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psych.neuroleptic-malignant-syndrome.v1PRODUCTION
psych.neuroleptic-malignant-syndrome.v1

Neuroleptic Malignant Syndrome (NMS) — toxidrome from antipsychotic D2 blockade (Strawn AJP 2007 PMID 17541055; Levenson AJP 1985 PMID 2862613; DSM-5-TR 2022); STOP AP IMMEDIATELY + ICU + supportive (cooling + IV hydration) + dantrolene 1-2.5 mg/kg IV q6h + bromocriptine 2.5 mg PO TID + ECT for refractory; AVOID succinylcholine + re-introduction of offending AP + abrupt clozapine discontinuation

psychiatryacuteadultgeriatricpediatricpregnancy
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Canonical 12-phase frame with authored status for this dossier.

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Detailed

Neuroleptic Malignant Syndrome (NMS) = drug-induced toxidrome from idiosyncratic reaction to antipsychotic (AP) D2 blockade — typical (haloperidol > fluphenazine) > atypical (olanzapine, risperidone, quetiapine, aripiprazole, paliperidone, lurasidone) > clozapine (rare); also anti-emetic D2 blockers (metoclopramide, prochlorperazine, droperidol); LAI depot AP; dopamine-agonist withdrawal (Parkinsonism-hyperpyrexia syndrome). Tetrad = severe rigidity + hyperthermia + autonomic instability + altered MS (stupor/mutism/catatonic). Diagnosis via DSM-5-TR 2022 + Levenson 1985 criteria. Pharmacology pivot: STOP all AP IMMEDIATELY; ICU + supportive (cooling + IV hydration); benzodiazepine (lorazepam) for agitation + neuromuscular control; dantrolene 1-2.5 mg/kg IV q6h for severe rigidity + hyperthermia + rhabdo; bromocriptine 2.5 mg PO TID titrate up to 7.5 mg TID for D2 agonism (opposes AP blockade); ECT rescue for refractory or catatonia-NMS continuum (Fink + Taylor). AVOID succinylcholine (rhabdo hyperK; use rocuronium), re-introduction of offending AP without 2-week wash-out (~ 30% recurrence per Pope 1991), abrupt clozapine discontinuation (withdrawal NMS), parenteral AP during NMS (extends syndrome), dopamine antagonist anti-emetics during acute NMS (extends syndrome — use ondansetron) (Strawn AJP 2007 PMID 17541055).

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NMS diagnosis confirmed by DSM-5-TR criteria + AP exposure within 72 h to 2 weeks documented (DSM-5-TR 2022; Strawn AJP 2007)

Patient inputs (21)

Geriatric patients have highest mortality; pediatric NMS rare but described with similar recognition + treatment (pediatric dose adjustment for dantrolene + bromocriptine)

Post-partum is high-risk period; pregnant patient on AP presenting with NMS requires reproductive psychiatry consult for alternative AP planning after recovery

Full medication reconciliation incl. typical AP (haloperidol, fluphenazine, chlorpromazine), atypical AP (olanzapine, risperidone, quetiapine, aripiprazole, paliperidone, lurasidone, ziprasidone, clozapine), LAI depot AP (fluphenazine decanoate, haloperidol decanoate, paliperidone palmitate, aripiprazole monohydrate), anti-emetic D2 blockers (metoclopramide, prochlorperazine, droperidol, promethazine), VMAT2 inhibitors (tetrabenazine, deutetrabenazine, valbenazine), and recently discontinued dopamine agonists (levodopa, pramipexole, ropinirole) or clozapine — mandatory for diagnosis (DSM-5-TR 2022; Strawn AJP 2007)

Severe generalized rigidity (lead-pipe — uniform resistance throughout passive ROM) is DSM-5-TR core criterion; distinguishes NMS from serotonin syndrome (which has clonus + hyperreflexia)

Stupor / mutism / catatonic features in NMS — distinguishes from serotonin syndrome (which has agitation + confusion); also drives differential vs malignant catatonia continuum (Fink + Taylor Lancet 2003)

Labile / elevated BP + tachycardia + diaphoresis + tachypnea — DSM-5-TR criterion for autonomic instability (DSM-5-TR 2022)

QTc baseline before any sedative / paralytic / dopamine agonist; arrhythmia risk from autonomic instability + electrolyte derangement (rhabdo-hyperK)

CK > 1000 (often > 10× ULN) is hallmark lab finding; drives diagnosis confidence + rhabdo-AKI risk + dantrolene threshold (CK > 5000 → consider hemodialysis if AKI severe) (Levenson AJP 1985)

Rhabdomyolysis-AKI risk; drives fluid + dose adjustment for renal-cleared agents; eGFR baseline + serial monitoring during dantrolene + bromocriptine treatment

Electrolyte derangement (hyperK in rhabdo-AKI, hyperNa from diaphoresis dehydration) + acid-base (metabolic acidosis is supporting feature)

Leukocytosis is DSM-5-TR supporting criterion; rule out infection differential (sepsis); baseline before AP re-introduction strategy

Hepatic clearance baseline before dantrolene initiation (hepatotoxicity risk — black box warning); serial LFT monitoring during dantrolene course

T > 38°C is DSM-5-TR criterion for hyperthermia; T > 41°C = life-threatening — ICU + intubation + paralysis (rocuronium, AVOID succinylcholine) + aggressive cooling (Strawn AJP 2007)

Sinus tachycardia universal; HR > 120 + labile BP supports autonomic instability criterion (DSM-5-TR 2022)

