Nervous System & Special Senses

Guillain-Barre syndrome: diagnosis and management

Clinical Overview and When to Suspect Guillain-Barré Syndrome

— Campylobacter jejuni gastroenteritis (most common, ~30%) — associated with axonal variants (AMAN/AMSAN) and worse prognosis

— CMV, EBV, Mycoplasma pneumoniae, HIV seroconversion, hepatitis E, influenza

— Zika virus — outbreak-associated clusters

— SARS-CoV-2 infection (modest association); mRNA COVID vaccines not causally linked; Ad26.COV2.S (Janssen) had a small signal

— Surgery, trauma, immune checkpoint inhibitors (ipilimumab, nivolumab)

— Progressive symmetric leg-then-arm weakness over hours to days, often with paresthesias preceding weakness

— Hyporeflexia or areflexia out of proportion to weakness

— Recent diarrheal or upper respiratory illness 1–3 weeks prior

— Bulbar symptoms (dysphagia, dysarthria) or facial diplegia

— Autonomic instability (BP lability, arrhythmias, ileus, urinary retention)

— AIDP (acute inflammatory demyelinating, most common US form)

— AMAN/AMSAN (axonal, Asia/Latin America, post-Campylobacter)

— Miller Fisher syndrome: ophthalmoplegia + ataxia + areflexia, anti-GQ1b positive

— Bickerstaff brainstem encephalitis: encephalopathy + ophthalmoplegia

Board pearl: GBS is a clinical diagnosis; do not delay treatment waiting for LP or NCS if the syndrome fits. Step 3 management: Any patient with suspected GBS warrants immediate ED admission with serial respiratory mechanics, not outpatient workup, because rapid neuromuscular respiratory failure is the proximate cause of mortality.

Definition: Acute immune-mediated polyradiculoneuropathy producing ascending, symmetric, flaccid weakness with areflexia, typically peaking within 2–4 weeks of onset.

Epidemiology: Annual incidence ~1–2 per 100,000; most common cause of acute flaccid paralysis in the developed world since polio eradication. Slight male predominance, all ages affected but bimodal peaks in young adults and >50.

Antecedent triggers (2/3 of cases):

When to suspect on Step 3:

Variants to recognize:

Presentation Patterns and Key History

— Distal paresthesias in fingertips/toes are often the first complaint, preceding weakness

— Symmetric ascending weakness — patient reports difficulty climbing stairs, rising from chair, then upper extremity heaviness

— Back/radicular pain in up to 2/3 — can mislead toward cauda equina or musculoskeletal diagnoses

— Cranial nerve involvement in 50% — bilateral facial weakness (CN VII), dysphagia, dysarthria, ophthalmoplegia

— Autonomic features — sinus tachycardia, labile BP, ileus, urinary retention, anhidrosis or diaphoresis

— Respiratory: dyspnea, orthopnea, weak cough, single-breath count <20

— Gastrointestinal illness in prior 1–6 weeks (Campylobacter)

— URI, influenza-like illness, recent immunizations, surgery

— HIV risk factors, tick exposure, travel (Zika, dengue, rabies, diphtheria)

— Medications: checkpoint inhibitors, TNF-alpha inhibitors

— Family history of porphyria, lead exposure, alcohol use (for differentials)

— Pharyngeal-cervical-brachial variant — bulbar and upper limb weakness mimicking botulism or myasthenia

— Paraparetic variant — pure lower extremity weakness mimicking cord compression

— Pure sensory or pure ataxic forms

Key distinction: Unlike transverse myelitis or cord compression, GBS has no sensory level, no early bowel/bladder dysfunction (urinary retention can occur late but is uncommon early), and reflexes are lost rather than hyperactive. Board pearl: Children may present with refusal to walk, irritability, and prominent pain — easily mistaken for hip pathology or meningitis; check reflexes early.

Classic tempo: Onset over hours to days, progression for up to 4 weeks (by definition; anything progressing >8 weeks is CIDP). Nadir typically reached by 2 weeks in 50%, by 4 weeks in >90%.

Cardinal symptoms:

Sensory complaints exceed sensory findings — patients describe burning, tingling, "tight band" sensations but objective sensory loss is mild.

Key history to elicit:

Atypical presentations that still warrant GBS workup:

Physical Exam Findings and Hemodynamic Assessment

— Symmetric flaccid weakness, typically legs > arms initially; proximal and distal involvement

— Hypotonia with preserved muscle bulk (acute process)

— Hyporeflexia or areflexia — universal feature; reflexes lost even in mildly weak segments

— Plantar responses flexor or absent (extensor response should prompt CNS workup)

— Mild distal pinprick/vibration loss, often glove-and-stocking

— No spinal sensory level (rules out myelopathy)

— Romberg may be positive

— Bilateral facial weakness in ~50% — pathognomonic clue when symmetric

— Weak gag, dysarthria, tongue weakness

— Miller Fisher: ophthalmoplegia, ptosis, ataxia, areflexia

— Single-breath count <20 suggests impending failure

— Forced vital capacity (FVC) <20 mL/kg, NIF less negative than −30 cm H₂O, maximal expiratory pressure <40 cm H₂O — the "20/30/40 rule" triggers ICU transfer and intubation planning

— Paradoxical abdominal breathing, accessory muscle use, weak cough, inability to count to 10 in one breath

