What is the typical presentation of Guillain-Barré Syndrome (GBS) in an adult patient?

Typical Guillain-Barré Syndrome Presentation

Guillain-Barré syndrome classically presents as rapidly progressive bilateral ascending weakness starting in the legs, accompanied by diminished or absent reflexes, often preceded by an infection within the prior 6 weeks. 1, 2

Core Clinical Features

Motor Symptoms

• Bilateral ascending weakness is the hallmark, typically beginning in the lower extremities and progressing upward to the arms and cranial muscles over days to 4 weeks (most commonly within 2 weeks) 1, 2, 3
• Areflexia or hyporeflexia is present in most patients at presentation and nearly all at disease nadir—this is a key diagnostic feature 2
• Weakness progresses to maximum disability typically within 2 weeks of onset 1, 2
• Approximately 70% of patients in Europe and the Americas present with the classic sensorimotor form 1

Sensory Symptoms

• Distal paresthesias or sensory loss frequently precede or accompany the weakness 1, 2
• Sensory symptoms typically start in the feet and hands 1

Cranial Nerve Involvement

• Facial nerve weakness occurs in approximately 30-60% of patients and is the most commonly affected cranial nerve due to its extensive myelin coverage and long intracranial course 1, 4, 5
• Bilateral facial palsy is particularly characteristic—simultaneous bilateral facial weakness should immediately raise suspicion for GBS rather than Bell's palsy 1
• Bulbar involvement (glossopharyngeal and vagus nerves) occurs in approximately 30% of patients, causing dysphagia and aspiration risk 1, 4
• Ophthalmoplegia, ataxia, and areflexia characterize the Miller Fisher variant (5-25% of cases) 1

Pain

• Back and limb pain is an early symptom in approximately two-thirds of patients 1, 2
• Pain can be muscular, radicular, or neuropathic in nature 1, 2

Autonomic Dysfunction

• Dysautonomia is common and includes blood pressure or heart rate instability, pupillary dysfunction, and bowel or bladder dysfunction 1, 2
• Cardiac arrhythmias and blood pressure instability contribute significantly to the 3-10% mortality rate 3

Antecedent Infection History

• Approximately two-thirds of patients report symptoms of infection in the 6 weeks preceding disease onset 1, 2, 4
• The most commonly implicated pathogens include Campylobacter jejuni, cytomegalovirus, Epstein-Barr virus, Mycoplasma pneumoniae, hepatitis E virus, and Zika virus 2, 3, 6
• Antecedent diarrhea or respiratory infection increases diagnostic likelihood 7

Critical Respiratory Assessment

• Approximately 20% of patients develop respiratory failure requiring mechanical ventilation, which can occur rapidly and sometimes without obvious dyspnea 1, 3
• Apply the "20/30/40 rule" at presentation and serially: 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, 3
• Single breath count ≤19 predicts need for mechanical ventilation 1

Disease Course

• The disease is typically monophasic with progression over days to 4 weeks 2, 6
• Recovery can continue for more than 3 years after onset, with full recovery expected in approximately 90% of cases 1
• 60-80% of patients regain independent walking ability at 6 months 1, 2, 3
• Recurrence is rare, occurring in only 2-5% of cases 1, 2

Common Pitfalls

• Do not dismiss GBS based on normal CSF protein in the first week—albumino-cytological dissociation may not be present early in the disease course 1, 7
• Bilateral simultaneous facial weakness is extremely rare in Bell's palsy and should immediately raise suspicion for GBS 1
• Marked persistent asymmetry, bladder dysfunction at onset, or marked CSF pleocytosis should prompt reconsideration of the diagnosis 1
• Consider changing the diagnosis to acute-onset CIDP if progression continues after 8 weeks from onset, which occurs in approximately 5% of patients initially diagnosed with GBS 1, 7