Guillain-Barré Syndrome

complete reference · ascending paralysis · albuminocytologic dissociation · FVC monitoring · IVIG/PLEX · Full Card

Symptoms / Associated Sx

• Progressive, symmetric, ascending weakness beginning in the legs and moving upward, with hyporeflexia or areflexia — the cardinal combination. Develops over days, reaching nadir within 2–4 weeks. Often preceded by distal paresthesias and accompanied by neuropathic pain. Cranial nerve involvement (facial diplegia, bulbar weakness → dysphagia, dysarthria), respiratory muscle weakness, and autonomic dysfunction (labile blood pressure, tachy-/bradyarrhythmias, ileus, urinary retention) signal severe disease. The Miller-Fisher variant is the triad of ophthalmoplegia, ataxia, and areflexia (anti-GQ1b antibodies).

Neg

• No discrete sensory level and no early bowel/bladder dysfunction — argues against spinal cord compression/transverse myelitis (cord lesions give upper-motor-neuron signs, a sensory level, and sphincter involvement; GBS is lower-motor-neuron with areflexia — MRI spine excludes the surgical emergency)

• Weakness is not fatigable or predominantly ocular, and reflexes are reduced (not preserved) — argues against myasthenia gravis (MG fatigues, spares reflexes, and favors ocular/bulbar onset)

• Weakness is ascending, not descending, and pupils are spared — argues against botulism (botulism descends and causes fixed dilated pupils, prominent autonomic/cholinergic signs)

• Course is over days-to-weeks, not chronic >8 weeks — argues against CIDP (the chronic counterpart)

Social History (SHx)

• Antecedent infection 1–3 weeks prior in ~two-thirds — most classically Campylobacter jejuni gastroenteritis (associated with axonal variants and more severe disease); also CMV, EBV, Mycoplasma pneumoniae, influenza, Zika, and (rarely) recent vaccination or surgery.

Main Etiology

• A post-infectious autoimmune attack on peripheral nerves and roots via molecular mimicry — antibodies raised against a preceding pathogen cross-react with myelin or axonal gangliosides. Subtypes: acute inflammatory demyelinating polyradiculoneuropathy (AIDP — most common in North America/Europe), acute motor axonal neuropathy (AMAN) and AMSAN (axonal, often post-Campylobacter, anti-ganglioside antibodies), and Miller-Fisher syndrome (anti-GQ1b).

RF

• Modifiable: none of major clinical significance (food hygiene reduces Campylobacter exposure).

• Non-modifiable: recent infection (especially Campylobacter), male sex, increasing age.

Data

• Lumbar puncture — albuminocytologic dissociation (elevated CSF protein with a normal white cell count) (characteristic, but may be normal in the first week — a normal early LP does not exclude GBS)

• Nerve conduction studies/EMG (demyelinating features — prolonged distal latencies, conduction block, slowed velocities; or axonal patterns in AMAN — confirms and subtypes, though changes can lag early)

• Serial bedside spirometry — forced vital capacity (FVC) and negative inspiratory force (NIF/MIP) (the most important monitoring test; tracks respiratory muscle strength and predicts the need for intubation BEFORE hypoxia)

• MRI spine with contrast (exclude cord compression/transverse myelitis; may show nerve-root enhancement in GBS)

• Electrolytes (autonomic/SIADH), anti-GQ1b antibody if Miller-Fisher suspected; consider anti-ganglioside panel.

DDx

Spinal cord compression / transverse myelitis (sensory level, UMN signs, sphincter loss — MRI emergency) · myasthenia gravis (fatigable, ocular/bulbar, normal reflexes) · botulism (descending, dilated pupils, autonomic) · tick paralysis (ascending, find the tick) · hypokalemic/periodic paralysis (potassium) · CIDP (chronic >8 weeks) · toxic/critical-illness neuropathy · West Nile poliomyelitis

Home Meds

• Do NOT give corticosteroids — they are ineffective and possibly harmful in GBS (unlike many other neuro-inflammatory conditions).

• Reconcile and hold drugs that exacerbate autonomic instability; avoid neuromuscular-depressant agents where possible.

Plan

Consults

• Neurology — confirm diagnosis/subtype, direct immunotherapy.

• ICU / pulmonary — respiratory monitoring and airway management.

• PT / OT — prevent contractures, rehabilitation.

