The Pediatric Page
Tics and Tourette Syndrome
Definitions: Tics are sudden, rapid, purposeless, stereotyped movements or vocalizations. They are classified as simple or complex, and either motor or vocal. Simple tics are ill-defined sounds (such as grunts) or brief movements of limited muscle groups, such as shoulder shrugs. Complex tics are seemingly meaningful sounds such as coprolalia, or distinct, coordinated patterns of successive movements with several muscle groups, such as obscene gestures or touching people.
Classification: Tic disorders have a broad spectrum of severity. Tics may be transient or chronic. Classification is based on the DSM-IV. In all cases, tics must have had their onset prior to age 21.
Transient Tic Disorder: Motor and/or vocal tics that occur many times a day, nearly every day, for at least 2 weeks, but for no longer than 12 consecutive months.
Chronic Tic Disorder: Either multiple motor or vocal tics, but not both, that have been present at some time during the illness. The tics occur many times a day, nearly every day, or intermittently throughout a period of more than 1 year.
When do tics become Tourette syndrome? The most severe form of tic conditions is Tourette Syndrome (TS). In general, for a TS diagnosis, the tics must have started prior to age 21, with the presence of both motor and vocal tics (not necessarily concurrent) occurring for at least one year. Periods of remission are common. Social disruption is usually necessary for the strict definition.
Incidence: Tourette syndrome affects people of all ethnic groups; males are affected 3 to 4 times more often than females. Transient tic disorders are relatively common in children (3-15% in different studies). The best current estimate of Tourette syndrome prevalence is about 1 in 1000.
Etiology: Multiple theories exist on the pathophysiology of tics. Defective inhibitory mechanisms in the brain, overactivity of the dopamine system, and basal ganglia dysfunction are proposed mechanisms. All are thought to result in excess motor activity manifesting as tics. A post- Streptococcal infection autoimmune phenomenon has also been suggested. Hormonal influences and environment may play a role. TS is thought to have a genetic basis, with autosomal dominance and mostly male penetrance. TS is familial with a prevalence of TS in first-degree relatives of 5-15%.
Clinical course: Tics tend to fluctuate in severity and character over time. Patients can usually suppress their tics for short periods of time. Tics tend to worsen in stressful situations and improve when the person is relaxed, sleeping or absorbed in an activity. The onset of tics is typically around age 6 to 7. In TS, the course then proceeds from simple to more complex tics. Tics often start with midline involvement (e.g., neck movements or eye blinking) and proceed peripherally (e.g., arm movements). The severity peaks between 9-11 years of age. In many cases, (the data varying between 30-85%), symptoms improve or decrease after adolescence.
Comorbid disorders: TS often occurs concurrently with other disorders—most commonly ADHD, learning difficulties and Obsessive-Compulsive Disorder (OCD). Males seem to exhibit more tics, and females more OCD, supporting a theory that tics and OCD may be alternative phenotypes of a proposed, yet unidentified, TS gene. Other complications include depression, sleep problems, social discomfort and self-injurious behaviors. Comorbid features may be more debilitating than the tics.
Workup: In general, no testing is necessary if the history and clinical features are typical for TS. There are no standard tests for tic disorders. Further workup may be needed if unusual historical or examination features are present. Careful vigilance is required to identify potentially treatable conditions such as thyroid problems, substance use or liver disease early in one’s course of illness. Exam findings besides tics, such as rigidity, myoclonus, or psychosis warrant further evaluation.
Non Pharmaceutical approaches:
- Education: Education about tics and involvement in support groups and behavioral programs have dropped the need for medications by 50% in the past decade. See below for resources.
- Habit Reversal Therapies: These programs require a motivated patient. At follow-up, studies report that at least one-half of the treated patients had greater than 75% reduction in tic severity. Anecdotally, results have been mixed.
- Neuroleptics (e.g., haloperidol): Thought to exert their effect by dopamine antagonism. On average, tic severity declines by approximately 50-80%. Haldol has a much higher risk of tardive dyskinesias and is being replaced by next generation neuroleptics such as Risperdal.
- Clonidine: This drug has been used frequently to treat tics. However, no convincing data exists of efficacy after several small trials. It may be most appropriate as a first agent in patients with problematic ADHD and mild tics.
- Other therapies with variable efficacy and limited studies include benzodiazepines, guanfacine, baclofen, and botulinum toxin.
- 15% of patients may need long-term medications. However, after six months of tic freedom it is reasonable to attempt a medication taper.
Prognosis: The most common disability is social in nature. Little or no excess mortality is associated with TS. TS may persist to some degree throughout life, usually to a lesser severity over time. These children and families need support, both medically and emotionally. There are many resources including: TS Association, Inc: www.tsa-usa.org; and Family Village: www.familyvillage.wisc.edu
When to refer for neurological consultation:
- When a child has Tourette syndrome or the diagnosis is unclear.
- Any abnormalities on neurological examination other than tics themselves.
- Comorbid features are present.
- Severe tics requiring medication therapy.
- Medication refractory patients.
- Complicated cases.