When to intubate in GCS?

GCS ≤ 8 requires intubation for airway protection. The patient cannot protect their own airway at this level of consciousness. Motor score is the most prognostically important component.

What is the best initial fluid for sepsis resuscitation?

Lactated Ringer's (LR) is the preferred resuscitation fluid. The SMART trial (2018) showed balanced crystalloids reduced death, new renal failure, and persistent renal dysfunction compared to normal saline.

When to start vasopressors in septic shock?

Start norepinephrine (first-line vasopressor) if MAP remains < 65 mmHg after initial 30 mL/kg crystalloid resuscitation, or earlier if patient is profoundly hypotensive. Do not delay pressors to complete full fluid resuscitation.

Why can serum uric acid be normal during acute gout?

During acute inflammation, IL-6 increases renal urate excretion and redistributes urate from plasma to tissues. Up to 40% of acute gout flares have normal serum uric acid. Joint aspiration with polarized microscopy is needed for definitive diagnosis.

How do you distinguish lupus flare from infection in SLE?

Key clues: CRP is low/normal in flare but elevated in infection. Complement (C3/C4) drops in flare but is normal/elevated in infection. Procalcitonin is elevated in bacterial infection but normal in flare. Anti-dsDNA rises in flare, stable in infection.

What is the difference between DKA and HHS?

DKA features acidosis (pH 600), hyperosmolality (> 320), and minimal ketosis -typically in Type 2 DM. DKA requires insulin drip; HHS requires aggressive fluid resuscitation first.

When to give tPA in acute ischemic stroke?

IV alteplase (tPA) can be given within 4.5 hours of last known well time in eligible patients. CT head must rule out hemorrhage first. For large vessel occlusion, mechanical thrombectomy can be performed up to 24 hours with favorable imaging.

What antibiotics for community-acquired pneumonia?

Inpatient non-ICU: ceftriaxone + azithromycin. ICU: ceftriaxone + azithromycin (add vancomycin if MRSA risk). Outpatient healthy: amoxicillin. Outpatient with comorbidities: augmentin + azithromycin or respiratory fluoroquinolone. Duration: 5 days if clinically stable for 48 hours.

How to interpret iron studies?

Iron deficiency: low ferritin (< 30), high TIBC, low iron, low transferrin saturation (< 20%). Anemia of chronic disease: normal/high ferritin (acute phase reactant), low TIBC, low iron. A ferritin of 50-100 in an inflamed patient may still represent iron deficiency.

What is the correction rate for hyponatremia?

Correct sodium no more than 8 mEq/L in 24 hours to avoid osmotic demyelination syndrome (ODS). For symptomatic severe hyponatremia with seizures, give 3% hypertonic saline 100-150 mL bolus over 10-20 minutes. If overcorrected, use D5W + DDAVP rescue protocol.

When to start antibiotics in meningitis?

Within 30-60 minutes. Do NOT delay antibiotics for LP or CT. Draw blood cultures, start empiric antibiotics (vancomycin + ceftriaxone ± ampicillin if > 50 or immunocompromised), then perform LP when possible. Dexamethasone should be given before or with the first antibiotic dose.

DOACs vs warfarin in antiphospholipid syndrome?

DOACs are contraindicated in APS. The TRAPS trial (2018) showed rivaroxaban was inferior to warfarin with more thrombotic events in triple-positive APS patients. Warfarin with INR target 2-3 is the standard for APS, indefinitely.

How to manage scleroderma renal crisis?

ACE inhibitors (captopril) are life-saving -start immediately and titrate aggressively. Do NOT hold for rising creatinine. Steroids > 15 mg prednisone per day precipitate scleroderma renal crisis. ARBs are NOT a substitute -evidence is only for ACEi.

What are the 4 pillars of heart failure treatment?

Guideline-directed medical therapy (GDMT) for HFrEF: (1) ARNI or ACEi/ARB, (2) beta-blocker (carvedilol, metoprolol succinate, or bisoprolol), (3) MRA (spironolactone or eplerenone), (4) SGLT2 inhibitor (dapagliflozin or empagliflozin). All four should be initiated and titrated to target doses.

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NMS vs Serotonin Syndrome

Two life-threatening drug-induced hyperthermic syndromes that look similar but have different causes, key findings, and treatments. NMS = dopamine blockade (antipsychotics) with RIGIDITY. Serotonin syndrome = serotonin excess (SSRIs, MAOIs) with CLONUS. Getting the diagnosis right determines the treatment.

🔍 Overview

Side-by-Side Comparison

The #1 distinguishing feature: NMS = RIGIDITY (lead-pipe), SS = CLONUS (hyperreflexia). If the patient is stiff everywhere → think NMS. If they're twitching/jerking → think SS.