— Continuous telemetry mandatory — sinus tachycardia is most common; bradyarrhythmias and asystole can occur, particularly during suctioning or Valsalva

— BP lability — alternating hypertension and hypotension; avoid aggressive antihypertensives (precipitates hypotension)

— Orthostatics, bowel sounds (ileus), bladder scan for retention

— Pupillary asymmetry suggests alternate diagnosis (botulism, brainstem lesion)

CCS pearl: On a CCS case, order bedside FVC and NIF q4–6h, continuous cardiac monitoring, pulse oximetry, and bladder scan in the first hour. Step 3 management: A patient unable to lift the head off the bed or with bulbar weakness and pooling secretions needs early elective intubation — do not wait for hypercapnia, because GBS respiratory failure is restrictive and rapid.

Motor exam:

Sensory exam:

Cranial nerves:

Respiratory assessment (critical):

Autonomic/hemodynamic assessment:

Diagnostic Workup — Initial Labs, Imaging, ECG, and Lumbar Puncture

— Albuminocytologic dissociation: elevated CSF protein (>45 mg/dL) with WBC <10/µL — present in ~50% in first week, >75% by week 2

— Normal CSF in early presentation does not exclude GBS — repeat in 1 week if diagnosis uncertain

— WBC >50/µL should prompt evaluation for HIV, Lyme, sarcoidosis, leptomeningeal malignancy, or West Nile

— Normal glucose; elevated glucose or low glucose suggests alternate process

— CBC, CMP — exclude electrolyte-driven weakness (hypokalemia, hypophosphatemia, hypermagnesemia)

— TSH — thyrotoxic periodic paralysis differential

— CK — typically normal or mildly elevated (helps exclude myositis/rhabdomyolysis)

— HIV testing — seroconversion can present as GBS-like syndrome; also affects CSF interpretation

— Hepatitis profile, HbA1c (baseline)

— Pregnancy test in women of reproductive age (affects treatment counseling)

— Order when diagnosis uncertain, sensory level present, bowel/bladder dysfunction, or pure paraparesis — to exclude cord compression, transverse myelitis, epidural abscess

— GBS finding: enhancement of anterior spinal nerve roots and cauda equina (supportive but not required)

Board pearl: Order LP after MRI if cord compression is on the differential. Step 3 management: Do not delay IVIG or plasmapheresis pending LP or antibody results — empirical treatment is appropriate once clinical criteria are met.

GBS is clinical, but supporting studies confirm and exclude mimics.

Lumbar puncture (cornerstone):

Basic labs:

ECG: baseline and continuous telemetry — look for sinus tachycardia, AV block, QT prolongation, arrhythmias from autonomic dysfunction.

Spine MRI (with contrast):

Stool studies: Campylobacter culture/PCR if recent diarrhea (epidemiologic value; doesn't change acute management).

Antiganglioside antibodies: anti-GQ1b for Miller Fisher (>90% sensitive); anti-GM1 for AMAN — confirmatory but results return too late to guide initial therapy.

Diagnostic Workup — Advanced and Confirmatory Studies

— Most useful after 1–2 weeks of symptoms — early studies can be normal or nonspecific

— AIDP findings: prolonged distal motor latencies, conduction block, temporal dispersion, prolonged or absent F-waves (earliest abnormality — reflects proximal root demyelination), reduced conduction velocities

— AMAN findings: reduced compound muscle action potential (CMAP) amplitudes without demyelinating features; normal sensory studies

— AMSAN: axonal motor and sensory loss

— EMG: acute denervation (fibrillations, positive sharp waves) appears at 2–4 weeks in axonal forms

— Anti-GQ1b — Miller Fisher syndrome, Bickerstaff encephalitis

— Anti-GM1, anti-GD1a — AMAN, AMSAN (post-Campylobacter)

— Anti-GT1a — pharyngeal-cervical-brachial variant

— Heavy metal screen (lead, arsenic, thallium) — for atypical sensory-motor neuropathy with GI symptoms

— Porphyria screen (urine porphobilinogen) — abdominal pain + neuropathy + psychiatric features

— Tick-borne paralysis — examine scalp/hairline thoroughly

— Anti-AChR and anti-MuSK antibodies, edrophonium/ice-pack test — myasthenia gravis differential when bulbar/ocular predominate

— Botulinum toxin assay of serum/stool — descending paralysis, mydriasis

Key distinction: Early-normal NCS does not exclude GBS — clinical syndrome + albuminocytologic dissociation is sufficient to treat. Board pearl: F-wave abnormalities are the earliest electrodiagnostic finding in AIDP because demyelination begins at nerve roots — useful when distal NCS is still normal.

Electrodiagnostic studies (NCS/EMG):

Antiganglioside antibody panel:

MRI brain: when ophthalmoplegia or encephalopathy is present — rules out brainstem stroke, Wernicke's, Bickerstaff (may show brainstem hyperintensity).

Specialized testing when indicated:

Brighton Collaboration criteria: standardized diagnostic certainty levels — used in research/vaccine safety; not required clinically.

