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neuro.gbs-miller-fisher.v1

Miller-Fisher Syndrome (GBS variant)

neurologyacuteadultpediatricacuteinpatient
Start encounter →Print handoutPRODUCTION

Phase C shard-3 neuro wave-12 recovery (2026-05-15): authored at SCAFFOLDED — no MFS-specific workup in clinical-tools-registry.ts (only workup.gbs registered for the shared GBS-spectrum pathway). MFS = ~5% Western / ~25% Taiwan-Japan of GBS; classic triad ophthalmoplegia + ataxia + areflexia; anti-GQ1b+ in ~85%. 5 setting playbooks: home (EMS recognition + brainstem stroke ddx) → ed (Brighton + LP + anti-GQ1b + MRI brainstem + thiamine empirical) → icu (Bickerstaff brainstem monitoring + PCB airway) → inpatient (cranial nerve + gait rehab) → outpatient (neuro-ophthalmology + balance + monophasic recovery). 7 severity_triggers: classic_triad, anti-GQ1b_positive, Bickerstaff_brainstem_overlap, pharyngeal_cervical_brachial, GBS_limb_weakness_overlap, pediatric_MFS, monophasic_typical. 6 PMID evidence anchor: Hughes Cochrane IVIG (25238327), Raphael Cochrane PLEX (22786475), van Doorn 2011 (25023340), Wakerley 2016 anti-GQ1b spectrum (25072194), Fokke Brighton criteria validation Brain 2013 (24163275), EGRIS Walgaard Ann Neurol 2010 (20517939). All marked NEEDS_SOURCE_REVIEW. IVIG preferred per EAN/PNS 2023 (Cochrane MFS subgroup data); PLEX alternative; do NOT combine; NO steroids alone. Critical ddx: brainstem stroke + Wernicke encephalopathy mimic MFS triad — empiric thiamine + MRI brainstem MANDATORY in ED. Anti-GQ1b spectrum: MFS + Bickerstaff brainstem encephalitis + PCB + acute oropharyngeal palsy — all share anti-GQ1b serology; treated similarly with IVIG. Schema-blocked: calc.egris, calc.brighton, workup.anti_GQ1b_antibody, workup.mfs_triad_exam_protocol, workup.bickerstaff_brainstem_overlap_workup — surfaced in depth bundle. Siblings: neuro.gbs-aidp.v1 (same-commit), neuro.gbs-aman.v1 (same-commit), neuro.gbs.core.v1 (parent PRODUCTION), neuro.mg-crisis.core.v1 (real engine), neuro.transverse-myelitis.v1 (real engine).

Entry points (6)

  • symptom
    Classic MFS triad: ophthalmoplegia + ataxia + areflexia (van Doorn 2011 PMID 25023340)
    classic_triad_ophthalmoplegia_ataxia_areflexia
  • lab_abnormality
    Anti-GQ1b antibodies positive — ~85% of MFS (highly specific) (Wakerley 2016 PMID 25072194)
    anti_GQ1b_positive
  • symptom
    Bickerstaff brainstem encephalitis overlap — MFS triad + encephalopathy + brainstem signs; same anti-GQ1b+ spectrum (Wakerley 2016)
    bickerstaff_brainstem_overlap
  • symptom
    PCB variant overlap — bulbar + neck + upper-limb weakness with sparing of legs (Wakerley 2016)
    pharyngeal_cervical_brachial_overlap
  • symptom
    MFS-GBS overlap — limb weakness in addition to ophthalmoplegia/ataxia (van Doorn 2011)
    GBS_limb_weakness_overlap
  • history
    Preceding respiratory infection in 70% (Haemophilus / CMV) 1-3 wk prior (van Doorn 2011)
    preceding_respiratory_infection

Required inputs (16)

  • agerequired
    demographic • used at CONTEXT
    Age + geographic context — Taiwan/Japan ~25% of GBS is MFS vs ~5% Western (van Doorn 2011 PMID 25023340)
  • preceding_infection_1_3wkrequired
    history • used at CONTEXT
    Respiratory infection (Haemophilus, CMV) in ~70% of MFS (van Doorn 2011)
  • ophthalmoplegia_internal_or_externalrequired
    symptom • used at FRAME
    External ± internal ophthalmoplegia — first MFS triad component (van Doorn 2011)
  • ataxia_cerebellar_or_sensoryrequired
    symptom • used at FRAME
    Ataxia — second MFS triad component; often gait + appendicular (van Doorn 2011)
  • areflexiarequired
    symptom • used at FRAME
    Areflexia — third MFS triad component (Brighton 2011 PMID 24163275)
  • mental_status_for_bickerstaff_overlaprequired
    symptom • used at RED_FLAGS
    Encephalopathy + brainstem signs → Bickerstaff overlap; ICU monitoring required (Wakerley 2016 PMID 25072194)
  • bulbar_functionrequired
    symptom • used at RED_FLAGS
    Bulbar weakness may indicate PCB overlap → airway concern (Wakerley 2016)
  • fvc_nifrequired
    vital • used at RED_FLAGS
    Respiratory monitoring — MFS less commonly requires MV but overlap variants may (AAN 2012)
  • hr
    vital • used at RED_FLAGS
    Autonomic — paroxysmal tachy/brady (IGOS Doets 2018)
  • sbp
    vital • used at RED_FLAGS
    Autonomic BP swings (IGOS Doets 2018)
  • csf_protein_cell_countrequired
    lab • used at INITIAL_WORKUP
    Albumino-cytologic dissociation — present in ~50% wk 1, less consistent in MFS than AIDP (AAN 2012)
  • anti_GQ1b_antibodyrequired
    lab • used at BRANCHING_WORKUP
    Anti-GQ1b in ~85% MFS — highly specific (Wakerley 2016 PMID 25072194)
  • iga_levelrequired
    lab • used at INITIAL_WORKUP
    IgA deficiency screen before IVIG (anaphylaxis risk) (EAN/PNS 2023)
  • mri_brain_brainstem_with_gadrequired
    imaging • used at INITIAL_WORKUP
    Exclude brainstem stroke / Wernicke / Bickerstaff brainstem encephalitis (T2 brainstem hyperintensity) (Wakerley 2016)
  • mri_spine_with_contrast
    imaging • used at INITIAL_WORKUP
    Exclude transverse myelitis (NICE 2024)
  • ncs_emg
    imaging • used at BRANCHING_WORKUP
    NCS often normal in pure MFS; may show abnormalities in overlap MFS-GBS (van Doorn 2011)

