A 34-year-old woman self-medicating with pyridoxine 500 mg daily for premenstrual symptoms for two years develops numbness of the feet and hands with loss of ankle jerks. Nerve conduction studies show a distal symmetric sensory axonal neuropathy. The most likely diagnosis is:

• A Guillain-Barre syndrome
• B Diabetic distal polyneuropathy
• C Subacute combined degeneration of the cord
• D Pyridoxine-induced sensory neuropathy ✓

Explanation

Chronic intake of very high dose pyridoxine, classically above several hundred milligrams daily, paradoxically causes a purely sensory axonal neuropathy with ataxia and numbness; the mechanism is thought to be direct neurotoxicity of pyridoxine to dorsal root ganglion neurons. It improves slowly after withdrawal. Guillain-Barre is acute and motor-dominant, subacute combined degeneration includes corticospinal tract signs and posterior column loss with macrocytosis, and there is no history of diabetes here.

Reference: Katzung Basic and Clinical Pharmacology, 16th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.