A 32-year-old man with schizophrenia has been on antipsychotic therapy for 6 months. He now presents with involuntary orofacial movements, tongue protrusion, and choreiform limb movements. Which is the most common antipsychotic-induced movement disorder he is experiencing?

Explanation

## Tardive Dyskinesia: The Most Common Late-Onset Movement Disorder **Key Point:** Tardive dyskinesia (TD) is the most common **persistent** antipsychotic-induced movement disorder, occurring in 20–30% of patients on chronic antipsychotic therapy, particularly with first-generation agents. ### Clinical Features of Tardive Dyskinesia - **Onset:** Develops after months to years of antipsychotic exposure (typically ≥3 months, but can occur earlier with second-generation agents). - **Characteristics:** Involuntary choreiform, athetoid, or rhythmic movements. - **Common sites:** Orofacial region (lip smacking, tongue protrusion, jaw movements), limbs (choreiform movements), trunk. - **Persistence:** Often irreversible, even after drug withdrawal. ### Pathophysiology ```mermaid flowchart TD A[Chronic D2 receptor blockade]:::action --> B[Denervation supersensitivity]:::outcome B --> C[Upregulation of D2 receptors]:::outcome C --> D[Increased dopaminergic activity in basal ganglia]:::outcome D --> E[Involuntary movements]:::outcome A --> F[Possible GABA neuron dysfunction]:::outcome F --> E ``` ### Risk Factors for Tardive Dyskinesia - Older age (>50 years). - Female gender. - Longer duration of antipsychotic use. - Higher cumulative doses. - First-generation antipsychotics (haloperidol, chlorpromazine) >> second-generation agents. - Presence of mood disorders. **High-Yield:** TD is **irreversible in ~50% of cases** even after drug discontinuation, making prevention critical. ### Prevention and Management 1. **Prevention:** Use lowest effective dose; prefer second-generation antipsychotics; regular monitoring with Abnormal Involuntary Movement Scale (AIMS). 2. **Management:** Reduce dose or switch to quetiapine/clozapine (lowest TD risk); consider tetrabenazine or valbenazine (VMAT2 inhibitors). **Clinical Pearl:** Unlike acute dystonia or akathisia (which occur within hours to days), TD emerges insidiously over months, making it a late-onset complication. ### Comparison with Other Antipsychotic-Induced Movement Disorders | Feature | Tardive Dyskinesia | Acute Dystonia | Akathisia | Parkinsonism | |---------|-------------------|----------------|-----------|---------------| | **Onset** | Months–years | Hours–days | Hours–weeks | Days–weeks | | **Prevalence** | 20–30% (FGA) | 5–10% (FGA) | 10–20% | 30–40% | | **Reversibility** | Often irreversible | Fully reversible | Reversible | Reversible | | **Pathophysiology** | D2 supersensitivity | Acute D2 blockade | Unclear; serotonin? | Acute D2 blockade | | **Treatment** | Reduce dose; valbenazine | Anticholinergic (IM benztropine) | Beta-blocker (propranolol) | Anticholinergic; reduce dose | [cite:KD Tripathi 8e Ch 12]