Labile / elevated BP is autonomic instability marker; SBP swings > 20-25 mmHg between recordings supports diagnosis (DSM-5-TR 2022)

Component of MAP for cardiovascular support; DBP swings contribute to autonomic instability criterion (DSM-5-TR 2022)

Tachypnea component of Levenson 1985 minor criteria; respiratory failure risk in severe NMS with rhabdo-DIC-ARDS (Levenson AJP 1985)

Supporting features in DSM-5-TR criteria (≥ 2 of: diaphoresis, dysphagia, tremor, incontinence, AMS, mutism, tachycardia, labile BP, leukocytosis, CK elevation)

Urine drug screen — rule out illicit co-ingestants (sympathomimetics, anticholinergics, serotonergic agents); informs differential vs serotonin syndrome + sympathomimetic toxidrome

Hyperthermia + neuromuscular activity + sepsis differential → lactate elevation; tracks severity + response to cooling + dantrolene

Myoglobinuria + CK > 5000 → rhabdo-AKI; drives aggressive IV hydration + alkalinization + CRRT planning if AKI severe

* = hard-required. Engine cannot meaningfully run until these are filled.

Severity triggers (10)

10 need judgement
  • informationallife_threateningnms_at_diagnosis_icu_admission
    NMS diagnosis confirmed (DSM-5-TR criteria positive + AP exposure within 72 h to 2 weeks) — life-threatening; STOP all AP IMMEDIATELY + ICU admission + supportive care foundation (cooling + IV crystalloid + DVT prophylaxis) + benzo (lorazepam) + dantrolene + bromocriptine (Strawn AJP 2007 PMID 17541055; DSM-5-TR 2022)
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationallife_threateningsevere_hyperthermia_above_41c
    Severe hyperthermia T > 41°C in NMS — life-threatening; aggressive cooling + intubation + paralysis (rocuronium, AVOID succinylcholine) + benzo infusion + dantrolene IV + cyproheptadine-equivalent dopaminergic support via bromocriptine NG; rhabdo + DIC + AKI risk (Strawn AJP 2007 PMID 17541055)
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalsevererhabdomyolysis_with_aki
    Rhabdomyolysis (CK > 5000) with AKI (rising Cr) in NMS — severe; aggressive IV hydration with UOP monitoring (target > 1 mL/kg/h) + serial CK trend + sodium bicarbonate alkalinization if severe + CRRT if AKI severe (Strawn AJP 2007 PMID 17541055)
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalseverecatatonia_nms_continuum
    Catatonia-NMS continuum suspected (stupor + mutism + waxy flexibility + posturing + AP exposure + hyperthermia + rigidity) — severe; overlap with catatonia per Fink + Taylor Lancet 2003; routes to psych.catatonia.core.v1 sibling dossier; lorazepam challenge (2 mg IV) + ECT consideration (Fink + Taylor Lancet 2003)
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalsevereserotonin_syndrome_differential
    Serotonin syndrome converging differential — serotonergic agent + hours onset + clonus + hyperreflexia + agitation + mydriasis + diarrhoea (distinguishes from NMS which has AP exposure + days-weeks onset + lead-pipe rigidity + hyporeflexia + stupor + normal pupils); treatment differs — cyproheptadine + benzo for SS, NOT dantrolene + bromocriptine (bromocriptine is pro-serotonergic and WORSENS SS) — the key NMS-vs-SS pharmacological pivot (Strawn AJP 2007; Boyer NEJM 2005 PMID 15784664)
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalseverenms_with_clozapine_withdrawal
    NMS with clozapine on board OR clozapine-withdrawal-related NMS — severe; do NOT abruptly stop clozapine even during NMS (withdrawal NMS reported); restart clozapine cautiously OR transition to ECT as alternative (Strawn AJP 2007 PMID 17541055)
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalseverere_challenge_after_resolution_high_recurrence
    AP re-challenge planning after NMS resolution — severe; recurrence ~ 30% per Pope J Clin Psychiatry 1991; 2-week wash-out + alternative AP class (atypical preferred if typical was trigger; clozapine sometimes used as lowest-NMS-risk) + low starting dose + slow titration + chart-flag in EHR allergy/ADR list permanent (Pope 1991; Strawn AJP 2007)
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalsevereavoid_succinylcholine_rhabdomyolysis
    Severe NMS requiring intubation + paralysis — use rocuronium (non-depolarising); AVOID succinylcholine (depolarising) due to precipitation of hyperkalaemia from rhabdomyolysis (Strawn AJP 2007 PMID 17541055)
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalseverepediatric_nms
    Pediatric NMS — severe; rare but described in pediatric population (typically adolescents on AP for psychosis, bipolar, or tic disorders); same recognition (DSM-5-TR tetrad) + treatment with pediatric dose adjustment for dantrolene (1-2 mg/kg IV q 6 h; max 10 mg/kg/day) + bromocriptine (start 0.625 mg PO/NG TID, titrate to 2.5-5 mg TID per pediatric dosing) + amantadine (4.4-8.8 mg/kg/day PO divided BID); pediatric ICU + family-centred care (Strawn AJP 2007 — pediatric population referenced; pediatric-specific NMS literature pending Stage-A review)
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalmildpsych_history_with_first_episode_nms_documentation
    Patient with primary psychiatric disorder (psychosis / bipolar / treatment-resistant depression with adjunctive AP) experiencing first NMS episode — mild severity tier (documentation focus); chart-flag in EHR allergy/ADR list permanent + medication-allergy alert + alternative AP regimen documentation + patient + caregiver education on NMS recognition + 24-h ED return precaution (Strawn AJP 2007)
    Trigger could not be auto-evaluated — needs clinician judgement.

