Study guide
24.2 Guillain-Barré Syndrome (03.O.1)
ABIM Neurocritical Care Subspecialty Certification Exam
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1 Introduction & Exam Overview
1.1 Current Exam Facts 1.2 Eligibility, Practice Pathway, and the IM Training Route 1.3 Format, Scoring, Pearson VUE, and Score Reports 1.4 How to Use This Independent Study Guide
2 ICU Neurologic Exam, Cerebral Physiology, and CSF
2.1 Neurological Examination in the ICU 2.2 Cerebral Physiology, ICP, CBF, and Autoregulation 2.3 CSF Physiology
3 Core Neuropharmacology
3.1 Osmotic Agents 3.2 Anti-Seizure Drugs 3.3 Anesthetics, Sedatives, Analgesia, and Paralytics 3.4 Antihypertensives, Vasopressors, and Inotropes
4 Reperfusion Drugs, Airway, and Ventilation
4.1 Thrombolytics, Anticoagulants, and Antiplatelets 4.2 Reversal of Anticoagulation After Acute Hemorrhage 4.3 Airway Management and Tracheostomy 4.4 Mechanical Ventilation
5 Hemodynamics and Shock
5.1 Hemodynamic Monitoring 5.2 IABP, Temporary VADs, LVAD, and ECMO 5.3 Diagnosis and Management of Shock
6 Nutrition, Temperature, and ICU Prophylaxis
6.1 Nutrition (01.J) 6.2 Temperature Control (01.K) 6.3 ICU Prophylaxis, Delirium, and Early Mobility (01.L)
7 General Trauma
7.1 Emergency Evaluation of Polytrauma, Chest, and Abdominal Trauma 7.2 Long-Bone Fractures and Fat Embolism 7.3 Burns, Electrical Injury, and Hanging/Strangulation
8 Pulmonary Critical Care
8.1 Pulmonary Physiology and ARDS (01.N.1–2) 8.2 PE, Pneumonia, and Pulmonary Edema (01.N.3, 7–8) 8.3 COPD, Asthma, PAH, and Bronchoscopy Basics (01.N.4–6, 9)
9 Cardiovascular Critical Care
9.1 Cardiovascular Physiology, Stress Cardiomyopathy, ACS, and Valves 9.2 Arrhythmias and Pacing 9.3 Acute Aortic Dissection and Cardiac Ultrasound
10 Renal and Infectious Disease
10.1 AKI, RRT, and Renal Drug Dosing 10.2 Acid-Base and Electrolyte Disorders 10.3 Severe Sepsis, Septic Shock, and Infective Endocarditis 10.4 Antimicrobial Use and Infection in the Immunosuppressed
11 Endocrine and Salt-Water Disorders
11.1 Pituitary Apoplexy, DI, and Panhypopituitarism (01.R.1–4) 11.2 SIADH and Cerebral Salt Wasting (01.R.5–6) 11.3 Thyrotoxicosis, Myxedema, Adrenal Crisis, and Dysglycemia (01.R.7–9)
12 Gastrointestinal Critical Care
12.1 GI Physiology, Acute Abdomen, Bleed, Ileus, and Perforation (01.S.1–5) 12.2 Mesenteric Ischemia and Abdominal Compartment Syndrome (01.S.6–7) 12.3 Fulminant Liver Failure, Cirrhosis Decompensation, and Hepatic Dosing (01.S.8–10)
13 Hematologic Disorders
13.1 Anemia, Transfusion, Thrombocytopenia, Coagulopathy, and DIC (01.T.1–4) 13.2 VTE in the Neuro ICU (01.T.5) 13.3 Chemo/Immune, SCT, CAR-T, Sickle Cell, and TMA (01.T.6–10)
14 Neuroimaging
14.1 CT of Brain and Spine 14.2 MRI and CT/MR Perfusion 14.3 Noninvasive Angiography and Catheter Angiography
15 EEG, EMG, and CSF Analysis
15.1 EEG, Standard and Processed (02.B) 15.2 Basic EMG Interpretation (02.G) 15.3 CSF Analysis (02.H)
16 ICP, TCD, and Multimodality Monitoring
