Guillain-Barré Syndrome: Clinical Case Discussion & Key Points
Model Case Presentation
Patient Demographics
Name: Master Arjun, Age: 8 years, Gender: Male, Informant: Mother (Reliable)
Chief Complaints
- Weakness of both legs – 7 days, progressively worsening
- Weakness of both arms – 3 days
- Difficulty walking – 5 days
History Summary
Master Arjun was in good health until 2 weeks ago when he had an episode of loose stools (5–6 episodes/day) with mild fever, which resolved in 4 days. One week later, he noticed weakness and tingling in both feet. The weakness progressively ascended over the next 5–7 days to involve the thighs, then hands and forearms. He cannot stand unassisted and has difficulty climbing stairs. No bowel or bladder dysfunction. No back pain. No preceding immunization. No family history of similar illness.
Born and raised normally, all developmental milestones achieved. Immunizations up to date.
Examination Summary
| Parameter | Finding | Significance |
|---|---|---|
| Consciousness | Alert, oriented | Normal |
| Motor — Proximal LL | 2/5 power | Severe weakness |
| Motor — Distal LL | 3/5 power | Weakness |
| Motor — UL | 3/5 power | Moderate weakness |
| Tone | Hypotonia (flaccid) | LMN pattern |
| Deep Tendon Reflexes | Absent bilaterally | Areflexia — hallmark |
| Sensory | Mild glove-and-stocking hypoesthesia | Sensory involvement |
| Cranial Nerves | Bilateral mild facial palsy | Facial diplegia |
| Autonomic | HR 112/min, BP labile | Autonomic dysfunction |
| Bladder/Bowel | Normal | Rules out cord compression |
| Spine | No tenderness, no deformity | Rules out myelopathy |
Respiratory assessment: RR 24/min, able to count to 20 in one breath. No use of accessory muscles at rest.
✅ Complete Diagnosis
Guillain-Barré Syndrome (Acute Inflammatory Demyelinating Polyneuropathy — AIDP subtype) presenting as Acute Ascending Flaccid Paralysis with Areflexia and Facial Diplegia, following Campylobacter-associated diarrheal illness, with mild autonomic dysfunction. GBS Disability Scale: Grade 3 (can walk with support).
📝 History — Exam Q&A
GBS is an acute immune-mediated polyradiculoneuropathy characterized by rapidly progressive, ascending, flaccid paralysis with areflexia, typically following a preceding infection. It is the most common cause of acute flaccid paralysis (AFP) in children in the post-polio era. It involves the peripheral nervous system (nerve roots + peripheral nerves).
| Organism | Notes |
|---|---|
| Campylobacter jejuni | Most common trigger (~30%); associated with axonal subtypes (AMAN/AMSAN) and worse prognosis |
| Cytomegalovirus (CMV) | Associated with more severe sensory involvement |
| Epstein-Barr Virus (EBV) | Common viral trigger |
| Mycoplasma pneumoniae | Respiratory illness precedes |
| Influenza, Zika, COVID-19 | Documented associations |
| Hepatitis E | Emerging association |
💡 Pearl
The latency between preceding infection and onset of GBS is typically 1–3 weeks. This latency is the time required for the autoimmune response to develop.