Risk Stratification and First-Line Management Logic

1. Airway and respiratory monitoring — FVC, NIF, single-breath count

2. Cardiac/autonomic monitoring — continuous telemetry

3. VTE prophylaxis — LMWH or UFH from admission; immobility risk is high

4. DVT prevention with sequential compression devices

5. Initiate disease-modifying therapy (IVIG or plasmapheresis)

6. Pain control (gabapentin, carbamazepine; acetaminophen; opioids if severe)

7. Bowel/bladder management, skin care, nutrition, PT/OT consultation

— Erasmus GBS Outcome Score (EGOS) and modified EGOS (mEGOS): predict 6-month walking ability based on age, preceding diarrhea, and MRC sum score

— Erasmus GBS Respiratory Insufficiency Score (EGRIS): predicts mechanical ventilation need within 1 week using days from onset to admission, facial/bulbar weakness, and MRC sum score

— Inability to walk unaided (≥grade 3 on GBS disability scale) within 4 weeks of symptom onset

— Rapidly progressive weakness even in ambulatory patients

— Bulbar or respiratory involvement

— Significant autonomic dysfunction

— Equally effective; combination offers no added benefit

— IVIG preferred for ease of administration, fewer hemodynamic effects, availability

— Plasmapheresis preferred when IVIG contraindicated (IgA deficiency with anti-IgA antibodies, hypercoagulability, severe renal disease) or unavailable

— Best benefit when started within 2 weeks of symptom onset (IVIG) or 4 weeks (plasmapheresis)

Step 3 management: A patient who can still walk but has progressing weakness over 48 hours should receive early IVIG; waiting until they cannot walk worsens outcomes. Board pearl: Steroids are wrong in GBS — high-yield distractor.

Initial management priorities (in order):

Prognostic scores:

Indications for disease-modifying therapy:

Choice between IVIG and plasmapheresis:

Corticosteroids are NOT indicated — multiple RCTs show no benefit and possible harm.

Pharmacotherapy — IVIG and Adjunctive Medications

— Dose: 2 g/kg total, divided over 5 days (0.4 g/kg/day) — standard regimen

— Mechanism: neutralizes pathogenic antibodies, blocks Fc receptors, modulates complement

— Pre-infusion checks: IgA level (anaphylaxis risk in IgA-deficient patients with anti-IgA antibodies), renal function, hydration status, baseline CBC

— Adverse effects:

— Headache, fever, myalgia (most common; slow infusion rate)

— Aseptic meningitis (1–10%)

— Acute kidney injury — osmotic nephrosis from sucrose-containing products; use sucrose-free formulations in CKD

— Thromboembolism (MI, stroke, DVT) — especially in elderly, hypercoagulable, dehydrated; ensure hydration, consider risk

— Hemolysis — particularly in non-O blood types

— Volume overload in CHF — slow rate, monitor weights

— Re-treatment: consider second dose of IVIG (2 g/kg) for treatment-related fluctuations (deterioration after initial improvement) within 8 weeks

— 5 sessions of 1–1.5 plasma volumes over 1–2 weeks

— Requires central venous access (large-bore)

— Adverse effects: hypotension, hypocalcemia (citrate), bleeding, line infection, hemodynamic shifts

— Avoid in sepsis, hemodynamic instability, severe coagulopathy

— Neuropathic pain: gabapentin (start 300 mg TID, titrate) or carbamazepine; tricyclics second-line

— Acute pain: acetaminophen, short courses of opioids

— VTE prophylaxis: enoxaparin 40 mg SC daily (or 30 mg BID) plus mechanical prophylaxis

— Stool softeners, bowel regimen for ileus and immobility

— Avoid drugs worsening autonomic instability: β-blockers can precipitate hypotension; atropine for bradycardia events

Key distinction: Corticosteroids and oral IVIG-like agents have no role — choosing them on a vignette is incorrect. Board pearl: Always check IgA before IVIG; anaphylaxis in IgA-deficient patient is the classic adverse event question.

IVIG (intravenous immunoglobulin):

Plasmapheresis (therapeutic plasma exchange):

Supportive pharmacotherapy:

Plasmapheresis Logistics, Refractory Disease, and Emerging Therapy

— Volume: 200–250 mL/kg total exchange across 5 sessions, every other day typically

— Replacement fluid: 5% albumin (preferred) or FFP (if bleeding risk)

— Vascular access: double-lumen central catheter (femoral or IJ); peripheral access rarely adequate

— Anticoagulation: citrate-based; monitor ionized calcium

— Monitoring during session: BP, HR, ionized calcium, signs of bleeding, mental status

— IVIG and PLEX are equivalent in disability outcomes at 4 weeks

— IVIG more convenient, fewer access complications

— PLEX may be preferable in fluid-overloaded, post-MI, or hypercoagulable patients

— ~10% of patients deteriorate after initial improvement within 8 weeks

— Repeat IVIG 2 g/kg is standard practice; if patient was on PLEX, switching to IVIG (or repeating PLEX) reasonable

— TRF distinct from acute-onset CIDP (deterioration >8 weeks or >3 episodes)

— No proven second-line agent; eculizumab and other complement inhibitors under investigation

— SID-GBS trial: second IVIG dose did not improve outcomes in poor prognosis patients — guideline now suggests against routine second course solely for severity

— Mechanical ventilation strategies — lung-protective, early tracheostomy at 2 weeks if extubation unlikely

— Enteral nutrition via NG/PEG to prevent catabolism

— DVT prophylaxis throughout — paralysis duration often 4–8 weeks

— Aggressive PT/OT to prevent contractures, pressure injuries

— Pain management often requires multimodal regimens including gabapentinoids and opioids

CCS pearl: On a CCS case, after starting IVIG, advance the clock and re-check FVC/NIF every 4–6 hours; do not skip days as deterioration can occur even after treatment initiation. Step 3 management: A patient deteriorating 4 weeks out should prompt re-evaluation for acute-onset CIDP rather than reflexively redosing immunotherapy.

