by:Virgilio Evidente, MD
Tics are defined as brief, intermittent, repetitive, nonrhythmic, unpredictable, purposeless, stereotyped movements (motor tics) or sounds (phonic or vocal tics). They are associated with an urge, and voluntary suppression results in psychic tension and anxiety. Subsequent "release" of the movements or sounds results in relief.
Although tics appear to be voluntary, the affected person often feels compelled to move to relieve an unexplainable urge. Thus, some authorities consider tics as "semivoluntary" or "unvoluntary". Although tics may resemble other types of hyperkinetic movements (eg, myoclonus, dystonia), the urge is considered the key characteristic that suggests that the movement is a tic rather than another movement disorder.
Classification of tics
Tics are classified as either simple or complex. Simple motor tics are focal movements involving one group of muscles, such as eye blinking, tongue protrusion, facial grimacing, shoulder shrug, or head turning. Complex motor tics are coordinated or sequential patterns of movement that resemble normal motor tasks or gestures. Examples include jumping, throwing, head shaking, making obscene gestures such as "giving the finger" (copropraxia), and imitating gestures of others (echopraxia).
Simple phonic tics are elementary, meaningless noises and sounds, such as grunting, sniffing, clearing the throat, squeaking, coughing, wheezing, belching, hiccupping, whistling, or producing animal sounds. Complex phonic tics include meaningful syllables, words, or phrases (such as saying "okay" or "shut up"); repeating one's own utterances, especially the last syllables of words (palilalia); repeating someone else's words or phrases (echolalia); or shouting obscenities or profanities without any reason or provocation (coprolalia).
Motor tics can also be classified according to speed of movement. Those that are brief, sudden, and jerklike are known as clonic tics (eg, blinking, facial twitching). Motor tics that involve brief twisting or posturing are called dystonic tics (eg, torticollis, blepharospasm), whereas those that involve sustained or prolonged movements or contraction of muscles are labeled tonic tics (eg, prolonged bending of the trunk or tensing of the abdomen).
Sensory tics refer to uncomfortable sensations, such as pressure, tickle, cold, warmth, or paresthesias that are localized to certain body parts and that are relieved by the performance of an intentional act in the affected area. Rarely, motor tics may be provoked by a mental projection of sensory impressions to other persons or objects and are relieved by touching or scratching that person or object. These are known as phantom tics.
Types of tic disorders
The fourth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) (4) lists three types of tic disorders: Gilles de la Tourette (Tourette's) syndrome, chronic motor or vocal tic disorder, and transient tic disorder.
By DSM-IV criteria, Tourette's syndrome is characterized by the following features:
If only motor or vocal tics are present (not both), the appropriate diagnosis is chronic tic disorder. If single or multiple motor or vocal tics are present many times a day, nearly every day for at least 4 weeks but no longer than 12 consecutive months, the term "transient tic disorder" applies. Transient tics are seen in 20% of children during their first decade of life.
Clinical features of Tourette's
Tourette's syndrome is the most common and severe form of multiple tic disorder, with a prevalence of 10 cases per 10,000 population. Its onset is usually between ages 2 and 15 years (mean, 6.5 years). On average, phonic tics begin 1 to 2 years after the onset of motor tics. Symptoms remit by a median age of 18 years in about 75% of cases. In rare cases, Tourette's syndrome may start during adulthood in the absence of precipitating factors (eg, exposure to neuroleptic drugs, infections, stroke). Focal tics may also appear in adults in relation to peripheral nerve injury in the area of the tic.
Tics increase in frequency and severity with stress, relaxation after physical exertion, excitement, idleness, fatigue, exposure to heat, and use of dopaminergic drugs, steroids, caffeine, and CNS stimulants. Rarely, motor tics may be induced by an unexpected startling stimulus (ie, reflex tics or startle-induced tics).
Tics usually diminish with performance of engaging mental or physical activities (eg, playing computer games, playing sports) or with consumption of cannabinoid substances (eg, marijuana), alcohol, or nicotine. Unlike most hyperkinetic movement disorders, tics may persist during light stages of sleep.
Tourette's syndrome is often accompanied by other conditions, particularly attention-deficit/hyperactivity disorder (ADHD) and obsessive-compulsive disorder. Both of these disorders can contribute substantially to the disability and management problems of the illness.
ADHD afflicts 50% of Tourette's syndrome patients with or without hyperactivity. It manifests as impulsivity, inattention, restlessness, fidgeting, poor concentration, poor school or work performance, and learning impairment. Not uncommonly, ADHD becomes the major problem because severely hyperactive kids, especially those with severe phonic tics or coprolalia, become disruptive to other children in class.
Obsessive-compulsive symptoms are repetitive, stereotyped, involuntary, senseless thoughts or behaviors that intrude into the patient's consciousness or actions. These symptoms become a disorder (obsessive-compulsive disorder) if they cause significant social impairment and emotional distress. Between 30% and 50% of patients with Tourette's syndrome also have obsessive-compulsive disorder, which may be more troublesome than the tics.
What are the Causes?
Tic disorders and Tourette's syndrome are multifactorial in etiology. Although genetic factors play a major role in causing Tourette's syndrome, the environment seems to influence the risk, severity, and course of the disorder. Genetic factors are present in about 75% of cases, with 25% presenting with bilineal transmission (both parents affected). However, the exact genetic basis for Tourette's syndrome has been elusive.
Tics and the conditions with which they are associated can be difficult to treat. Education of the patient and family about tics and Tourette's syndrome is essential. The promotion of support and understanding should form the basis of both pharmacologic and nonpharmacologic treatment strategies. Pharmacologic treatment, because of potential side effects, should start with agents that can do the least harm.
Behavioral and cognitive treatment
About 85% of children with Tourette's syndrome experience diminution or remission of their symptoms during or after adolescence. Tics persisting beyond teenage years usually become permanent, and idiopathic adult-onset tics usually persist. A poorer prognosis in adulthood is associated with perinatal complications, chronic physical illness, unsupportive and unstable family milieu, co-morbid mental and developmental disorders, and exposure to cocaine and anabolic steroids.