Molecular mimicry is the key mechanism. Antigens on the infectious pathogen share structural similarity with gangliosides on peripheral nerve myelin or axolemma. This triggers an aberrant autoimmune response:
- In AIDP: T-cells and macrophages attack peripheral nerve myelin → demyelination → slowed conduction
- In AMAN: IgG antibodies (anti-GM1, anti-GD1a) target nodes of Ranvier on motor axons → axonal damage → more severe, longer recovery
- In Miller Fisher Syndrome: Anti-GQ1b antibodies target cranial nerve myelin → ophthalmoplegia, ataxia, areflexia
| Subtype | Full Form | Key Features |
|---|---|---|
| AIDP | Acute Inflammatory Demyelinating Polyneuropathy | Most common (~85–90%); demyelinating; all nerves affected; good recovery |
| AMAN | Acute Motor Axonal Neuropathy | Pure motor; axonal; anti-GM1/GD1a; common after C. jejuni; prevalent in Asia |
| AMSAN | Acute Motor and Sensory Axonal Neuropathy | Motor + sensory axonal damage; more severe; slow recovery |
| MFS | Miller Fisher Syndrome | Ophthalmoplegia + Ataxia + Areflexia; anti-GQ1b antibodies; good prognosis |
| PCB | Pharyngeal-Cervical-Brachial | Dysphagia, facial weakness, arm weakness; anti-GT1a antibodies |
| ASAN | Acute Sensory Axonal Neuropathy | Pure sensory; rare |
- Onset and progression: Ascending weakness, bilateral, symmetric, progressive over days (typically peaks within 4 weeks)
- Preceding illness: URTI or diarrheal illness 1–3 weeks before onset
- Sensory symptoms: Paresthesia, tingling, pain (especially back and limb pain — common early feature)
- Cranial nerve involvement: Diplopia, facial weakness, dysphagia, dysarthria
- Autonomic symptoms: Palpitations, dizziness, urinary retention (transient)
- Respiratory: Breathlessness, inability to count, difficulty phonating
- Pertinent negatives: No bladder/bowel incontinence (rules out cord), no fever at onset, no back pain (rules out cord compression), no fluctuating symptoms (rules out myasthenia)
- Vaccination history: Recent immunization (rare trigger — influenza vaccine)
GBS follows a triphasic course:
- Progressive phase: Ascending weakness over days to 4 weeks maximum
- Plateau phase: Symptoms stabilize (days to weeks)
- Recovery phase: Gradual, can take months; descending order (proximal before distal)
By definition, progression must stop by 4 weeks. If progression continues beyond 4 weeks, consider CIDP (Chronic Inflammatory Demyelinating Polyneuropathy).
Brighton Collaboration criteria classify GBS into 4 levels of diagnostic certainty. Level 1 (highest certainty):
- Bilateral flaccid limb weakness
- Decreased or absent DTRs in weak limbs
- Monophasic illness with interval from onset to nadir of 12 hours to 28 days, followed by plateau
- CSF protein elevated above normal lab value WITH CSF WBC <50 cells/μL (albuminocytologic dissociation)
- Electrodiagnostic evidence of polyneuropathy
Level 2: First 3 criteria + CSF OR electrodiagnostics (not both). Level 3: First 3 criteria alone. Level 4: Does not meet criteria / unclassified.
| Grade | Description |
|---|---|
| 0 | Healthy, no complaints |
| 1 | Minor symptoms, capable of running |
| 2 | Can walk ≥10 m without aid |
| 3 | Can walk ≥10 m with aid (walker/stick) |
| 4 | Bedridden or chairbound |
| 5 | Requires assisted ventilation (for at least part of the day) |
| 6 | Dead |
Indication for treatment: Grade ≥3 (unable to walk independently) OR rapid progression.
🩺 Examination — Exam Q&A
- Motor: Bilateral, symmetric, ascending flaccid weakness (legs → arms); proximal > distal (but variable)
- Tone: Hypotonia (flaccid) — LMN pattern
- Reflexes: Absent (areflexia) — most consistent finding; even in clinically strong muscles
- Sensory: Mild glove-and-stocking hypoesthesia; pain and paresthesia are common early; vibration/proprioception may be impaired
- Plantar response: Absent or flexor (NOT extensor, as cord is not involved)
- No upper motor neuron signs: No spasticity, no clonus, no Babinski
💡 Key Distinction
Areflexia is the most consistent clinical finding in GBS. It can be present even in limbs with near-normal power, making it the single most important sign to elicit.
- Facial nerve (VII): Bilateral LMN facial palsy (facial diplegia) — most common CN finding; present in ~50% of cases
- Bulbar nerves (IX, X): Dysphagia, dysarthria, nasal regurgitation — risk of aspiration
- Oculomotor nerves (III, IV, VI): Ophthalmoplegia — especially in Miller Fisher Syndrome
- CN XII: Tongue weakness (less common)
Cranial nerve involvement does not affect progression or prognosis significantly but increases risk of aspiration and need for airway protection.
