What are the clinical features of Guillain-Barré Syndrome (GBS)?

Clinical Features of Guillain-Barré Syndrome (GBS)

Guillain-Barré syndrome (GBS) is characterized by rapidly progressive bilateral weakness of the limbs, typically starting in the legs and ascending to the arms and cranial muscles, accompanied by decreased or absent reflexes, and often preceded by an infection.

Classic Clinical Presentation

• GBS typically presents with rapidly progressive bilateral weakness of the legs and/or arms, in the absence of CNS involvement or other obvious causes 1, 2
• Distal paresthesias or sensory loss often precede or accompany weakness, with symptoms starting in the legs and progressing to the arms and cranial muscles 1, 2
• Reflexes are decreased or absent in most patients at presentation and in almost all patients at nadir 1, 3
• Disease progression is rapid, with patients typically reaching maximum disability within 2 weeks 1
• About two-thirds of patients report symptoms of an infection in the 6 weeks preceding GBS onset 1, 2
• Pain is frequently reported and can be muscular, radicular, or neuropathic in nature 1, 2
• GBS is a monophasic illness, although treatment-related fluctuations (TRFs) and relapses occur in a minority of patients (2-5%) 1, 4

Autonomic Dysfunction

• Dysautonomia is common and can include blood pressure or heart rate instability, pupillary dysfunction, and bowel or bladder dysfunction 1, 2
• Cardiac arrhythmias and blood pressure instability can occur due to autonomic nervous system involvement 1, 3
• Autonomic dysfunction contributes to mortality, which is estimated at 3-10% even with the best medical care available 1

Respiratory Involvement

• About 20% of patients with GBS develop respiratory failure and require mechanical ventilation 1, 3
• Respiratory function should be monitored in all patients as respiratory failure can occur without symptoms of dyspnoea 2, 3

Atypical Presentations

• GBS can present atypically with weakness and sensory signs that are asymmetrical or predominantly proximal or distal 1
• Weakness can start in the legs, arms, or simultaneously in all limbs 1
• Severe and diffuse pain or isolated cranial nerve dysfunction can precede the onset of weakness 1
• Young children (<6 years) may present with nonspecific features such as poorly localized pain, refusal to bear weight, irritability, meningism, or unsteady gait 1
• In a minority of patients with atypical GBS, particularly those with only motor signs (pure motor variant) and an AMAN subtype, normal or even exaggerated reflexes might be observed 1

Clinical Variants

• Several distinct clinical variants of GBS exist that do not progress to the classic pattern of sensory loss and weakness 1:
  • Pure motor variant (5-70%): Motor weakness without sensory signs 1
  • Paraparetic variant (5-10%): Paresis restricted to the legs 1
  • Pharyngeal-cervical-brachial weakness (<5%): Weakness of pharyngeal, cervical, and brachial muscles without lower limb weakness 1
  • Bilateral facial palsy with paresthesias (<5%): Bilateral facial weakness with paresthesias and reduced reflexes 1
  • Miller Fisher syndrome (5-25%): Characterized by ophthalmoplegia, ataxia, and areflexia 1, 4
  • Pure sensory variant (<1%): Acute or subacute sensory neuropathy without other deficits 1
  • Bickerstaff brainstem encephalitis (<5%): Ophthalmoplegia, ataxia, areflexia, pyramidal tract signs, and impaired consciousness 1

Disease Course and Outcomes

• After the initial progressive phase, patients reach a plateau phase lasting from days to weeks or months 1
• Following the plateau phase, patients begin to recover, with 60-80% able to walk independently 6 months after disease onset 1
• Clinical improvement is usually most extensive in the first year after disease onset and can continue for >5 years 1, 2
• Many patients have pain, fatigue, or other residual complaints that may persist for months or years 4, 5

Diagnostic Features

• Albumino-cytological dissociation (elevated protein levels with normal cell count) in cerebrospinal fluid is a classic finding, though protein levels may be normal early in the disease course 2, 6
• Electrophysiological studies can distinguish between subtypes: acute inflammatory demyelinating polyradiculoneuropathy (AIDP), acute motor axonal neuropathy (AMAN), and acute motor sensory axonal neuropathy (AMSAN) 1, 7
• Anti-ganglioside antibodies may be present in a subgroup of patients, with anti-GQ1b antibodies found in up to 90% of patients with Miller Fisher syndrome 2, 6

Red Flags for Alternative Diagnoses

• Maximum disability reached within 24 hours of disease onset or after 4 weeks should prompt consideration of alternative diagnoses 1, 3
• Continued progression beyond 8 weeks from onset suggests acute-onset chronic inflammatory demyelinating polyradiculoneuropathy (A-CIDP), which occurs in about 5% of patients initially diagnosed with GBS 6, 7
• Marked asymmetry of symptoms, fever, or signs of CNS involvement should raise suspicion for alternative diagnoses 1, 3