Tourette syndrome is a neurological condition affecting the brain and nervous system. The condition normally develops in childhood and is characterized by involuntary movements and utterances called tics. Involuntary movements are referred to as motor tics and tics involving involuntary noises or utterances are called phonic tics.
Tourette syndrome has been classified by the Diagnostic and Statistical Manual of Mental Disorders (DSM) into various sub-groups. Definitions and classifications are also offered by the World Health Organization (International Statistical Classification of Diseases and Related Health Problems, ICD-10 codes).
The DSM classifications are based on the type and duration of the tics. For example, some individuals may have predominantly motor tics such as sudden jerking of the head or jumping up and down, while in other sufferers, the tics may be mainly phonic.
Regarding the duration of the tics, they may be described as either transient or chronic. Transient tics may involve multiple motor tics, phonic tics or a combination of the two, but only last for a month to one year. Chronic or long lasting tics on the other hand, are described as either multiple or single motor or phonic tics, but never a combination of the two, and may last for over a year. The ICD-10 codes classify Tourette syndrome in almost the same way.
Examples of motor tics include jerking or nodding of the head, sudden movements and jumping up and down. Examples of phonic tics include grunting, clearing of the throat, coughing, and shouting out words or phrases. Words or phrases may be repetitive and echoing words heard spoken by others. The vocal tics often involve movement of air through the mouth, nose or throat.
The severity of the symptoms may vary but in most cases they are mild. Transient cases are more likely to be undiagnosed as they may resolve within a few weeks to months. In some individuals, the tics may come and go, with periods of no symptoms followed by a sudden worsening of the condition.