Respiratory failure is the leading cause of death in GBS. Bedside assessment:
- Breath count test: Ask child to count aloud in one breath — counting <20 suggests significant respiratory compromise
- Phonation: Inability to phonate at normal volume → diaphragmatic weakness
- Single-breath sentence test: Unable to complete a sentence in one breath
- Accessory muscle use: SCM, intercostal, abdominal muscles
- Paradoxical breathing: Inward movement of abdomen on inspiration → diaphragmatic palsy
- Spirometry: FVC — critical investigation (see Investigations tab)
🚨 20-30-40 Rule for Intubation
Elective intubation is indicated if FVC < 20 mL/kg OR MIP (maximal inspiratory pressure) < −30 cmH₂O OR MEP (maximal expiratory pressure) < 40 cmH₂O. Do not wait for hypoxia — it is a late sign.
Autonomic dysfunction occurs in ~65% of GBS patients and is a major cause of morbidity and mortality:
- Cardiovascular: Tachycardia (most common), bradycardia (dangerous), BP lability — hypertension or hypotension, heart block, asystole
- Urinary: Retention (temporary), rarely incontinence
- GI: Ileus, constipation, diarrhea
- Sweating: Anhidrosis or hyperhidrosis
- Pupillary abnormalities: Rare
Cardiac monitoring (continuous ECG) is mandatory in all hospitalized GBS patients. Sudden cardiac death can occur due to arrhythmia.
Miller Fisher Syndrome (MFS) is a GBS variant with the classic triad:
- Ophthalmoplegia — bilateral, external > internal; may mimic CN III, IV, VI palsy
- Ataxia — cerebellar-type gait ataxia (out of proportion to limb weakness)
- Areflexia — generalized
Limb weakness is minimal or absent. Anti-GQ1b antibodies are positive in >90% of MFS. Pupils are usually spared. Prognosis is excellent — most recover fully within 1–3 months without specific treatment.
| Feature | GBS | Transverse Myelitis | Poliomyelitis | Myasthenia Gravis | Hypokalemic Paralysis |
|---|---|---|---|---|---|
| Distribution | Ascending, symmetric | Below level of lesion | Asymmetric, focal | Proximal, fatigable | Proximal, symmetric |
| Reflexes | Absent | Absent then brisk | Absent (affected limb) | Normal/brisk | Absent/diminished |
| Sensory level | No | Yes (cord level) | No | No | No |
| Bladder/Bowel | Rare, transient | Yes (retention/incontinence) | No | No | No |
| Fever at onset | No | May be present | Yes (prodromal) | No | No |
| CSF | Albuminocytologic dissociation | Pleocytosis | Pleocytosis (early) | Normal | Normal |
| NCS | Demyelinating/Axonal | Normal | Reduced CMAP | Decremental response | Normal |
| Serum K⁺ | Normal | Normal | Normal | Normal | Low |
The Erasmus GBS Respiratory Insufficiency Score (EGRIS) predicts risk of respiratory failure within the first week of admission.
| Parameter | Finding | Score |
|---|---|---|
| Days from weakness onset to admission | ≤7 days | +1 |
| Facial and/or bulbar weakness | Present | +1 |
| MRC Sum Score (0–60) at admission | 60 (normal) | 0 |
| 51–60 | +1 | |
| 41–50 / ≤40 | +2 / +3 |
Total score 0–1: Low risk (1%). Score 2–3: Intermediate (3–9%). Score 4–6: High risk (26–65%). Guides decision for ICU admission.
🔬 Investigations — Exam Q&A
Albuminocytologic dissociation (also called cytoalbuminous dissociation) is the hallmark CSF finding:
- Elevated CSF protein: Usually 100–1000 mg/dL (normal: 15–45 mg/dL)
- Normal or near-normal cell count: <10 cells/μL (normal is <5)
- There is dissociation — protein is high but cells are not, suggesting nerve root inflammation (protein leaks from inflamed roots but there is no infection/inflammation within the CSF space)
⚠️ Important Caveat
In the first week of illness, CSF protein may be normal in up to 50% of cases. The finding becomes more reliable after the 1st week. Do NOT rule out GBS on the basis of normal CSF protein in the first 7 days.
