Pub Date : 2017-03-01Epub Date: 2017-03-28DOI: 10.1097/itx.0000000000000002
Hjalte H Andersen, Jesper Elberling, Silvia Lo Vecchio, Lars Arendt-Nielsen
Introduction: Little is known about the topographical distribution of pruriception (in particular for nonhistaminergic itch), although conditions with chronic itch frequently occur in distinct anatomic and often bilateral patterns. This study aimed to investigate regional differences in the sensitivity to itch stimuli by assessing the intensity of itch, pain, and cutaneous neurogenic flare evoked by histamine and cowhage in different anatomic regions in 20 healthy volunteers.
Methods: Itch was induced by 1% histamine applied with a prick lancet or by insertion of 25±5 cowhage spicules in 4 regions: volar/dorsal forearm, lower back, and chin. The duration and intensity of itch and pain following each pruritic stimulus were measured by a continuous visual analogue scale (VAS0-100). Sensitivity to touch-evoked itch was assessed by von Frey filaments and cutaneous flare was quantified by full-field laser perfusion imaging.
Results: Peak itch intensity was lower at the chin (19.4±3.6) compared with other areas (mean of 3 locations; 41.3±4.4), independently of whether histamine or cowhage was applied (P<0.01). Baseline sensitivity to touch-evoked itch was higher on the chin (P<0.01), but here hyperknesis did not develop in contrast to other areas (P<0.05). Cutaneous flare was more intense but had a smaller dispersion at the chin, compared with other areas (P<0.01).
Discussion: In conclusion, sensitivity to histaminergic and non-histaminergic itch diverges considerably between body regions. Lower density of pruriceptive CMH and CMI-neurons or distinct neuronal substrates for itch in the mandibular part of the trigeminal area may explain the observed reduced itch and vasomotor responses.
{"title":"Topography of itch: evidence of distinct coding for pruriception in the trigeminal nerve.","authors":"Hjalte H Andersen, Jesper Elberling, Silvia Lo Vecchio, Lars Arendt-Nielsen","doi":"10.1097/itx.0000000000000002","DOIUrl":"https://doi.org/10.1097/itx.0000000000000002","url":null,"abstract":"<p><strong>Introduction: </strong>Little is known about the topographical distribution of pruriception (in particular for nonhistaminergic itch), although conditions with chronic itch frequently occur in distinct anatomic and often bilateral patterns. This study aimed to investigate regional differences in the sensitivity to itch stimuli by assessing the intensity of itch, pain, and cutaneous neurogenic flare evoked by histamine and cowhage in different anatomic regions in 20 healthy volunteers.</p><p><strong>Methods: </strong>Itch was induced by 1% histamine applied with a prick lancet or by insertion of 25±5 cowhage spicules in 4 regions: volar/dorsal forearm, lower back, and chin. The duration and intensity of itch and pain following each pruritic stimulus were measured by a continuous visual analogue scale (VAS<sub>0-100</sub>). Sensitivity to touch-evoked itch was assessed by von Frey filaments and cutaneous flare was quantified by full-field laser perfusion imaging.</p><p><strong>Results: </strong>Peak itch intensity was lower at the chin (19.4±3.6) compared with other areas (mean of 3 locations; 41.3±4.4), independently of whether histamine or cowhage was applied (<i>P</i><0.01). Baseline sensitivity to touch-evoked itch was higher on the chin (<i>P</i><0.01), but here hyperknesis did not develop in contrast to other areas (<i>P</i><0.05). Cutaneous flare was more intense but had a smaller dispersion at the chin, compared with other areas (<i>P</i><0.01).</p><p><strong>Discussion: </strong>In conclusion, sensitivity to histaminergic and non-histaminergic itch diverges considerably between body regions. Lower density of pruriceptive CMH and CMI-neurons or distinct neuronal substrates for itch in the mandibular part of the trigeminal area may explain the observed reduced itch and vasomotor responses.</p>","PeriodicalId":73523,"journal":{"name":"Itch (Philadelphia, Pa.)","volume":"2 1","pages":"e2"},"PeriodicalIF":0.0,"publicationDate":"2017-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1097/itx.0000000000000002","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"36189156","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-03-01Epub Date: 2017-03-28DOI: 10.1097/itx.0000000000000004
Carolyn Stull, Rodrigo Valdes-Rodriguez, Brian M Shafer, Alina Shevchenko, Leigh A Nattkemper, Yiong-Huak Chan, Sydney Tabaac, Martin J Schardt, Dany M Najjar, William J Foster, Gil Yosipovitch
Introduction: In this cross-sectional study, we aimed to determine the prevalence and characteristics of chronic ocular itch in an outpatient ophthalmology and optometry clinic.
