What are the diagnostic criteria and treatment options for a patient presenting with rapidly progressive weakness suspected to have Guillain-Barré Syndrome (GBS)?

Guillain-Barré Syndrome Diagnosis

Diagnose GBS clinically when a patient presents with rapidly progressive, bilateral ascending weakness with diminished or absent reflexes, particularly if preceded by infection within 6 weeks, and immediately initiate treatment with IVIg 0.4 g/kg/day for 5 days without waiting for confirmatory testing if the patient cannot walk unaided. 1, 2, 3

Immediate Life-Threatening Assessment

Before pursuing diagnostic confirmation, assess for complications that determine mortality risk:

• Respiratory function: Apply the "20/30/40 rule" - patient requires ICU monitoring if vital capacity <20 ml/kg, maximum inspiratory pressure <30 cmH₂O, or maximum expiratory pressure <40 cmH₂O 2, 4
• Single breath count: ≤19 predicts need for mechanical ventilation 2, 4
• Cardiovascular monitoring: Perform ECG and continuous monitoring for arrhythmias and blood pressure instability from autonomic dysfunction 1, 4
• Swallowing assessment: Test for dysphagia and diminished gag reflex to identify aspiration risk 2, 4

Approximately 20% develop respiratory failure requiring mechanical ventilation, which can occur rapidly without obvious dyspnea 1. Mortality is 3-10% primarily from cardiovascular and respiratory complications 1, 4.

Clinical Diagnostic Criteria

Core Features (Present in Most Cases)

• Bilateral ascending weakness: Typically starts in legs, progresses to arms and cranial muscles over days to 4 weeks 2, 5
• Diminished or absent reflexes: Beginning in lower limbs 2
• Distal paresthesias or sensory loss: Often precedes or accompanies weakness 2
• Recent infection history: Present in two-thirds of patients within 6 weeks before onset 2
• Back and limb pain: Affects two-thirds of patients, can be muscular, radicular, or neuropathic 2

Cranial Nerve Involvement

• Bilateral facial palsy: Most frequently affected cranial nerve due to longest intracranial course and extensive myelin coverage 2
• Isolated bilateral facial weakness can be the presenting feature before limb weakness develops 2
• Critical pitfall: Bilateral simultaneous facial weakness is extremely rare in Bell's palsy and should immediately raise suspicion for GBS 2

Autonomic Dysfunction

• Blood pressure or heart rate instability 2
• Pupillary dysfunction 2
• Bowel or bladder dysfunction 2

Confirmatory Testing

Cerebrospinal Fluid Analysis

• Albumino-cytological dissociation: Elevated protein with normal cell count 2, 3
• Critical pitfall: Do not dismiss GBS based on normal CSF protein in the first week - protein elevation may not appear until later 2
• Red flags for alternative diagnosis: Marked CSF pleocytosis (>50 cells/μL) should prompt reconsideration 2, 3

Electrodiagnostic Studies

Perform nerve conduction studies and EMG to support diagnosis and classify neuropathy pattern 2, 3:

• Look for sensorimotor polyradiculoneuropathy with reduced conduction velocities, reduced amplitudes, temporal dispersion, or conduction blocks 2
• "Sural sparing pattern": Normal sural sensory nerve action potential with abnormal median/ulnar responses is typical 2

Laboratory Testing

Initial tests to exclude alternative diagnoses 2:

• Complete blood count, glucose, electrolytes
• Kidney function, liver enzymes
• Serum creatine kinase (elevated suggests muscle involvement but is nonspecific)

Antibody Testing

• Do not wait for antibody results before starting treatment 2
• Anti-GQ1b antibody testing should be considered when Miller Fisher syndrome is suspected 3
• Anti-ganglioside antibody testing is of limited clinical value in typical motor-sensory GBS 3

