The effect of menthol on cold allodynia in patients with neuropathic pain.
OBJECTIVE
Cutaneous application of menthol in healthy subjects induces cold allodynia via sensitization of cold-sensitive nociceptors. We investigated the effects of menthol on preexisting cold allodynia in patients to test whether the allodynia was exacerbated.


METHODS
In eight neuropathic pain patients (six of peripheral, two of central origin), 40% menthol was applied topically to an area of preexisting cold allodynia. Mirror-image skin areas and aged-matched healthy subjects served as controls in patients with unilateral and bilateral neuropathic pain, respectively. Prior to and after menthol, cold pain thresholds were measured using a thermotest device.


RESULTS
Menthol induced significant cold allodynia in control areas. However, in neuropathic areas, results were more heterogeneous. Overall, preexisting cold allodynia was not aggravated by topical menthol and was attenuated in 6/8 patients.


CONCLUSIONS
These results suggest that, unlike in controls, menthol is not more hyperalgesic, but may be analgesic in some patients with peripheral and central neuropathic pain.
Wasner
Gunnar
G
Prince of Wales Medical Research Institute, Sydney, New South Wales, Australia. g.wasner@unsw.edu.au
Naleschinski
Dennis
D
Binder
Andreas
A
Schattschneider
Jörn
J
McLachlan
Elspeth M
EM
Baron
Ralf
R
D000328:Adult; D000368:Aged; D003080:Cold Temperature; D005260:Female; D006801:Humans; D006941:Hyperesthesia / Q000188:drug therapy*; D008297:Male; D008610:Menthol / Q000008:administration & dosage / Q000627:therapeutic use*; D008875:Middle Aged; D009437:Neuralgia / Q000188:drug therapy*; D010147:Pain Measurement; D017288:Pain Threshold; D012881:Skin Temperature
D008610:Menthol