ABSTRACT
Itch can be suppressed by scratching. At the same time, scratching evokes a pleasurable sensation. In the present study, we investigated the peripheral mechanism of scratching-induced pleasurability and its association with itch relief using compression nerve block. We found that myelinated nerve fibers (Aß-fibers and possibly Aδ-fibers), are involved in transmission of scratching-induced pleasurability. We observed that itch relief effect was the same regardless of whether the pleasurable sensation was evoked by scratching an itch, indicating that pleasure is not a necessary component to induce itch relief. This is the first study to investigate the peripheral mechanism of scratching-induced pleasurability and itch relief.
ABSTRACT
A cross-sectional study of geriatric patients was performed to provide a comprehensive description of the prevalence and clinical characteristics of chronic itch affecting Hispanic geriatric subjects in Mexico. Participants were recruited from both nursing homes and geriatric ambulatory care centers. Patients without dementia were evaluated using an itch intensity and characteristic questionnaire and were assessed for itch-related dermatoses (n = 302). Data on medications and underlying systemic diseases were obtained from medical records. The prevalence of chronic itch was 25% in this population. Of those with chronic itch, 69% had xerosis, 28% had itch-related dermatoses, and 96% had documented comorbidities. The most common comorbidities were diabetes mellitus (OR = 2.3, 95% CI 1.3-3.9, p = 0.003) and chronic venous insufficiency (OR = 4.4, 95% CI 1.6-12.2, p = 0.002). The most common areas where patients experienced itch were legs (54%), back (45%), scalp (28%) and arms (27%). Patients experienced the greatest amount of itch in the winter (77%) and during the night (65%). Chronic itch is a common problem in the studied Hispanic geriatric population, and its presence significantly correlates with xerosis, diabetes, and venous insufficiency.