Which antipsychotic-induced extrapyramidal side effect is characterized by involuntary choreiform movements of the mouth, tongue, and limbs that may persist even after drug discontinuation?

Explanation

## Tardive Dyskinesia: Persistent EPS **Key Point:** Tardive dyskinesia (TD) is a LATE-ONSET, potentially IRREVERSIBLE movement disorder caused by chronic antipsychotic exposure, characterized by involuntary choreiform, athetoid, or rhythmic movements. ### Clinical Features of Tardive Dyskinesia **Onset & Duration:** - Develops after **≥3 months** of continuous antipsychotic use (or ≥1 month in patients >50 years) - May persist **months to years** after drug discontinuation (hence "tardive" = late) - Risk increases with cumulative exposure and higher doses **Movement Characteristics:** 1. **Orofacial dyskinesia** (most common): lip smacking, tongue protrusion, jaw clenching, grimacing 2. **Limb dyskinesia**: choreiform movements of fingers, hands, feet 3. **Truncal dyskinesia**: rocking, twisting of torso 4. **Respiratory dyskinesia**: irregular breathing patterns (rare but serious) ### Pathophysiology **High-Yield:** TD results from **dopamine supersensitivity** in the basal ganglia following chronic D₂ receptor blockade. When antipsychotics are withdrawn, unopposed dopaminergic activity causes involuntary movements. ### EPS Timeline & Comparison | EPS Type | Onset | Reversibility | Mechanism | Risk Factors | |---|---|---|---|---| | **Acute Dystonia** | Hours–days | Fully reversible | Acute cholinergic/dopaminergic imbalance | Young age, high-potency typical | | **Akathisia** | Days–weeks | Reversible | Dopamine blockade in limbic regions | Any antipsychotic | | **Parkinsonism** | Days–weeks | Reversible | Dopamine blockade in nigrostriatal pathway | Typical > atypical | | **Tardive Dyskinesia** | Months–years | **Often irreversible** | Dopamine supersensitivity | Older age, high cumulative dose, typical | **Mnemonic:** **TADS** = **T**ardive (late), **A**cute dystonia (early), **D**rug-induced parkinsonism (early), **S**ubacute akathisia (early) ### Prevention & Management 1. **Prevention:** - Use lowest effective dose - Prefer atypical antipsychotics (lower TD risk) - Regular monitoring with Abnormal Involuntary Movement Scale (AIMS) 2. **If TD develops:** - Do NOT abruptly discontinue (may worsen dyskinesia) - Consider switching to clozapine (only antipsychotic shown to reduce TD) - Tetrabenazine or valbenazine (VMAT₂ inhibitors) for symptomatic relief **Clinical Pearl:** TD is one of the most serious long-term complications of antipsychotic therapy and represents a major medicolegal concern. Informed consent documenting TD risk is essential before initiating antipsychotics. **Warning:** Paradoxically, increasing the antipsychotic dose may temporarily mask TD symptoms but worsens the underlying condition — this is a common clinical trap.