TRPM8 and trigeminal nerve disorder: Two studies have shown that activation of TRPM8 can exacerbate pain sensation,11,12 and we recently characterized a gain-of-function mutant in TRPM8 in a patient with trigeminal neuralgia.13 TRPM8 has also been indicated as a key contributor to the physiology of the eye, including tear production and cold thermoreception that triggers basal tear flow.14, -, 19