16.1 ICP Monitoring (02.C) 16.2 Transcranial Doppler (02.D) 16.3 Brain-Tissue Oxygen and Multimodality Monitoring (02.E–F)
17 Brain Death and Bedside Procedures
17.1 Brain Death Prerequisites and Clinical Exam (02.I) 17.2 Apnea Testing and Ancillary Studies (02.I) 17.3 Vascular Access, Thoracic Echo, and Lung Ultrasound (02.J–L)
18 Coma, Anoxia, and Intracranial Hypertension
18.1 Coma and Other States of Altered Consciousness (03.A) 18.2 Global Anoxia-Ischemia and Post-Resuscitation Encephalopathy (03.A.1) 18.3 Toxidromes, ICU Delirium, and Hypertensive Encephalopathy (03.A.2–4) 18.4 Intracranial Hypertension as a Disease State (03.B)
19 Acute Ischemic Stroke
19.1 IV Reperfusion Therapy (03.C.3) 19.2 Mechanical Thrombectomy Windows and Imaging Selection (03.C.3) 19.3 Malignant Hemispheric Infarction and Basilar Artery Occlusion (03.C.1–2)
20 Intraparenchymal Hemorrhage
20.1 Intracerebral Hematoma (03.D.1) 20.2 Cerebellar Hematoma (03.D.2) 20.3 Intraventricular Hemorrhage (03.D.3)
21 SAH, CVST, and Spinal Cord Infarction
21.1 Aneurysmal Subarachnoid Hemorrhage (03.E.1) 21.2 Non-Aneurysmal SAH (03.E.2) 21.3 Cerebral Venous Sinus Thrombosis (03.F) 21.4 Spinal Cord Infarction (03.G)
22 Vascular Anomalies and Traumatic Brain Injury
22.1 Unruptured Aneurysm, Cavernoma, AVM, and Dural AVF (03.H) 22.2 Diffuse Axonal Injury and Cerebral Contusions (03.I.1–2) 22.3 Epidural Hematoma, Subdural Hematoma, and Penetrating Injury (03.I.3–4, 7) 22.4 Arterial Dissection and Carotid-Cavernous Fistula (03.I.5–6)
23 Spine, Hydrocephalus, and CNS Infection
23.1 Spinal Cord Injury, Central Cord, and Neurogenic Shock (03.J) 23.2 Unstable Spine Fractures (03.K) 23.3 Hydrocephalus and CSF Diversion (03.L) 23.4 Acute CNS Infections (03.M)
24 Seizures and Neuromuscular Emergencies
24.1 Status Epilepticus and Seizures (03.N) 24.2 Guillain-Barré Syndrome (03.O.1) 24.3 Myasthenic Crisis (03.O.2) 24.4 Motor Neuron Disease, Acute Myopathies, Rhabdomyolysis, and CINM (03.O.3–6)
25 Inflammatory Disease, Neuro-Oncology, and Special Populations
25.1 Fulminant Demyelinating Diseases (03.P) 25.2 Autoimmune Encephalitis and Acute Autonomic Hyperactivity (03.Q–R) 25.3 Neuro-Oncology and Treatment Complications (03.S) 25.4 Pregnancy/Post-Partum, Post-Transplant, and Pediatric Patients (03.T–U)
26 Neurosurgical and Perioperative Complications
26.1 Postoperative Seizures, Hemorrhage, Ischemia, and Hyperperfusion (04.A, C, D, H) 26.2 Infection, CSF Leak, and Pneumocephalus (04.B, E, F) 26.3 Complications of EVD and Lumbar Drain (04.G, I)
27 Ethics, Prognostication, and Organ Donation
27.1 Communication, Decision-Makers, Advance Directives, and DNR (05.A, B, G) 27.2 Uncertainties of Prognostication and the Self-Fulfilling Prophecy (05.C) 27.3 Palliative Care, Withdrawal, Withholding, and Futility (05.D–F) 27.4 Donation After Cardiac Death and Care of the Organ Donor (05.H–I)
24.2 Guillain-Barré Syndrome (03.O.1)
Key Takeaways Explain This Topic AI
Guillain-Barré syndrome includes AIDP, AMAN, AMSAN, and Miller Fisher syndrome (ophthalmoplegia, ataxia, areflexia, often anti-GQ1b).
