Tourette syndrome

It is a neurological disorder caused by defective metabolism of the neurotransmitters in the brain.

Georges Gilles de la Tourette

Pathophysiology

File:Tic Disorders.webm

• It is characterized by repeated involuntary movements (motor tics) and uncontrollable vocal sounds (vocal tics). The symptoms are usually manifested before the age of eighteen.
• Tourette syndrome (TS) presents with repetitive, stereotyped, involuntary movements and vocalizations called tics.

Onset

• The first symptoms of TS are almost always noticed in childhood.  
• Some of the more common tics include eye blinking and other vision irregularities, facial grimacing, shoulder shrugging, and head or shoulder jerking. Perhaps the most dramatic and disabling tics are those that result in self-harm such as punching oneself in the face, or vocal tics including coprolalia (uttering swear words) or echolalia (repeating the words or phrases of others).  
• Many with TS experience additional neurobehavioral problems including inattention, hyperactivity and impulsivity, and obsessive-compulsive symptoms such as intrusive thoughts/worries and repetitive behaviors.

Cause

Although the cause of Tourette syndrome is unknown, current research points to abnormalities in certain brain regions (including the basal ganglia, frontal lobes, and cortex), the circuits that interconnect these regions, and the neurotransmitters (dopamine, serotonin, and norepinephrine) responsible for communication among nerve cells.Given the often complex presentation of Tourette syndrome, the cause of the disorder is likely to be equally complex. In many cases, there is a family history of tics, Tourette Syndrome, ADHD, OCD.

In 2005, scientists discovered the first gene mutation that may cause some cases of Tourette syndrome. This gene, named SLITRK1, is normally involved with the growth of nerve cells and how they connect with other neurons. The mutated gene is located in regions of the brain (basal ganglia, cortex, and frontal lobes) previously identified as being associated with Tourette syndrome.

Inheritance

Evidence from twin and family studies suggests that Tourette syndrome is an inherited disorder. Although early family studies suggested an autosomal dominant mode of inheritance (an autosomal dominant disorder is one in which only one copy of the defective gene, inherited from one parent, is necessary to produce the disorder), more recent studies suggest that the pattern of inheritance is much more complex. Although there may be a few genes with substantial effects, it is also possible that many genes with smaller effects and environmental factors may play a role in the development of Tourette syndrome. Genetic studies also suggest that some forms of ADHD and OCD are genetically related to Tourette syndrome, but there is less evidence for a genetic relationship between Tourette syndrome and other neurobehavioral problems that commonly co-occur with Tourette syndrome.

Symptoms

Although the symptoms of Tourette syndrome vary from person to person and range from very mild to severe, the majority of cases fall into the mild category. The repetitive, stereotyped, involuntary movements and vocalizations called tics are classified as either simple or complex.

Simple motor tics are sudden, brief, repetitive movements that involve a limited number of muscle groups. Some of the more common simple tics include eye blinking and other eye movements, facial grimacing, shoulder shrugging, and head or shoulder jerking. Simple vocalizations might include repetitive throat-clearing, sniffing/snorting, grunting, or barking sounds.

Complex tics are distinct, coordinated patterns of movements involving several muscle groups. Complex motor tics might include facial grimacing combined with a head twist and a shoulder shrug. Other complex motor tics may actually appear purposeful, including sniffing or touching objects, hopping, jumping, bending, or twisting.

Complex vocal tics include words or phrases. Perhaps the most dramatic and disabling tics include motor movements that result in self-harm such as punching oneself in the face or vocal tics including coprolalia (uttering swear words) or echolalia(repeating the words or phrases of others). Some tics are preceded by an urge or sensation in the affected muscle group, commonly called a premonitory urge. Some individuals with Tourette syndrome will describe a need to complete a tic in a certain way or a certain number of times in order to relieve the urge or decrease the sensation. Tics are often worse with excitement or anxiety and better during calm, focused activities. Certain physical experiences can trigger or worsen tics, for example tight collars may trigger neck tics, or hearing another person sniff or throat-clear may trigger similar sounds. Tics do not go away during sleep but are often significantly diminished.

Diagnosis

To be diagnosed with TS, a person must:

• have two or more motor tics (for example, blinking or shrugging the shoulders) and at least one vocal tic (for example, humming, clearing the throat, or yelling out a word or phrase), although they might not always happen at the same time.
• have had tics for at least a year. The tics can occur many times a day (usually in bouts) nearly every day, or off and on.
• have tics that begin before age 18 years.
• have symptoms that are not due to taking medicine or other drugs or due to having another medical condition (for example, seizures, Huntington disease, or postviral encephalitis).

There are no blood, laboratory, or imaging tests needed for diagnosis. In rare cases, neuroimaging studies, such as magnetic resonance imaging (MRI) or computerized tomography (CT), electroencephalogram (EEG) studies, or certain blood tests may be used to rule out other conditions that might be confused with TS when the history or clinical examination is atypical.

Treatment

Many individuals with Tourette syndrome have mild symptoms and do not require medication.

Neuroleptics are the most consistently useful medications for tic suppression; a number are available but some are more effective than others (for example, haloperidol and pimozide).

Additional medications with demonstrated efficacy include alpha-adrenergic agonists such as clonidine and guanfacine. These medications are used primarily for hypertension but are also used in the treatment of tics.

Effective medications are also available to treat some of the associated neurobehavioral disorders that can occur in patients with Tourette syndrome. Recent research shows that stimulant medications such as methylphenidate and dextroamphetamine can lessen ADHD symptoms in people with Tourette syndrome without causing tics to become more severe. For obsessive-compulsive symptoms that significantly disrupt daily functioning, the serotonin reuptake inhibitors (clomipramine, fluoxetine, fluvoxamine, paroxetine, and sertraline) have been proven effective in some individuals.

Psychotherapy may be helpful as well. It can help with accompanying problems, such as ADHD, obsessions, depression and anxiety. Therapy can also help people cope with Tourette syndrome. For debilitating tics that don't respond to other treatment, deep brain stimulation (DBS) may help. DBS consists of implanting a battery-operated medical device (neurostimulator) in the brain to deliver electrical stimulation to targeted areas that control movement. Further research is needed to determine whether DBS is beneficial for people with Tourette syndrome. The medication(s) listed below have been approved by the Food and Drug Administration (FDA) as orphan products for treatment of this condition.

• aripiprazole (Brand name: Abilify)Treatment of pediatric patients with Tourette's disorder.

Prognosis

Although TS can be a chronic condition with symptoms lasting a lifetime, most people with the condition experience their worst symptoms in their early teens, with improvement occurring in the late teens and continuing into adulthood.  As a result, some individuals may actually become symptom free or no longer need medication for tic suppression.

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