Tic and Tic syndrome classification article

[Claire]

http://www.postgradmed.com/issues/2000/10_...vidente_tic.htm

 

Is it a tic or Tourette's?

Clues for differentiating simple from more complex tic disorders

Virgilio Gerald H. Evidente, MD

 

 

Preview: Transient tics are common, particularly among children under the age of 10 years. In fact, about 20% of kids in this age-group have tics that disappear as they get older. Nonetheless, parents often are concerned about what strange movements or sounds mean and what can be done about them. Many have heard horror stories about Tourette's syndrome and fear a life of social rejection because of uncontrollable "urges." In this article, the author discusses the various types of tics and the wide range of treatments available for their management.

Evidente VGH. Is it a tic or Tourette's?: clues for differentiating simple from more complex tic disorders. Postgrad Med 2000;108(5):175-82

 

 

 

--------------------------------------------------------------------------------

 

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" (1). 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, hiccuping, 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 (2). 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 (3).

 

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:

 

Multiple motor and one or more phonic tics (not necessarily concurrently)

Onset before age 18 years

Tics that occur many times a day, nearly every day or intermittently for more than a year, with symptom-free intervals not exceeding 3 months

Variations in anatomic location, number, frequency, complexity, and severity of the tics over time

Tics that are not related to intoxication with psychoactive substances or central nervous system (CNS) disease (eg, encephalitis)

Symptoms that cause significant impairment of social, academic, and occupational functioning

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.

 

Several conditions, termed tourettism, may mimic Tourette's syndrome. Drugs, including stimulants, levodopa (Dopar, Larodopa), and antiepileptic medications (eg, phenytoin [Dilantin], carbamazepine [Atretol, Epitol, Tegretol], lamotrigine [Lamictal]), may cause tourettism. Discontinuation of the offending drug leads to prompt remission of the tics. Neuroleptic medications with potent dopamine2 (D2) antagonist activity (eg, haloperidol [Haldol]) may cause tardive tourettism, which presents with delayed and often permanent tics identical to Tourette's syndrome.

 

Other causes of tourettism include infections (eg, Creutzfeld-Jakob disease, encephalitis), toxins (eg, carbon monoxide), Huntington's disease, head trauma, stroke, neuroacanthocytosis, chromosomal abnormalities, cerebral palsy, neurocutaneous syndromes, and schizophrenia (1).

 

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 (5). Its onset is usually between ages 2 and 15 years (mean, 6.5 years) (2). 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 (1). Rarely, motor tics may be induced by an unexpected startling stimulus (ie, reflex tics or startle-induced tics). Exacerbation or precipitation of tics in children may also occur after infection with group A beta-hemolytic streptococci (6).

 

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 (2,7). Unlike most hyperkinetic movement disorders, tics may persist during light stages of sleep.

 

Although the disability with Tourette's syndrome is often confined to social embarrassment, severe motor tics may lead to physical injury, including fractures, cervical radiculomyelopathy, joint dislocation, and falls. Severe phonic tics may also impair respiration, swallowing, and speech.

 

Comorbidity

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 (2). 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. Other behavioral problems that are also seen in Tourette's syndrome include quick temper, mood swings, overreaction, exhibitionism, negativism, rage attacks, oppositional defiant disorder, bipolar disorder, schizo-affective disorder, and cyclothymic disorder (5).

 

Etiology and pathogenesis

Idiopathic 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) (1,2,8). However, the exact genetic basis for Tourette's syndrome has been elusive. Autosomal dominant, autosomal recessive, and sex-linked inheritance have been considered but have been rejected (9). Numerous candidate genes have been tested and excluded, and complete genome screens have failed to show significant results (10).

 

Neuropsychiatric disorders, such as tic disorders and obsessive-compulsive disorder, may develop after streptococcal infection (termed pediatric autoimmune neuropsychiatric disorders associated with streptococcal infection [PANDAS]). The mechanism is most likely autoimmune-related, whereby antibodies against bacterial antigens cross-react with proteins in the brain (6). The manner in which genetic factors and environmental factors interrelate in Tourette's syndrome is unknown.

 

...