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Recommended regimen

NMS treatment ladder — STOP AP + ICU + supportive (cooling + IV fluids) → benzo (lorazepam) → dantrolene 1-2.5 mg/kg IV q6h → bromocriptine 2.5 mg PO TID titrate to 7.5 mg TID → amantadine 100 mg PO BID adjunct → ECT for refractory or catatonia-NMS continuum; AVOID succinylcholine + re-introduction of offending AP + abrupt clozapine discontinuation + parenteral AP during NMS + dopamine antagonist anti-emetics during acute NMS (Strawn AJP 2007 PMID 17541055; Levenson AJP 1985 PMID 2862613; Velamoor 2017)
axis: nms_treatment_ladderstep 1 - Step 1 — STOP all antipsychotics IMMEDIATELY + ICU admission + supportive foundation (cooling + IV crystalloid + DVT prophylaxis + electrolyte management) (Strawn AJP 2007 PMID 17541055 mandatory first step)
Selected step "Step 1 — STOP all antipsychotics IMMEDIATELY + ICU admission + supportive foundation (cooling + IV crystalloid + DVT prophylaxis + electrolyte management) (Strawn AJP 2007 PMID 17541055 mandatory first step)" — Any patient with DSM-5-TR NMS criteria positive + AP exposure within 72 h to 2 weeks (DSM-5-TR 2022)
  • STOP all antipsychotics
    first line
    discontinuation_action
    discontinue immediately • NA • immediate
    triggers: nms_diagnosis_dsm5tr_positive, ap_exposure_within_72h_to_2weeks
    Strawn AJP 2007 PMID 17541055 — mandatory first step; for LAI depot AP washout is not possible — supportive duration extended by weeks; for dopamine-agonist withdrawal NMS, RESTART agonist (different pivot)
  • lorazepam
    first line
    benzodiazepine
    1-2 mg IV q 4-6 h (also serves as lorazepam challenge for catatonia-NMS continuum per Fink + Taylor 2003) • IV • q 4-6 h PRN (max: 8 mg in 1 h initial; infusion if persistent)
    triggers: nms_with_agitation, nms_neuromuscular_control, catatonia_nms_continuum_lorazepam_challenge
    Strawn AJP 2007 — benzodiazepine first-line for agitation + neuromuscular control + serves as lorazepam challenge for catatonia-NMS continuum (Fink + Taylor Lancet 2003); lorazepam preferred for predictable hepatic metabolism (no active metabolite); 2 mg IV challenge for catatonia-NMS continuum diagnosis
    rxcui 6470
  • IV crystalloid (NS or LR)
    first line
    fluid_resuscitation
    500-1000 mL bolus then maintenance 100-150 mL/h with UOP target > 1 mL/kg/h for rhabdo prophylaxis • IV • continuous
    triggers: rhabdomyolysis_prophylaxis, volume_depletion_from_diaphoresis_dehydration
    Strawn AJP 2007 — volume + rhabdo prophylaxis; UOP target > 1 mL/kg/h; isotonic crystalloid first-line (NS or LR); consider sodium bicarbonate for urinary alkalinization if CK > 5000
  • passive + active cooling (cooling blankets, ice packs, evaporative, cold IV fluids)
    first line
    cooling_supportive
    NA — supportive • NA • continuous until T < 38.5°C
    triggers: temperature_above_38.5C, severe_hyperthermia_above_41C_requires_aggressive_cooling_plus_intubation_plus_paralysis
    Strawn AJP 2007 — temperature control foundational; passive cooling (remove blankets, fans) for T > 38.5°C; aggressive cooling (ice packs, evaporative, surface cooling, cold IV fluids) + intubation + paralysis (rocuronium, AVOID succinylcholine) for T > 41°C; mortality correlates with peak temperature

outpatient playbook — drug actions (5)

  1. 1. IF AP required → alternative AP class at low starting dose with slow titration; atypical preferred if typical was trigger; low-potency preferred if high-potency; clozapine sometimes used as lowest-NMS-risk for required AP (REMS ANC monitoring); 2-week wash-out from offending AP mandatory
    rxcui 2626
    clozapine 12.5 mg PO daily, titrate by 25-50 mg q 2-3 days to target 200-600 mg/day; OR alternative atypical AP at lowest effective dose with slow titration • PO • BID-TID typical maintenance
    trigger: Patient with treatment-resistant psychosis + NMS history requiring AP (CANMAT/ISBD 2018; APA 2020; Pope 1991)
    Pope 1991 — clozapine has lowest reported NMS recurrence rate; reserved for treatment-resistant psychosis with prior NMS; REMS ANC monitoring (agranulocytosis); slow titration mandatory; 2-week wash-out from offending AP before initiation
  2. 2. IF bipolar maintenance → lithium 300 mg PO BID titrate to serum 0.6-1.0 mEq/L; allows AP minimization or AP holiday
    rxcui 6448
    300 mg PO BID titrate to serum level • PO • BID typical
    trigger: Bipolar maintenance post-NMS without AP (CANMAT/ISBD 2018)
    CANMAT/ISBD 2018 — lithium for bipolar maintenance; serum level + renal + thyroid + parathyroid baseline + annual monitoring; allows AP minimization in patients with NMS history
  3. 3. IF Parkinson disease and dopamine-agonist withdrawal NMS → restart agonist (levodopa, pramipexole, ropinirole) at prior dose
    per pre-NMS regimen • PO • per regimen
    trigger: Parkinson disease patient with dopamine-agonist withdrawal NMS (Strawn AJP 2007)
    Strawn AJP 2007 — Parkinsonism-hyperpyrexia syndrome = NMS-like physiology from dopamine-agonist withdrawal; restart agonist (different pivot from AP-driven NMS)
  4. 4. IF anti-emetic required → ondansetron 4-8 mg PO q 8 h PRN (AVOID metoclopramide / prochlorperazine / droperidol)
    rxcui 26225
    4-8 mg PO PRN • PO • q 8 h PRN
    trigger: Patient with NMS history requiring anti-emetic (Strawn AJP 2007)
    Non-D2 blocker anti-emetic preferred for NMS history; AVOID dopamine antagonist anti-emetics permanently
  5. 5. IF anti-vertigo required → meclizine (non-D2 blocker); AVOID prochlorperazine + metoclopramide
    rxcui 6676
    meclizine 12.5-25 mg PO q 6 h PRN • PO • q 6 h PRN
    trigger: Patient with NMS history requiring anti-vertigo treatment (Strawn AJP 2007)
    H1 antagonist; non-D2 blocker; safe in NMS history