| Parameter | AIDP (Demyelinating) | AMAN (Axonal) |
|---|---|---|
| Nerve conduction velocity (NCV) | Markedly slowed (<75% of lower limit normal) | Normal or mildly reduced |
| Distal motor latency | Prolonged | Normal or slightly prolonged |
| CMAP amplitude | Normal or mildly reduced | Markedly reduced |
| F-waves | Prolonged or absent (early, sensitive finding) | Absent |
| Conduction block | Present (hallmark of demyelination) | Absent |
| Sensory NCS | Abnormal | Normal (pure motor subtype) |
💡 Early Sensitive Finding
Prolonged or absent F-waves are the earliest electrodiagnostic abnormality in GBS, reflecting proximal nerve root involvement before distal changes appear.
| Antibody | Association | Clinical Significance |
|---|---|---|
| Anti-GQ1b | Miller Fisher Syndrome | Sensitivity >90% for MFS; also in Bickerstaff's brainstem encephalitis |
| Anti-GM1 | AMAN, Classic GBS | Associated with C. jejuni infection; poorer prognosis |
| Anti-GD1a | AMAN, AMSAN | Associated with axonal subtypes |
| Anti-GT1a | Pharyngeal-Cervical-Brachial | Bulbar and arm weakness predominant |
| Anti-GD1b | Ataxic GBS, ASAN | Sensory ataxia prominent |
- Spirometry — Forced Vital Capacity (FVC): Serial monitoring every 4–6 hours. FVC <20 mL/kg → intubation. FVC <30 mL/kg → consider ICU transfer.
- Maximal Inspiratory Pressure (MIP): MIP less negative than −30 cmH₂O → impending respiratory failure
- Maximal Expiratory Pressure (MEP): MEP <40 cmH₂O → poor cough, risk of aspiration
- ABG / SpO₂: Hypoxia is a late sign; do not rely on SpO₂ alone
- Chest X-Ray: Rule out aspiration pneumonia, atelectasis
MRI spine is indicated to exclude structural cord pathology (transverse myelitis, cord compression) especially when:
- Sensory level is present
- Bladder/bowel dysfunction is prominent
- Asymmetric weakness with hyperreflexia
- Back pain with tenderness
In confirmed GBS, MRI may show enhancement of spinal nerve roots and cauda equina with gadolinium contrast — supporting the diagnosis. However, MRI is not required for diagnosis.
- Serum electrolytes: Especially potassium (rule out hypokalemic paralysis) and sodium (SIADH can occur in GBS)
- Renal and liver function tests: Baseline before immunotherapy
- CBC: Baseline; mild leukocytosis may be present
- Campylobacter serology / stool culture: If recent diarrhea
- Serum IgA level: IgA deficiency → risk of anaphylaxis with IVIG (check before administering IVIG)
- Continuous ECG monitoring: Detect arrhythmias from autonomic dysfunction
- Blood glucose: Rule out hypoglycemia
💊 Management — Exam Q&A
Disease-specific treatment (IVIG or plasmapheresis) is indicated when:
- GBS Disability Scale ≥ 3 (unable to walk without assistance) OR
- Rapid progression (even if currently at Grade 2)
- Respiratory failure (ventilator-dependent)
- Bulbar dysfunction (dysphagia, risk of aspiration)
- Significant autonomic dysfunction
Treatment should be started ideally within 2 weeks of onset (most benefit within first 4 weeks). Both treatments are equally effective.
- Total dose: 2 g/kg
- Regimen 1: 0.4 g/kg/day IV for 5 days (standard)
- Regimen 2: 1 g/kg/day IV for 2 days (alternative)
- Both regimens are equivalent in efficacy
Check IgA levels before administering IVIG. Patients with selective IgA deficiency are at risk of severe anaphylactic reactions (anti-IgA antibodies react with IgA in IVIG product).
Plasmapheresis removes circulating antibodies and complement from the plasma. It is equally effective to IVIG.
- Regimen: 5 exchanges over 10–14 days (total of ~200–250 mL/kg plasma removed)
- Each session replaces removed plasma with albumin or fresh frozen plasma
- Advantages over IVIG: No risk of IgA anaphylaxis, immediate removal of pathogenic antibodies
- Disadvantages: Requires central venous access, technically demanding, not widely available in resource-limited settings, greater complication risk (hypotension, infection)
⚠️ Combination NOT recommended
Combining IVIG + plasmapheresis does NOT provide additional benefit over either alone. If plasmapheresis is done first, IVIG given subsequently may be partially removed. Hence, do NOT combine.
