How is a patient with Tourette's syndrome diagnosed?

Diagnosis of Tourette's Syndrome

Tourette's syndrome is diagnosed clinically when a patient has multiple motor tics AND at least one vocal tic persisting for at least 1 year with onset in childhood, meeting DSM-IV-TR criteria and Diagnostic Confidence Index standards. 1

Essential Diagnostic Criteria

The diagnosis requires all of the following components:

• Multiple motor tics (not just a single tic) must be present 1, 2
• At least one vocal (phonic) tic must be present 1, 2
• Duration of at least 1 year with symptoms present (though not necessarily continuous) 1
• Onset in childhood (typically between ages 6-8 years) 3, 4
• The patient must be classified as a definitive case according to Diagnostic Confidence Index standards 1

Clinical Features That Support the Diagnosis

Several characteristic features help distinguish tics from other movement disorders:

• Suppressibility: Patients can temporarily suppress tics voluntarily, followed by intensification of the premonitory sensation 2
• Premonitory urges: Nearly irresistible somatosensory sensations that precede tics, typically developing by age 10 years 3, 2
• Waxing and waning pattern: Tic severity fluctuates over weeks to months 1, 2
• Variability: Tics change in location, frequency, and type over time 1
• Distractibility and suggestibility: Tics can be evoked by mentioning them and diminish during goal-directed activities 3, 2
• Momentary relief: Completion of a tic typically provides temporary relief 3

Types of Tics to Identify

Motor tics include:

• Simple motor tics: eye blinking, facial grimacing, head jerking, shoulder shrugging 1, 2
• Complex motor tics: more elaborate, seemingly purposeful movements 3

Phonic (vocal) tics include:

• Simple phonic tics: throat clearing, sniffing, grunting, coughing, squeaking, barking 5, 1, 2
• Complex phonic tics: words or phrases 5

Critical Differential Diagnoses to Exclude

Before diagnosing Tourette's syndrome, rule out:

• Transient tic disorder: More common (4-24% of elementary school children) but resolves within 1 year 1, 2
• Chronic motor or vocal tic disorder: Only motor OR vocal tics present, not both 2
• Tic cough (formerly called "habit cough"): Use updated terminology and distinguish from Tourette's 1
• Other movement disorders: Chorea, dystonia, hemiballismus—these lack suppressibility and premonitory urges 5, 2
• Secondary causes: Drug-induced tics, chromosomal abnormalities, genetic disorders (Hallervorden-Spatz disease), autism spectrum disorders 5

Mandatory Comorbidity Assessment

A comprehensive evaluation must screen for common comorbidities that often cause more impairment than tics:

• ADHD: Present in 50-75% of children with Tourette's 1, 6
• Obsessive-compulsive disorder or behaviors: Present in 30-60% of cases 1, 6
• Anxiety and depression 3
• Learning disabilities and behavioral difficulties 7

Required Clinical Assessment

• Multidisciplinary evaluation by neurologist, psychiatrist, and clinically qualified psychologist 1
• Neurological, neuropsychiatric, and neuropsychological assessment 1
• Document impact on function and quality of life, as this is crucial for treatment decisions 1

Key Diagnostic Pitfalls to Avoid

• Do not perform excessive medical testing: Diagnosis is primarily clinical, and unnecessary testing causes iatrogenic harm 1, 2
• Do not misdiagnose tics as "habit behaviors" or "psychogenic symptoms": This leads to inappropriate interventions and delays proper treatment 1, 2
• Do not use outdated terminology: Replace "habit cough" with "tic cough" and "psychogenic cough" with "somatic cough disorder" 1
• Do not diagnose Tourette's without ruling out biological and genetic tic disorders 5
• Do not overlook comorbidities: Failing to identify and address ADHD, OCD, or other conditions is a common error 6

Epidemiological Context

• Boys are affected more commonly than girls, with prevalence approximately 1 per 1,000 male children 1, 2
• Peak severity typically occurs between ages 8-12 years 3
• Nearly half of patients experience spontaneous remission by age 18, with less than 20% continuing to have clinically impairing tics as adults 1, 3