Plasma exchange protocol:

Comparative considerations:

Treatment-related fluctuations (TRF):

Refractory or severe disease:

Supportive ICU management:

Special Populations — Elderly and Renal/Hepatic Impairment

— Worse prognosis — older age is independent predictor of poor walking recovery at 6 months (component of EGOS)

— Higher risk of autonomic complications, arrhythmias, MI, stroke during illness

— IVIG thromboembolic risk elevated — ensure euvolemia, monitor for chest pain/neurologic changes, consider prophylactic anticoagulation balance

— Higher aspiration risk with bulbar involvement — lower threshold for early intubation and PEG

— Polypharmacy review — discontinue contributing agents (e.g., recent fluoroquinolones, statins exacerbating weakness)

— Functional decline: anticipate prolonged rehabilitation, SNF or acute rehab placement on discharge

— IVIG and AKI: osmotic nephrosis from sucrose-stabilized IVIG products — use sucrose-free formulations (most modern products) and ensure hydration

— Pre-existing CKD — slow infusion rate (≤0.08 mL/kg/min), monitor creatinine daily

— Dialysis patients: IVIG can be given; coordinate timing around HD sessions; PLEX is alternative

— Adjust gabapentin for CrCl (300 mg daily if CrCl 30–59, lower if worse) to avoid sedation

— No specific IVIG dose adjustment

— Carbamazepine for neuropathic pain — avoid; hepatotoxicity, drug interactions

— Monitor LFTs during IVIG (transient transaminitis possible)

— IVIG volume load can precipitate decompensated HF — split dosing, slow infusion, diuretic coverage

— Autonomic arrhythmias in GBS more dangerous with structural heart disease — low threshold for ICU

— Preexisting neuropathy can mask early GBS; key feature is reflex loss disproportionate to chronic neuropathy and acute progression

— Sucrose-containing IVIG can cause hyperglycemia; monitor closely

Step 3 management: In an 80-year-old with CKD stage 3 and new GBS, choose PLEX or sucrose-free IVIG with slow rate and hydration, monitor creatinine and troponin, and admit to a monitored bed regardless of initial walking ability. Board pearl: Age >60, preceding diarrhea, and rapid progression predict need for ventilation.

Elderly patients:

Renal impairment:

Hepatic impairment:

Cardiac disease:

Diabetes:

Special Populations — Pregnancy and Pediatrics

— GBS incidence not increased in pregnancy but postpartum risk is elevated (first 2 weeks)

— IVIG is safe and preferred in pregnancy — no fetal toxicity; PLEX also safe but logistically harder

— Avoid corticosteroids (not indicated for GBS anyway)

— Respiratory monitoring critical — pregnancy decreases FRC, accelerates desaturation

— VTE prophylaxis essential — pregnancy + GBS is high-risk; use LMWH, mechanical compression

— Delivery planning: vaginal delivery feasible if respiratory and bulbar function adequate; assisted second stage often needed due to weak Valsalva; epidural anesthesia generally safe; avoid succinylcholine (risk of hyperkalemia in denervated muscle after ~72 hours)

— Coordinate MFM, neurology, anesthesia, neonatology

— Annual incidence ~0.5–1.5 per 100,000 in <18 years

— Pain is prominent — may present with refusal to walk, irritability, "growing pains," or be mistaken for hip pathology, meningitis, viral myositis

— Reflex examination crucial — areflexia distinguishes from transient synovitis

— Treatment: IVIG 2 g/kg over 2–5 days; PLEX also effective but technically harder in small children

— Generally better prognosis than adults — >90% full recovery

— Differentials weighted to pediatric mimics: acute flaccid myelitis (enterovirus D68), transverse myelitis, tick paralysis, botulism (infantile), poliomyelitis

— Historical association with 1976 swine flu vaccine (~1 excess case per 100,000)

— Modern influenza vaccines: small risk (~1–2 per million)

— Prior GBS within 6 weeks of vaccination is a precaution for that vaccine in future seasons — discuss risk/benefit

— COVID-19 vaccines: no causal link for mRNA; small signal with Ad26.COV2.S (no longer routinely used)

Board pearl: A child refusing to bear weight after a viral illness with absent DTRs is GBS until proven otherwise — order LP and admit. Key distinction: Postpartum GBS peaks in first 2 weeks — counsel patients with significant motor symptoms during this window.

