A 25-year-old woman presents with bilateral ascending weakness over 3 weeks, areflexia, and albuminocytologic dissociation in CSF (protein 180 mg/dL, cells 4/µL). Nerve conduction studies show prolonged distal latencies, reduced conduction velocities, and conduction block. This pattern identifies which variant of GBS?

• A Acute motor axonal neuropathy (AMAN)
• B Miller Fisher syndrome
• C Acute inflammatory demyelinating polyneuropathy (AIDP) ✓
• D Acute motor and sensory axonal neuropathy (AMSAN)

Explanation

Prolonged distal latencies, slowed conduction velocities, and conduction block are electrophysiological hallmarks of demyelinating neuropathy, identifying AIDP — the most common GBS variant in Western countries. AMAN and AMSAN show reduced CMAP amplitudes without conduction slowing (axonal loss pattern) and are more common in Asia, associated with anti-GM1/GD1a antibodies. Miller Fisher syndrome presents with ophthalmoplegia, ataxia, and areflexia with anti-GQ1b antibodies.

Reference: Harrison's Principles of Internal Medicine, 21st ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.