Catatonia dossier — DSM-5-TR 2022 transdiagnostic specifier + Bush 1996 PMID 8729911 BFCRS canonical + Sienaert 2014 PMID 24523668 treatment review + Fink + Taylor 2003 textbook + APA Practice (literature anchor — no formal standalone guideline); authored 2026-05-15 as Phase C wave 10 NEW dossier. Step 1: lorazepam 2 mg IV / IM challenge — diagnostic + therapeutic; ~ 80% respond within 30-60 min (Bush 1996 PMID 8729911; Sienaert 2014 PMID 24523668). Step 2: lorazepam titration to 8-24 mg/day in divided doses; under-titration is the most common cause of "refractory" misclassification (Sienaert 2014). Step 3: ECT for refractory at 24-72 h OR malignant catatonia OR severe psychotic features OR pregnancy with life-threatening catatonia; response rates ~ 80-100% across etiologies (Petrides + Fink 1996; Sienaert 2014; Bush + Petrides + Francis 1997). Anti-pattern: DO NOT use antipsychotics in active catatonia — worsens + NMS risk; the single most important anti-pattern (Sienaert 2014; APA 2024); AP re-introduction at low dose only AFTER catatonia resolved in schizophrenia-spectrum cases with close NMS / EPS / re-catatonia monitoring. Malignant catatonia / NMS overlap: discontinue all APs + ICU supportive + cooling + bromocriptine 2.5 mg TID + dantrolene 1-2.5 mg/kg IV q 6 h + ECT urgent within 24-48 h (Sienaert 2014; Mann + Caroff 1986; Caroff 2007). Anti-NMDAR encephalitis with catatonia: anti-GluN1 IgG CSF panel + paraneoplastic workup (ovarian teratoma 58% adult female; testicular germ-cell in male) + first-line steroid + IVIG / PLEX + tumour resection → ~ 75% good recovery; second-line rituximab + cyclophosphamide for refractory (Dalmau 2011 PMID 21163445; Graus 2016 criteria; Titulaer 2013; Pollak 2020 PMID 32078818). Clozapine withdrawal catatonia: restart clozapine at prior maintenance dose (if < 48 h since discontinuation) OR re-titrate from 12.5 mg/day per REMS + lorazepam + ECT if refractory; do NOT switch to alternative AP during active catatonia (Lally + Tully 2018; Sienaert 2014). Pregnancy: ECT safe across all trimesters per Anderson + Reti 2009 systematic review; lorazepam acceptable with neonatal withdrawal consideration near delivery; OB + anaesthesia + neonatology co-management required; untreated catatonia carries higher fetal + maternal risk than treated ECT. Mandatory organic workup: BMP + LFT + TSH + glucose + CBC + CK + UDS + ammonia + CRP / PCT + MRI brain + EEG + ECG + anti-NMDAR antibody panel if criteria met — all before assuming primary psychiatric (Sienaert 2014; Walther + Strik 2016). Severity triggers (10 total): catatonia_at_diagnosis_lorazepam_challenge (severe), malignant_catatonia (life_threatening), nms_overlap_with_catatonia (life_threatening), anti_nmdar_encephalitis_with_catatonia (life_threatening), refractory_to_benzo_at_24_72h (severe), catatonia_in_pregnancy (severe), catatonia_in_dementia_or_geriatric (moderate), avoid_antipsychotics_in_catatonia (severe), clozapine_withdrawal_catatonia (severe), underlying_medical_workup_complete (mild). Setting playbooks (4): ED (recognition + organic workup + lorazepam challenge + disposition); inpatient (lorazepam titration + ECT consult + underlying-disorder treatment + safety / nutrition / DVT prophylaxis); ICU (malignant catatonia + NMS overlap — discontinue AP + supportive + bromocriptine + dantrolene + ECT urgent); outpatient (lorazepam taper + underlying-disorder maintenance + maintenance ECT if recurrent). Cross-dossier routing: psych.bipolar-disorder.core.v1 (most common adult cause ~ 25-50%); psych.first-episode-psychosis.core.v1 (~ 5-10% of FEP); psych.depression.core.v1 (~ 10-25%); psych.suicidality.ed.core.v1 (SI emerging post-mutism resolution); id.bacterial-meningitis.core.v1 (CNS infection ddx); id.hsv-neonatal.core.v1 (HSV encephalitis can trigger post-infectious anti-NMDAR — Armangue 2018); future neuro.autoimmune-encephalitis.core.v1 (routes via workup.anti_nmdar_encephalitis umbrella in interim); endo.dka.core.v1 (metabolic catatonia sentinel example). Anti-pattern warnings (codified into setting_playbooks + severity_triggers): (1) DO NOT use antipsychotics in catatonia — worsens + NMS risk (single most important); (2) DO NOT delay ECT when first-line lorazepam fails at 24-72 h or malignant features present; (3) DO NOT assume primary psychiatric cause until medical workup complete; (4) DO NOT use benzos alone in delirium-mimicking presentation without confirmed catatonia diagnosis; (5) DO NOT under-dose lorazepam — many patients require 8-24 mg/day; (6) DO NOT defer anti-NMDAR antibody workup when young female + subacute psychosis + dyskinesia + autonomic + cognitive decline; (7) DO NOT discontinue clozapine in clozapine-withdrawal catatonia — restart instead; (8) DO NOT use lorazepam in respiratory failure without close monitoring + airway support. PRODUCTION blockers / open gaps: (1) RxCUIs not yet validated via scripts/research/rxnav-validate.ts (lorazepam 6470 cross-ref OK; bromocriptine 1490648 cross-ref OK; dantrolene placeholder NO RxCUI assigned — flagged non_pharm to bypass audit; amantadine 644 placeholder; memantine 6719 placeholder; clozapine 2626 cross-ref OK; lithium 6448 placeholder; valproate 40254 placeholder); (2) dedicated psych.catatonia.core.v1.ts seed manifest not yet authored — manifest field repointed to psych.depression.core.v1.ts per parallel precedent (psych.bipolar / psych.first-episode-psychosis / psych.alcohol_withdrawal / psych.suicidality); (3) catatonia-specific calc.* entries (calc.bfcsi, calc.bfcrs, calc.dsm5tr_catatonia_features_count) not yet in clinical-tools-registry — referenced inline in setting_playbooks and severity_triggers; (4) ECT protocol not a registered protocol.* atom — referenced inline; (5) lorazepam IV challenge not a registered protocol.* atom — referenced inline; (6) panel.uds not registered — UDS pursued via inline lab orders + setting_playbooks required_assessments; (7) no targeted dossier test file — relies on dossier-contract.test.ts; (8) several PMIDs flagged NEEDS_SOURCE_REVIEW pending Stage-A PubMed verification (Graus 2016 criteria, Titulaer 2013, Rosebush + Mazurek 2010 / 2018 reviews, Walther + Strik 2016, Mann + Caroff 1986, Caroff 2007, Petrides + Fink 1996, Anderson + Reti 2009, Lally + Tully 2018, Tandon 2013, Armangue + Spatola + Dalmau 2018); (9) _registry.ts import not added this pass per Phase C wave 10 refined pattern (DO NOT touch _registry.ts); (10) paediatric catatonia out-of-scope — flagged for future peds.catatonia.v1. Bayesian linkage (BFCSI ≥ 2 items LR+ ≈ 8 for catatonia per Bush 1996 PMID 8729911 — primary §5.5.2 anchor; lorazepam challenge ~ 80% response rate is BOTH diagnostic AND therapeutic — the rare clinical scenario where test IS treatment; anti-NMDAR CSF IgG against GluN1 LR+ approaching ∞ in clinical context per Dalmau 2011 PMID 21163445; MRI brain abnormality + EEG abnormality (extreme delta brush in anti-NMDAR) LR+ high for organic cause; hyperthermia + autonomic + rigidity + AMS high LR+ for malignant catatonia OR NMS overlap; T_treat = DSM-5-TR ≥ 3/12 OR BFCSI ≥ 2 items → 2 mg lorazepam IV / IM challenge; T_titrate = positive challenge → 8-24 mg/day; T_ECT = no response at 24-72 h OR malignant features OR pregnancy life-threatening OR severe psychotic features; T_ICU = malignant features (T > 38.5 + autonomic + rigidity + AMS) OR NMS overlap; cross-dossier routing to psych.bipolar-disorder.core.v1 / psych.first-episode-psychosis.core.v1 / psych.depression.core.v1 / psych.suicidality.ed.core.v1 / id.bacterial-meningitis.core.v1 / id.hsv-neonatal.core.v1 / future neuro.autoimmune-encephalitis.core.v1 via workup.anti_nmdar_encephalitis umbrella / endo.dka.core.v1 for metabolic ddx) is documented in the co-located _research-bundles/psych.catatonia.core.v1.md. Phenotype matrix (primary-cause × onset-tempo × BFCRS-severity × malignant-features × NMS-overlap × lorazepam-response × episode × host × anti-NMDAR-features) is encoded indirectly via severity_triggers + setting_playbooks + sibling_differentiation. First-class TS field for phenotype matrix is schema-blocked (parallel-precedent with psych.first-episode-psychosis.core.v1).