Tourette syndrome is a common tic disorder that is a subset of hyperkinetic movement disorders. Hyperkinetic disorders are characterized by abnormal involuntary movements. These can range from jerks, chorea, and dystonia to tics.
The tics may be either simple or complex. Simple tics may be:
Complex ones include:
The tics are suppressible, but they are associated with an irresistible urge and sensations that are relieved when the tic occurs. Involuntary vocalizations, may range from sounds to words. The words may be obscene (coprolalia) which occurs in 40% of patients with word tics. Some may repeat a single word many times. Many also experience copropraxia (obscene gestures), echopraxia (mimicking of gestures) with unusual fixations and fanaticises. The neurologic exam is usually normal except for the tic .
Once the history and exam is taken there is no further workup required to make the diagnosis.
Diagnostic criteria for Tourette syndrome (DSM-IV) are as follows:
The condition can persist throughout life, in children it can go into remission and 50% will have reduced tics by the age of 18. Some tics are not distressing or life limiting, but other can cause a lot of distress and anxiety. The vocal sounds and words can be profane or loud causing the sufferer to be very conscious in public. Some tics are violent and cause injury to the patient.
The discovery of genes that may be responsible for the syndrome was a big step in trying to elucidate the cause of the Tourette syndrome. The mutation in the SLITRK1 gene on chromosome 13q is expressed in the regions in the brain that are implicated in the disease; these include the hippocampus, cortex, thalamic, subthalamic and globus pallidus nuclei). The gene appears also to be important in dendritic growth.
Other genes have been discovered in families with Tourettes; one of note is the HDC gene located in chromosome 15. There also appears to be non-genetic factors, because there have been differences in monozygotic twins. Proposed postulates include a difference in the immune response to streptococcus infection. There is on-going research to the possible connection with streptococcus infections  .
The overall international data shows are prevalence of about 1%, but these figures are thought to be unreliable due to different propensities for people to seek medical care in different communities and cultures. The typical age of onset is five to ten years of age.
There is a high incidence of attention deficit hyperactivity disorder (ADHD) (60 percent), and obsessive-compulsive disorder (OCD), in this population   .
The neurophysiology of this syndrome is not yet known. It is thought to be caused by pathologies in the inferior frontal cortex and the basal ganglia. There appears to be loss of normal asymmetry in these regions on imaging. Biochemical studies from autopsies have shown decreased levels of dopamine but its role in the pathophysiology is not known. There have been signs from of increased dopamine receptors and production. It is thought that problems in the synthesis and uptake of dopamine could be the cause  .
Tourette syndrome (TS) is a neurological disorder characterized by tics. Tics are repeated, individually recognizable, intermittent movements or movement fragments that are almost always briefly suppressible and are usually associated with awareness of an urge to perform the movement. The tic can be brief movements of utterances such as sounds or words. Of note these movement disappear with sleep. The tic are suppressible, but the longer they are suppressed the stronger the urge .