• Cardiology — if significant dysautonomia/arrhythmia.

Respiratory monitoring (the priority)

• Serial FVC and NIF every 4–6 hours. Apply the "20/30/40 rule" — consider intubation for FVC <20 mL/kg, NIF less negative than −30 cmH₂O, or MIP/peak pressures consistent with a >30% drop; a single-breath count and bulbar dysfunction also guide. Intubate electively before respiratory collapse — do not wait for hypoxia or hypercapnia, which are late and dangerous signs. About a quarter of patients require mechanical ventilation.

Disease-modifying therapy

• IVIG 0.4 g/kg/day for 5 days OR plasma exchange (PLEX) — equally effective; the choice is by availability, access, and comorbidity (IVIG is more convenient; PLEX needs vascular access). Do not combine them (no added benefit). Indicated for non-ambulatory patients or those with rapid progression/respiratory or bulbar involvement; start as early as possible.

• Corticosteroids are NOT used — reiterated because it differs from most inflammatory neurology.

Autonomic / supportive

• Continuous cardiac telemetry and blood-pressure monitoring for dysautonomia (labile BP, brady-/tachyarrhythmias, ileus, retention); treat hemodynamic swings cautiously (responses are exaggerated; avoid overcorrection). VTE prophylaxis (immobile), neuropathic pain control (gabapentin/pregabalin; opioids sparingly), bowel/bladder care, aspiration precautions with bulbar weakness, meticulous positioning and PT to prevent contractures and pressure injury.

Always

• PT / OT eval and treat — early mobilization as able, contracture prevention, then graded rehabilitation (recovery is often slow over months).

• Trend: FVC/NIF (the key vital sign), serial strength and reflex exam for progression vs plateau, swallow/bulbar function, autonomic vitals; watch for the nadir before plateau and recovery.

• Escalation triggers: declining FVC/NIF toward thresholds → ICU, elective intubation · bulbar weakness with aspiration risk → ICU/airway · autonomic instability (significant arrhythmia, severe BP lability) → ICU telemetry · rapid ascending progression → ICU.

• Discharge checklist: completed IVIG/PLEX course · inpatient-rehab or intensive outpatient PT/OT referral (recovery is gradual; most improve substantially over weeks-months) · neuropathic pain regimen · neurology follow-up to monitor for plateau/relapse and to distinguish from CIDP if it recurs/persists · counseling on the expected slow recovery and residual fatigue · return precautions (worsening weakness, breathing difficulty, swallowing trouble).

Red Flags — ICU

• Falling FVC/NIF (toward FVC <20 mL/kg or NIF > −30) → elective intubation BEFORE collapse; don't wait for hypoxia.
• Bulbar weakness / aspiration (dysphagia, weak cough, secretions) → airway protection.
• Autonomic instability — dangerous brady-/tachyarrhythmias, wide BP swings, asystole → continuous telemetry, ICU.
• Rapidly ascending weakness → close ICU-level monitoring.
• Sensory level / sphincter loss → reconsider cord compression; MRI urgently.

Senior IM Resident Pearls

• Watch the FVC, not the pulse ox. Respiratory failure in GBS is neuromuscular — the FVC and NIF fall long before oxygen desaturation. Trend them every few hours and intubate electively; waiting for hypoxia is waiting too long.
• Ascending weakness + areflexia = GBS until proven otherwise. The lost reflexes are the key exam finding that separates it from most mimics.
• No steroids. This is the classic exception — corticosteroids don't help GBS and may harm. The treatments are IVIG or plasma exchange, and you pick one, not both.
• A normal early LP doesn't exclude it. Albuminocytologic dissociation may not appear until the second week — treat on the clinical picture.
• Rule out the cord first. A sensory level, sphincter involvement, or UMN signs should send you to an urgent spine MRI — cord compression is the can't-miss surgical mimic.
• The autonomics can kill. Arrhythmias and blood-pressure swings are a leading cause of death — keep them on telemetry and treat hemodynamic changes gently (responses are exaggerated).
• Think Campylobacter. A diarrheal illness 1–3 weeks prior is the classic trigger and predicts the axonal, more severe variants.
• Common mistake: giving steroids, or combining IVIG and PLEX, or discharging a "stable" patient whose FVC is quietly trending down — the respiratory decline can be insidious.