Tics are sudden, repetitive movements, gestures, or utterances that typically mimic an aspect of normal behavior. Individual tics rarely last more than a second. Many tics occur in bouts with brief inter-tic intervals of less than one second. Individual tics can occur singly or together in an orchestrated pattern. They vary in intensity or forcefulness. Motor tics, which can be viewed as disinhibited fragments of normal movement, can vary from simple, abrupt movements such as eye blinking, nose twitching, head or arm jerking, or shoulder shrugging to more complex movements that appear to have a purpose, such as facial or hand gestures or sustained looks. These two phenotypic extremes of motor tics are classified as simple and complex motor tics respectively. Similarly, phonic tics can be classified into simple and complex. Simple vocal tics are sudden, meaningless sounds such as throat clearing, coughing, sniffing, spitting, or grunting. Complex phonic tics are more protracted, meaningful utterances, which vary from prolonged throat clearing to syllables, words or phrases and to even more complex behaviors such as repeating ones own words (palalalia) or those of others (echolalia) and, in rare cases, the use of obscenities (coprolalia).
The severity of tics in TS waxes and wanes throughout the course of the disorder. The tics of TS and other tic disorders are highly variable from minute-to-minute, hour-to-hour, day-to-day, week-to-week, month-to-month, and even year-to-year. Tic episodes occur in bouts, which in turn also tend to cluster. Tic symptoms, however, can be exacerbated by stress, fatigue, extremes of temperature and external stimuli (e.g., in echolalia). Intentional movement attenuates tics in the affected area and intense involvement in activities tends to dissipate tic symptoms.
Many individuals with tics, especially those post-pubertal, are aware of premonitory urges: feelings of tightness, tension, or itching that are accompanied by a mounting sense of discomfort or anxiety relieved only by the performance of a tic. Premonitory urges are similar to the sensation preceding a sneeze or an itch. Premonitory urges cause many TS patients to suffer from an endless cycle of rising tension and tic performance because the relief provided by tic performance is ephemeral. Thus, soon after tic performance the tension of the premonitory urge again rises to a crescendo. A majority of patients also report a fleeting sense of relief after a bout of tics has occurred. Most are able to suppress their tics for short intervals of time.
With increasing awareness of premonitory urges, TS patients begin to exhibit a variable degree of voluntary control over tic performance. 92% of TS subjects in one study reported that the tics they exhibited were either partially or totally voluntary. However, this voluntary control should be likened to that governing eye blinking. Eye blinking and tics can both be inhibited voluntarily, but only for a limited period of time and only with mounting discomfort. Thus, some adult TS patients are able to demonstrate nearly complete control over when their tics will occur. However, when complete or near complete control of tics is present, resistance to the mounting tension of premonitory urges can produce mental and physical exhaustion even more distracting than the tics themselves.
The tics, which are the most prominent feature of TS, may be neither the first nor the most impairing psychological disturbance TS patients endure. Children with TS have higher rates of OCD, ADHD, and disinhibited speech and behavior compared to the general population. In one study, 65% of TS patients in late adolescence regarded their behavioral problems (including ADHD and OCD) and learning difficulties to have had an equal or greater impact on their life function than the tics themselves did. In the natural course of comorbid psychiatric illness in TS, ADHD symptom, typically precede the onset of tic symptoms by a couple of years, whereas OCD symptoms typically present around the age of 12–13 after tics have reached their peak severity. Approximately 50% of children with TS experience comorbid ADHD, and an even greater proportion of children with comorbid disorders reach clinical attention. Roughly one-third to one-half of TS patients will experience clinically significant OCD symptoms during the course of their lifetime.