Auto-drafted A&P note

outpatient

Subjective

- Possible entry pathways: Antipsychotic (typical / atypical / LAI depot / clozapine) initiated, dose-escalated, switched, or new agent added within 72 h to 2 weeks (Strawn AJP 2007 PMID 17541055; DSM-5-TR 2022); Tetrad of severe lead-pipe muscle rigidity + hyperthermia (often > 41°C) + autonomic instability (labile BP, tachycardia, diaphoresis) + altered mental status (stupor / mutism / catatonic — NOT agitation) (Strawn AJP 2007); Lead-pipe muscle rigidity (generalized) + hyporeflexia in patient on antipsychotic (Strawn AJP 2007; distinguishes from serotonin syndrome which has clonus + hyperreflexia).

Objective

- No vitals, labs, or imaging entered for this encounter.

Assessment

**Neuroleptic Malignant Syndrome (NMS) — toxidrome from antipsychotic D2 blockade (Strawn AJP 2007 PMID 17541055; Levenson AJP 1985 PMID 2862613; DSM-5-TR 2022); STOP AP IMMEDIATELY + ICU + supportive (cooling + IV hydration) + dantrolene 1-2.5 mg/kg IV q6h + bromocriptine 2.5 mg PO TID + ECT for refractory; AVOID succinylcholine + re-introduction of offending AP + abrupt clozapine discontinuation** (psych.neuroleptic-malignant-syndrome.v1).
Phenotype framing: NMS vs serotonin syndrome (serotonergic agent + hours onset + clonus + hyperreflexia + agitation + diarrhoea + mydriasis; treatment = benzo + cyproheptadine — bromocriptine WORSENS SS) vs malignant catatonia (catatonic features dominant; lorazepam challenge + ECT — continuum with NMS per Fink + Taylor 2003) vs malignant hyperthermia (volatile anaesthetic exposure + masseter rigidity + ↑↑↑ CK + ↑↑↑ EtCO2; treatment = dantrolene + discontinue trigger) vs anticholinergic toxidrome (mydriasis + dry skin + urinary retention + delirium WITHOUT severe rigidity) vs sympathomimetic (MDMA / cocaine / methamphetamine + mydriasis + tachycardia + HTN + agitation) vs sepsis-driven encephalopathy (procalcitonin + culture + lactate; AP exposure incidental) vs heat stroke (environmental / exertional history) vs thyroid storm (TSH suppressed + Burch-Wartofsky score) vs serotonin-norepinephrine reuptake inhibitor withdrawal (less severe, more SSRI-discontinuation-syndrome features)
Scope: Neuroleptic Malignant Syndrome (NMS) = drug-induced toxidrome from idiosyncratic reaction to antipsychotic (AP) D2 blockade — typical (haloperidol > fluphenazine) > atypical (olanzapine, risperidone, quetiapine, aripiprazole, paliperidone, lurasidone) > clozapine (rare); also anti-emetic D2 blockers (metoclopramide, prochlorperazine, droperidol); LAI depot AP; dopamine-agonist withdrawal (Parkinsonism-hyperpyrexia syndrome). Tetrad = severe rigidity + hyperthermia + autonomic instability + altered MS (stupor/mutism/catatonic). Diagnosis via DSM-5-TR 2022 + Levenson 1985 criteria. Pharmacology pivot: STOP all AP IMMEDIATELY; ICU + supportive (cooling + IV hydration); benzodiazepine (lorazepam) for agitation + neuromuscular control; dantrolene 1-2.5 mg/kg IV q6h for severe rigidity + hyperthermia + rhabdo; bromocriptine 2.5 mg PO TID titrate up to 7.5 mg TID for D2 agonism (opposes AP blockade); ECT rescue for refractory or catatonia-NMS continuum (Fink + Taylor). AVOID succinylcholine (rhabdo hyperK; use rocuronium), re-introduction of offending AP without 2-week wash-out (~ 30% recurrence per Pope 1991), abrupt clozapine discontinuation (withdrawal NMS), parenteral AP during NMS (extends syndrome), dopamine antagonist anti-emetics during acute NMS (extends syndrome — use ondansetron) (Strawn AJP 2007 PMID 17541055).

