Capsaicin cream relieves neuropathic toe pain by affecting which type of sensory fiber?

• A. A delta fibers
• B. C fibers
• C. A beta fibers
• D. Motor neurons

Answer: (B)

Capsaicin cream relieves neuropathic pain by acting on the pain-sensing nerve fibers in the skin. It binds to TRPV1 receptors on small-diameter nociceptors, which are unmyelinated C fibers. Activation of these receptors causes an initial burning sensation, followed by depletion of Substance P and prolonged desensitization of the nociceptors, reducing their ability to transmit pain signals. A-delta fibers carry fast, sharp pain and are less affected by capsaicin in this context, while A-beta fibers are involved in touch rather than pain. Motor neurons are not part of sensory pain pathways.