Clinical Variants

• Classic sensorimotor GBS (30-85%): Rapidly progressive symmetrical weakness and sensory signs with absent/reduced reflexes 2
• Pure motor variant (5-70%): Motor weakness without sensory signs 2
• Miller Fisher syndrome (5-25%): Ophthalmoplegia, ataxia, and areflexia 2

Red Flags Suggesting Alternative Diagnosis

• Marked persistent asymmetry 2, 3
• Bladder dysfunction at onset 2, 3
• Marked CSF pleocytosis 2, 3
• Progression continuing beyond 8 weeks (suggests acute-onset CIDP) 3

Treatment Approach

First-Line Immunotherapy

For patients unable to walk unaided within 2-4 weeks of symptom onset 2, 3:

• IVIg 0.4 g/kg/day for 5 consecutive days (total dose 2 g/kg) 1, 4, 3
• Alternative: Plasma exchange 200-250 ml/kg over 4-5 sessions 2, 3
• Early treatment within first 2 weeks is associated with better outcomes 1, 4

Treatment Equivalence

IVIg and plasma exchange are equally effective 3. IVIg is usually preferred for practical reasons 6.

Treatments to Avoid

• Do not use corticosteroids alone - they are ineffective and may worsen outcomes 4, 7, 3
• Do not combine PE followed immediately by IVIg - no additional benefit 3
• Avoid medications that worsen neuromuscular function: β-blockers, IV magnesium, fluoroquinolones, aminoglycosides, macrolides 4

Managing Treatment Failures and Fluctuations

• Insufficient response: 40% do not improve in first 4 weeks - this does not necessarily mean treatment failed 8
• Treatment-related fluctuations (TRFs): Occur in 6-10% within 2 months after initial improvement 8, 1
• Repeating full course of IVIg or PE is common practice for TRFs, though evidence is lacking 8
• Do not give second IVIg course to patients with poor prognosis - not recommended based on current evidence 3

Acute-Onset CIDP

In ~5% of patients, repeated relapses (≥3 TRFs) or deterioration ≥8 weeks after onset suggests acute-onset CIDP requiring different treatment 8, 3

ICU Admission Criteria

Admit immediately if 4:

• Severe autonomic cardiovascular dysfunction (arrhythmias, blood pressure instability)
• Imminent or evolving respiratory failure
• Severe swallowing dysfunction or diminished gag reflex
• Rapid progression of weakness

Supportive Care

Multidisciplinary Team Involvement

• Nurses, physiotherapists, rehabilitation specialists, occupational therapists, speech therapists, dietitians 8
• Early rehabilitation with range of motion exercises, stationary cycling, walking, strength training 4

Pain Management

• Recognize pain early - affects two-thirds of patients and significantly impacts quality of life 2, 4
• Consider gabapentinoids, tricyclic antidepressants, or carbamazepine 3

Psychological Support

• Patients with complete paralysis usually have intact consciousness, vision, and hearing 8, 2
• Screen for anxiety, depression, and hallucinations 8, 2
• Be mindful of bedside conversations and explain procedures to reduce anxiety 8, 2

Prognosis

• Recovery: 80% regain independent walking ability at 6 months 8, 1, 4
• Mortality: 3-10%, primarily from cardiovascular and respiratory complications 8, 1, 4
• Risk factors for poor outcome: Advanced age and severe disease at onset 8, 4
• Recovery can continue for >3 years, with improvement possible even >5 years after onset 8, 2, 4
• Long-term residual complaints (neuropathic pain, weakness, fatigue) are common 8

Prognostic Tools

• Use modified Erasmus GBS outcome score (mEGOS) to predict walking ability 8, 3
• Use modified Erasmus GBS Respiratory Insufficiency Score (mEGRIS) to assess risk of requiring artificial ventilation 3

Recurrence and Vaccination

• Recurrence is rare (2-5% of patients) but higher than general population lifetime risk (0.1%) 8
• Prior GBS is not a strict contraindication for vaccination 8
• Discuss with experts for patients diagnosed with GBS <1 year before planned vaccination or who developed GBS shortly after the same vaccination previously 8