What is the diagnosis and treatment for a patient with rapidly progressing muscle weakness, particularly Guillain-Barré Syndrome (GBS), with a recent medical history of potential infections, vaccinations, or surgeries?

Guillain-Barré Syndrome: Diagnosis and Management

Immediate Life-Threatening Assessment

All patients with suspected GBS require immediate assessment of respiratory function and autonomic stability, as approximately 20% develop respiratory failure that can occur rapidly without obvious dyspnea, and mortality remains 3-10% even with optimal care. 1, 2

Critical Respiratory Monitoring

• Measure vital capacity, negative inspiratory force (NIF), and maximum inspiratory/expiratory pressures at presentation and serially 1
• Apply the "20/30/40 rule": patient is at risk of respiratory failure if vital capacity <20 ml/kg, maximum inspiratory pressure <30 cmH₂O, or maximum expiratory pressure <40 cmH₂O 1, 2
• Single breath count ≤19 predicts need for mechanical ventilation 1
• Admit patients with Grade 3-4 disease (severe weakness limiting self-care, dysphagia, facial weakness, respiratory muscle weakness, or rapidly progressive symptoms) to units with capability for rapid ICU transfer 1

Autonomic Monitoring

• Perform electrocardiography and continuously monitor heart rate and blood pressure for arrhythmias and blood pressure instability 1
• Monitor for dysautonomia including pupillary dysfunction and bowel/bladder dysfunction 1, 3

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Clinical Diagnosis

Diagnosis is primarily clinical, based on rapidly progressive bilateral ascending weakness with areflexia, typically reaching maximum disability within 2 weeks of symptom onset. 2, 3

Key Diagnostic Features

• Bilateral ascending weakness starting in legs and progressing to arms and cranial muscles over days to 4 weeks (typically <2 weeks) 1, 2
• Diminished or absent reflexes in affected limbs—present in most patients at presentation and almost all at nadir 1, 3
• Distal paresthesias or sensory loss often precede or accompany weakness 1, 3
• Recent infection history (within 6 weeks) present in approximately two-thirds of patients—Campylobacter jejuni, cytomegalovirus, Epstein-Barr virus, Mycoplasma pneumoniae, hepatitis E virus, and Zika virus are most commonly implicated 1, 2, 4
• Back and limb pain affects approximately two-thirds of patients and can be muscular, radicular, or neuropathic 1

Clinical Variants to Recognize

• Classic sensorimotor GBS (30-85% of cases): rapidly progressive symmetrical weakness and sensory signs with absent/reduced reflexes 1, 3
• Pure motor variant (5-70% of cases): motor weakness without sensory signs 1, 3
• Miller Fisher syndrome (5-25% of cases): ophthalmoplegia, ataxia, and areflexia 1, 5
• Bilateral facial palsy can be the presenting feature before limb weakness develops—bilateral simultaneous facial weakness is extremely rare in Bell's palsy and should immediately raise suspicion for GBS 1

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Diagnostic Workup

Essential Testing

• Cerebrospinal fluid analysis: Look for albumino-cytological dissociation (elevated protein with normal cell count), though do not dismiss GBS based on normal CSF protein in the first week—this may be absent early in disease course 1, 2, 6
• Electrodiagnostic studies (nerve conduction studies and EMG): Perform to support diagnosis and classify neuropathy pattern (AIDP, AMAN, or AMSAN) 1, 6
  • Look for sensorimotor polyradiculoneuropathy with reduced conduction velocities, reduced amplitudes, temporal dispersion, or conduction blocks 1
  • "Sural sparing pattern" (normal sural sensory nerve action potential with abnormal median/ulnar responses) is typical for GBS 1
  • Electrodiagnostic measurements might be normal when performed early (within 1 week)—repeat testing in 2-3 weeks if clinical suspicion remains high 1