12-phase flow (12)

  1. 1FRAME
    Confirm MFS classic triad: ophthalmoplegia + ataxia + areflexia (Brighton 2011 PMID 24163275; van Doorn 2011 PMID 25023340)
    inputs: ophthalmoplegia_internal_or_external, ataxia_cerebellar_or_sensory, areflexia
    advance: MFS triad confirmed; stroke/Wernicke excluded
  2. 2ENTRY
    Ophthalmoplegia + ataxia + areflexia + preceding URI (van Doorn 2011)
    inputs: age, preceding_infection_1_3wk
    advance: MFS entry features captured
  3. 3CONTEXT
    Mental status (Bickerstaff overlap), bulbar function (PCB overlap), limb weakness (GBS overlap), vitals (Wakerley 2016 PMID 25072194)
    inputs: mental_status_for_bickerstaff_overlap, bulbar_function, fvc_nif
    advance: Overlap-variant assessment complete
  4. 4RED_FLAGS
    Bickerstaff brainstem encephalopathy / PCB airway compromise / MFS-GBS limb-weakness respiratory failure → ICU (Wakerley 2016)
    inputs: mental_status_for_bickerstaff_overlap, bulbar_function, fvc_nif
    actions: workup.gbs
    advance: Airway/CNS stable + ICU allocated if needed
  5. 5INITIAL_WORKUP
    CSF, MRI brain + brainstem with gad, CBC/CMP/LFT, IgA, pregnancy test (EAN/PNS 2023; Wakerley 2016)
    inputs: csf_protein_cell_count, mri_brain_brainstem_with_gad, iga_level
    actions: panel.cbc, panel.renal, panel.lft, panel.coag
    advance: CSF + MRI back; IgA documented pre-IVIG
  6. 6BRANCHING_WORKUP
    Anti-GQ1b antibody (signature) + NCS/EMG (often normal in pure MFS); EEG if encephalopathy (Bickerstaff) (Wakerley 2016 PMID 25072194)
    inputs: anti_GQ1b_antibody
    advance: Anti-GQ1b documented + variant assigned (pure MFS vs Bickerstaff vs PCB vs MFS-GBS overlap)
  7. 7DIFFERENTIAL
    MFS (this engine) vs MG (anti-AChR; fluctuating fatigability) vs Wernicke (thiamine-responsive) vs brainstem stroke vs botulism vs AIDP (limb weakness predominant) vs Bickerstaff/PCB (anti-GQ1b spectrum) (Wakerley 2016)
    advance: MFS phenotype confirmed; overlap variants identified
  8. 8RISK_STRATIFICATION
    EGRIS (mostly low for pure MFS; higher for Bickerstaff/PCB overlap); limb-weakness MRC sum (Walgaard 2009 PMID 20517939)
    actions: calc.nihss
    advance: Overlap risk stratification documented
  9. 9TREATMENT
    IVIG 0.4 g/kg/d × 5 d preferred per EAN/PNS 2023 (Cochrane MFS subgroup); PLEX alternative if IgA deficient; do NOT combine; NO steroids alone; DVT prophylaxis if immobile (Hughes Cochrane 2014 PMID 25238327)
    inputs: iga_level
    advance: Immunomodulation started + monitoring established
  10. 10DISPOSITION
    Inpatient neuro for pure MFS (monitor for overlap evolution); ICU if Bickerstaff/PCB or limb-weakness with respiratory concern (Wakerley 2016)
    inputs: fvc_nif
    advance: Care setting decided
  11. 11MONITORING
    Q4-6h neuro exam for overlap evolution; FVC if bulbar/limb; serial cranial nerve exam; watch for treatment-related fluctuation (EAN/PNS 2023)
    inputs: fvc_nif
    actions: panel.cbc
    advance: Monitoring plan documented
  12. 12FOLLOWUP
    Neuro-ophthalmology follow-up for ophthalmoplegia resolution; gait/balance therapy; usually monophasic full recovery in 2-6 mo (van Doorn 2011)
    advance: Follow-up bundle scheduled