A 28-year-old woman presents with progressive ascending weakness over 10 days, areflexia, and bilateral facial diplegia. CSF shows cytoalbuminous dissociation (protein 280 mg/dL, cells 4/mm³). Nerve conduction studies show prolonged distal motor latencies, absent F waves, and dispersed CMAPs. Which GBS variant does this pattern represent?
- A Acute inflammatory demyelinating polyneuropathy (AIDP) — most common GBS variant ✓
- B Acute motor axonal neuropathy (AMAN)
- C Miller Fisher syndrome (MFS)
- D Pharyngeal-cervical-brachial (PCB) variant
Explanation
AIDP is the most common form of GBS (70-80% in Western countries), characterised by demyelinating NCS pattern: prolonged distal latencies, reduced conduction velocity, absent/prolonged F waves, conduction block, and temporal dispersion of CMAPs. Cytoalbuminous dissociation (elevated protein, normal cells) is classic. Facial diplegia is common. AMAN (acute motor axonal neuropathy) shows normal latencies and velocities with low CMAP amplitude (axonal pattern), is more common in Asia and associated with anti-GM1/GD1a antibodies. Miller Fisher shows ataxia, ophthalmoplegia, areflexia with anti-GQ1b antibodies. PCB variant involves oro-pharyngeal and proximal arm weakness.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.