Significant differences in central imaging of histamine-induced itch between atopic dermatitis and healthy subjects.
OBJECTIVE
This is the first investigation of the central processing of itch in the brain in 8 subjects with atopic dermatitis (AD) in comparison to 6 healthy controls (HC), comparing histamine-induced itch related activations in the frontal, prefrontal, parietal, cingulate cortex, thalamus, basal ganglia and cerebellum.


METHODS
We employed 1% histamine-dihydrochlorid-iontophoresis of the left hand, recorded H2(15)O-PET-scans and perception of itch intensity on a numeric rating scale.


RESULTS
There was no significant difference in perceived itch intensity between AD and HC. Significant increase in rCBF was found in HC in the contralateral somatosensory and motor cortex, midcingulate gyrus, and ipsilateral prefrontal cortex; in AD: in the contralateral thalamus, somatosensory, motor and prefrontal cortex and cerebellum, in the ipsilateral precentral, prefrontal, orbitofrontal cortex, insula, pallidum and cerebellum. More brain sites were activated in AD than in HC. Activation in AD was significantly higher in the contralateral thalamus, ipsilateral caudate and pallidum.


CONCLUSIONS
We interpret our findings as possible central correlates of changes in the motor system in subjects with chronic itch, with activation of the basal ganglia possibly correlating to the vicious itch-scratch-circle in subjects with chronic itching skin diseases. However, further neuroimaging studies in healthy subjects and also in different skin diseases are needed to understand the complex mechanisms of the processing of itch.
Schneider
Gudrun
G
Department of Psychosomatics and Psychotherapy, University of Münster, Domagkstr. 22, D-48149 Münster, Germany. schneig@mednet.uni-muenster.de
Ständer
Sonja
S
Burgmer
Markus
M
Driesch
Georg
G
Heuft
Gereon
G
Weckesser
Matthias
M
D000328:Adult; D000344:Afferent Pathways; D001921:Brain / Q000000981:diagnostic imaging*; D001931:Brain Mapping; D002421:Caudate Nucleus / Q000000981:diagnostic imaging / Q000503:physiopathology; D002560:Cerebrovascular Circulation; D003876:Dermatitis, Atopic / Q000503:physiopathology*; D005260:Female; D005917:Globus Pallidus / Q000000981:diagnostic imaging / Q000503:physiopathology; D006179:Gyrus Cinguli / Q000000981:diagnostic imaging / Q000503:physiopathology; D006225:Hand; D006632:Histamine / Q000008:administration & dosage / Q000633:toxicity*; D006801:Humans; D007478:Iontophoresis; D008297:Male; D010465:Perception / Q000502:physiology*; D049268:Positron-Emission Tomography; D017397:Prefrontal Cortex / Q000000981:diagnostic imaging / Q000503:physiopathology; D011537:Pruritus / Q000139:chemically induced / Q000000981:diagnostic imaging / Q000503:physiopathology*; D013003:Somatosensory Cortex / Q000000981:diagnostic imaging / Q000503:physiopathology; D013788:Thalamus / Q000000981:diagnostic imaging / Q000503:physiopathology
D006632:Histamine