Albuminocytologic dissociation—high CSF protein with few white cells—may be absent in the first week and does not exclude Guillain-Barré syndrome.
Disease-modifying treatment is IVIG 0.4 g/kg/day for 5 days or plasma exchange; do not use both routinely, and do not use corticosteroids as primary Guillain-Barré therapy.
The 20/30/40 rule (FVC under 20 mL/kg, NIF weaker than −30 cm H2O, PaCO2 over 40 mm Hg) plus dysautonomia should trigger ICU care and early intubation rather than a crash airway.
Last updated: September 2026
Why Guillain-Barré syndrome is an ICU airway disease
Guillain-Barré syndrome (GBS) is an acute, typically post-infectious immune attack on peripheral nerve myelin, axon, or the nodal apparatus. Patients walk into the emergency department and, days later, cannot protect an airway. The neurocritical care task is pattern recognition across variants, knowing that cerebrospinal fluid (CSF) and nerve conduction studies lag the clinic, choosing intravenous immunoglobulin (IVIG) or plasma exchange (PLEX) rather than steroids, and intubating before hypercapnic arrest.
Clinical pattern
The classic picture is rapidly progressive, relatively symmetric limb weakness, hyporeflexia or areflexia , and often distal paresthesias, peaking by 2 weeks and always by 4 weeks. Pain in the back or limbs is common and does not exclude GBS. A history of diarrhea (often Campylobacter jejuni ), respiratory infection, cytomegalovirus, Mycoplasma , or surgery 1–3 weeks earlier supports the diagnosis. Progression beyond 8 weeks should prompt reconsideration of acute-onset chronic inflammatory demyelinating polyradiculoneuropathy (A-CIDP) , which occurs in about 5% of patients first labeled as GBS.
West Nile virus poliomyelitis, botulism, myasthenic crisis, tick paralysis, spinal cord compression, and periodic paralysis enter the differential. Asymmetric, purely motor weakness with CSF pleocytosis points away from typical GBS and toward infectious myelitis or poliomyelitis-like illness.
Variants you must name
Variant Pathology and geography Bedside signature Antibodies / notes
AIDP (acute inflammatory demyelinating polyradiculoneuropathy) Demyelinating; most common in North America and Europe Ascending weakness, areflexia, albuminocytologic dissociation Nerve conduction: prolonged latencies, conduction block, temporal dispersion
AMAN (acute motor axonal neuropathy) Axonal motor; more common in East Asia and after Campylobacter Pure motor, sometimes preserved reflexes early, rapid nadir Anti-GM1, anti-GD1a
AMSAN (acute motor-sensory axonal neuropathy) Axonal motor and sensory Weakness plus sensory loss, slower recovery than AIDP Related to AMAN biology; worse axonal injury
Miller Fisher syndrome GQ1b-spectrum Ophthalmoplegia, ataxia, areflexia ; limb weakness may be absent Anti-GQ1b; overlaps Bickerstaff brainstem encephalitis when there is hypersomnolence or pyramidal signs
Pharyngeal-cervical-brachial Localized GBS Bulbar, neck, and arm weakness with relatively spared legs Overlaps botulism and myasthenia
Anti-ganglioside antibodies are not required to treat typical AIDP. Anti-GQ1b is useful when Miller Fisher syndrome is the question. Nodal-paranodal antibodies belong to the autoimmune nodopathy discussion, not to routine AIDP.
Albuminocytologic dissociation is often late
Albuminocytologic dissociation means elevated CSF protein with few white blood cells , typically fewer than 10 cells/µL and almost always fewer than 50. Protein is frequently normal in the first week . A normal day-3 lumbar puncture does not exclude GBS. Repeat CSF later if the diagnosis remains uncertain. More than 50 white cells should make you think of Lyme disease, HIV seroconversion, sarcoidosis, leptomeningeal cancer, or West Nile virus rather than textbook GBS.
Nerve conduction studies may also be normal or nonspecific in the first days, especially in very proximal or purely axonal disease. Do not withhold ICU monitoring or immunotherapy while waiting for an EMG slot if the clinical diagnosis is GBS and the patient cannot walk unaided.
Immunotherapy: IVIG or PLEX, not both, not steroids
The European Academy of Neurology / Peripheral Nerve Society 2023 guideline recommends:
IVIG 0.4 g/kg/day for 5 days (total 2 g/kg), started as soon as possible, especially within 2 weeks of weakness if the patient cannot walk unaided.
