Children who become nervous about a test or are in a stressful environment may develop a tic. A tic is a sudden, repetitive sound or movement that is difficult to control. Most tics, transient tics, are only temporary and usually last less than three months. Rarely do children have chronic tic disorder which lasts for more than a year. According to Kids Health, transient tic disorder is a temporary condition that affects up to 25 percent of children before the age of 18.

Motor tics can be either simple or complex. Simple motor tics involve one muscle group and complex motor tics involve more than one muscle group. Motor tics usually begin before vocal tics. Simple motor tics include shoulder shrugging, which is the most common, nose wrinkling, eye blinking, lip biting, head twitching or finger flexing. Complex motor tics include touching other people, smelling objects, obscene gestures, flapping the arms, jumping, kicking or hopping. The cause of motor tics is unknown.

Simple vocal tics include one sound and complex vocal tics involve meaningful speech, such as words. According to Kids Health, complex motor tics may appear as if the child is performing the tic on purpose. Common simple vocal tics include throat clearing, grunting, coughing, sniffing, hissing or barking. Complex vocal tics include repeating one's own phrases or words, repeating others, using expletives or using different voice intonations. The cause of vocal tics is unknown.

A child with both vocal and motor tics for a period longer than a year without going more than three months tic free is usually diagnosed with Tourette syndrome. Tourette syndrome is a neurological disorder in which your child makes sounds or unusual movements with little or no control for an extended period of time. According to MayoClinic.com, this disorder typically shows up in children between the ages of 7 and 10 and males are three to four times more likely to develop Tourette syndrome. Children normally outgrow this disorder after adolescence without any treatment. The cause of Tourette syndrome is unknown, and there is no way to prevent it.