Additional Laboratory Tests

• Complete blood count, glucose, electrolytes, kidney function, liver enzymes to exclude metabolic or electrolyte dysfunction 1
• Serum creatine kinase (CK)—elevation suggests muscle involvement 1
• Anti-GQ1b antibody testing when Miller Fisher syndrome is suspected 1, 6
• Screen for reversible neuropathy causes: HbA1c, vitamin B12, TSH, vitamin B6, folate 1

Red Flags Requiring Diagnostic Reconsideration

• Marked persistent asymmetry 1
• Bladder dysfunction at onset 1
• Marked CSF pleocytosis 1
• Progression continuing after 8 weeks from onset—consider acute-onset CIDP, which occurs in approximately 5% of patients initially diagnosed with GBS 1, 6

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First-Line Treatment

Initiate immunotherapy immediately in patients unable to walk unaided within 2-4 weeks of symptom onset—do not wait for antibody test results. 1, 2, 6

Treatment Options (Equally Effective)

• IVIg 0.4 g/kg/day for 5 consecutive days (total dose 2 g/kg) 1, 2, 6
• Plasma exchange 200-250 ml/kg over 4-5 sessions within 4 weeks of symptom onset 1, 2, 6

What NOT to Use

• Corticosteroids are NOT recommended for idiopathic GBS 1, 6, 4
• Do not use PE followed immediately by IVIg—no added benefit 6

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Managing Treatment Response

Expected Timeline

• Approximately 40% of patients do not improve in the first 4 weeks—this does not necessarily mean treatment failed, as progression might have been worse without therapy 1
• Recovery can continue for more than 3 years, with improvement possible even more than 5 years after onset 1, 2

Treatment-Related Fluctuations (TRFs)

• Occur in 6-10% of patients within 2 months after initial improvement 1, 7
• Defined as disease progression within 2 months following initial treatment-induced improvement or stabilization 1
• Repeating a full course of IVIg or plasma exchange is common practice for TRFs 1

When to Reconsider Diagnosis

• If progression continues after 8 weeks from onset 1, 6
• If patient has three or more TRFs—consider acute-onset CIDP 1

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Supportive Care and Pain Management

Neuropathic Pain Treatment

• Use gabapentinoids (gabapentin, pregabalin), tricyclic antidepressants, or carbamazepine for neuropathic pain 1, 6
• Gabapentin can be used alongside IVIg—there is no contraindication or interaction, as they work through completely different mechanisms 1
• Do not delay gabapentin initiation waiting for IVIg to "work first"—pain control should begin immediately 1

Essential Supportive Measures

• Daily neurologic evaluation 1
• Frequent pulmonary function assessment with serial vital capacity and NIF measurements 1
• Test swallowing and coughing ability to identify aspiration risk 1
• Check corneal reflex in patients with facial palsy to prevent corneal ulceration 1
• Standard preventive measures for pressure ulcers, hospital-acquired infections, and deep vein thrombosis 1
• Treatment of constipation/ileus 1

Medications to Avoid

• Avoid medications that can worsen neuromuscular transmission: β-blockers, IV magnesium, fluoroquinolones, aminoglycosides, and macrolides 1

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Rehabilitation

• Arrange a rehabilitation programme with a rehabilitation specialist, physiotherapist, and occupational therapist as a crucial step towards recovery 1
• Exercise programmes, including range-of-motion exercises, stationary cycling, walking, and strength training, can improve physical fitness, walking ability, and independence in activities of daily living 1

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Prognosis

• 80% of patients regain independent walking ability at 6 months 1, 2
• Mortality is 3-10%, primarily from cardiovascular and respiratory complications 1, 2, 3
• Advanced age and severe disease at onset are risk factors for poor outcome 1
• Use the modified Erasmus GBS outcome score (mEGOS) to predict probability of regaining walking ability 1, 6
• Recurrence is rare (2-5% of patients) 1

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Psychological Considerations

• Recognize that patients with GBS, even those with complete paralysis, usually have intact consciousness, vision, and hearing 1
• Screen for anxiety, depression, and hallucinations, which are frequent complications 1
• Be mindful of what is said at bedside and explain procedures to reduce anxiety 1