Plasma exchange , typically 4–5 exchanges totaling about 12–15 L over 1–2 weeks, within 4 weeks of onset if the patient cannot walk unaided.
IVIG and PLEX are considered similarly effective. Choose by access, hemodynamics, infection, thrombosis risk, and renal function. IVIG is logistically easier. PLEX needs adequate venous access and can destabilize a dysautonomic patient.
Do not routinely give IVIG and PLEX together. Sequencing PLEX immediately after IVIG washes out the immunoglobulin. The SID-GBS randomized trial did not support a second IVIG course for poor prognosis, and the 2023 guideline recommends against a routine second IVIG course.
Do not give corticosteroids as primary GBS therapy. Oral steroids do not help and may slow recovery. Intravenous steroids, with or without IVIG, are not recommended. This is the opposite of myasthenic crisis, in which steroids are part of longer-term control after rescue therapy. Mixing those two rules is a frequent examination error.
IVIG risks include aseptic meningitis, thrombosis, anaphylaxis in IgA deficiency, and acute kidney injury with older sucrose-stabilized products. PLEX risks include hypotension, line infection, coagulopathy, and hypocalcemia from citrate.
The 20/30/40 rule and early intubation
Respiratory failure in GBS is diaphragmatic and bulbar, not a primary lung problem. Patients look comfortable until they are not. Measure forced vital capacity (FVC) and negative inspiratory force (NIF) every 4–6 hours while the patient is still declining. A single-breath count under 20 is a crude bedside surrogate.
Neurocritical care examinations commonly test a 20/30/40 respiratory rule:
Threshold Meaning Action
FVC <20 mL/kg Diaphragm and accessory muscles can no longer generate a vital breath ICU; plan a controlled intubation
- NIF weaker than −30 cm H2O A NIF of −20 is worse than −40; the number is closer to zero Same
- PaCO2 >40 mm Hg Alveolar hypoventilation Late sign; do not wait for this if FVC and NIF are already collapsing
Lawn and colleagues originally paired FVC 20 mL/kg and maximal inspiratory pressure 30 cm H2O with maximal expiratory pressure (MEP) <40 cm H2O , not with PaCO2. Both versions circulate. Rising PaCO2 or a falling vital capacity by more than 30% in 24 hours should move the patient to an ICU regardless of which mnemonic you recite. Bulbar palsy, a weak cough, aspiration, or rapidly progressive weakness are intubation indications even when the numbers have not yet crossed 20/30/40.
Intubate early and electively . Crash intubation in a dysautonomic, full-stomach, weak-neck patient is how GBS deaths occur. Avoid succinylcholine (denervation hyperkalemia); rocuronium is the usual neuromuscular blocker. Noninvasive ventilation is a bridge at best and fails when bulbar function is poor.
Dysautonomia
Autonomic involvement can kill a patient whose limbs still move. Expect labile blood pressure, resting tachycardia or sudden bradycardia, ileus, urinary retention, and sudomotor changes. A tracheal suction pass can trigger asystole. Place the patient on continuous telemetry. Treat hypotension with fluids and short-acting vasopressors, hypertension with short-acting agents, and avoid sustained beta blockade that you cannot reverse when the next hypotensive swing arrives. Ileus complicates feeding and electrolyte management.
Supportive care that is not optional
Venous thromboembolism prophylaxis, neuropathic pain control (gabapentinoids, carbamazepine, or tricyclic antidepressants are reasonable), corneal protection if facial weakness is severe, bowel and bladder care, and early physical therapy all matter. The modified Erasmus GBS Respiratory Insufficiency Score (mEGRIS) estimates ventilation risk; the modified Erasmus GBS Outcome Score (mEGOS) estimates recovery. Neither replaces serial FVC.
Examination traps
Ruling out GBS because day-2 CSF protein is normal.
Starting high-dose methylprednisolone because the patient has an inflammatory neuropathy.
Giving IVIG and then PLEX the next morning as a routine stack.
Waiting for PaCO2 of 60 mm Hg before calling the ICU.
Using succinylcholine for intubation.
Missing Miller Fisher syndrome because limb strength is normal.