A 38-year-old man with schizophrenia has been on haloperidol 10 mg daily for 6 months. He presents to the psychiatry clinic with involuntary repetitive movements of his mouth and tongue, grimacing, and choreiform movements of his limbs. His wife reports these movements are worse when he is stressed. Vital signs are normal. Mental status examination shows no acute psychotic symptoms. What is the most likely diagnosis?

## Clinical Presentation & Diagnosis This patient presents with **tardive dyskinesia (TD)**, a late-onset extrapyramidal side effect of antipsychotics. ### Key Clinical Features **Key Point:** Tardive dyskinesia is characterized by involuntary, repetitive, purposeless movements that emerge after prolonged antipsychotic exposure (typically ≥3 months, often years). | Feature | Tardive Dyskinesia | Acute Dystonia | Akathisia | NMS | |---------|-------------------|-----------------|-----------|-----| | **Onset** | Months to years | Minutes to hours | Hours to days | Hours to days | | **Movement type** | Choreiform, orofacial | Sustained muscle contractions | Restlessness, inability to sit | Rigidity + hyperthermia | | **Orofacial involvement** | Common (tongue, lips, jaw) | Possible (jaw clenching) | No | No | | **Stress sensitivity** | Increases symptoms | No | Worsens | No | | **Reversibility** | Often irreversible | Reversible with anticholinergics | Reversible | Reversible | ### Pathophysiology 1. Chronic dopamine D~2~ blockade → denervation supersensitivity in basal ganglia 2. Upregulation of dopamine receptors and increased dopaminergic activity 3. Imbalance in cholinergic-dopaminergic equilibrium 4. Possible involvement of GABA and glutamate dysfunction ### Risk Factors for TD - **High-potency typical antipsychotics** (haloperidol, fluphenazine) — highest risk - Duration of exposure ≥3–5 years - Age >50 years - Female gender - Presence of mood disorder - Higher cumulative antipsychotic dose **High-Yield:** Atypical antipsychotics carry lower (but non-zero) risk of TD compared to typical agents. ### Management Approach ```mermaid flowchart TD A[Tardive Dyskinesia Diagnosed]:::outcome --> B{Severity?}:::decision B -->|Mild| C[Continue current antipsychotic<br/>or switch to atypical]:::action B -->|Moderate-Severe| D[Switch to atypical antipsychotic<br/>e.g., quetiapine, clozapine]:::action C --> E[Add vestigial agent if needed:<br/>tetrabenazine, valbenazine]:::action D --> E E --> F[Monitor for improvement<br/>over 3-6 months]:::action F --> G{Response?}:::decision G -->|Yes| H[Continue management]:::outcome G -->|No| I[Consider clozapine<br/>if not already used]:::action ``` **Clinical Pearl:** Clozapine is unique among antipsychotics in that it may actually *improve* tardive dyskinesia, making it the agent of choice if TD develops and antipsychotic continuation is necessary. **Key Point:** Anticholinergic medications (benztropine, trihexyphenidyl) do NOT treat tardive dyskinesia and may worsen it — they are used only for acute dystonia and parkinsonism. ### Prevention Strategies - Use lowest effective antipsychotic dose - Prefer atypical antipsychotics when possible - Regular monitoring with abnormal involuntary movement scale (AIMS) - Educate patients about risk and need for periodic reassessment