Pregnancy:

Pediatric GBS:

Post-vaccination considerations:

Complications and Adverse Outcomes

— Most feared acute complication; leading cause of death

— Driven by diaphragmatic weakness, intercostal weakness, bulbar weakness causing aspiration

— Predictors: rapid onset (<7 days to admission), bulbar/facial weakness, autonomic dysfunction, severe limb weakness (MRC sum score <40)

— Mechanical ventilation often 3–6 weeks; consider tracheostomy at 2 weeks

— Cardiac arrhythmias: sinus tachycardia, bradyarrhythmias, AV block, asystole (especially with suctioning, Valsalva)

— BP lability — alternating hypertension and hypotension

— Paralytic ileus, gastroparesis, urinary retention

— SIADH in subset of patients

— Immobility-related DVT and PE — leading cause of late mortality

— Prophylaxis throughout illness and rehabilitation

— Neuropathic pain in 2/3 — persists in 1/3 long-term

— Back pain, radicular pain, dysesthesias

— 20% have residual disability at 1 year

— 5–10% mortality even with optimal care

— Fatigue in 60–80% — major persistent disability

— Persistent weakness, paresthesias, depression, anxiety, PTSD

— IVIG: aseptic meningitis, AKI, thrombosis, hemolysis, anaphylaxis

— PLEX: hypotension, hypocalcemia, line complications, bleeding

Step 3 management: Patient on day 4 of GBS develops sudden bradycardia during tracheal suctioning — stop suctioning, administer atropine 0.5 mg IV, continue monitoring; consider preprocedural atropine for known autonomic instability. Board pearl: Fatigue is the most common persistent complaint at 1 year.

Respiratory failure (20–30%):

Autonomic dysfunction (>60%):

Venous thromboembolism:

Aspiration pneumonia, ventilator-associated pneumonia, UTI, line infections, pressure injuries, contractures, corneal abrasions (from facial weakness with incomplete eye closure)

Pain syndromes:

Long-term sequelae:

Treatment-related complications:

Recurrent GBS: 2–5% lifetime risk

Acute-onset CIDP: initial GBS-like presentation that continues to progress beyond 8 weeks or relapses >3 times — switch to chronic immunotherapy

When to Escalate Care — ICU and Consults

— FVC <20 mL/kg, NIF less negative than −30, MEP <40 ("20/30/40 rule")

— Rapid progression (<7 days from onset to admission)

— Bulbar dysfunction with aspiration risk — pooled secretions, weak cough

— Autonomic instability — arrhythmias, BP lability, ileus with hemodynamic effects

— Inability to lift head off bed — strong predictor of respiratory failure

— Single-breath count <20

— Clinical respiratory distress, hypoxemia, hypercapnia

— FVC trending down rapidly, even if absolute value not yet at threshold

— Aspiration with inability to protect airway

— Anticipated PLEX/IVIG response delay in deteriorating patient

— Elective intubation preferred over emergent — controlled setting, lower complication rate

— Avoid succinylcholine after ~72 hours of weakness (hyperkalemia from denervated muscle); use rocuronium

— Anticipated ventilation >2 weeks

— Failed extubation attempts

— Neurology — diagnosis, treatment, EMG/NCS coordination

— Pulmonary/critical care — respiratory monitoring, ventilator management

— Physical medicine and rehabilitation (early) — prevent contractures, plan rehab

— PT, OT, speech therapy — early mobilization, swallow evaluation, communication aids

— Nutrition — enteral feeding plan, prevent catabolism

— Psychiatry/psychology — patients are awake, locked-in, terrified during paralysis; ICU delirium and PTSD common

— Social work, case management — discharge planning to acute rehab or LTAC

— All suspected GBS patients admit to monitored bed minimum; never discharge for outpatient workup

— Even ambulatory patients with mild symptoms warrant 24–48h observation given rapid progression risk

CCS pearl: On a CCS GBS case, always order ICU transfer when FVC drops to 20 mL/kg or single-breath count <20, even before respiratory distress is overt. Step 3 management: Communication board, alphabet board, or eye-blink communication for ventilated GBS patients — they are cognitively intact.

Indications for ICU admission:

Indications for intubation:

Indications for tracheostomy:

Consults to obtain:

Inpatient vs outpatient:

Key Differentials — Same-Category (Neuromuscular) Causes

— Fluctuating, fatigable weakness with ocular/bulbar predominance

— Reflexes preserved (vs absent in GBS)

— Anti-AChR or anti-MuSK antibodies; positive edrophonium/ice pack test

— Treatment: pyridostigmine, immunosuppression, IVIG/PLEX for crisis

— Proximal weakness, post-exercise facilitation (reflexes increase with activity)

— Autonomic features (dry mouth, impotence)

— Anti-VGCC antibodies; paraneoplastic (small cell lung cancer)

— Descending paralysis, prominent bulbar involvement first (diplopia, dysphagia, dysarthria)

— Mydriasis, dry mouth, ileus (anticholinergic-like)

— Reflexes preserved early

— Source: home-canned foods, infant honey, wound botulism (IV drug use)

— Treatment: equine antitoxin (adults), BabyBIG (infants); supportive care

— Ascending paralysis mimicking GBS; normal CSF

— Resolves with tick removal — examine scalp, axilla, groin meticulously

— Pediatric predominance

— Children, asymmetric flaccid weakness, enterovirus D68 association

— MRI shows gray matter cord lesions; CSF pleocytosis

— Asymmetric weakness, fever, meningismus, CSF pleocytosis

— Develops in ICU patients with sepsis/multiorgan failure; weaning failure

— Abdominal pain + neuropathy + psychiatric/autonomic symptoms

— Elevated urine porphobilinogen

— Treatment: hemin, glucose, avoid triggers

Key distinction: Botulism is descending with reflexes preserved and autonomic anticholinergic signs; GBS is ascending with areflexia and mixed autonomic signs. Board pearl: Mydriasis in a paralyzed patient → botulism; preserved reflexes with fatigability → myasthenia.