No severity triggers fired against current inputs.

Plan

Regimen axis: **NMS treatment ladder — STOP AP + ICU + supportive (cooling + IV fluids) → benzo (lorazepam) → dantrolene 1-2.5 mg/kg IV q6h → bromocriptine 2.5 mg PO TID titrate to 7.5 mg TID → amantadine 100 mg PO BID adjunct → ECT for refractory or catatonia-NMS continuum; AVOID succinylcholine + re-introduction of offending AP + abrupt clozapine discontinuation + parenteral AP during NMS + dopamine antagonist anti-emetics during acute NMS (Strawn AJP 2007 PMID 17541055; Levenson AJP 1985 PMID 2862613; Velamoor 2017)** — step "Step 1 — STOP all antipsychotics IMMEDIATELY + ICU admission + supportive foundation (cooling + IV crystalloid + DVT prophylaxis + electrolyte management) (Strawn AJP 2007 PMID 17541055 mandatory first step)".
1. STOP all antipsychotics discontinue immediately NA immediate (discontinuation_action, first line) — Strawn AJP 2007 PMID 17541055 — mandatory first step; for LAI depot AP washout is not possible — supportive duration extended by weeks; for dopamine-agonist withdrawal NMS, RESTART agonist (different pivot)
2. lorazepam 1-2 mg IV q 4-6 h (also serves as lorazepam challenge for catatonia-NMS continuum per Fink + Taylor 2003) IV q 4-6 h PRN (benzodiazepine, first line) — Strawn AJP 2007 — benzodiazepine first-line for agitation + neuromuscular control + serves as lorazepam challenge for catatonia-NMS continuum (Fink + Taylor Lancet 2003); lorazepam preferred for predictable hepatic metabolism (no active metabolite); 2 mg IV challenge for catatonia-NMS continuum diagnosis
3. IV crystalloid (NS or LR) 500-1000 mL bolus then maintenance 100-150 mL/h with UOP target > 1 mL/kg/h for rhabdo prophylaxis IV continuous (fluid_resuscitation, first line) — Strawn AJP 2007 — volume + rhabdo prophylaxis; UOP target > 1 mL/kg/h; isotonic crystalloid first-line (NS or LR); consider sodium bicarbonate for urinary alkalinization if CK > 5000
4. passive + active cooling (cooling blankets, ice packs, evaporative, cold IV fluids) NA — supportive NA continuous until T < 38.5°C (cooling_supportive, first line) — Strawn AJP 2007 — temperature control foundational; passive cooling (remove blankets, fans) for T > 38.5°C; aggressive cooling (ice packs, evaporative, surface cooling, cold IV fluids) + intubation + paralysis (rocuronium, AVOID succinylcholine) for T > 41°C; mortality correlates with peak temperature

Setting playbook (outpatient) — Prevent recurrence — chart-flag in EHR allergy/ADR list permanent, medication review at every visit, alternative AP regimen counselling, slow titration if AP re-introduction needed, patient + caregiver education on NMS recognition + 24-h ED return precaution (Strawn AJP 2007; Pope 1991)
5. IF AP required → alternative AP class at low starting dose with slow titration; atypical preferred if typical was trigger; low-potency preferred if high-potency; clozapine sometimes used as lowest-NMS-risk for required AP (REMS ANC monitoring); 2-week wash-out from offending AP mandatory clozapine 12.5 mg PO daily, titrate by 25-50 mg q 2-3 days to target 200-600 mg/day; OR alternative atypical AP at lowest effective dose with slow titration PO BID-TID typical maintenance — Patient with treatment-resistant psychosis + NMS history requiring AP (CANMAT/ISBD 2018; APA 2020; Pope 1991) (Pope 1991 — clozapine has lowest reported NMS recurrence rate; reserved for treatment-resistant psychosis with prior NMS; REMS ANC monitoring (agranulocytosis); slow titration mandatory; 2-week wash-out from offending AP before initiation)
6. IF bipolar maintenance → lithium 300 mg PO BID titrate to serum 0.6-1.0 mEq/L; allows AP minimization or AP holiday 300 mg PO BID titrate to serum level PO BID typical — Bipolar maintenance post-NMS without AP (CANMAT/ISBD 2018) (CANMAT/ISBD 2018 — lithium for bipolar maintenance; serum level + renal + thyroid + parathyroid baseline + annual monitoring; allows AP minimization in patients with NMS history)
7. IF Parkinson disease and dopamine-agonist withdrawal NMS → restart agonist (levodopa, pramipexole, ropinirole) at prior dose per pre-NMS regimen PO per regimen — Parkinson disease patient with dopamine-agonist withdrawal NMS (Strawn AJP 2007) (Strawn AJP 2007 — Parkinsonism-hyperpyrexia syndrome = NMS-like physiology from dopamine-agonist withdrawal; restart agonist (different pivot from AP-driven NMS))
8. IF anti-emetic required → ondansetron 4-8 mg PO q 8 h PRN (AVOID metoclopramide / prochlorperazine / droperidol) 4-8 mg PO PRN PO q 8 h PRN — Patient with NMS history requiring anti-emetic (Strawn AJP 2007) (Non-D2 blocker anti-emetic preferred for NMS history; AVOID dopamine antagonist anti-emetics permanently)
9. IF anti-vertigo required → meclizine (non-D2 blocker); AVOID prochlorperazine + metoclopramide meclizine 12.5-25 mg PO q 6 h PRN PO q 6 h PRN — Patient with NMS history requiring anti-vertigo treatment (Strawn AJP 2007) (H1 antagonist; non-D2 blocker; safe in NMS history)

