## Diagnosis: Neuroleptic Malignant Syndrome (NMS) ### Clinical Recognition **Key Point:** NMS is a life-threatening idiosyncratic reaction to antipsychotics (especially typical agents like haloperidol) characterized by the **tetrad**: 1. **Fever** (often > 38.5°C) — 39.5°C here 2. **Muscle rigidity** (lead-pipe, waxy flexibility) — present 3. **Altered mental status** (confusion, delirium) — present 4. **Autonomic instability** (diaphoresis, tachycardia) — present ### Diagnostic Criteria (DSM-5) All four cardinal features must be present, plus: - **Temporal relationship** to antipsychotic exposure (haloperidol × 2 years; acute decompensation in past 3 days suggests trigger or dose escalation) - **Laboratory abnormalities**: ↑ CK (3,800 U/L — marked elevation), ↑ WBC (14,500), ↑ creatinine (1.8, up from 1.0), myoglobinuria **High-Yield:** CK > 1,000 U/L with myoglobinuria indicates **rhabdomyolysis** — the most dangerous complication of NMS. This patient is at imminent risk of acute kidney injury (creatinine already rising). ### Pathophysiology ```mermaid flowchart TD A[Antipsychotic<br/>Dopamine D2 Blockade]:::action --> B[↓ Dopamine in<br/>Hypothalamus & Brainstem]:::outcome B --> C1[Loss of thermoregulation<br/>↑ Heat production] B --> C2[↑ Muscle tone<br/>Rigidity] B --> C3[↑ Sympathetic tone<br/>Autonomic instability] C1 --> D[Fever + Diaphoresis]:::urgent C2 --> E[Rhabdomyolysis<br/>Myoglobinuria]:::urgent C3 --> F[Tachycardia<br/>Hypertension]:::urgent E --> G[Acute Kidney Injury]:::urgent ``` ### Immediate Management Algorithm ```mermaid flowchart TD A[NMS Suspected]:::outcome --> B[STOP Antipsychotic<br/>IMMEDIATELY]:::urgent B --> C[Supportive Care]:::action C --> C1[IV fluids aggressive<br/>Target UOP > 200 mL/hr] C --> C2[Active cooling<br/>Ice packs, cool IV saline] C --> C3[Monitor: temp, CK, Cr,<br/>K+, urine myoglobin] A --> D{Severity?}:::decision D -->|Mild| E[Observation + fluids<br/>CK < 1000]:::action D -->|Moderate-Severe| F[ICU admission<br/>CK > 1000 + Cr↑]:::action F --> G[Consider dantrolene<br/>if no response in 24 hrs]:::action E --> H[Recover in 5–7 days]:::outcome G --> I[Dantrolene 1 mg/kg IV<br/>Repeat Q4-6H max 10 mg/kg/day]:::action I --> J[Monitor for recurrence]:::outcome ``` **Clinical Pearl:** The **golden rule** is **immediate cessation of the antipsychotic**. Continuing or reducing the dose (as in option C) perpetuates the trigger and worsens outcomes. ### Why NOT the Other Approaches | Approach | Why Wrong | |----------|----------| | **Continue haloperidol** (option A) | Perpetuates dopamine blockade; mortality increases if drug not stopped. Benzodiazepines alone are insufficient. | | **Dantrolene + continue haloperidol** (option C) | Dantrolene is adjunctive only; the antipsychotic MUST be stopped first. Continuing it is dangerous. | | **Bromocriptine + restart haloperidol** (option D) | Bromocriptine (dopamine agonist) may be used as adjunct in severe NMS, but restarting haloperidol after 48 hours risks recurrence. Antipsychotic should be avoided or switched to atypical agent much later (weeks). | **Warning:** Restarting the same antipsychotic within days is a common exam trap. NMS recurrence risk is high if the same agent is reintroduced; if an antipsychotic is needed later, switch to an atypical agent (e.g., olanzapine, risperidone) after full recovery (2–4 weeks). ### Monitoring & Prognosis - **CK trend**: Will peak at 3–5 days, then decline if fluids adequate - **Creatinine**: Will rise if rhabdomyolysis severe; aggressive hydration prevents AKI - **Recovery**: 5–7 days with supportive care; mortality 5–20% if untreated - **Recurrence**: 30% if same antipsychotic reused; < 5% if switched to atypical **High-Yield:** This patient's myoglobinuria + rising creatinine demand **ICU-level monitoring** and **aggressive IV hydration** — not just observation. 
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