Myasthenia gravis (MG):

Lambert-Eaton myasthenic syndrome (LEMS):

Botulism:

Tick paralysis:

Acute flaccid myelitis (AFM):

Poliomyelitis / non-polio enterovirus:

Critical illness polyneuropathy/myopathy:

Acute intermittent porphyria:

Toxic neuropathies: lead, arsenic, thallium, organophosphates (cholinergic crisis), n-hexane

Key Differentials — Other-Category Causes

— Transverse myelitis: sensory level, bowel/bladder dysfunction early, hyperreflexia after spinal shock resolves, MRI shows cord T2 hyperintensity

— Acute cord compression (epidural abscess, hematoma, metastasis): sensory level, focal back pain, MRI diagnostic — always rule out before LP if features suggest myelopathy

— Anterior spinal artery infarct: abrupt onset, dissociated sensory loss (preserved vibration/proprioception)

— Sudden onset, cranial nerve findings, often unilateral, decreased consciousness possible

— MRI brain with DWI

— Severe hypokalemia (<2.5) — flaccid weakness, areflexia possible; ECG U waves

— Hypophosphatemia, hypermagnesemia — refeeding syndrome, antacid abuse

— Hypoglycemia, thyrotoxic periodic paralysis

— West Nile virus neuroinvasive disease: acute flaccid paralysis, often asymmetric, CSF pleocytosis with elevated protein

— Lyme polyradiculitis (Bannwarth syndrome): facial palsy, radiculopathy, CSF pleocytosis

— HIV seroconversion-related GBS-like syndrome (CSF pleocytosis present)

— Diphtheritic polyneuropathy — palatal paralysis after pharyngitis

— Rabies: ascending paralysis variant

— Organophosphate poisoning: SLUDGE/cholinergic crisis, fasciculations

— Heavy metals (chronic)

— Snake envenomation (elapid neurotoxin)

— Inconsistent exam, give-way weakness, preserved reflexes — diagnosis of exclusion after appropriate workup

— CIDP: progression >8 weeks, relapsing course; requires chronic immunotherapy

— MMN (multifocal motor neuropathy): chronic, asymmetric, conduction block

Step 3 management: A patient with ascending weakness, sensory level at T8, and bladder retention needs emergent MRI of the spine to exclude cord compression before any other workup. Board pearl: CSF pleocytosis >50 cells in suspected GBS → look for HIV, Lyme, West Nile, or leptomeningeal disease.

Spinal cord pathology:

Brainstem stroke:

Electrolyte/metabolic disturbances:

Infectious mimics:

Toxic exposures:

Functional/conversion disorder:

Conversion to chronic disease:

Secondary Prevention and Discharge Planning

— No maintenance immunotherapy after acute GBS — single course of IVIG or PLEX suffices for most

— Recurrence risk 2–5% — counsel patients to seek evaluation immediately if symptoms recur

— Acute-onset CIDP: if relapsing or progressing beyond 8 weeks, transition to CIDP regimen (chronic IVIG, steroids, or other immunosuppression)

— History of GBS within 6 weeks of vaccination is a precaution for that specific vaccine; document carefully

— Otherwise, routine vaccinations (including influenza) are generally encouraged after recovery — risk of GBS from natural influenza exceeds vaccine-attributed risk

— Avoid live vaccines for 3 months after IVIG (impaired immune response, including MMR, varicella)

— Neuropathic pain: gabapentin or pregabalin, titrate as needed; reassess at follow-up

— DVT prophylaxis: continue enoxaparin until ambulation regained (typically through rehab stay)

— Bowel regimen, bladder management as needed

— Antidepressants/anxiolytics if mood disorder identified

— Reconcile home medications: resume statins, antihypertensives cautiously given autonomic recovery

— Acute inpatient rehabilitation — most non-ambulatory patients benefit from 2–6 weeks of intensive PT/OT

— Equipment needs: walker, wheelchair, AFO braces, shower chair, home modifications

— Speech therapy for residual dysarthria/dysphagia

— Recovery timeline: improvement begins within 2–4 weeks of nadir; 80% walk independently by 6 months; full recovery may take 1–2 years

— Fatigue is common and underrecognized — affects 60–80% long-term

— Support groups (GBS/CIDP Foundation International)

— Defer driving until adequate strength, reflexes, reaction time confirmed

— Occupational health clearance before return to work

Step 3 management: A patient asking about future flu vaccination — if GBS was not within 6 weeks of vaccination, vaccinate per usual schedule; document shared decision-making. Board pearl: Hold live vaccines 3 months after IVIG.

