Which antipsychotic-induced movement disorder is characterized by involuntary orofacial dyskinesias, choreiform limb movements, and trunk dystonia that typically emerge after months to years of continuous exposure?

Explanation

## Tardive Dyskinesia (TD): Late-Onset Extrapyramidal Side Effect **Key Point:** Tardive dyskinesia is a **late-onset, involuntary movement disorder** that develops after prolonged antipsychotic exposure (typically >3 months, often years). It is **irreversible** in 50% of cases, even after drug discontinuation. ### Clinical Features of Tardive Dyskinesia **Orofacial manifestations:** - Lip smacking, tongue protrusion, chewing movements - Grimacing, blinking, eye deviation - Jaw clenching and dental trauma **Limb and trunk involvement:** - Choreiform (jerky, irregular) movements of arms and legs - Dystonic posturing (sustained muscle contractions) - Rocking, swaying of trunk ### Comparison: Acute vs. Late Extrapyramidal Side Effects | Feature | Acute Dystonia | Akathisia | Tardive Dyskinesia | |---|---|---|---| | **Onset** | Hours to days | Days to weeks | Months to years | | **Reversibility** | Yes (within hours) | Yes (within days) | No (50% irreversible) | | **Presentation** | Sustained muscle contraction (torticollis, oculogyric crisis) | Subjective restlessness, inability to sit still | Involuntary choreiform/dystonic movements | | **Mechanism** | Acute D2 blockade → relative cholinergic excess | D2 blockade + dopamine supersensitivity | Dopamine receptor supersensitivity | | **Treatment** | Anticholinergic (benztropine) | Beta-blocker or benzodiazepine | Tetrabenazine, valbenazine (FDA-approved) | **High-Yield:** Tardive dyskinesia risk is **higher with first-generation antipsychotics** (10–20% per year) than atypicals (1–3% per year), but can occur with any dopamine antagonist. **Clinical Pearl:** The **Abnormal Involuntary Movement Scale (AIMS)** is the gold standard screening tool. Baseline and periodic monitoring (every 6–12 months) is mandatory in all patients on chronic antipsychotics. **Warning:** Anticholinergic medications (benztropine) **worsen** tardive dyskinesia — they should NOT be used for treatment. Use tetrabenazine or valbenazine instead. **Mnemonic:** **"Tardive = LATE"** — Late-onset, After prolonged exposure, Tardive (late), Extrapyramidal.