What is the workup for suspected Guillain-Barré Syndrome (GBS)?

Workup for Suspected Guillain-Barré Syndrome

When GBS is suspected, immediately obtain neurology consultation, perform lumbar puncture for CSF analysis, order nerve conduction studies/EMG, obtain MRI spine with and without contrast, and initiate pulmonary function monitoring—all patients warrant urgent workup given the risk of rapid progression to respiratory failure. 1

Essential Clinical Assessment

Look for these specific features:

• Progressive, typically symmetrical ascending muscle weakness with absent or reduced deep tendon reflexes 1, 2
• Sensory symptoms or neuropathic pain localized to lower back and thighs that often precede weakness 1
• Involvement of facial, respiratory, bulbar, or oculomotor nerves 2
• Signs of autonomic dysfunction including blood pressure fluctuations, arrhythmias, bowel/bladder dysfunction 1, 2
• Recent history of diarrhea or respiratory infection (increases likelihood of GBS) 3

Mandatory Diagnostic Tests

Lumbar Puncture and CSF Analysis

• Perform early to look for albumino-cytological dissociation (elevated protein with normal white cell count) 1, 2
• Send CSF for: cell count and differential, protein, glucose, cytology (especially in cancer patients), viral/bacterial cultures 1
• Critical caveat: Protein may be normal in 30-50% of patients in the first week and 10-30% in the second week—normal CSF protein does NOT rule out GBS 2
• Marked pleocytosis (>50 cells/μL) suggests an alternative diagnosis 2

Electrodiagnostic Studies

• Obtain nerve conduction studies (NCS) and electromyography (EMG) to support diagnosis and differentiate GBS subtypes 1, 2
• Look for: reduced conduction velocities, reduced sensory and motor amplitudes, abnormal temporal dispersion, partial motor conduction blocks 2
• If initial studies are normal or inconclusive, repeat in 2-3 weeks 2

MRI Imaging

• MRI spine with and without contrast to rule out compressive lesions and evaluate for nerve root enhancement/thickening 1, 2
• MRI brain if cranial nerve involvement is present 1, 2
• Ultrasound of peripheral nerves may reveal enlarged cervical nerve roots early in disease 2

Serologic Testing

Antiganglioside antibodies:

• Test for serum antiganglioside antibodies for GBS and its subtypes 1
• Specifically test anti-GQ1b antibodies when Miller Fisher variant is suspected (ataxia and ophthalmoplegia) 1
• Note: Testing has limited clinical value in typical motor-sensory GBS 3

Screen for reversible neuropathy causes:

• HbA1c, vitamin B12, folate, TSH, vitamin B6, HIV 1, 2
• Consider serum protein electrophoresis, immunofixation, CPK 1
• Consider additional autoimmune/vasculitic screen: ANA, ESR, CRP, ANCA, anti-smooth muscle, SSA/SSB 1
• Consider paraneoplastic workup (ANNA-1 antibody) in cancer patients 1

Pulmonary Function Assessment

• Initiate immediately with pulmonary function testing (negative inspiratory force/vital capacity) 1, 2
• Monitor for signs of respiratory distress: breathlessness at rest/talking, inability to count to 15 in single breath, use of accessory muscles 2
• Apply the "20/30/40 rule": patient at risk if vital capacity <20 mL/kg, maximum inspiratory pressure <30 cmH₂O, or maximum expiratory pressure <40 cmH₂O 1, 4
• Calculate Erasmus GBS Respiratory Insufficiency Score (EGRIS) to determine probability of requiring ventilation 4, 3

Grading and Disposition

All grades warrant immediate workup and intervention—there is no Grade 1 GBS 1

Grade 2 (Moderate):

• Some interference with activities of daily living, symptoms concerning to patient 1
• Discontinue immune checkpoint inhibitors if applicable 1
• Obtain neurology consultation 1

Grade 3-4 (Severe):

• Limiting self-care, weakness limiting walking, ANY dysphagia, facial weakness, respiratory muscle weakness, or rapidly progressive symptoms 1
• Admit to inpatient unit with capability for rapid ICU transfer 1
• Frequent neurologic checks and continuous pulmonary function monitoring 1

Important Diagnostic Pitfalls

• Pain can precede weakness by days and may confuse the diagnosis—maintain high suspicion 5
• Consider GBS variants: Miller Fisher syndrome (ataxia, ophthalmoplegia, areflexia), pharyngeal-cervical-brachial, paraparetic variants 2
• Change diagnosis to acute-onset CIDP (A-CIDP) if progression continues beyond 8 weeks from onset (occurs in ~5% of cases) 1, 3
• Treatment-related fluctuations occur in 6-10% within 2 months of initial improvement 4, 5
• Flow cytometry should be sent in patients with hematologic malignancies 1