Feature	NMS	Serotonin Syndrome
Mechanism	Dopamine ANTAGONISM (decreased dopamine)	Serotonin EXCESS (increased serotonin)
Causative drugs	Haloperidol, olanzapine, risperidone, metoclopramide, prochlorperazine. Also sudden withdrawal of dopamine agonists (levodopa).	SSRIs, SNRIs, MAOIs, tramadol, linezolid (weak MAOI!), fentanyl, ondansetron, triptans, St. John's Wort, MDMA, dextromethorphan
Onset	SLOW -days to weeks after starting/increasing dose	FAST -hours after starting, dose change, or drug interaction
Key finding	LEAD-PIPE RIGIDITY (diffuse, not clonus)	CLONUS (especially lower extremity) + hyperreflexia
Temperature	Very high (> 40°C common)	Variable (mild to very high)
Mental status	Altered (encephalopathy, obtundation)	Agitation, confusion, restlessness
Autonomic	Tachycardia, labile BP, diaphoresis	Tachycardia, hypertension, diaphoresis, mydriasis
GI symptoms	Usually absent	Diarrhea (serotonin stimulates gut motility)
Labs	CK markedly elevated (often > 1,000), leukocytosis, metabolic acidosis	CK may be mildly elevated, otherwise normal
Treatment	STOP offending agent, dantrolene + bromocriptine, cooling, ICU	STOP offending agent, benzodiazepines (first-line), cyproheptadine, cooling
Duration	Days to weeks to resolve	Usually resolves within 24 hours of stopping drug

NMS -Neuroleptic Malignant Syndrome

NMS results from acute dopamine D2 receptor blockade in the hypothalamus (thermoregulation failure) and basal ganglia (rigidity). Most common with high-potency antipsychotics (haloperidol) but can occur with ANY dopamine antagonist -including metoclopramide (Reglan) and prochlorperazine (Compazine). Can also occur with abrupt withdrawal of dopaminergic agents (levodopa in Parkinson's patients). Mortality: 10–20% if untreated.

Serotonin Syndrome -Hunter Criteria

Diagnosed using the Hunter Serotonin Toxicity Criteria (most accurate) in a patient on a serotonergic drug: (1) Spontaneous clonus, OR (2) Inducible clonus + agitation or diaphoresis, OR (3) Ocular clonus + agitation or diaphoresis, OR (4) Tremor + hyperreflexia, OR (5) Hypertonia + temperature > 38°C + ocular or inducible clonus. Key drug interaction to know: linezolid is a reversible MAOI -can precipitate SS when combined with SSRIs/SNRIs. This is a classic boards trap.

🚨 Management

NMS Treatment Algorithm

Step	Intervention	Details
1. STOP offending agent	Discontinue ALL antipsychotics/dopamine antagonists	This is the most important step. If NMS from levodopa withdrawal → restart levodopa immediately.
2. Aggressive cooling	Ice packs, cooling blankets, cold IV fluids	Target temp < 39°C. Antipyretics (acetaminophen) do NOT work -this is not cytokine-mediated fever, it's muscle-generated heat.
3. Dantrolene	Dantrolene (Dantrium) 1–2.5 mg/kg IV	Direct-acting muscle relaxant (blocks ryanodine receptor → reduces Ca²⁺ release from SR → reduces muscle contraction and heat generation). May repeat q5–10 min to max 10 mg/kg/day.
4. Bromocriptine	Bromocriptine (Parlodel) 2.5 mg PO/NG q8h	Dopamine agonist -directly counteracts the dopamine blockade causing NMS. Continue for 10 days after NMS resolves (prevent relapse).
5. Supportive	ICU admission, IVF, monitoring	Watch for rhabdomyolysis (check CK), AKI, DIC, aspiration, respiratory failure. Intubation may be needed.

Serotonin Syndrome Treatment Algorithm

Step	Intervention	Details
1. STOP offending agent	Discontinue ALL serotonergic drugs	Most cases resolve within 24h of stopping the offending drug(s). Review full medication list carefully.
2. Benzodiazepines	Lorazepam 1–2 mg IV or diazepam 5–10 mg IV	FIRST-LINE -controls agitation, reduces muscle activity and heat generation, lowers seizure threshold. Repeat as needed.
3. Cyproheptadine	Cyproheptadine (Periactin) 12 mg PO/NG load, then 2 mg q2h	Serotonin 5-HT2A antagonist -directly blocks excess serotonin. Only available PO/NG (no IV form). Max 32 mg/day.
4. Cooling	External cooling measures	For temperature > 41°C. Avoid antipyretics (ineffective).
5. Avoid	Do NOT give antipsychotics for agitation	Some antipsychotics have serotonergic activity and could worsen SS. Do NOT give dantrolene (ineffective -muscle activity in SS is from neural excitation, not peripheral).

