Tics and Tourette Syndrome

Tics and related diseases represent a set of neurobehavioral disorders of childhood that are characterized by sudden, repeated, nonrhythmic, stereotyped muscle movements sometimes accompanied by sounds or vocalizations. Tourette syndrome is a severe form with symptoms lasting more than 1 year and involving both motor and vocal tics. Although there is no definitive cause of Tourette syndrome, the condition has genetic and environmental factors that contribute to disease development. Tourette syndrome is clinically diagnosed. Treatment involves behavioral therapy, antipsychotics, and the treatment of comorbid conditions. The majority of children outgrow their symptoms in adulthood, although a minority of adults will continue to demonstrate severe tics.

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Overview

Definition

Tics are repeated, nonrhythmic movements or vocalizations. 

Tourette syndrome is a disorder characterized by at least 1 motor and 1 vocal tic (may not occur at the same time) not caused by medication or other physiological processes, with an age of onset before 18, and lasting for more than 1 year.

Classification

  • Tourette syndrome: motor and vocal tics for 1+ year 
  • Provisional tic disorder: lasting < 1 year, diagnosed in retrospect
  • Chronic motor tics: presence of motor tics (no vocal tics) for 1+ year 
  • Chronic vocal tics: presence of vocal tics (no motor tics) for 1+ year

Epidemiology

  • Tics affect 20% of children worldwide; the severe form (Tourette syndrome) affects 3–8 per 1,000 children.
  • Boy:girl prevalence: 3:1
  • Mainly affects children aged 4–9 years
  • Often improves as patient grows older, and disappears in adulthood 
  • Prenatal maternal smoking thought to be a risk factor
  • Comorbid conditions:
    • OCD
    • Depression
    • Anxiety
    • ADHD
    • Self-injurious behavior

Pathophysiology

Causative pathway remains largely unknown, although several theories exist.

  • Genetic influence theory: 
    • Genetic mutation in developmental period
    • HDC gene on chromosome 15q21-q22, inherited in autosomal dominant pattern with incomplete penetrance  
    • SLITRK1 gene on chromosome 13q31.1 expressed in thalamic, subthalamic, and globus pallidus nuclei, striatum, cortex, hippocampus, and cerebellum, which are thought to be involved in Tourette syndrome
    • Offspring of parents with tics have a 45% chance of presenting any variant of tics and a 15% chance of developing Tourette syndrome.
  • Autoimmune theory:
    • Preceding infection with group A β-hemolytic streptococci → antibodies to basal ganglia → pediatric autoimmune neuropsychiatric disorder associated with streptococcal infection (PANDAS)
    • Other associated infections: herpes simplex virus infection, HIV, mycoplasma pneumonia, and varicella zoster virus (VZV)
  • Neurobiological theory: 
    • Disorder of fibers of cortico-striatal-thalamic-cortical (CSTC) pathway
    • Dopamine linked to improvement

Clinical Presentation

Tics

Simple tics:

  • Brief movement of single muscle or muscle groups or vocalization
  • Movement and vocalizations have no social meaning.
  • Examples of simple motor tics:
    • Eye blinking
    • Eye rolling
    • Limb and head jerking
    • Grimacing
    • Shoulder shrugging
  • Examples of simple sensory tics:
    • Throat clearing
    • Whistling
    • Coughs
    • Grunting
    • Animal sounds

Complex tics:

  • Cluster of simple actions, coordinated movements, or vocalizations that involve repetition of words 
  • Often, movements or words have social meaning.
  • Examples of complex motor tics:
    • Jumping
    • Touching objects and other people
    • Copropraxia: making obscene gestures in public or touching genitals
    • Echopraxia: imitating gestures of others
  • Examples of complex sensory tics:
    • Coprolalia: use of obscene words in public
    • Echolalia: repetition of words said by others
    • Palilalia: repetition of one’s own words

Other tic characteristics:

  • Fluctuating course: 
    • Waxing and waning pattern:  
      • More prominent during stress or fatigue
      • Less prominent when patient is engaged in activity
    • Always absent during sleep
  • Most common 1st symptom is facial tic (e.g., eye blink, nose twitch, or grimace)
  • Voluntary suppressibility: often associated with build-up of inner tension that resolves when tic is permitted to occur
  • Premonitory sensations: 
    • Sensory phenomena that occur before motor or phonic tic 
    • Take the form of urge, impulse, tension, pressure, itch, or tingle
    • More common in adults

