Tourette's Syndrome - Diagnosis

Diagnostic criteria and methods for assessing Tourette syndrome

Transient tics are common, occurring in about a quarter of school-age children. The diagnosis is established when tics persist for at least 4 weeks but not more than 12 months. Several episodes of transient tics may precede the development of chronic tics or Tourette syndrome. Chronic tics (CT) are motor or vocal tics (but not a combination of both) that persist for more than 1 year. The diagnostic criteria for Tourette syndrome require the presence of multiple motor tics and at least one vocal tic, not necessarily at the same time. For example, a 16-year-old boy with multiple motor tics but no vocal tics at the time of examination would be diagnosed with Tourette syndrome if he had vocal tics at age 12. Many consider the distinctions between Tourette syndrome and chronic multiple motor tics to be artificial, especially given the similar inheritance patterns reported in genealogical studies. Symptoms of Tourette syndrome must persist for more than 1 year, with remissions lasting no longer than 3 months. According to the DSM-TV, the disorder must begin before age 18, although this criterion has varied in the past. If tics begin after age 18, they should be classified as "tics not otherwise specified."

The classification of mild tics remains unclear. Current DSM-IV criteria for the diagnosis of all tics require that they cause “marked distress or significant impairment in functioning.” However, many children with tics do not come to the attention of health care providers. Mild or moderate tics may nevertheless cause some distress, and their presence, even if there is no need for pharmacological suppression of tics, may influence the treatment of comorbid disorders such as OCD or ADHD. In this regard, tics may serve as a useful clinical marker that deserves mention even if they themselves do not require treatment. The classification of tic severity affects the results of epidemiological and family genetic studies: if mild cases are taken into account, the incidence of tics will be higher, while if DSM-IV criteria are applied, the incidence will be lower.

[ 1 ], [ 2 ], [ 3 ]

Diagnostic criteria for Tourette syndrome

• A. The presence of multiple motor tics and at least one vocal tic at any time during the illness, but not necessarily at the same time (a tic is a sudden, rapid, repetitive, non-rhythmic, stereotyped movement or vocalization)
• B. Tics occur repeatedly during the day (usually in bursts) almost daily or periodically for more than 1 year, and during this time the period of absence of tics does not exceed 3 months
• B. The disorder causes significant discomfort or significantly disrupts the patient's life in social, professional or other important areas
• G. Onset - up to 18 years of age
• D. The disorder is not caused by direct physiological effects of exogenous substances (eg, psychostimulants) or a general disease (eg, Huntington's disease or viral encephalitis)

The patient's examination includes a thorough physical and neurological examination to exclude a disease that could cause hyperkinesis (eg, thyrotoxicosis). Mild nonspecific neurological symptoms ("micro symptoms") are often found in patients with Tourette syndrome. Choreiform movements have been reported to be more common in patients with OCD and ADHD tics. A psychiatric examination and neuropsychological testing are necessary to identify comorbid mental disorders or poor learning abilities, which may be the main cause of maladjustment in patients. The study of hyperkinesis is best carried out using clinical rating scales that assess the type, frequency, and severity of each tic. An excellent example of such a scale is the Yale Global Tic Severity Rating Scale (YGTSS). Self-report or parent-report scales, such as the Tourette Syndrome Symptom Checklist (TSSL), are also used. Asking the patient to reproduce his or her tics sometimes produces a tic storm. Because tics often diminish or disappear in an unfamiliar environment, such as a doctor's office, video recording of tics in the home environment can be an important method of investigating tics to assess the effectiveness of therapy.

[ 4 ], [ 5 ], [ 6 ], [ 7 ], [ 8 ]

Diagnostic criteria for other tic variants

Transient tics

• A. Combative or multiple motor or vocal tics (i.e., sudden, rapid, repetitive, non-rhythmic, stereotyped movements or vocalizations)
• B. Tics occur many times a day, almost daily, for at least 4 weeks but no more than 12 months in a row
• B. The disorder causes significant discomfort or significantly disrupts the patient's life in social, professional or other important areas
• G. Onset - before the age of 18
• D. The disorder is not related to the direct physiological effects of exogenous substances (eg, psychostimulants) or a general disease (eg, Schtington's disease or viral encephalitis)
• E. The disorder does not meet the criteria for Tourette syndrome, chronic motor or vocal tics

Chronic motor or vocal tics

• A. Tics or multiple motor or vocal tics (i.e., sudden, rapid, repetitive, non-rhythmic, stereotyped movements or vocalizations), but not a combination of these, are present during the illness period
• B. Tics occur many times a day (usually in bursts) almost daily or periodically for at least 1 year, and during this time the tic-free period does not exceed 3 months
• B. The disorder causes significant discomfort or significantly disrupts the patient's life in social, professional or other important areas
• G. Onset - before the age of 18
• D. The disorder is not related to the direct physiological effects of exogenous substances (eg, psychostimulants) or a general disease (eg, Huntington's disease or viral encephalitis)
• E. The disorder does not meet the criteria for Tourette syndrome, chronic motor or vocal tics

Tiki without further clarification

[ 9 ], [ 10 ], [ 11 ], [ 12 ]

Differential diagnosis of Tourette syndrome

Given the variability and diversity of manifestations of Tourette syndrome, it must be differentiated from a wide range of neurological and psychiatric diseases, including Sydenham's chorea, Huntington's chorea, progressive muscular dystonia, blepharospasm, neuroacanthocytosis, postinfectious encephalitis, drug-induced dyskinesias, compulsions and stereotypies associated with autism, mental retardation, psychoses. Differential diagnosis may require paraclinical examination and trial therapeutic intervention.

Differential diagnosis between simple tics and other hyperkinesis is carried out taking into account the duration, localization, time dynamics and connection with movement. For example, typical chorea is characterized by longer muscle contractions and chaotic involvement of various muscle groups. Sydenham's chorea develops acutely, soon after a streptococcal infection and is characterized by a combination of behavioral changes and hyperkinesis. Some of these excessive movements may resemble tics. On the other hand, choreiform movements have been described in Tourette's syndrome, arising against the background of simple and complex motor or vocal tics. A thorough study of the anamnesis, the course of the disease, a detailed examination to identify other symptoms of rheumatism should help in the differential diagnosis between Sydenham's chorea and Tourette's syndrome.

Dystonia differs from dystonic tics by the greater persistence of hyperkinesis and the absence of clonic tics. Myoclonus usually has a limited localization, while tics vary in localization and occur in bursts. Eye movements such as twitching or prolonged abduction are characteristic of tics and are rarely observed in other hyperkinesis. Exceptions include:

1. dystonic oculogyric crises that occur as a side effect of neuroleptic therapy or as a complication of lethargic encephalitis;
2. myoclonus of the eyeballs, which often accompanies myoclonus of the soft palate;
3. opsoclonus.

Idiopathic blepharospasm, when it has minor manifestations, can be difficult to distinguish from tic blinking or squinting, but their differential diagnosis is usually facilitated by the presence of tics in other locations. Blepharospasm usually affects elderly people, while Tourette syndrome usually manifests in children.

[ 13 ], [ 14 ], [ 15 ], [ 16 ]