🧪 Workup

Laboratory Workup (Both NMS and SS)

CK (creatine kinase) -markedly elevated in NMS (often > 1,000, can be > 10,000). Mildly elevated or normal in SS.
BMP -Cr (AKI from rhabdo in NMS), K⁺ (hyperK from muscle breakdown), glucose
CBC -leukocytosis common in NMS (not from infection -stress response)
LFTs -may be elevated in NMS (hepatic injury)
Coags (PT/INR, aPTT, fibrinogen) -DIC screening in severe NMS
UA -myoglobinuria in NMS (dipstick + blood, no RBCs)
TSH -rule out thyroid storm (hyperthermia + tachycardia differential)
Toxicology screen -rule out sympathomimetic toxicity, anticholinergic syndrome
Medication reconciliation -CRITICAL. Identify the offending drug(s). Review ALL medications, supplements, and OTC drugs for serotonergic or dopamine-blocking activity.

💊 Medications

Key Medications

Drug	Dose	Indication	Key Notes
Dantrolene (Dantrium)	1–2.5 mg/kg IV, repeat q5–10 min	NMS only	Direct muscle relaxant (ryanodine receptor blocker). Max 10 mg/kg/day. Monitor for hepatotoxicity. NOT for SS.
Bromocriptine (Parlodel)	2.5 mg PO/NG q8h	NMS only	Dopamine agonist -directly counteracts D2 blockade. Continue 10 days after resolution. Can also use amantadine 100 mg PO q12h.
Cyproheptadine (Periactin)	12 mg PO/NG load, then 2 mg q2h	SS only	5-HT2A antagonist. PO only (no IV form). Max 32 mg/day. Sedating (antihistamine). NOT for NMS.
Lorazepam	1–2 mg IV PRN	SS first-line; adjunct in NMS	Controls agitation, reduces muscle hyperactivity, prevents seizures. Can use diazepam 5–10 mg IV as alternative.

📋 On Rounds

What is the key distinguishing physical exam finding between NMS and Serotonin Syndrome?

NMS = Lead-pipe RIGIDITY. The patient is stiff, with diffuse muscle rigidity that resists passive movement uniformly throughout the range of motion (like bending a lead pipe). Reflexes may be normal or diminished. SS = CLONUS + hyperreflexia. The patient has rhythmic, involuntary muscular contractions (especially in lower extremities -ankle clonus), plus brisk/exaggerated deep tendon reflexes. Tremor is also common.

Can linezolid cause serotonin syndrome?

Yes! Linezolid (Zyvox) is a reversible, nonselective monoamine oxidase inhibitor (MAOI) in addition to being an oxazolidinone antibiotic. When given to patients already on SSRIs, SNRIs, or other serotonergic drugs, it can precipitate serotonin syndrome. This is a classic boards question and a real clinical trap -always check the medication list before starting linezolid.

Why is bromocriptine used in NMS?

Bromocriptine (Parlodel) is a dopamine D2 receptor agonist. NMS is caused by dopamine D2 blockade (from antipsychotics or other dopamine antagonists), leading to loss of thermoregulation (hypothalamus), rigidity (basal ganglia), and autonomic instability. Bromocriptine directly counteracts the dopamine blockade by stimulating D2 receptors. It restores dopaminergic tone in the hypothalamus and basal ganglia.

What are the Hunter Criteria for Serotonin Syndrome?

The Hunter Serotonin Toxicity Criteria are the most sensitive (84%) and specific (97%) diagnostic criteria for SS. In a patient taking a serotonergic agent, ANY ONE of the following: (1) Spontaneous clonus. (2) Inducible clonus + agitation OR diaphoresis. (3) Ocular clonus + agitation OR diaphoresis. (4) Tremor + hyperreflexia. (5) Hypertonia + temperature > 38°C + (ocular clonus OR inducible clonus).

Clinical Examples

📋 Case 1, Neuroleptic Malignant Syndrome

Patient: 34M brought to ED after found confused at group home. Started haloperidol 10 mg IM 3 days ago for acute psychosis. Temp 40.2°C, HR 128, BP 170/95. Diffuse lead-pipe rigidity.

Key findings: CK 18,400, WBC 16K, Cr 2.8 (baseline 0.9). Diaphoretic, mute, tremulous. Recently started high-potency antipsychotic. Classic NMS: fever + rigidity + AMS + autonomic instability.