Methods: Four hundred patients from an outpatient ophthalmology and optometry clinic were enrolled. The presence and characteristics of chronic ocular itch were assessed by a questionnaire. Data regarding ophthalmologic, dermatologic, and systemic conditions as well as current medications were extracted from medical records.
Results: Chronic ocular itch was present in 118 (29.5%) of 400 participants. Chronic ocular pruritus was significantly more prevalent in females [P=0.015; odds ratio (OR)=1.8; 95% confidence interval (CI), 1.1-2.8] and was significantly associated with the presence of allergic conjunctivitis [51.8% (n=45); P<0.001; OR=5.0; 95% CI, 3.0-8.3], dry eye syndrome [40.1% (75); P<0.001; OR=2.6; 95% CI, 1.7-4.1], blepharitis [43.8% (n=21); P=0.021; OR=2.0; 95% CI, 1.1-3.8], and atopic dermatitis [50.0% (n=10); P=0.023; OR=2.6; 95% CI, 1.1-5.8]. Chronic ocular itch was not significantly associated with systemic conditions, or the use of prescribed ophthalmologic medications.
Discussion: Chronic ocular itch is common and may be related to ophthalmologic or dermatologic pathologies. The present findings highlight the importance of identifying and managing this uncomfortable symptom that may negatively impact the quality of life and sleep of affected patients.
{"title":"The prevalence and characteristics of chronic ocular itch: a cross-sectional survey.","authors":"Carolyn Stull, Rodrigo Valdes-Rodriguez, Brian M Shafer, Alina Shevchenko, Leigh A Nattkemper, Yiong-Huak Chan, Sydney Tabaac, Martin J Schardt, Dany M Najjar, William J Foster, Gil Yosipovitch","doi":"10.1097/itx.0000000000000004","DOIUrl":"https://doi.org/10.1097/itx.0000000000000004","url":null,"abstract":"<p><strong>Introduction: </strong>In this cross-sectional study, we aimed to determine the prevalence and characteristics of chronic ocular itch in an outpatient ophthalmology and optometry clinic.</p><p><strong>Methods: </strong>Four hundred patients from an outpatient ophthalmology and optometry clinic were enrolled. The presence and characteristics of chronic ocular itch were assessed by a questionnaire. Data regarding ophthalmologic, dermatologic, and systemic conditions as well as current medications were extracted from medical records.</p><p><strong>Results: </strong>Chronic ocular itch was present in 118 (29.5%) of 400 participants. Chronic ocular pruritus was significantly more prevalent in females [<i>P</i>=0.015; odds ratio (OR)=1.8; 95% confidence interval (CI), 1.1-2.8] and was significantly associated with the presence of allergic conjunctivitis [51.8% (n=45); <i>P</i><0.001; OR=5.0; 95% CI, 3.0-8.3], dry eye syndrome [40.1% (75); <i>P</i><0.001; OR=2.6; 95% CI, 1.7-4.1], blepharitis [43.8% (n=21); <i>P</i>=0.021; OR=2.0; 95% CI, 1.1-3.8], and atopic dermatitis [50.0% (n=10); <i>P</i>=0.023; OR=2.6; 95% CI, 1.1-5.8]. Chronic ocular itch was not significantly associated with systemic conditions, or the use of prescribed ophthalmologic medications.</p><p><strong>Discussion: </strong>Chronic ocular itch is common and may be related to ophthalmologic or dermatologic pathologies. The present findings highlight the importance of identifying and managing this uncomfortable symptom that may negatively impact the quality of life and sleep of affected patients.</p>","PeriodicalId":73523,"journal":{"name":"Itch (Philadelphia, Pa.)","volume":"2 1","pages":"e4"},"PeriodicalIF":0.0,"publicationDate":"2017-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1097/itx.0000000000000004","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"36189157","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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