Non-pharmacologic actions:
- Chart-flag in EHR — NMS in allergy/ADR list permanent at every visit (Pope 1991)
- Patient + caregiver education on NMS recognition (severe rigidity, hyperthermia, autonomic instability, AMS) + 24-h ED return precaution (Strawn AJP 2007)
- Medication review at every visit — verify no inadvertent re-introduction of trigger AP or new D2 blocker combination (Strawn AJP 2007)
- Alternative regimen counselling for any prescription change involving D2 blocker (including anti-emetics) (Strawn AJP 2007)
- Pharmacist MTM annually for NMS-prevention review (Strawn AJP 2007)
- Psychiatry consult if psychosis / bipolar / depression requires continued AP — slow titration if re-introduction; alternative agent preferred (CANMAT/ISBD 2018; APA 2020)
- Family / caregiver re-education annually on NMS recognition (Strawn AJP 2007)
- Verify 2-week wash-out before any AP re-introduction (Pope 1991)
- Restart dopamine agonist if Parkinson disease post-NMS (Strawn AJP 2007)
- Avoid hyperthermic environment + dehydration (NMS recurrence triggers) (Strawn AJP 2007)

AVOID / contraindication checks:
- AVOID_succinylcholine_in_severe_NMS_with_rhabdomyolysis (Strawn AJP 2007 PMID 17541055) — use rocuronium (sugammadex available for reversal)
- AVOID_re_introduction_of_offending_AP_without_2_week_washout_plus_alternative_AP_plus_low_dose_plus_slow_titration (Pope J Clin Psychiatry 1991) — recurrence ~ 30%
- AVOID_abrupt_clozapine_discontinuation (Strawn AJP 2007) — withdrawal NMS; restart cautiously OR transition to ECT
- AVOID_parenteral_AP_for_agitation_during_NMS (Strawn AJP 2007) — extends syndrome; use benzodiazepine (lorazepam)
- AVOID_dopamine_antagonist_antiemetics_metoclopramide_prochlorperazine_droperidol_during_acute_NMS (Strawn AJP 2007) — extends syndrome; use ondansetron
- STOP_all_antipsychotics_mandatory_first_step (Strawn AJP 2007)
- Dantrolene_LFT_baseline_plus_serial_monitoring_hepatotoxicity_black_box_warning (FDA dantrolene label)
- Bromocriptine_PO_NG_only_crush_and_NG_if_intubated (Strawn AJP 2007)
- Amantadine_renal_dose_adjustment_for_CrCl_below_50 (FDA amantadine label)
- Chart_flag_in_EHR_allergy_ADR_list_after_NMS_episode_for_recurrence_prevention (Pope 1991)
- LAI_depot_AP_no_washout_possible_supportive_duration_extended_by_weeks (Strawn AJP 2007)
- Dopamine_agonist_withdrawal_NMS_Parkinsonism_hyperpyrexia_RESTART_AGONIST (different pivot from AP driven NMS) (Strawn AJP 2007)
- Pre_ECT_anesthesia_uses_rocuronium_AVOID_succinylcholine_in_rhabdo (Strawn AJP 2007)

Monitoring

Regimen monitoring:
- DSM 5TR NMS criteria re rate q 4 6h until resolution (DSM-5-TR 2022)
- Temperature q 15 30 min until T below 38C (Strawn AJP 2007)
- Vital signs HR BP RR SpO2 q 15 30 min until stable (Strawn AJP 2007)
- CK q 6h until trending down (rhabdo monitoring)
- Cr BMP q 6 12h until AKI excluded or resolving (rhabdo-AKI monitoring during dantrolene)
- UOP target above 1 mL per kg per h if rhabdo (Strawn AJP 2007)
- Mental status q 1 2h until AMS resolved (Strawn AJP 2007)
- ECG QTc baseline then q 24h during treatment (Strawn AJP 2007)
- LFT baseline plus q 24h during dantrolene course (FDA dantrolene black box hepatotoxicity warning)
- Sedation level continuous if benzo infusion (Strawn AJP 2007)
- Respiratory rate SpO2 continuous if benzo infusion or intubated (Strawn AJP 2007)
- Bromocriptine effect at 24 48h post initiation assess autonomic AMS improvement (Strawn AJP 2007)
- C SSRS at every clinical encounter in patient with underlying psychiatric disorder on AP (Posner 2011)
- Chart flag in EHR allergy ADR list at discharge permanent to prevent recurrence (Pope 1991)

Setting (outpatient) monitoring:
- Medication adherence + side effects at every visit (CANMAT/ISBD 2018; APA 2020)
- PHQ-9 + GAD-7 q 1-3 months if longitudinal psych care (Kroenke 2001; Spitzer 2006)
- C-SSRS at every visit if AP continued (Posner 2011)
- Drug interaction screen at every new prescription (Strawn AJP 2007)
- Chart-flag review at every visit permanent (Pope 1991)
- Annual labs — CK, CMP, LFT, CBC — for surveillance if AP continued (Strawn AJP 2007)

