Tics and Tourette Syndrome

The spectrum of tics includes transient tics of childhood when present for less than 1 year, chronic motor or vocal tics when tics are present for more than 12 months, and Tourette syndrome, defined by the presence of both motor and vocal tics for more than 12 months.

Tics may be classified according to complexity of symptoms as simple motor or vocal tics when involving only a few muscles or simple sounds, such as eye blinking, shoulder shrugging, facial grimacing, whistling, grunting, throat clearing, snorting, chirping, or sniffing. Many such youngsters are initially mistakenly diagnosed as having chronic rhinitis or “allergies,” or punished unnecessarily for loud behaviors. Once considered rare, schoolteachers now easily identify tics and may be the first to call attention to a child’s unique behavior. In complex motor or vocal tics, multiple muscle groups are recruited in orchestrated bouts of involuntary movements or utterances of words and sentences or phrases. Examples include hand gestures, jumping, touching, pressing, shouting words, or speech blocking. Some individuals may exhibit copropraxia, the sudden performance of obscene gestures or echopraxia, the involuntary spontaneous imitation of someone else’s movements.

Tourette syndrome (TS) is characterized by multiple motor and vocal tics. In many TS patients, obsessivecompulsive behaviors and attention deficit disorder, or both, may be present. Anxiety, depression, and selfinjury behaviors may complicate the clinical picture.

Tics may be primary or “idiopathic” or secondary, in which a definable cause is found. Primary tics are by far the more common in children and adolescents, with secondary disorders in that age group being rare. In adults, trauma, encephalitis, stroke, carbon monoxide poisoning, neurosyphilis, Creutzfeldt-Jakob disease, and central nervous system (CNS) injury from hypoglycemia may result in tics or Tourettism. Some genetics disorders in which tics have been described include Huntington disease, neuroacanthocytosis, neuroferritinopathy (Hallervorden-Spatz disease), dystonia with tics, tuberous sclerosis complex, and some cases of Duchenne muscular dystrophy. A few patients with Down syndrome, Asperger/autism spectrum, and fragile X-tremor syndrome have also been reported to have tics. The use of illicit drugs or medications may result in tics, Tourettism, or punding, particularly the use of cocaine, amphetamines, and antiepileptic medications (phenobarbital, phenytoin, and carbamazepine). Less commonly, opioids, lithium, levodopa, and antidepressants may induce or worsen tics.

The substrate for tics and Tourette syndrome seems to reside in the basal ganglia and related structures. Supporting evidence for this concept includes the clinical observation of tic improvement when patients are treated with dopamine-blocking or dopaminedepleting agents. Other evidence comes from functional imaging studies demonstrating volumetric striatal changes and, in some, increased dopamine synaptic content. Recently, deep brain stimulation has demonstrated improvement of tics when stimulating different targets of the corticostriatothalamic and limbic pathways/structures.

The goal of treatment of tics and Tourette syndrome is to relieve some of the more pressing symptoms. For some affected persons, tics may be the most bothersome aspect of their illness. For others, obsessive-compulsive behaviors, attention deficit with hyperactivity, anxiety, or depression may be more distressing. There is no general agreement as to the best treatment for tics. Most authors recommend alpha-2 agonists, such as guanfacine or clonidine, as first-line therapy. Dopamine-blocking agents are the most potent anti-tic medications but are also associated with a high incidence of side effects. Tetrabenazine, a dopamine depletor, may be useful in some cases. A stimulant such as methylphenidate does not worsen tics as previously thought. It can therefore be safely used in those with tics and attention deficit disorder. The serotonin reuptake inhibitors are helpful in treating anxiety, depression, or obsessivecompulsive disorder in patients with tics or Tourette syndrome. Botulinum toxin therapy has proven to be of some value when used in patients with dystonic tics. A behavioral therapeutic approach using habit reversal therapy at its core has been shown to be effective in a recent large multicenter study. Thalamic or pallidal deep brain stimulation is a promising strategy in refractory cases.

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