Hikaru Sulu experiencing frostbite
Frostbite is a medical condition, which comes as a result of exposure to extreme cold, where an individuals appendages blister, peel and turn gangrenous.
Zoumas, an alien trader was once left alone in a forest on Burala Prime where he lost several toes due to frostbite. Following the incident, Zoumas walked with a slight limp. (ENT: "Canamar")
Hikaru Sulu suffered severe exposure and frostbite after spending the night on the surface of Alfa 177 where there temperature dipped below 75° below zero. (TOS: "The Enemy Within")
In a deleted scene from Broken Bow, Hoshi Sato was wondering if she had frostbite after returning from Rigel X.