Disease-modifying long-term:

Vaccination counseling:

Discharge medication review:

Functional preparation:

Patient/family counseling:

Driving and work return:

Follow-Up, Monitoring Parameters, and Rehabilitation

— Respiratory mechanics (FVC, NIF) every 4–6 hours during progression

— Continuous cardiac telemetry until autonomic stability for 48–72 hours

— Daily neurologic exam — MRC sum score, cranial nerves, reflexes

— Daily CBC, BMP during IVIG/PLEX

— DVT surveillance — lower extremity exam, consider screening Doppler if symptoms

— Skin checks for pressure injuries

— Neurology at 4–6 weeks post-discharge, then 3 and 6 months, then annually

— Primary care at 2 weeks post-discharge — medication reconciliation, mood screening, return-to-function planning

— PM&R / rehab weekly during initial outpatient rehab phase

— Repeat EMG/NCS at 3–6 months if recovery atypical or considering CIDP diagnosis

— Early mobilization during admission — passive ROM, positioning, splinting to prevent contractures

— Progressive strengthening during recovery — avoid overexertion (paradoxical weakness in fatigued reinnervating muscle)

— Gait training, balance, proprioception

— Occupational therapy — ADLs, fine motor recovery, adaptive equipment

— Pulmonary rehab if prolonged ventilation

— Cognitive-behavioral therapy for ICU-related PTSD, fatigue management

— Monitor for CIDP conversion — progressive or relapsing weakness beyond 8 weeks

— Screen for depression, anxiety, fatigue, chronic pain at each visit

— Reassess driving capacity, return-to-work status

— Bone health if prolonged immobility (consider DEXA, vitamin D)

— Report new weakness, sensory changes, autonomic symptoms promptly

— Recognize and manage fatigue (pacing, energy conservation)

— Avoid triggers for fatigue exacerbation (infections, heat)

CCS pearl: Schedule the neurology follow-up at 4–6 weeks post-discharge on a CCS case — it's a frequently missed order. Board pearl: Persistent fatigue at 1 year is not equivalent to recurrence — screen for depression and deconditioning before reinitiating immunotherapy.

Inpatient monitoring during acute phase:

Post-discharge follow-up:

Rehabilitation focus:

Long-term surveillance:

Patient education and self-monitoring:

Ethical, Legal, and Patient Safety Considerations

— Document goals of care discussions early — patients with progressing weakness may lose ability to communicate before intubation decision

— Discuss mechanical ventilation, tracheostomy, PEG, prolonged ICU course, potential for full recovery while patient can participate

— Identify healthcare proxy / surrogate decision-maker on admission

— Advance directives review

— GBS patients on ventilators are cognitively intact but paralyzed — provide communication aids (eye-gaze boards, blink codes, letter boards) from day one

— Address pain, anxiety, sleep — undertreatment is a major safety issue

— Orient frequently, explain procedures, never speak as if patient is absent

— Failure to monitor respiratory mechanics is a leading sentinel event

— Delayed intubation with emergent reintubation has higher complication rate than elective

— Succinylcholine in denervated patients → fatal hyperkalemia (after ~72 hours of paralysis) — use rocuronium; document allergy/alert

— DVT/PE from missed prophylaxis — verify on every transfer of care

— Pressure injuries, corneal abrasions, contractures — preventable with diligent nursing care, eye lubrication, splinting

— Handoff communication at every level (ED→floor→ICU→rehab) must include respiratory parameters, autonomic instability, anticoagulation status, treatment day, allergies (especially IgA status)

— Discharge summary to rehab facility must specify mobilization restrictions, swallow precautions, medication doses, follow-up appointments

— Suspected botulism (a key differential) is reportable to public health within 24 hours

— Polio is also reportable

— Vaccine-attributed adverse events reportable via VAERS

— IVIG cost is significant; prior authorization typically needed; document failure of/contraindications to alternatives carefully

— Plan for acute rehab placement coverage early in admission

Step 3 management: A patient signing out to night float — explicitly communicate last FVC, trend, time of next check, autonomic status, and intubation threshold. Board pearl: Document the succinylcholine contraindication prominently — this is a tested patient safety scenario.

Informed consent in evolving paralysis:

Locked-in patients:

Patient safety risks:

Transitions of care:

Mandatory reporting and public health:

Insurance and access:

High-Yield Associations and Rapid-Fire Clinical Facts

Board pearl: Three "wrong answers" on GBS vignettes: steroids, succinylcholine, observation without monitoring. Key distinction: Tick paralysis = remove the tick, no immunotherapy needed; always check the scalp.

Most common antecedent infection: Campylobacter jejuni (post-diarrheal, AMAN variant, anti-GM1)

Most common GBS variant in US/Europe: AIDP (demyelinating)

Most common GBS variant in Asia/Latin America: AMAN (axonal, post-Campylobacter)

Miller Fisher triad: ophthalmoplegia + ataxia + areflexia; anti-GQ1b antibodies

Bickerstaff brainstem encephalitis: Miller Fisher features + encephalopathy + hyperreflexia

Pharyngeal-cervical-brachial variant: anti-GT1a; mimics botulism

CSF hallmark: albuminocytologic dissociation (high protein, normal WBC) — present by week 2

Earliest electrodiagnostic finding (AIDP): prolonged or absent F-waves

Treatment: IVIG 2 g/kg over 5 days OR PLEX 5 sessions — no combination, no steroids

Best window for treatment: within 2 weeks (IVIG) or 4 weeks (PLEX) of symptom onset

Pre-IVIG check: IgA level (anaphylaxis risk in IgA deficiency)