Management:

Stop haloperidol immediately
Dantrolene 1-2.5 mg/kg IV q6h (skeletal muscle relaxant, reduces rigidity and thermogenesis)
Bromocriptine 2.5 mg PO/NG TID (dopamine agonist, reverses central dopamine blockade)
Aggressive IVF (NS 200 mL/hr) for rhabdomyolysis, target UOP > 200 mL/hr
ICU admission, continuous temperature monitoring, serial CK q6h

Teaching point: NMS = "lead-pipe rigidity" with slow onset (days). High-potency typical antipsychotics (haloperidol) are highest risk. CK is often dramatically elevated (> 1000).

📋 Case 2, Serotonin Syndrome

Patient: 45F on sertraline 200 mg daily, presents 6 hours after starting tramadol for back pain. Temp 38.6°C, HR 112, agitated, diaphoretic. Bilateral ankle clonus, hyperreflexia throughout. Dilated pupils.

Key findings: Hunter Criteria positive: inducible clonus + agitation + diaphoresis. Precipitant: addition of tramadol (serotonergic) to SSRI. CK 380 (mildly elevated). Onset within hours.

Management:

Stop all serotonergic agents (sertraline and tramadol)
Cyproheptadine 12 mg PO load → 4 mg q6h (serotonin antagonist, first-line antidote)
Benzodiazepines for agitation: lorazepam 2 mg IV PRN
Active cooling if temp > 40°C; avoid antipyretics (ineffective, heat is from muscle activity)
IVF resuscitation, cardiac monitoring, most cases resolve within 24-72h

Teaching point: SS = "clonus + hyperreflexia" with rapid onset (hours). Key distinguisher from NMS: clonus and hyperreflexia (NMS has rigidity and hyporeflexia). Tramadol is a commonly missed serotonergic agent.

📋 Case 3, NMS vs Serotonin Syndrome Diagnostic Dilemma

Patient: 58M on quetiapine and duloxetine, presents with confusion, temp 39.4°C, diaphoresis, tremor. Exam: increased tone in lower extremities, 3+ reflexes bilaterally, bilateral ankle clonus.

Key findings: On both an antipsychotic (quetiapine) and serotonergic agent (duloxetine). CK 620. Features overlap: fever + AMS + autonomic instability present in both conditions.

Management:

Stop both quetiapine and duloxetine
Key distinguisher: clonus + hyperreflexia → favors serotonin syndrome over NMS
Start cyproheptadine 12 mg PO load (treat as SS given clonus)
Benzodiazepines for agitation and muscle hyperactivity
Monitor CK trending, if > 5000 or rising, add dantrolene for possible NMS component

Teaching point: The exam is the key differentiator: NMS → lead-pipe rigidity + hyporeflexia. SS → clonus + hyperreflexia + tremor. When in doubt, treat both, cyproheptadine won't worsen NMS, and supportive care overlaps.

Monitoring Parameters

Parameter	Frequency	Target / Action
Temperature	q1–2h	Target < 39°C. Active cooling if > 40°C. Antipyretics ineffective.
CK	q6–12h (NMS)	Trend for rhabdomyolysis severity. If rising → aggressive IVF for renal protection.
BMP (K⁺, Cr)	q6–12h	Watch for hyperK (NMS) and AKI.
Neurological exam	q2–4h	Rigidity assessment (NMS), clonus assessment (SS), mental status.
Vitals	q1–2h ICU	HR, BP (labile in both), SpO₂, RR.
Coags	Daily if NMS severe	DIC screening (PT, fibrinogen, D-dimer).

⚡ Summary

NMS vs Serotonin Syndrome -Key Points

NMS Cause

Dopamine ANTAGONISTS: haloperidol, olanzapine, metoclopramide. Also levodopa withdrawal. Onset: days–weeks.

SS Cause

Serotonergic drugs: SSRIs, SNRIs, MAOIs, tramadol, linezolid, MDMA. Usually drug interaction. Onset: hours.

Key Finding

NMS = RIGIDITY (lead-pipe). SS = CLONUS (hyperreflexia, especially lower extremity). This is the #1 distinguishing feature.

NMS Treatment

Stop drug. Dantrolene 1–2.5 mg/kg IV. Bromocriptine 2.5 mg PO q8h (continue 10 days). Cooling. ICU.

SS Treatment

Stop drug. Benzodiazepines (first-line). Cyproheptadine 12 mg load then 2 mg q2h. Cooling. Usually resolves in 24h.

Pearl

Linezolid is a weak MAOI → can cause SS with SSRIs. Do NOT give dantrolene for SS. Do NOT give cyproheptadine for NMS.