Follow-up plan: Comprehensive medication review at discharge + alternative AP regimen counselling (atypical preferred if typical was trigger; low-potency preferred if high-potency was trigger; clozapine sometimes used as the lowest-NMS-risk agent for required AP; 2-week wash-out + low starting dose + slow titration); psychiatry consult for AP regimen continuation if psychosis / bipolar / treatment-resistant depression with adjunctive AP; pharmacy MTM for NMS-prevention education; document NMS in EHR allergy/ADR list + chart-flag permanent (recurrence ~ 30%); pain medicine consult NOT required (NMS is not chronic pain); if Parkinson disease, restart dopamine agonist post-resolution; outpatient PCP / psychiatry follow-up at 1 week + 1 month + q 1-3 months; patient + caregiver education on NMS recognition + 24-h ED return precaution; recurrence-prevention counselling (alternative AP regimen, slow titration, chart-flag at every visit) (Strawn AJP 2007; Pope 1991)
- Close-out criterion: Alternative AP regimen documented + ADR documented + chart-flag in EHR + follow-up booked + patient/caregiver education completed (Strawn AJP 2007)

Monitoring phase: Continuous ECG + telemetry (autonomic instability arrhythmia risk); q 15-30 min BP + temp until stable; serial neuromuscular exam q 2-4 h (rigidity resolution); CK q 6 h until trending down; UOP target > 1 mL/kg/h if rhabdo; Cr q 12 h (AKI monitoring during dantrolene); mental status reassessment q 1 h initially; LFT q 24 h during dantrolene course (hepatotoxicity); CBC + electrolytes + acid-base q 6-12 h until stable; sedation level + airway protection assessment q 2 h if intubated. Resolution criteria: T < 38°C + rigidity resolved + autonomic features resolved + AMS resolved + CK trending down to baseline (Strawn AJP 2007; typically 1-2 weeks)

Disposition

Current setting: outpatient — Prevent recurrence — chart-flag in EHR allergy/ADR list permanent, medication review at every visit, alternative AP regimen counselling, slow titration if AP re-introduction needed, patient + caregiver education on NMS recognition + 24-h ED return precaution (Strawn AJP 2007; Pope 1991)

Disposition criteria:
- Continue outpatient indefinitely with chart-flag in EHR permanent + annual NMS-prevention review + pharmacist MTM (Pope 1991)
- Step to community PCP if stable + on non-D2-blocker regimen + no psych comorbidity needing specialty (CANMAT/ISBD 2018)
- Refer to psychiatry if psychosis / bipolar / depression requires AP re-introduction with slow titration + close monitoring (CANMAT/ISBD 2018; APA 2020)
- Refer to neurology if Parkinson disease + dopamine agonist regimen optimization (Strawn AJP 2007)

Escalation triggers (move to higher acuity):
- Recurrence of NMS features (rigidity, hyperthermia, autonomic, AMS) after AP re-introduction → STOP + ED for acute management (Strawn AJP 2007; severity_trigger:recurrence_after_re_introduction)
- Active SI on C-SSRS → ED + possible psych admission (Posner 2011; route to psych.suicidality.ed.core.v1)
- Worsening psychosis / mania / depression without AP → reconsider AP re-introduction with slow titration + close monitoring + chart-flag awareness (CANMAT/ISBD 2018; APA 2020)
- New AP / anti-emetic / VMAT2 inhibitor / anti-vertigo prescription identified at pharmacy or specialty clinic → review with patient + alternative consideration (Strawn AJP 2007)
- Catatonia features emerging (stupor + mutism + waxy flexibility + posturing) → ED + lorazepam challenge + ECT consultation; route to psych.catatonia.core.v1 (Fink + Taylor 2003)

Patient Action Plan

**NMS action plan — recurrence prevention + early warning signs (Strawn AJP 2007; Pope 1991)**
Personalised values: prior_nms_episode_features, current_psychiatric_regimen, current_anti_emetic_regimen, identified_supports, crisis_line_numbers, allergy_ADR_chart_flag_status, pharmacist_contact, PCP_psychiatrist_contact.

**Doing well — on alternative AP regimen OR on non-AP psychiatric agents OR off psychiatric meds; chart-flag in EHR active (Strawn AJP 2007)** (green):
Triggers:
- No severe rigidity, hyperthermia, autonomic instability, AMS (Strawn AJP 2007)
- No new D2 blocker prescribed at any visit (Strawn AJP 2007)
- Chart-flag in EHR active and reviewed at every visit permanent (Pope 1991)
- Stable psychiatric symptoms on alternative regimen (CANMAT/ISBD 2018; APA 2020)
- Patient + caregiver know NMS warning signs (Strawn AJP 2007)
Actions:
- Take psychiatric medications as prescribed (CANMAT/ISBD 2018; APA 2020)
- Verify NMS chart-flag at every clinical visit (Pope 1991)
- Show your current med list to every new provider + pharmacist (Strawn AJP 2007)
- Avoid new OTC anti-emetics, anti-vertigo medications, anti-migraine medications without checking with pharmacist (Strawn AJP 2007)
- Keep crisis line numbers available (988 US) (APA 2020)
- Stay hydrated and avoid hyperthermic environments (NMS recurrence trigger) (Strawn AJP 2007)

