Topical high-concentration L-menthol is the only established human experimental pain model to study mechanisms underlying cold hyperalgesia. We aimed at investigating the combinatorial effect of cold stimuli and topical L-menthol on cold pain and secondary mechanical hyperalgesia. Analogue to the heat-capsaicin model on skin sensitization, we proposed that cold/menthol enhances or prolong L-menthol-evoked sensitization. Topical 40% L-menthol or vehicle was applied (20 minutes) on the volar forearms of 20 healthy females and males (age, 28.7 ± 0.6 years). Cold stimulation of 5°C for 5 minutes was then applied to the treated area 3 times with 40-minute intervals. Cold detection threshold and pain, mechanical hyperalgesia (pinprick), static and dynamic mechanical allodynia (von Frey and brush), skin blood flow (laser speckle), and temperature (thermocamera) were assessed. Cold detection threshold and cold pain threshold (CPT) increased after L-menthol and remained high after the cold rekindling cycles (P < 0.001). L-menthol evoked secondary hyperalgesia to pinprick (P < 0.001) particularly in females (P < 0.05) and also induced secondary allodynia to von Frey and brush (P < 0.001). Application of cold stimuli kept these areas enlarged with a higher response in females to brush after the third cold cycle (P < 0.05). Skin blood flow increased after L-menthol (P < 0.001) and stayed stable after cold cycles. Repeated application of cold on skin treated by L-menthol facilitated and prolonged L-menthol-induced cold pain and hyperalgesia. This model may prove beneficial for testing analgesic compounds when a sufficient duration of time is needed to see drug effects on CPT or mechanical hypersensitivity.

Women of reproductive age present one or more emotional or physical symptoms in premenstrual phase of their menstrual cycle, which is collectively called premenstrual syndrome (PMS). Estimates show that about 5 to 8% of women suffer from severe PMS. This form has been termed as premenstrual dysphoric disorder (PMDD). Diagnostic criteria have been proposed for PMDD. For the purpose of this research work, the term PMS was used to include variants of premenstrual syndrome in general. Common symptoms include but not limited to breast swelling, food cravings, bloating, mood swings and backache. The etiology of PMS remains unclear; but available evidence suggests that genetics and environmental factors may influence the PMS experience and its severity. The present study was designed to investigate PMS experience and characteristics in two ethnic groups of Caucasian and Asian women living in Denmark. An online survey-based methodology was applied to target Asians and Caucasians women (18-55 years) with PMS, living in different regions in Denmark. The questionnaire consisted of 36 questions to cover the required information for the purpose of this study. Regression analysis was applied to find the association between PMSassociated factors and ethnicity. Asian (47) in comparison with Caucasian women (47) presented with higher ratings of several PMS symptoms such as mood swings, depression and food cravings (p < 0.05). Asian women were also found with higher rate in digestion problems (p < 0.05) and higher rate of cramps and nausea during menstruation and a shorter menstruation period compared with the Caucasians (p < 0.05). This study highlighted that Asian women had higher rates of both psychological and physiological factors in relation to PMS. Potential reasons for a difference between Asian and Caucasian women living in Demark is not clear, and need further investigation.

Stroke is a complicated condition that leaves stroke survivors with prolonged disability. Common poststroke conditions are spasticity and pain, which directly affect daily activities and quality of life in these patients. Botulinum neurotoxin type A is an effective and well-tolerated treatment option for upper-limb spasticity. It reduces muscle tone and improves basic upper-limb activities. Functional electrical stimulation is also used widely as a therapeutic modality in the upper-limb muscle rehabilitation. Here, we present a case in which Botulinum neurotoxin type A injections combined with functional electrical stimulation were applied for upper-limb spasticity accompanied with pain in a poststroke patient.