tic disorder

**DSM-5 classification (all require onset before age 18, not attributable to substances or another medical condition):** - **Tourette disorder:** ≥2 motor tics AND ≥1 vocal (phonic) tic (need not occur concurrently), present >1 year since first tic onset. - **Persistent (chronic) motor or vocal tic disorder:** single or multiple motor tics OR vocal tics, but NOT both; >1 year. - **Provisional tic disorder:** motor and/or vocal tics present <1 year.

**Tic types:** - Simple motor: eye blinking, shoulder shrug, facial grimacing, head jerking. - Complex motor: hopping, touching, gestures; copropraxia (obscene gestures). - Simple vocal: throat clearing, sniffing, grunting. - Complex vocal: words/phrases; coprolalia (involuntary obscenities, only ~10–15% of patients), echolalia, palilalia. - Key features: preceded by a premonitory urge, temporary voluntary suppression is possible, relief after the tic, worsened by stress/fatigue/excitement, usually absent during sleep, waxing and waning course.

**Epidemiology/course:** Onset ~4–6 years, peak severity ~10–12 years, often improves in late adolescence/early adulthood. Male > female (~3–4:1). Strong genetic component (high heritability).

**Pathophysiology:** Dysfunction of cortico-striato-thalamo-cortical (CSTC) circuits (basal ganglia), with dopaminergic hyperactivity/excess dopamine signaling in the striatum. This explains response to D2 blockers.

**Associations/comorbidities:** ADHD (most common, ~50%+), OCD (~30–50%), anxiety, and depression. Often the comorbidity causes more impairment than the tics. PANDAS/PANS (post-streptococcal or abrupt-onset OCD/tics) is a related but controversial entity.

**Differential diagnosis:** Stereotypic movement disorder (earlier onset, rhythmic, fixed, seemingly purposeful), chorea (Huntington, Sydenham), myoclonus, dystonia, seizures, stimulant-induced tics, Wilson disease, tardive dyskinesia, neuroacanthocytosis, compulsions in OCD.

**Management:** - Mild tics: education and reassurance; treat comorbidities. - First-line: Comprehensive Behavioral Intervention for Tics (CBIT), including habit reversal training. - Pharmacologic (when tics are impairing): alpha-2 agonists (clonidine, guanfacine; first-line pharmacotherapy especially with ADHD); antipsychotics (aripiprazole, risperidone, haloperidol, pimozide) for severe tics; others include VMAT2 inhibitors (tetrabenazine, deutetrabenazine, valbenazine); topiramate; botulinum toxin for focal tics. Deep brain stimulation for rare refractory severe cases. - Stimulants can be used for comorbid ADHD (current evidence does not show they consistently worsen tics). - Antipsychotic side effects to know: EPS, tardive dyskinesia, metabolic syndrome/weight gain, QT prolongation (pimozide).

**Board pearls:** Tourette = motor + vocal tics >1 year, onset <18. Coprolalia is uncommon. Tics are suppressible and have a premonitory urge (unlike chorea/myoclonus). CBIT is first-line. ADHD and OCD are the most common comorbidities.