A tic is a repetitive movement that is challenging, if not impossible, to control voluntarily. Tics can occur in any muscle group, with facial tics being the most prevalent. These include actions like blinking, twitching the nose, or making grimaces. Tics involving the muscles used for speech are called vocal tics and may involve sounds such as grunts or whistles, or even the repetition of words or phrases. More complex motor tics consist of multiple, sequenced actions, which might involve twirling, tapping a certain number of times, or bending down to touch the ground. Tics are thought to result from abnormalities or damage to the basal ganglia, a deep-seated brain structure that regulates automatic movements and influences behavior.
