What is the evaluation and treatment approach for a patient suspected of having Guillain-Barré Syndrome (GBS)?

Evaluation of Guillain-Barré Syndrome

When GBS is suspected, immediately assess respiratory function and autonomic stability, as these determine mortality risk and need for ICU admission, then proceed with diagnostic confirmation through CSF examination and electrodiagnostic studies while initiating treatment without waiting for antibody results. 1, 2

Immediate Life-Threatening Assessment

Respiratory function must be measured at presentation and serially monitored, as approximately 20-30% of patients develop respiratory failure requiring mechanical ventilation, sometimes without obvious dyspnea. 2, 3

• 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, 3
• Single breath count ≤19 predicts need for mechanical ventilation 2, 3
• Perform continuous ECG monitoring and blood pressure monitoring for arrhythmias and autonomic instability 1, 2
• Assess swallowing and coughing ability to identify aspiration risk 1, 2

Admit to ICU if any of the following are present: evolving respiratory distress, severe autonomic cardiovascular dysfunction, severe swallowing dysfunction or diminished cough reflex, or rapid progression of weakness 3

Clinical Diagnostic Criteria

The diagnosis of GBS is primarily clinical, requiring bilateral limb weakness that progresses over days to 4 weeks, with diminished or absent reflexes. 1

• History of recent infection (within 6 weeks) is present in approximately two-thirds of patients 2
• Bilateral ascending weakness typically starts in legs and progresses to arms and cranial muscles 2
• Distal paresthesias or sensory loss often precede or accompany weakness 2
• Facial weakness occurs in approximately 34% of patients and is the most frequently affected cranial nerve 2, 4
• Back and limb pain affects approximately two-thirds of patients and can be an early symptom 2

Red flags that should prompt reconsideration of the diagnosis: marked persistent asymmetry, bladder dysfunction at onset, or marked CSF pleocytosis (>50 cells/μl) 1, 2

Laboratory Investigations

All patients with suspected GBS should have complete blood counts and blood tests for glucose, electrolytes, kidney function, and liver enzymes to exclude other causes of acute flaccid paralysis. 1

• Serum creatine kinase (CK) is sensitive though nonspecific; elevation suggests muscle involvement 2
• Testing for anti-ganglioside antibodies has limited diagnostic value and a negative result does not rule out GBS 1, 5
• Anti-GQ1b antibodies are found in up to 90% of patients with Miller Fisher syndrome and should be tested when MFS is suspected 1, 5
• Do not wait for antibody test results before starting treatment 1, 2

Cerebrospinal Fluid Examination

CSF examination should be performed during initial evaluation to rule out alternative diagnoses and look for albumino-cytological dissociation (elevated protein with normal cell count). 1, 2

• CSF protein levels are normal in 30-50% of patients in the first week and 10-30% in the second week, so normal CSF protein does not rule out GBS 1, 2
• Mean CSF protein level when elevated is approximately 113.8 mg/dl 4
• Marked pleocytosis (>50 cells/μl) suggests other pathologies 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 1

Electrodiagnostic Studies

Nerve conduction studies and EMG should be performed to support the diagnosis and classify the neuropathy pattern, particularly in patients with atypical presentation. 1, 2, 5

• 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 for GBS 1, 2
• Conduction block determined indirectly by absent H-reflex is noted in approximately 90% of patients 4
• Electrophysiological measurements may be normal when performed within 1 week of symptom onset or in patients with initially proximal weakness—repeat study 2-3 weeks later can be helpful 1

Neurological Examination

Grade muscle strength using Medical Research Council scale in neck, arms, and legs, and assess functional disability using the GBS disability scale. 1, 2

• Test for cranial nerve involvement, particularly bilateral facial palsy 2
• Check corneal reflex in patients with facial palsy to prevent corneal ulceration 2
• Assess for ophthalmoplegia and ataxia (Miller Fisher syndrome variant) 2
• Evaluate bowel and bladder function for autonomic dysfunction 1, 2

Imaging Studies

MRI of spine with and without contrast should be considered in atypical cases to rule out compressive lesions and evaluate for nerve root enhancement/thickening. 2, 5

Treatment Initiation

Initiate intravenous immunoglobulin (IVIg) 0.4 g/kg/day for 5 consecutive days in any patient with GBS who cannot walk unaided, starting as early as possible within 2 weeks of symptom onset. 3, 5

• Plasma exchange (200-250 ml/kg over 4-5 sessions) is an alternative effective treatment within 4 weeks of symptom onset 3, 5
• IVIg is preferred over plasma exchange because it is easier to administer, more widely available, and causes fewer complications 3
• Corticosteroids alone are not recommended as they show no significant benefit and oral corticosteroids may worsen outcomes 3, 5

Ongoing Monitoring During Hospitalization

The nature and frequency of monitoring depends on disease severity and should include serial respiratory function tests, muscle strength assessment, autonomic function monitoring, and assessment for complications. 1

• Up to two-thirds of deaths occur during the recovery phase from cardiovascular and respiratory dysfunction, so maintain vigilance even after ICU discharge 1
• Monitor for psychological symptoms including anxiety, depression, and hallucinations, which are frequent complications 2
• Recognize that patients with GBS, even those with complete paralysis, usually have intact consciousness, vision, and hearing 1, 2

Prognostic Assessment

Use the modified Erasmus GBS outcome score (mEGOS) to predict probability of regaining walking ability and the modified Erasmus GBS Respiratory Insufficiency Score (mEGRIS) to assess risk of requiring artificial ventilation. 3, 5

• Approximately 80% of patients regain independent walking ability at 6 months 3, 5
• Mortality is 3-10%, primarily from cardiovascular and respiratory complications 3, 5
• Advanced age and severe disease at onset are risk factors for poor outcome 3, 5
• Recovery can continue for more than 3 years, with improvement possible even more than 5 years after onset 3

Consideration of Alternative Diagnoses

Consider changing the diagnosis to acute-onset chronic inflammatory demyelinating polyradiculoneuropathy (A-CIDP) if progression continues after 8 weeks from onset or if patient has three or more treatment-related fluctuations, which occurs in approximately 5% of patients initially diagnosed with GBS. 2, 5, 6