Tourette's Syndrome & other Tic Disorders

Definition

Tourette’s Syndrome (TS) is a neurodevelopmental disorder characterized by multiple motor tics and at least one vocal tic, present for more than one year, often beginning in childhood. Other tic disorders include chronic motor or vocal tic disorder and provisional tic disorder.

Epidemiology

• Prevalence of TS: approximately 0.3–1% of children
• More common in boys than girls (ratio ~4:1)
• Onset typically between ages 5–10 years
• Motor tics often precede vocal tics
• Tics may fluctuate in frequency and severity over time

Etiology

• Genetic factors: strong familial aggregation and heritability
• Neurobiological abnormalities: dysfunction in cortico-striato-thalamo-cortical circuits
• Neurotransmitter dysregulation: dopamine hyperactivity
• Environmental factors: prenatal complications, infections, stress
• Comorbid neuropsychiatric conditions: ADHD, OCD
• Interaction between genetic susceptibility and environmental triggers

Pathophysiology

• Hyperactivity in dopaminergic pathways in basal ganglia
• Abnormal cortical-striatal-thalamo-cortical loop activity
• Impaired inhibitory control of motor and vocal output
• Sensory phenomena (premonitory urges) preceding tics
• Neurodevelopmental alterations during childhood
• Interaction of neurochemical, genetic, and environmental factors
• Fluctuating tic expression due to stress or fatigue