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How do local anesthetics affect cold warmth touch and pain sensations?

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thermoreception in polar bears — Thermoreception Warm-blooded animals, such as polar bears, maintain stable body temperatures and adapt to substantial geographic and seasonal temperature fluctuations. Thermal adaptation is supported by the function of sensory structures called thermoreceptors.

Local anesthetics function by temporarily blocking the conduction of nerve impulses along peripheral nerve fibers, which prevents the transmission of sensory information to the brain. This process occurs because the anesthetic molecules penetrate the nerve membrane and block the ion channels that allow sodium ions to flow, effectively halting the electrical currents required for nerve signaling.12

The susceptibility of different sensations to this blockade depends on the diameter and type of the nerve fibers involved. Because local anesthetics generally affect thinner fibers first, the order in which sensations are lost is predictable. When sufficient amounts of a local anesthetic are administered, pain is the first sensation to disappear, followed sequentially by the sensations of cold, warmth, touch, and deep pressure. This sequence is distinct from other types of nerve conduction blockades, such as those caused by pressure, which interrupt these sensations in the reverse order.13