Tourette syndrome

  • Symptoms appear before age 18:
    • Typically appear in school-aged children 
    • Generally worst around age 10
    • Adults usually have mild symptoms that may go unnoticed.
  • Associated with ADHD and OCD 
  • Motor tics normally appear 1st: 
    • Upper body tics more common than lower body tics
    • Examples: blinking, grimacing

Diagnosis

  • Diagnosis is clinical, involving identification of specific tic phenomenology. 
  • History and physical examination: 
    • Observe for tics during interview and physical examination.
    • Ask about past medical history of ADHD and OCD.
    • Ask about family history of tic disorders.
  • Diagnosed when patient has both motor and vocal tics for 1+ year, beginning before age 18
  • Imaging and blood testing may rule out other potential etiologies: 
    • Functional MRI: 
      • Used to demonstrate brain function during occurrence of tics
      • Shows reduced caudate volumes
    • CT: 
      • Employed in investigating associated structural abnormalities 
      • May show reduced caudate volumes
    • EEG: performed during sleep to ascertain nature of brain activity during tics and distinguish from other causes of involuntary movement
    • PET: shows increased brain activity during tics in thalamus and striatum
    • Blood testing: rules out chronic disease
    • Urine testing: drug screening (e.g., stimulant use) if there is suspicion for intoxication

Management

Treatment is only needed when the disease interferes with a patient’s image, social activity, or education. Most patients do well with education and CBT, without the need for medication or deep brain stimulation.

  • CBT:
    • Habit reversal therapy:
      • Most effective nonpharmacological treatment
      • Include detailed description of tic to find competing response 
      • Reduces chances of tic occurrence
    • Education about tics: Understanding tics as a neurobehavioral disease helps patients to cope with the disorder.
    • Social support and reward system: Good support reduces associated psychiatric conditions.
    • Functional intervention: identifies environmental events that worsen tics 
    • Relaxation training: reduces stress that could trigger tics
  • Pharmacological therapy/antipsychotics:
    • Alpha-adrenergic agonist (e.g., clonidine, guanfacine) 
    • 1st-generation antipsychotics (e.g., haloperidol)
    • 2nd-generation antipsychotics (e.g., risperidone, olanzapine) 
    • Currently: 2nd-generation antipsychotics are preferred pharmacological treatment due to fewer side effects.
  • Deep brain stimulation:
    • Implantation of electrodes and passage of stimulatory current to selected areas of brain in which increased activity is likely to cause tics
    • Includes thalamus and globus pallidus
  • Treatment of comorbid conditions:
    • ADHD: low-dose stimulants 
    • OCD: antidepressants (e.g., selective serotonin reuptake inhibitors (SSRIs) such as fluoxetine and clomipramine)
    • Anxiety: CBT and anxiolytics

Differential Diagnosis

  • ADHD: characterized by limited attention and hyperactivity for 6+ months in 2 different social environments. Presentation is classified as predominantly inattentive, predominantly hyperactive, or combined. Patients are diagnosed clinically based upon symptoms lasting more than 6 months, with onset before the age of 12. The disease usually continues into adulthood. Treatment is stimulant medication with other options including non-stimulant medications (e.g., atomoxetine) and behavioral therapy. The disease can cause functional decline.
  • OCD: characterized by recurring intrusive thoughts, feelings, or sensations (known as obsessions) that are time consuming and cause severe distress; relieved partially by performance of repetitive actions (known as compulsions). Patients diagnosed clinically by presence of obsessions or compulsions that are time consuming and affecting daily life. Treatment includes CBT and medications (e.g., SSRIs).  
  • Oppositional defiant disorder (ODD): continuous pattern of angry/irritable mood, argumentative/defiant behavior, or vindictiveness that is present for at least 6 months. This diagnosis is frequently found in those with ADHD. Symptoms of ODD are mostly directed toward authoritative figures, such as parents or teachers.

References

  1. Muller, N. (2007). Tourette’s syndrome: clinical features, pathophysiology, and therapeutic approaches. Dialogues Clin Neurosci. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3181853/
  2. Novotny, M., Valls, M., Klimova, B. (2020). Tourette Syndrome: A mini-review. Front Neurol. https://www.frontiersin.org/articles/10.3389/fneur.2018.00139/full
  3. Pringsheim, T., OKun, M.S., Muller-Vahl, K., et al. (2019). Practice guideline recommendations summary: Treatment of tics in people with Tourette syndrome and chronic tic disorders. https://pubmed.ncbi.nlm.nih.gov/31061208/
  4. CDC. (2021). Diagnosing Tic Disorders. Centers for Disease Control and Prevention. https://www.cdc.gov/ncbddd/tourette/diagnosis.html#provisional

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