Tourette Syndrome and Other Tic Disorders

Definitions of Tic Disorders

Tics are involuntary, rapid, repetitive and stereotyped movements of individual muscle groups. They are more easily recognized than precisely defined. Tic disorders are generally categorized according to age of onset, duration of symptoms, severity of symptoms and the presence of vocal and/or motor tics.

Transient tic disorders often begin during the early school years and can occur in up to 18% of all children. Common tics include eye blinking, nose puckering, grimacing and squinting. Transient vocalizatins are less common and include various throat sounds, pinching the genitals are examples. Transient tics last only a few weeks or months and are usually not associated with specific behavioral or school problems. They are especially noticeable during times of heightened excitement or fatigue. As with all tic syndromes, boys are three to four times more often affected than girls. While transient tics by definition do not persist for more than a year, it is not uncommon for a child to have recurrent episodes of transient tics over the course of several years.

Chronic tic disorders are differentiated from transient tic disorders not only by their duration over many years, but by their relatively unchanging character. While transient tics come and go (sniffing may be replaced by forehead furrowing and the furrowing and furrowing may become finger snapping), chronic tics--such as facial contortions or blinking--may persist unchanged for years.

Chronic multiple tics suggest that an individual has several chronic motor tics (or, in rare cases, several chronic vocal tics). Often it is not an easy task to draw distinctions between transient tics, chronic tics and chronic multiple tics.

Tourette Syndrome (TS), first described by Gilles de la Tourette, can be the most debilitating tic disorder and is characterized by multiform, frequently changing motor and phonic tics. The current diagnostic criteria, as defined by the Diagnostic and Statistical Manual of Mental Disorders IV are as follows: A. Both multiple motor and one or more vocal tics have e been present at some time
during the illness, although not necessarily concurrently.

B. The tics occur many times a day (usually in bouts) nearly every day or
intermittently throughout a period of more than 1 year, and during this period
there was never a tic-free period of more than 3 consecutive months.

C. The disturbance causes marked distress or significant impairment in social,
occupational, or other important areas of functioning.

D. The onset is before age 18.

E. The disturbance is not due to the direct physiological effects of a substance (e.g.
stimulants) or a general medical condition (e.g. Huntington's disease or postviral

encephalitis).
While the criteria appear basically valid, they are not absolute. First, there have been rare cases of TS which have emerged later than age 18. Second, the concept of "involuntary" may be hard to define operationally, since many individuals experience their tics as having volitional component--either a capitulation to an internal sensory urge for motor discharge, or a more generalized psychological tension and anxiety, or both. Finally, the diagnostic criteria do not adequately portray the full range of behavioral difficulties that are commonly observed in individuals with TS, such as attentional problems, compulsions and obsessions.

Table 1: Range of Symptoms

Motor Vocal Behavioral and Developmental
Attention deficit hyperactivity disorder, obsessions and compulsions, emotional lability, irritability, impulsivity, aggressivity, and self-injurious behaviors; varied learning disabilities.
Differential Diagnosis

Today the full-blown case of TS is unlikely to be confused with any other disorder. In the past, however, TS was frequently misdiagnosed or undiagnosed.

The differentiation of TS from other tic syndromes may be no more than semantic, especially since recent genetic evidence links TS with multiple and transient tics of childhood and can only be defined in retrospect.

At times it may be difficult to distinguish children with extreme attention deficit hyperactivity disorder (ADHD) from those with TS. On close examination, many ADHD children have a few phonic or motor tics, grimace, or produce noises similar to those with TS. Since at least half of individuals with TS also have attention deficits and hyperactivity as children, a physician may well be confused. However, the treating doctor should be aware of the potential complications of treating a possible case of TS with stimulant medication.

On rare occasions, the differentiation between TS and a seizure disorder may be difficult. The symptoms of TS sometimes occur in a rather sharply separated paroxysmal manner and may resemble automatisms. Individuals with TS, however, retain a clear consciousness during such paroxysms. If the diagnosis is in doubt, an EEG may be useful.

We have seen TS in association with a number of developmental and other neurological disorders. It is possible that central nervous system injury from trauma or disease may cause a child to be vulnerable to the expression of the disorder, particularly if there is a genetic predisposition. Autistic and retarded children may display the entire gamut of TS symptoms. Whether an autistic or retarded individual require the additional diagnosis of TS may remain an open question until testing (biological or otherwise) is available for a definitive diagnosis of TS.

In older individuals, conditions such as Wilson's disease, tardive dyskinesia, Meige's syndrome, chronic amphetamine abuse, and the stereotypical movements of schizophrenia must be considered in the differential diagnosis. The distinction can usually be made by taking a good history or by blood tests.

Since more physicians are now aware of TS, there is a growing danger of over-diagnosis or over-treatment. Prevailing diagnostic criteria would require that all children with suppressible multiple motor and phonic tics, however minimal, of at least one year, should be diagnosed as having TS. It is up to the clinician to consider the effect that the symptoms have on the individual's ability to function as well as the severity of associated symptoms before deciding to treat with medication.

REPRINTED WITH PERMISSION FROM:

Wang, C., & Curry, L. (Eds.) Tourette Syndrome A Continuing Education Course for Registered Nurses, Tourette Syndrome Association - Southern California Chapter. TSA-SC Reseda, CA 1993.

Return To Main Menu