Neal Hermanowicz (Director of the Movement Disorders Program) gives expert video advice on: What is a 'tic'?; What is the difference between tic disorder and Tourette syndrome?; What type of movement is usually associated with tic or Tourette syndrome? and more...
What is a 'tic'?
A tic is either a motor or vocal manifestation, it's repetitive, it's stereotypical, meaning it's the same thing over and over. An example of a motor tic would be, a pretty common one, would be eye blinking, repetitive eye blinking or head jerking. An example of a vocal tic would be repetitive throat clearing or sniffing for example. Sometimes children who have vocal tics are misdiagnosed as having allergies and they're thought to have allergies because of the repetitive sniffing and throat clearing.
What is the difference between tic disorder and Tourette syndrome?
By definition Tourette syndrome lasts longer than a year in duration. And it is a combination of both motor tics and vocal tics. Some people may just have transient motor tics that last for weeks or months and subside and then don't come back. Or they may have isolated vocal tics. And by definition that doesn't qualify for a diagnosis of Tourette syndrome. Now this all may be the same thing, it's not clear that there's any clear separation or distinct separation between somebody who has a simple motor tic that lasts for several months verses Tourette syndrome. It's really a matter of definition only.
What type of movement is usually associated with tic or Tourette syndrome?
Tics in Tourette syndrome tend to evolve, and they tend to change over time. It can be repetitive eye blinking for awhile, then repetitive head jerking, or it could be a combination of several different movements. The key is that movements are brief, they are usually very quick, and are stereotypical -- which means that it's the same thing over and over. And also, they're associated with, usually, this sensory phenomenon, this internal urge of having to do something. Another key feature of tics is that they're usually suppressible, meaning that if the person thinks about it, they can try to keep it under control. Sometimes it's just for seconds, sometimes longer.
What are some of the earliest signs of a tic?
Early signs to just include repetitive blinking for example, or repetitive head jerking. And sometimes these are attributed to be a nervous habit even when it runs in families. People do not recognize it for what it is. People just say uncle Ernie has this nervous behavior, this nervous habit. But that is usually how it shows itself. Again, sometimes children are misdiagnosed as having allergies because of repetitive sniffing, or throat clearing, or coughing. Which is in fact, a form of a vocal tic. Some children at school may get negative attention from their teacher with being described as having an inability to sit still, or being nervous, or irritating those around them because of their movements or their sounds that they make as being distracting or attention-getting. When in fact these are tics.
What does a tic feel like?
Tics do have a phase where people have this internal sense of discomfort prior to the motor or vocal Tic, and it's vaguely described by people who experience it. They put it in the words of a very visceral, internal feeling that is uncomfortable, unpleasant; that's expelled somehow by the Tic movement, or by that vocal Tic itself.
Where in the brain does the tic start?
The precise location where tics are emanating from is not completely clear, but we suspect that structures referred to collectively as the basal ganglia, these are deep structures within the brain that have a role in modifying movement that have a role in emotion and also cognitive function, and it's suspected that this is the site of at least partially creating tic in people.
What is the 'basal ganglia'?
The basal ganglia are deep structures within the brain, they're a collection of neurons, brain cells. They play many roles in brain function, they modify mobility, they play a role in cognitive function, they play a role in mood. And one of the main neurotransmitters within the basal ganglia structures, specifically two structures called the putamen and the caudate nuclei utilize dopamine as one of it's main chemicals to communicate within itself. We've known for a long time that medications that block dopamine will help, in many cases, reduce tics. So that sort of implicates those structures as well. Those dopamine connections within the basal ganglia seem to play some role in generating tic.