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
- Mild / Non-impairing:
- Psychoeducation, watchful waiting, behavioral support, and classroom accommodations.
- First-Line / Behavioral Therapy (Mild-to-Moderate Impairment):
- Comprehensive Behavioral Intervention for Tics (CBIT) / Habit Reversal Therapy (HRT).
- First-Line Pharmacotherapy (Preferred initial med):
- Alpha-2 adrenergic agonists: Guanfacine or Clonidine (preferred first-line due to low side-effect profile; especially effective if comorbid ADHD).
- Second-Line Pharmacotherapy (Moderate-to-Severe Impairment):
- Second-Generation Antipsychotics (SGAs): Aripiprazole (FDA-approved), Risperidone.
- VMAT2 Inhibitors: Tetrabenazine, Deutetrabenazine, Valbenazine. c
- Vesicular monoamine transporter type 2 (VMAT2) inhibitors function as dopamine depleters
- Refractory / Severe Cases:
- First-Generation Antipsychotics (FGAs): Haloperidol, Pimozide (FDA-approved; limited by risk of EPS, tardive dyskinesia, and QTc prolongation).
- Deep Brain Stimulation (DBS): Reserved for severe, medically refractory adult cases.