12-phase flow (12)

1. 1FRAME
   Adult with back pain + ≥1 red flag (bilateral sciatica / saddle change / urinary or bowel change / progressive deficit / new sexual dysfunction) — frame as time-critical surgical emergency until MRI excludes structural compression (NICE NG59; BASS Germon Spine J 2015 PMID 25708139)
   inputs: age
   advance: CES suspected + STAT pathway activated
2. 2ENTRY
   ED or spinal-on-call activation — any single red flag warrants STAT MRI; full triad (saddle + urinary retention + bilateral motor deficit) is near-pathognomonic (Todd 2017 PMID 28637110)
   inputs: bilateral_sciatica, saddle_sensory_change, urinary_symptoms_retention_or_difficulty
   advance: Red-flag screen captured; spinal team paged
3. 3CONTEXT
   Capture phenotype drivers — known disc/stenosis, anticoagulation/recent neuraxial procedure (haematoma), immunosuppression/IVDU/recent infection (abscess), active malignancy (MESCC), trauma, precise time-of-onset (Srikandarajah Spine 2015 PMID 25646751)
   inputs: malignancy_or_cancer_history, anticoagulation_or_recent_neuraxial_procedure, immunosuppression_or_ivdu_or_recent_infection, time_of_symptom_onset, pain_acute_severe_back
   advance: Phenotype hypothesis primed; reversal/abx needs flagged
4. 4RED_FLAGS
   Bilateral sciatica + saddle change + urinary retention with overflow + faecal incontinence + ED + severe progressive motor deficit — any one fires STAT MRI; complete painless retention (CESR) + bilateral motor weakness ≥2 grades + PVR >200 mL escalate to STAT neurosurgical decompression (BASS Germon 2015 PMID 25708139; NICE NG59)
   inputs: bilateral_sciatica, saddle_sensory_change, urinary_symptoms_retention_or_difficulty, bowel_symptoms_incontinence_or_loss_of_sensation, progressive_lower_limb_motor_deficit, sexual_dysfunction_new
   actions: workup.acute_lbp
   advance: Red flags documented + STAT MRI ordered + spinal surgery aware
5. 5INITIAL_WORKUP
   STAT lumbosacral MRI (CT myelogram if contraindicated); digital rectal exam (tone + perianal sensation); bladder scan PVR; CBC + coags + CRP/ESR; pre-op type & screen (Lavy BMJ 2009 PMID 19336488; BASS Germon 2015 PMID 25708139)
   inputs: mri_lumbosacral_spine_emergent, post_void_residual_volume_bladder_scan, cbc, coagulation_inr_aptt
   actions: panel.cbc, panel.coag, panel.inflammation
   advance: MRI completed (or escalated) + PVR + DRE documented
6. 6BRANCHING_WORKUP
   MRI-positive → phenotype branch (disc / stenosis acute-on-chronic / tumor MESCC / haematoma / abscess / trauma) → emergency surgical disposition; MRI-negative → scan-negative pivot (Hoeritzauer Neurology 2020/21 PMID 33177221) with functional-disorder assessment, MDT pathway, opioid de-escalation
   inputs: functional_disorder_signs_or_panic_attack_onset
   advance: Branch assigned (operative vs scan-negative)
7. 7DIFFERENTIAL
   Scan-positive phenotypes: disc-herniation-CES / spinal-stenosis acute decompensation / metastatic-MESCC / epidural haematoma / epidural abscess / trauma / iatrogenic; differentials: lumbar disc without CES (unilateral, no saddle/bladder), conus medullaris syndrome (UMN + LMN mix), spinal-cord infarct, transverse myelitis (separate dossier), scan-negative functional CES (Hoeritzauer 2018 PMID 30298195; Hoeritzauer 2020/21 PMID 33177221)
   advance: Terminal phenotype assigned
8. 8RISK_STRATIFICATION
   Clinical severity bands (no validated calc): CESS (suspected — bilateral sciatica without bladder/bowel) / CESI (incomplete — urinary difficulty, intact sensation of fullness) / CESR (retention with overflow, painless, PVR usually >500 mL) / CESC (complete — perineal anaesthesia + total sphincter loss). CESI <24 h has substantially better bladder recovery than >24 h (Srikandarajah Spine 2015 PMID 25646751 — 11.1% vs 46.6% bladder dysfunction); CESR functional prognosis is worse and less time-sensitive numerically (interpret with DeLong PMID 27831995 caveat — absence of significance ≠ no effect)
   inputs: post_void_residual_volume_bladder_scan, progressive_lower_limb_motor_deficit, time_of_symptom_onset
   advance: Clinical band assigned + timing documented
9. 9TREATMENT
   SURGICAL emergency — no pharmacologic primary treatment. Decompression within 24-48 h ideal (Quaile Int Orthop 2019 PMID 30374638; Srikandarajah Spine 2015 PMID 25646751). Adjuncts: urgent catheterisation (straight then indwelling); analgesia (avoid NSAIDs pre-op if neuraxial); IV dexamethasone ONLY if neoplastic compression (MESCC bundle — Loblaw IJROBP 2012 PMID 22420969); IV abx + surgery if abscess; anticoag reversal + surgery if haematoma; thromboprophylaxis post-op (LMWH 24 h post-stable). Scan-negative branch: NO surgery, pain control + opioid de-escalation + functional-disorder education + MDT (Hoeritzauer 2020/21 PMID 33177221)
   inputs: malignancy_or_cancer_history, anticoagulation_or_recent_neuraxial_procedure, immunosuppression_or_ivdu_or_recent_infection
   advance: Surgical plan dispositioned (or scan-negative pathway initiated)
10. 10DISPOSITION
    Theatre → post-op neuro/ICU step-down; transfer to spinal centre if MRI/surgical capability unavailable locally — same-day transfer pathway per BASS standards (Germon Spine J 2015 PMID 25708139)
    advance: Surgical bed allocated or transfer initiated
11. 11MONITORING
    Post-op: hourly neuro obs × 24 h, voiding trial + serial PVR, bowel programme, wound surveillance, DVT prophylaxis. Scan-negative branch: pain + functional follow-up; serial neuro exam to detect late-developing compression (rare — Hoeritzauer 2020/21 PMID 33177221)
    advance: Stable post-op course or scan-negative pathway running
12. 12FOLLOWUP
    Multidisciplinary rehab — urology (bladder retraining + ISC if persistent retention), colorectal (bowel programme), sexual health, physiotherapy, clinical psychology (post-CES distress + functional overlap), counselling on recurrence-from-stenosis prevention (NICE NG59; Quaile Int Orthop 2019 PMID 30374638)
    advance: MDT rehab plan documented + outpatient spinal clinic + driving/return-to-work counselling