Tics are sudden, jerky, irregular and uncontrollable movements of a muscle or group of muscles that occur repeatedly for no apparent reason. They may involve any part of the body, as well as such activities as repeatedly clearing the throat or persistent coughing. They are said to occur in up to 10% of children, to be more common in boys than girls, and to last anywhere from a few weeks to months or sometimes many years. They occur in the school age or adolescent age group, and may persist into adult life. Sometimes tics have not been present during childhood and appear for the first time in adulthood.

Cause

The cause of tics is uncertain, but it is believed somehow to be related to stress. Tics often appear for the first time during a stressful period in the child’s life. Established tics certainly seem to become more frequent and exaggerated when the child is anxious but it is not always possible to identify any stressful events that may have precipitated or worsened the tics. Some children may be more highly strung or have a particular temperament or personality which may predispose them to tics, but even this is only supposition and has not been reliably demonstrated.

Very occasionally tics may have an underlying medical cause. For example, a child who is constantly screwing up his eyes may have a problem with vision, or a child with a persistent cough may have asthma or a chest infection. However, if the tic is caused by an underlying conditions, there will usually be separate evidence of the condition itself. For example, coughing due to a chest infection is present all the time, including when the child is asleep, whereas a habit cough or tic disappears when the child is sleeping.

Clinical features

The tics involve muscles or muscle groups in any part of the body. Sometimes more than one part of the body is affected. Tics often seem an exaggeration of normal movements. The common tics include facial grimacing, smiling, blinking or screwing up the eyes, twisting or stretching of the neck, shrugging of the shoulders, and so on. They also include repeated clearing of the throat or coughing.

They appear most frequently during periods of stress and when the child is anxious, such as when speaking in front of the class or before an examination, and are less prominent when the child is busy or distracted. At these times the tics can disappear for hours at a time. They always disappear during sleep.

Tics cause great concern and irritation to parents and sometimes teachers, and may be a cause of considerable embarrassment and even ridicule to the child who may be teased by his peer group.

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