Epidemiology
- Onset age < 18 (commonly age 6-15)
Etiology
Pathophysiology
- Exact mechanism unknown; strong genetic component (highly heritable).
- Involves dysregulation of the cortico-striato-thalamo-cortical circuitry.
- Excess dopaminergic transmission in the basal ganglia (caudate nucleus). t
- Associated with disinhibition of the motor and limbic system loops.
Clinical features
- Tics: sudden and rapid involuntary, intermittent, nonrhythmic movements or vocalizations without any recognizable purpose
- May wax and wane in frequency
- Temporarily suppressible
- Premonitory urge: An urge or sensation preceding the tic is relieved by its onset.
- Both multiple motor tics & ≥1 vocal tics (not necessarily concurrent) >1 year
- Motor: facial grimacing, blinking, head/neck jerking, shoulder shrugging, tongue protrusion, sniffing
- Vocal: grunting, snorting, throat clearing, barking, yelling, coprolalia (obscenities)
Diagnostics
DDx
- Stereotypic movement disorder
- Characterized by simple repetitive movements (eg, rocking, head banging), which are voluntary in nature and seemingly purposeless.
- They are often seen in children with autism spectrum disorders and intellectual disability and are a common form of self-soothing.
Treatment
- First-line (Non-pharmacologic): Psychoeducation and Comprehensive Behavioral Intervention for Tics (CBIT) / Habit Reversal Training.
- Pharmacotherapy (for bothersome tics interfering with daily life):
- Alpha-2 agonists: Guanfacine, Clonidine (First-line medical therapy, esp. if comorbid ADHD).
- Antipsychotics: High-potency D2 antagonists (e.g., Haloperidol, Pimozide, Fluphenazine) or Atypical antipsychotics (Risperidone, Aripiprazole).
- Note: Atypicals preferred over typicals due to ↓ risk of EPS/Tardive Dyskinesia.
- VMAT2 Inhibitors: Tetrabenazine (depletes dopamine).
- Refractory: Deep Brain Stimulation (DBS).