Tics and Tourette Syndrome
Tics are sudden, rapid, stereotyped,
repetitive, nonrhythmic
movements or vocalizations affecting discrete muscle groups. Most experts agree
and clinical experience dictates that tics are preceded by a sensory component,
described by patients as an “urge.” When patients are asked to prevent
movements from occurring, an uncomfortable inner sensation builds and an urge
to “release” develops, resulting in expression of the tics.
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 self
injury 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,
CreutzfeldtJakob
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 (HallervordenSpatz 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 Xtremor syndrome
have also been reportedto 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 dopamineblocking or dopaminedepleting agents. Other
evidence comes from func
tional imaging studies demonstrating volumetric striatal changes and, in some,
increased dopamine synaptic content. Recently, deep brain stimulation has 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.
