is often determined more by the psychiatric comorbidities rather than the tics themselves. In most cases, the prognosis is one of remission with half the patients in complete remission, by the end of adolescence. More recently, patients with intractable tic disorders may respond to a type of surgical treatment called deep brain stimulation (DBS). This procedure uses a brain pacemaker and involves placement of electrodes deep in the brain connected to this pacemaker to reduce the severity of the tics. The procedure has been widely used for Parkinson’s disease and tremors but its use in TS is considered experimental.