What is the appropriate diagnostic workup and treatment for a patient suspected of having Guillain-Barré Syndrome (GBS)?

Guillain-Barré Syndrome Diagnostic Workup

All patients with suspected GBS require immediate neurological consultation, admission to a unit with rapid ICU transfer capability, and initiation of a comprehensive diagnostic protocol that includes CSF analysis, electrodiagnostic studies, and spinal MRI to confirm the diagnosis and exclude mimics. 1, 2

Clinical Recognition and Initial Assessment

Key Clinical Features to Identify

• Progressive, typically symmetrical limb weakness with reduced or absent deep tendon reflexes is the hallmark presentation, though asymmetric patterns can occur 1

• Sensory symptoms or neuropathic pain often begin in the lower back and thighs before ascending, and may precede weakness 1, 2

• Critical warning signs requiring immediate escalation include ANY dysphagia, facial weakness, respiratory muscle weakness, or rapidly progressive symptoms 1, 2, 3

• Autonomic dysfunction may manifest as arrhythmias, blood pressure fluctuations, or cardiac complications 1, 2

• Preceding infection history (diarrhea or respiratory illness 1-3 weeks prior) increases diagnostic likelihood 1, 4

Essential Diagnostic Workup

Immediate Neurological Consultation

• Obtain neurology consultation immediately for all suspected cases, as GBS can progress rapidly to respiratory failure 1, 2, 4

Cerebrospinal Fluid Analysis

• Perform lumbar puncture to assess for albuminocytological dissociation (elevated protein with normal cell count), the classic CSF finding in GBS 1, 2

• Normal CSF protein does not exclude GBS, as 30-50% of patients have normal protein levels in the first week and 10-30% in the second week 1

• Marked pleocytosis (>50 cells/μl) suggests alternative diagnoses such as leptomeningeal malignancy or infectious polyradiculitis 1

• Mild pleocytosis (10-50 cells/μl) is compatible with GBS but should prompt consideration of infectious causes, particularly in cancer patients where cytology should be sent 1

Spinal Imaging

• Obtain MRI of spine with and without contrast to rule out compressive lesions and evaluate for nerve root enhancement/thickening, which supports the GBS diagnosis 1, 2

• MRI of brain with pituitary protocol should be added if cranial nerve involvement is present 1

Electrodiagnostic Studies

• Perform nerve conduction studies (NCS) and electromyography (EMG) to demonstrate sensorimotor polyradiculoneuropathy with reduced conduction velocities, reduced amplitudes, temporal dispersion, and/or conduction blocks 1

• "Sural sparing pattern" (normal sural sensory nerve action potential with abnormal median/ulnar responses) is typical for GBS 1

• Normal electrodiagnostic studies do not exclude GBS when performed within 1 week of symptom onset or in patients with proximal weakness, mild disease, or clinical variants 1

• Repeat electrodiagnostic studies 2-3 weeks later if initial testing is normal but clinical suspicion remains high 1

Serological Testing

• Serum antiganglioside antibody testing has limited diagnostic value in typical motor-sensory GBS but should be performed 1

• Anti-GQ1b antibody testing is highly valuable when Miller Fisher syndrome is suspected (ataxia, ophthalmoplegia, areflexia), as it is positive in up to 90% of MFS cases 1

Laboratory Exclusion Panel

• Complete blood count, glucose, electrolytes, kidney and liver function to exclude metabolic or electrolyte causes of acute flaccid paralysis 1

• Screen for reversible neuropathy causes: diabetic screen, B12, folate, TSH, HIV, and consider serum protein electrophoresis 1

Respiratory and Cardiac Monitoring

Pulmonary Function Assessment

• Establish baseline pulmonary function testing including negative inspiratory force (NIF), vital capacity (VC), and maximum inspiratory/expiratory pressures 1, 5, 2

• Apply the "20/30/40 rule" to assess respiratory failure risk: patient is at risk if VC <20 ml/kg, maximum inspiratory pressure <30 cmH₂O, or maximum expiratory pressure <40 cmH₂O 5

• Calculate the Erasmus GBS Respiratory Insufficiency Score (EGRIS) to determine probability of requiring mechanical ventilation 5, 4

• Perform frequent neurochecks and continuous pulmonary function monitoring as respiratory compromise can develop rapidly even during treatment 1, 5, 3

Cardiac Evaluation

• Obtain ECG and consider transthoracic echocardiogram if there is respiratory insufficiency or elevated CPK/troponin to evaluate for concomitant myocarditis, particularly in immune checkpoint inhibitor-related cases 2

• Monitor for arrhythmias and blood pressure fluctuations due to autonomic dysfunction 1, 2

Severity Grading for Treatment Planning

Grade 2 (Moderate)

• Moderate symptoms with some ADL interference but no severe weakness, limiting self-care, or respiratory involvement 1, 2

• Hold immune checkpoint inhibitors if applicable and resume only if symptoms resolve to Grade 1 1

Grade 3-4 (Severe)

• Severe disease with limiting self-care, weakness limiting walking, ANY dysphagia/facial/respiratory weakness, or rapidly progressive symptoms 1, 2

• Permanently discontinue immune checkpoint inhibitors if applicable 1

• Admit to inpatient unit with rapid ICU transfer capability given unpredictable potential for respiratory decompensation 1, 2, 3

Critical Medications to Avoid

• Avoid β-blockers, IV magnesium, fluoroquinolones, aminoglycosides, and macrolides as these can worsen neuromuscular function and exacerbate clinical condition 1, 5, 2, 3

Differential Diagnosis Considerations

• Consider acute-onset CIDP (A-CIDP) if progression continues beyond 8 weeks from onset, which occurs in approximately 5% of patients initially diagnosed with GBS 4, 6

• Suspect CIDP if a patient experiences three or more treatment-related fluctuations and/or clinical deterioration ≥8 weeks after onset 3