Tics and Tourette syndrome: An adult perspective
ABSTRACTTourette syndrome (TS) is a disorder characterized by childhood onset multiple motor and vocal tics often accompanied by features of obsessive compulsive disorder, attention deficit hyperactivity disorder (ADHD), or other behavioral manifestations. Tics may be simple or complex, and may include motor and vocal components. Abnormal function of the basal ganglia is thought to be an important underlying cause of tics and other movement disorders. Treatment of TS requires a thorough understanding of the phenomenology of the disease for the individual patient, and should focus on symptoms that are especially troubling. Some nonpharmacologic approaches may help to improve tic severity, including conditioning techniques, relaxation training, and hypnosis. Options for pharmacotherapy include dopamine blockers and depleters, benzodiazepines, central alpha-adrenergic blockers, and botulinum toxin. Many patients require therapy for comorbid conditions such as anxiety, depression, or ADHD. In case studies and small patient series, deep brain stimulation has been shown to markedly reduce tic severity and functional impairment associated with TS. While onset is most frequently in childhood, TS should not be considered exclusively a disorder of pediatric patients. The complications and comorbidities that are encountered in children and adolescents often persist into adulthood.
Tourette syndrome (TS) is part of a spectrum of tic disorders. Tics are sudden, rapid, stereotyped, repetitive, nonrhythmic movements or vocalizations affecting discrete muscle groups, and are preceded by a sensory component. Patients in whom tic suppression is attempted report the experience of a sensation of inner pressure that must be released. This eventually results in the performance of motor movement or vocal sounds. TS is a disorder of childhood onset that is characterized by multiple motor and vocal tics. In some cases, there are features of obsessive compulsive disorder (OCD), attention deficit hyperactivity disorder (ADHD), or other behavioral manifestations such as coprolalia, echopraxia, palilalia, and self-injury.1,2 The spectrum of tic disorders includes:
- Transient tics of childhood (tic duration less than 12 months)
- Chronic motor or vocal tics (lasting more than 12 months), and
- TS (variable motor and vocal tics lasting more than 12 months).
Many children meet the diagnostic criteria for TS between the ages of 6 and 9 years, but symptoms may improve by adulthood. The eventual loss of tics over time reflects the maturation of brain systems that control ballistic action.3
The tics that accompany TS may be defined as simple or complex, and as motor or vocal. Simple motor tics involve only a few muscles, such as eye blinking, shoulder shrugging, or facial grimacing. Complex motor tics involve multiple groups of muscles that are recruited in orchestrated bouts (eg, hand gestures, jumping, touching, or pressing), and may include copropraxia (a sudden tic-like vulgar, sexual, or obscene gesture) or echopraxia (involuntary, spontaneous imitation of someone else’s movements). Simple vocal tics are meaningless sounds such as throat clearing, grunting, sniffing, snorting, and chirping. Complex vocal tics involve speech and language such as sudden, spontaneous expression of single words or phrases, or speech blocking.4
Tics may be acquired as a consequence of other disorders, including head trauma, encephalitis, stroke, carbon monoxide poisoning, Creutzfeldt-Jakob disease, neurosyphilis, hypoglycemia, or Sydenham chorea.5 Genetic disorders such as Huntington disease may be associated with tics. Tics may also occur with certain chromosomal abnormalities or be associated with some neuropsychiatric disorders. Finally, tics may be caused by a large number of medications or illicit drugs, including cocaine, amphetamines, antipsychotics, and antidepressants.
The prevalence of all types of tics in childhood is approximately 6% to 12%, although the prevalence of chronic vocal tics is approximately 1 to 10 per 1,000 children and adolescents.6 TS is especially common among autistic children and in those with Asperger syndrome and other autistic spectrum disorders. A survey of patients at Cleveland Clinic Florida found that tics and TS accounted for 8% of all patients with movement disorders. Of patients with tics or TS who were older than 18 years, 70% were male.
PATHOPHYSIOLOGY OF TOURETTE SYNDROME: ROLE OF THE BASAL GANGLIA
Although the pathophysiology of TS is not completely understood, abnormal function of the basal ganglia is thought to be a central component of the disorder. The basal ganglia normally act to facilitate voluntary movements while suppressing competing involuntary ones. Abnormalities of basal ganglia activity are important in several disorders of motor function.7 Output neurons from the basal ganglia inhibit thalamic motor nuclei and midbrain neurons of the extrapyramidal motor system, and act to inhibit motor pattern generators in the cerebral cortex and brainstem. Hyperkinetic disorders, including tics, chorea, and dystonia, are thought to result at least in part from impaired inhibition of unwanted motor activity from the basal ganglia to downstream motor centers.7
Family heritability studies provide strong support that TS is a genetic disorder. For example, the concordance rate is 86% for monozygotic twins versus 20% for dizygotic twins.8 Chromosomes linked to TS include 2p32.2 and 13q31.1.9,10 Interactions between genetics and environment are also thought to play a significant role. The concept of pediatric autoimmune neuropsychiatric disorders associated with streptococcal (PANDAS) infections has been proposed to explain an apparent temporal association between streptococcal infections and exacerbation of tics. According to this model, molecular mimicry between streptococcal antigens and endogenous brain antigens results in an autoimmune attack.11 However, the identification of specific antibodies against basal ganglia cells remains controversial.12
MANAGEMENT OVERVIEW
Accurate diagnosis of TS is essential, and includes a complete history and neurologic examination. The tic phenomenology (complex vs simple) should be characterized, and the patient should be carefully questioned to identify the symptoms that are most bothersome (eg, motor or vocal tics, OCD, or ADHD). Pharmacotherapy should be reserved for problems that are functionally disabling and not remediable by nonpharmacologic interventions.
Treatment may also be required for other neuropsychiatric symptoms. Anxiety and depression have been reported in 19% to 80% of patients with tics, and depression is strongly correlated with the duration and severity of tics.13,14 Episodic outburst (rage), self-injurious, OCD, antisocial, and oppositional behaviors are all more common among individuals with tic disorders.15 Personality disorders may be related to OCD, ADHD, or to family or economic issues. Tic disorders are also associated with an increased incidence of somatic complaints, as well as higher rates of academic difficulties, which may be related to ADHD or medications. Sleep disturbances affect an estimated 20% to 50% of patients, and may include difficulty initiating or maintaining sleep, restlessness, movement-related arousal, or parasomnia.16
Education is an important part of treatment, and may include the patient, family members, teachers or other school staff, and work colleagues. A number of behavioral or psychosocial approaches may help to improve tics, including conditioning techniques, relaxation training, biofeedback, habit reversal, awareness training, and hypnosis.17