This is a classic examination question. Steroids are contraindicated/ineffective in GBS:
- Multiple randomized controlled trials (including the landmark Dutch GBS trial) have shown no benefit of IV or oral steroids in GBS
- In some studies, steroids were associated with worse outcomes and delayed recovery
- Steroids suppress the immune response globally but the particular pathogenic mechanisms in GBS (antibody-mediated, complement-dependent) are not adequately suppressed by steroids alone
Contrast this with CIDP (chronic form), where steroids ARE effective.
- Respiratory: Serial FVC monitoring; early elective intubation if FVC <20 mL/kg; avoid late intubation after crash arrest
- Cardiac monitoring: Continuous ECG for arrhythmias; treat bradycardia (temporary pacing if needed); avoid beta-blockers (can worsen bradycardia)
- BP management: Treat hypertension cautiously with short-acting agents; treat hypotension with fluids; avoid antihypertensives that cause reflex bradycardia
- DVT prophylaxis: Low molecular weight heparin (LMWH) + compression stockings in non-ambulant patients
- Nutrition: NG tube feeding if bulbar palsy; maintain caloric needs
- Pain management: Neuropathic pain is common — pregabalin, gabapentin, amitriptyline; AVOID NSAIDs/opioids as first-line
- Urinary care: Bladder catheterization if retention
- Physiotherapy: Passive range of motion exercises; prevent contractures; position to avoid pressure sores
- Psychological support: GBS is terrifying for children and families; counseling essential
Overall prognosis in children is better than in adults:
- ~85% of children achieve full recovery or near-normal function within 6–12 months
- ~10–15% have residual weakness or disability at 1–2 years
- Mortality: ~3–5% (mainly due to respiratory failure, autonomic cardiac events, infections)
Poor prognostic factors:
- Axonal subtype (AMAN/AMSAN) — slower recovery
- Campylobacter jejuni preceding infection
- Rapid onset to nadir (<7 days)
- Older age at onset
- Severe weakness (GBS-DS Grade 5 at nadir)
- Ventilator dependence
- Markedly reduced CMAP amplitude on NCS
GBS recurs in approximately 2–5% of patients. Recurrent GBS (termed RAIDP — Recurrent AIDP) should raise suspicion of an underlying diagnosis of CIDP (Chronic Inflammatory Demyelinating Polyneuropathy) if relapses are frequent or if progression continues beyond 8 weeks. Each recurrence should be treated with IVIG or plasmapheresis similarly to the initial episode.
- IGOS (International GBS Outcome Study): Large ongoing international prospective cohort study (started 2012) studying outcomes, biomarkers, and predictors in GBS across all subtypes and age groups
- mEGOS (modified Erasmus GBS Outcome Score): Predicts chance of unaided walking at 6 months. Validated clinical tool based on age, preceding diarrhea, and MRC sum score
- EGRIS: Predicts respiratory failure risk within 1st week of hospitalization (described in Examination tab)
- i-RODS (Inflammatory Rasch-built Overall Disability Scale): Activity and social participation assessment tool validated for GBS
🔭 Recent Advances — Exam Q&A
- Neurofilament light chain (NfL): Elevated serum and CSF NfL reflects axonal injury; higher levels predict worse outcomes and slower recovery; being explored as a prognostic biomarker
- GFAP (Glial Fibrillary Acidic Protein): Central nervous system involvement marker; elevated in overlap syndromes (Bickerstaff's)
- Complement activation products (sC5b-9): Elevated in GBS; correlate with severity; potential therapeutic target
- Anti-ganglioside antibody panels: Expanded panels now allow more precise subtype classification beyond anti-GQ1b and anti-GM1
Eculizumab is a humanized monoclonal antibody against complement protein C5, blocking the formation of the membrane attack complex (C5b-9). In GBS, complement activation mediates nerve damage in AIDP and AMAN subtypes. A phase 2 RCT (SID-GBS trial, 2023) showed that eculizumab significantly improved disability scores compared to placebo in severe GBS. Phase 3 trials are ongoing. It remains investigational but represents a promising complement-targeted therapy.