Major IVIG complications: AKI, aseptic meningitis, thrombosis, hemolysis

Respiratory failure rate: 20–30%; mechanical ventilation often 3–6 weeks

"20/30/40 rule" for intubation: FVC <20 mL/kg, NIF less negative than −30, MEP <40

Avoid in GBS: succinylcholine (after 72h), corticosteroids

Autonomic instability features: sinus tachycardia, BP lability, arrhythmias, ileus, urinary retention

Recurrence: 2–5% lifetime

Mortality: 3–10% with optimal care; aspiration, PE, arrhythmia leading causes

Long-term outcomes: 80% walk independently at 6 months; 20% with residual disability at 1 year

Persistent fatigue: 60–80%

Vaccine-related: small influenza vaccine signal; 1976 swine flu strongest historical association

CIDP threshold: progression >8 weeks → reclassify

EGRIS score predicts ventilation; mEGOS predicts walking

Childhood GBS: prominent pain, refusal to walk; better prognosis than adults

Pregnancy: IVIG preferred; postpartum risk peak first 2 weeks

Board Question Stem Patterns

— Answer: Admit, monitor respiratory mechanics, LP, start IVIG. Not: outpatient MRI, steroids, observation.

— Answer: Elective intubation. Avoid succinylcholine.

— Answer: Atropine, stop suctioning, anticipate autonomic dysreflexia, pretreat for future suctioning.

— Answer: Plasmapheresis (anaphylaxis risk with IVIG in anti-IgA antibody carriers).

— Answer: Repeat IVIG 2 g/kg for treatment-related fluctuation; if progression continues >8 weeks, reclassify as acute-onset CIDP.

— Answer: Emergent MRI spine to rule out cord compression — not LP first.

— Answer: Infant botulism, BabyBIG (human botulism immune globulin IV).

— Answer: Pediatric GBS — admit, monitor, IVIG.

— Answer: IVIG-induced aseptic meningitis — supportive care, slow rate.

— Answer: GBS workup and IVIG (peak postpartum window).

— Answer: If GBS was not within 6 weeks of a prior influenza vaccine, vaccination recommended; shared decision-making documented.

— Answer: Rocuronium, not succinylcholine.

Step 3 management: The recurring theme on Step 3 GBS questions is early respiratory monitoring, correct disease-modifying choice, avoidance of steroids/succinylcholine, and proactive autonomic anticipation. Board pearl: When the stem mentions "preceded by gastroenteritis with bloody stools" — think Campylobacter and AMAN.

Classic stem 1: A 35-year-old man presents with 4 days of progressive symmetric leg weakness 2 weeks after diarrheal illness. Reflexes absent. Next best step?

Stem 2: GBS patient with FVC declining from 35 to 18 mL/kg over 8 hours. Next step?

Stem 3: Patient with GBS develops bradycardia and asystole during tracheal suctioning. Management?

Stem 4: GBS patient with IgA deficiency. Best disease-modifying therapy?

Stem 5: Patient improves with IVIG, then deteriorates 3 weeks later. Next step?

Stem 6: Ascending weakness, T8 sensory level, urinary retention. Next step?

Stem 7: Descending weakness, mydriasis, dysphagia in toddler with honey exposure. Diagnosis and treatment?

Stem 8: Child refusing to walk after viral URI, absent DTRs. Diagnosis and management?

Stem 9: GBS patient receiving IVIG develops acute confusion, neck stiffness, headache. Diagnosis?

Stem 10: Postpartum patient at 1 week with ascending weakness, areflexia. Next step?

Stem 11: Patient with prior GBS asks about flu shot. Counsel?

Stem 12: GBS patient needs intubation — RSI agent?

One-Line Recap

Guillain-Barré syndrome is an acute, immune-mediated, ascending flaccid paralysis with areflexia, diagnosed clinically and supported by albuminocytologic dissociation, treated with IVIG or plasmapheresis (never steroids), and managed with vigilant respiratory and autonomic monitoring because the patient's life depends on anticipating — not reacting to — neuromuscular respiratory failure.

Board pearl: The three lethal mistakes on Step 3 GBS questions are (1) discharging an ambulatory patient, (2) giving corticosteroids, and (3) using succinylcholine for intubation. The three lifesaving moves are (1) serial respiratory mechanics, (2) early IVIG or PLEX, and (3) elective intubation with rocuronium plus DVT prophylaxis. Step 3 management: Always order communication aids for paralyzed but cognitively intact patients — neglecting this is a tested patient safety failure.

Diagnosis: Symmetric ascending weakness + areflexia + post-infectious context + CSF protein elevation with normal cells. Treat empirically; do not wait for antibodies or NCS.

Treatment: IVIG 2 g/kg over 5 days OR plasmapheresis 5 sessions. Steroids are wrong. Check IgA before IVIG. Avoid succinylcholine after 72 hours of paralysis.

Monitor: FVC, NIF, single-breath count every 4–6 hours; continuous telemetry; intubate electively at the 20/30/40 threshold before respiratory distress is overt. Anticipate autonomic instability — pretreat suctioning, avoid aggressive antihypertensives.

Disposition: All suspected GBS goes inpatient on monitored bed minimum; ICU for rapid progression, bulbar involvement, or borderline respiratory mechanics. Acute rehab post-acute care; neurology follow-up at 4–6 weeks; vaccinate cautiously thereafter.