Movement Disorders: Involuntary Tic Disorders

Introduction

Welcome to this comprehensive MCCQE1 preparation guide on Movement Disorders, specifically focusing on Involuntary Tic Disorders. This article is designed to help Canadian medical students prepare for the Medical Council of Canada Qualifying Examination Part I (MCCQE1) by providing in-depth knowledge on tic disorders within the Canadian healthcare context.

Definition and Classification

Tic disorders are neurodevelopmental conditions characterized by sudden, rapid, recurrent, non-rhythmic motor movements or vocalizations. In the context of MCCQE1 preparation, it's crucial to understand the classification of tic disorders according to the Diagnostic and Statistical Manual of Mental Disorders, 5th Edition (DSM-5):

1. Tourette Syndrome (TS)
2. Persistent (Chronic) Motor or Vocal Tic Disorder
3. Provisional Tic Disorder

Epidemiology in the Canadian Context

Understanding the prevalence and distribution of tic disorders in Canada is essential for MCCQE1 preparation:

• Prevalence of Tourette Syndrome in Canada: Approximately 1% of the population
• Male-to-female ratio: 3:1 to 4:1
• Typical age of onset: 5-7 years old
• Highest prevalence: School-age children (5-18 years)

Clinical Presentation

For MCCQE1 success, it's crucial to recognize the various types of tics:

Motor Tics

1. Simple Motor Tics

   • Eye blinking
   • Shoulder shrugging
   • Head jerking

2. Complex Motor Tics

   • Touching objects
   • Jumping
   • Twirling while walking

Vocal Tics

1. Simple Vocal Tics

   • Throat clearing
   • Sniffing
   • Grunting

2. Complex Vocal Tics

   • Echolalia (repeating others' words)
   • Palilalia (repeating one's own words)
   • Coprolalia (uttering socially inappropriate words)

Diagnostic Criteria

For MCCQE1 preparation, memorize the key diagnostic criteria for Tourette Syndrome:

1. Both multiple motor and one or more vocal tics present at some time
2. Tics may wax and wane in frequency but have persisted for more than 1 year
3. Onset before age 18 years
4. Disturbance not attributable to physiological effects of a substance or another medical condition

Canadian Guidelines for Management

The Canadian Guidelines for the Evidence-Based Treatment of Tic Disorders provide a framework for managing tic disorders in the Canadian healthcare system. Key points to remember for your MCCQE1 exam:

1. First-line treatments:

   • Psychoeducation
   • Behavioral interventions (e.g., Comprehensive Behavioral Intervention for Tics - CBIT)

2. Pharmacological treatments:

   • Alpha-2 agonists (e.g., guanfacine, clonidine)
   • Antipsychotics (e.g., risperidone, aripiprazole)

3. Alternative treatments:

   • Botulinum toxin injections for focal tics
   • Deep brain stimulation for severe, treatment-refractory cases

Comorbidities

For MCCQE1 success, be aware of common comorbidities associated with tic disorders:

• Attention-Deficit/Hyperactivity Disorder (ADHD)
• Obsessive-Compulsive Disorder (OCD)
• Anxiety disorders
• Learning disabilities
• Sleep disorders

Key Points to Remember for MCCQE1

1. Tic disorders are more common in males and typically onset in childhood
2. Tourette Syndrome requires both motor and vocal tics for >1 year
3. Tics are suppressible and often preceded by premonitory urges
4. First-line treatments in Canada include psychoeducation and behavioral interventions
5. Pharmacological treatments should be considered when tics cause significant impairment
6. Always assess for comorbid conditions, especially ADHD and OCD

MCCQE1 Practice Question

# Sample Question

A 10-year-old boy is brought to the clinic by his parents due to concerns about involuntary movements and vocalizations. The parents report that for the past 18 months, their son has been experiencing frequent eye blinking, shoulder shrugging, and occasional grunting sounds. These symptoms wax and wane in severity and can be suppressed temporarily. The boy reports feeling an urge to perform these actions. Which of the following is the most likely diagnosis?

- [ ] A. Provisional tic disorder
- [ ] B. Persistent motor tic disorder
- [ ] C. Persistent vocal tic disorder
- [ ] D. Tourette syndrome
- [ ] E. Huntington's disease

Explanation

The correct answer is:

• D. Tourette syndrome

Explanation: This case presents a classic picture of Tourette syndrome. The key features supporting this diagnosis are:

1. Presence of both motor tics (eye blinking, shoulder shrugging) and vocal tics (grunting)
2. Duration of symptoms for more than 1 year (18 months in this case)
3. Onset before age 18 (patient is 10 years old)
4. Waxing and waning of symptoms
5. Ability to suppress tics temporarily
6. Presence of premonitory urges

These features fulfill the diagnostic criteria for Tourette syndrome according to the DSM-5. The other options can be ruled out:

• Provisional tic disorder lasts less than 1 year
• Persistent motor or vocal tic disorders involve only one type of tic (motor or vocal)
• Huntington's disease is a progressive neurodegenerative disorder with a different clinical presentation

Canadian Guidelines

The Canadian Guidelines for the Evidence-Based Treatment of Tic Disorders emphasize a stepwise approach to management:

1. Psychoeducation and watchful waiting for mild tics
2. Behavioral interventions (e.g., CBIT) as first-line treatment
3. Pharmacological treatment for moderate to severe tics causing significant impairment
4. Consideration of alternative treatments for refractory cases

References

1. American Psychiatric Association. (2013). Diagnostic and statistical manual of mental disorders (5th ed.).
2. Pringsheim, T., et al. (2019). Canadian guidelines for the evidence-based treatment of tic disorders: pharmacotherapy, psychological therapy, deep brain stimulation, and complementary and alternative medicine. Canadian Journal of Psychiatry, 64(2), 76-95.
3. Martino, D., et al. (2013). Tourette syndrome and chronic tic disorders: the clinical spectrum beyond tics. International Review of Neurobiology, 112, 1-33.
4. Freeman, R. D., et al. (2000). An international perspective on Tourette syndrome: selected findings from 3,500 individuals in 22 countries. Developmental Medicine & Child Neurology, 42(7), 436-447.
5. Kurlan, R., et al. (2002). The behavioral spectrum of tic disorders: a community-based study. Neurology, 59(3), 414-420.

This comprehensive guide on Movement Disorders: Involuntary Tic Disorders is tailored for MCCQE1 preparation, focusing on Canadian medical practices and guidelines. Use this resource to enhance your understanding of tic disorders and improve your chances of success in the MCCQE1 exam. Remember to review other related topics in neurology and psychiatry for a well-rounded preparation.