**Caution — new prescription started OR mild rigidity / fatigue / sweating (Strawn AJP 2007)** (yellow):
Triggers:
- New antipsychotic / anti-emetic / VMAT2 inhibitor / anti-vertigo prescription (Strawn AJP 2007)
- Mild muscle stiffness or rigidity (Strawn AJP 2007)
- Mild diaphoresis or feeling warm without fever (Strawn AJP 2007)
- Mild fatigue or slowing of mental status (Strawn AJP 2007)
- Started new herbal supplement or OTC medication without checking (Strawn AJP 2007)
- Dose escalation or addition of second AP (Strawn AJP 2007)
Actions:
- Call your prescriber or pharmacist within 24 h to review new medication (Strawn AJP 2007)
- Do not start new herbal supplement without checking (Strawn AJP 2007)
- Take your temperature q 4 h while symptoms present (Strawn AJP 2007)
- Use coping strategies + contact support person (APA 2020)
- Stay hydrated + avoid heat (Strawn AJP 2007)
Contact provider when:
- New symptom persists > 24 h (Strawn AJP 2007)
- Temperature rises above 38°C (Strawn AJP 2007)
- Rigidity worsening (Strawn AJP 2007)
- Mental status worsening (stupor, mutism, confusion) (Strawn AJP 2007)

**Medical alert — frank NMS features (Strawn AJP 2007)** (red):
Triggers:
- Temperature > 38°C with severe rigid muscles (Strawn AJP 2007)
- Severe muscle stiffness throughout body (lead-pipe rigidity) (Strawn AJP 2007)
- Stupor, mutism, severe confusion, or being unable to respond normally (Strawn AJP 2007)
- Rapid heart rate + sweating + high or labile blood pressure (Strawn AJP 2007)
- Difficulty swallowing or breathing (Strawn AJP 2007)
- Dark/brown urine (myoglobinuria from rhabdomyolysis) (Strawn AJP 2007)
Actions:
- Call 911 (US) / your local emergency services NOW (Strawn AJP 2007)
- Go to the nearest emergency department — do not be alone (Strawn AJP 2007)
- Tell the ED you have a history of NMS — bring your med list (Strawn AJP 2007)
- Tell someone you trust what is happening immediately (Strawn AJP 2007)
- Do not take more of any medication (Strawn AJP 2007)
- Do not use any substances (Strawn AJP 2007)
Contact provider when:
- Any red zone trigger — emergency department immediately (Strawn AJP 2007)

Earlier-Return Triggers

Return-precaution thresholds (watch for):
- [LIFE_THREATENING] NMS diagnosis confirmed (DSM-5-TR criteria positive + AP exposure within 72 h to 2 weeks) — life-threatening; STOP all AP IMMEDIATELY + ICU admission + supportive care foundation (cooling + IV crystalloid + DVT prophylaxis) + benzo (lorazepam) + dantrolene + bromocriptine (Strawn AJP 2007 PMID 17541055; DSM-5-TR 2022)
- [LIFE_THREATENING] Severe hyperthermia T > 41°C in NMS — life-threatening; aggressive cooling + intubation + paralysis (rocuronium, AVOID succinylcholine) + benzo infusion + dantrolene IV + cyproheptadine-equivalent dopaminergic support via bromocriptine NG; rhabdo + DIC + AKI risk (Strawn AJP 2007 PMID 17541055)
- [SEVERE] Rhabdomyolysis (CK > 5000) with AKI (rising Cr) in NMS — severe; aggressive IV hydration with UOP monitoring (target > 1 mL/kg/h) + serial CK trend + sodium bicarbonate alkalinization if severe + CRRT if AKI severe (Strawn AJP 2007 PMID 17541055)

Citations

- Strawn + Keck + Caroff Am J Psychiatry 2007 PMID 17541055 (canonical NMS update review + management algorithm) + Levenson Am J Psychiatry 1985 PMID 2862613 (initial cardinal description + Levenson criteria) + Caroff + Mann Med Clin North Am 1993 (NMS clinical syndrome anchor; PMID NEEDS_SOURCE_REVIEW) + Caroff + Mann Psychiatr Clin North Am 1988 (Caroff + Mann criteria; PMID candidate 3349602 NEEDS_SOURCE_REVIEW) + DSM-5-TR 2022 (current diagnostic criteria) + Velamoor Asian J Psychiatry 2017 (modern management synthesis) + Pope J Clin Psychiatry 1991 (recurrence ~ 30% on AP re-challenge cohort) + Fink + Taylor Lancet 2003 (catatonia-NMS continuum framework) + FDA AP class boxed warnings (typical + atypical) [PMID:17541055](https://pubmed.ncbi.nlm.nih.gov/17541055/)
- Cited evidence (PMID 2862613) [PMID:2862613](https://pubmed.ncbi.nlm.nih.gov/2862613/)
- Cited evidence (PMID 15784664) [PMID:15784664](https://pubmed.ncbi.nlm.nih.gov/15784664/)

Last reconciled with current guidelines: 2026-05-15.
References
  • Strawn + Keck + Caroff Am J Psychiatry 2007 PMID 17541055 (canonical NMS update review + management algorithm) + Levenson Am J Psychiatry 1985 PMID 2862613 (initial cardinal description + Levenson criteria) + Caroff + Mann Med Clin North Am 1993 (NMS clinical syndrome anchor; PMID NEEDS_SOURCE_REVIEW) + Caroff + Mann Psychiatr Clin North Am 1988 (Caroff + Mann criteria; PMID candidate 3349602 NEEDS_SOURCE_REVIEW) + DSM-5-TR 2022 (current diagnostic criteria) + Velamoor Asian J Psychiatry 2017 (modern management synthesis) + Pope J Clin Psychiatry 1991 (recurrence ~ 30% on AP re-challenge cohort) + Fink + Taylor Lancet 2003 (catatonia-NMS continuum framework) + FDA AP class boxed warnings (typical + atypical) — PMID:17541055
  • Cited evidence (PMID 2862613) — PMID:2862613
  • Cited evidence (PMID 15784664) — PMID:15784664