Final answer:
Epidural analgesia blocks pain and temperature signals through the use of local anesthetics like lidocaine which inhibit nerve impulses by targeting sodium channels. Chronic pain can be perpetuated by the immune system despite healed injuries. Capsaicin can also serve as a topical analgesic by altering nociceptor sensitivity.
Step-by-step explanation:
The relationship between pain and temperature blockade in epidural analgesia involves the interruption of pain and temperature signals to the spinal cord, often using local anesthetics like lidocaine. These signals are transmitted by nociceptors and thermoreceptors. Lidocaine blocks voltage-gated sodium channels on nerve cells, which prevents the propagation of nerve impulses that carry pain and temperature sensations. As a result, pain and temperature sensations are not transmitted to the brain, leading to numbness and pain relief.
In cases of chronic pain, the immune system can contribute to continued pain perception even after the original tissue damage has healed. Chemical messengers from the innate immune system, such as from macrophages, can enhance the sensation of pain by activating nociceptors. Therefore, some chronic pain management strategies focus on modulating the immune response.
Additionally, drugs like capsaicin can bind to nociceptors and produce an analgesic effect by reducing the capacity of other stimuli to elicit pain, thus providing temporary pain relief.