A 35-year-old patient receiving vincristine for ALL develops bilateral foot drop, constipation, and absent deep tendon reflexes. These findings represent:

• A Paraneoplastic neuropathy caused by ALL-related antibodies
• B Vincristine-induced leukoencephalopathy from blood-brain barrier disruption
• C Vinca alkaloid-induced peripheral neuropathy from disruption of axonal microtubules ✓
• D Chemotherapy-induced demyelination from reactive oxygen species

Explanation

Vincristine binds to tubulin and inhibits microtubule polymerization, disrupting axonal transport which depends on microtubules. This causes a length-dependent peripheral neuropathy (most prominent distally) with loss of deep tendon reflexes, sensory changes, weakness, and autonomic neuropathy (constipation, paralytic ileus, urinary retention). Peripheral neurotoxicity is the dose-limiting toxicity of vincristine; notably, myelosuppression is minimal with vincristine compared to vinblastine.

Reference: KD Tripathi, Essentials of Medical Pharmacology, 8th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.