GBS has been documented as a neurological complication of both SARS-CoV-2 infection and COVID-19 vaccines (particularly adenoviral vector vaccines like AstraZeneca). Key points:
- Incidence post-COVID infection: ~0.15–0.5 per 1000 COVID patients (higher risk than baseline population)
- Most cases occur 2–4 weeks after COVID infection, suggesting immune-mediated mechanism
- MFS overlap (cranial nerve predominant) appears more common in COVID-associated GBS
- Vaccine-associated GBS: Estimated risk 1–3 per million doses with adenoviral vector vaccines; accepted as rare adverse event by regulatory authorities
- Management is identical to standard GBS — IVIG or plasmapheresis
Some patients who do not improve or worsen after the first course of IVIG (2 g/kg) may benefit from a second IVIG dose. The SID-GBS trial investigated a repeat IVIG dose (2 g/kg) in poor-prognosis GBS patients (identified using mEGOS score ≥6). Results showed modest improvement in some patients. The strategy is individualized — guided by predicted poor prognosis (high mEGOS) and lack of improvement after first IVIG course.
BBE is part of the anti-GQ1b antibody syndrome spectrum and overlaps with MFS:
- Features: Ophthalmoplegia, ataxia, areflexia (like MFS) PLUS impaired consciousness, hyperreflexia, Babinski sign (CNS involvement)
- Anti-GQ1b antibodies positive in ~70%
- MRI may show brainstem T2 signal changes
- Overlap with MFS (30% of BBE have MFS features) and with GBS (30% of BBE have limb weakness)
- Treatment: IVIG; steroids may have a role unlike classic GBS (brainstem encephalitis component)
The spectrum: Classic GBS ↔ Pharyngeal-Cervical-Brachial ↔ MFS ↔ BBE — unified by anti-ganglioside antibody pathology.
⚡ Key Points — Quick Revision
One-Liners for Exam
- Most common cause of AFP in post-polio era: GBS
- Most common subtype: AIDP (~85–90%)
- Most common trigger: Campylobacter jejuni (associated with AMAN, poorer prognosis)
- Latency from infection to GBS onset: 1–3 weeks
- Cardinal features: Ascending flaccid paralysis + Areflexia
- Most consistent sign: Areflexia (even in minimally weak limbs)
- CSF hallmark: Albuminocytologic dissociation (↑ protein, normal cells)
- CSF may be normal in: First week of illness (do not rule out GBS)
- Earliest NCS finding: Prolonged or absent F-waves
- MFS triad: Ophthalmoplegia + Ataxia + Areflexia; anti-GQ1b antibodies
- Anti-GM1: AMAN; Anti-GQ1b: MFS
- Intubate when: FVC < 20 mL/kg (20-30-40 rule)
- Treatment: IVIG 2 g/kg over 5 days OR Plasmapheresis 5 sessions — equally effective
- Steroids: NOT effective in GBS (contraindicated — worsen outcome)
- Do NOT combine: IVIG + Plasmapheresis — no added benefit
- GBS-DS ≥ 3: Indication to treat
- Maximum progression: Within 4 weeks; beyond 4 weeks → think CIDP
- Recurrence rate: 2–5%
- EGRIS score: Predicts respiratory failure risk
- Prognosis in children: Good — ~85% full/near-full recovery
- Poor prognosis: Axonal subtype, rapid onset, Campylobacter trigger, low CMAP
💡 High-Yield Exam Differentiators
- GBS vs Transverse Myelitis: GBS — no sensory level, no bladder/bowel; TM — sensory level, bladder/bowel involvement
- GBS vs Polio: GBS — symmetric, post-URTI/diarrhea, normal CSF cells; Polio — asymmetric, fever at onset, CSF pleocytosis
- GBS vs Hypokalemic paralysis: GBS — normal K⁺, areflexia persists; Hypokalemia — low K⁺, improves rapidly with K⁺ replacement
- AIDP vs AMAN: AIDP — demyelinating (slow NCV, conduction block); AMAN — axonal (reduced CMAP, normal NCV, worse prognosis)