Keith R. Ridel, MDJWM Pediatric Neurologist
Tics are a symptom of Tourette Syndrome. Tourette Syndrome is a disorder where a person has at least one vocal and at least two movement tics for more than one year, usually beginning before puberty. Not every person who has tics has Tourette Syndrome. If the tics last less than one year, the diagnosis is Transient Tic Disorder. Persons with other neurologic or psychiatric disorders may also have tics.
Tics are usually brief movements or sounds. They may be simple actions that we all do, such as blinking or humming, done too often. The tic should look or sound the same each time, at least for a while. Usually, in Tourette’s, tics move to different locations over time. Also, tics may become more complex, such as repeating a certain word or tapping a certain way. Young children may not be aware of their tics, but older children and adults often feel a sensation inside, an urge to tic. Holding a tic in may cause stress; letting it out may relieve it.
No one knows for sure what is different about the brain of a person who has Tourette’s. The brain contains 10 billion neurons that communicate with one another in complex ways, controlling thoughts, emotions, movements, and body functions. Studying a living brain to see why it behaves as it does is challenging for neuroscientists, but there are some new clues about why some brains tic.
Information travels to our brain through nerves in our faces, bodies, arms, and legs.
- For example, information that a bug is sitting on my arm must travel from the skin on my arm, up my arm to my spinal cord, then up to my brain.
- Then it must travel to the cortex, the surface of my brain, so I can become conscious of the location of the sensation (left forearm), the meaning of the sensation (a hungry mosquito), and perhaps some emotions associated with the sensation (fear, irritation).
- Then my cortex will form a plan (rotate left arm gently, swat mosquito with right hand) and issue a command to execute the action (rapid movement of flattened right hand onto mosquito on left forearm).
Beneath the brain’s surface are some important structures that communicate within the brain in complex circuits. These areas affect how the information about the mosquito gets to the surface of the brain. These areas also affect how we move in response to sensations. One of these areas that seems to be important in Tourette’s is called the Striatum (rhymes with “I ate ‘em”). The striatum is part of many important brain circuits. Although the striatum looks pretty much the same in people who tic and people who don’t (you can’t diagnose Tourette Syndrome with a brain MRI), there are some new research brain scans that show that areas of the striatum “light up” when someone tics, or tries to hold their tics in. In Tourette’s, it may be that the striatum works differently, in how it regulates sensory information coming in, in how it affects urges to respond to those sensations, or both.
Certain brain chemicals called neurotransmitters (used by neurons to communicate with each other) also appear to be abnormal in the brains of persons with Tourette’s. These include dopamine, which is involved in many movement disorders, and serotonin, which is involved in many mood disorders, such as depression and obsessive compulsive disorder. Currently, these chemical differences are difficult to measure. However, for many persons with Tourette’s, medicines, which block dopamine or increase serotonin can be helpful.
Tourette’s is an area of active research. New studies should increase our knowledge of what makes some people tic. Children with tics are often sent to child neurologists for evaluation and management.
