Functional magnetic resonance imaging in dermatology: The skin, the brain and the invisible

Mueller, Simon M.; Hogg, Samuel; Mueller, Jannis M.; McKie, Shane; Itin, Peter; Reinhardt, Julia; Griffiths, C.E.M.; Kleyn, C. Elise

doi:10.1111/exd.13305

Cited by 32 publications

(35 citation statements)

References 147 publications

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“…We examined sex differences in the perception and central processing of histaminergic itch using fMRI combined with measurements of the local skin reaction and serial itch ratings. Adopting the time series model by Kleyn et al, we observed BOLD signal changes in itch processing structures very similar to their report and also in line with previous fMRI studies on histaminergic itch which used a different methodology . In terms of sex differences, we found trends towards higher mean and peak itch intensities in women ( P = .056 and .073, respectively) paralleled by a much stronger positive correlation between itch intensity and BOLD activity in itch processing brain structures in women in comparison with men ( r s in women: .46, r s in men: .07).…”

Section: Discussionsupporting

confidence: 90%

“…Hence, it seems plausible that the higher itch intensities in women are reflected by increased activity in itch processing brain structures. However, we could not demonstrate higher activity in women specifically in structures reported to be involved in the processing of itch intensity (eg primary somatosensory cortex, the ACC, claustrum and insula) to corroborate this assumption.…”

Section: Discussioncontrasting

confidence: 84%

“…We are aware that the used itch model is only a crude approximation to itch in skin diseases, which is usually caused by a complex interplay of various itch mediators and neuromodulating factors including peripheral and central sensitisation . Additional ‘peripheral’ reasons not assessed in our study may contribute to sex differences in itch.…”

Section: Discussionmentioning

confidence: 97%

“…The results of the few murine and human studies available investigating sex differences using standardised itch models are inconsistent . Functional magnetic resonance imaging (fMRI) is a method which is becoming increasingly used in itch research to indirectly visualise central itch processing, thereby allowing a more objective examination of this subjective sensation . The cerebral representation of itch includes the thalamus, prefrontal cortex (PFC), supplementary motor area (SMA), premotor area (PMA), primary motor cortex, primary and secondary somatosensory cortex (S1,2), parietal cortex, anterior (ACC) and posterior cingulate cortex, precuneus, insula, basal ganglia, the midbrain and cerebellum .…”

Section: Introductionmentioning

confidence: 99%

“…Functional magnetic resonance imaging (fMRI) is a method which is becoming increasingly used in itch research to indirectly visualise central itch processing, thereby allowing a more objective examination of this subjective sensation . The cerebral representation of itch includes the thalamus, prefrontal cortex (PFC), supplementary motor area (SMA), premotor area (PMA), primary motor cortex, primary and secondary somatosensory cortex (S1,2), parietal cortex, anterior (ACC) and posterior cingulate cortex, precuneus, insula, basal ganglia, the midbrain and cerebellum . The sensory (ACC, insula and thalamus), motor (PMA and cerebellum), emotional (ACC, insula and thalamus), attentional (S2), executive/decisional (PFC and nucleus caudatus) and memory‐related (precuneus and S2) components of itch are simultaneously processed within this functional network …”

Section: Introductionmentioning

confidence: 99%

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Assessment of the impact of sex in intensity, skin flares and central processing of histaminergic itch—A pilot study

Mueller

Reinhardt

et al. 2019

Experimental Dermatology

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Itch is the commonest skin‐related symptom, and sex differences are increasingly recognised as important determinants in stratified medicine, but only little is known about sex differences in itch. Questionnaire‐based studies indicated that women perceive itch as more intensive and bothersome in comparison with men. However, data of studies using standardised itch models to objectify sex differences are scarce and inconsistent. To determine sex differences in intensity, skin flares and central processing of histaminergic itch, we compared 15 female and 15 male healthy subjects in a double‐blinded, within‐subject, placebo‐controlled study using a histamine skin prick itch model (histamine 1% applied onto the volar forearm) and functional MRI. We found trends in higher mean itch intensity (0.58 VAS, CI 95% 0.004‐1.19, P = .056) and maximum itch intensity (men 3.93 VAS ± 0.39 SD at 3 minutes, women 4.73 VAS ± 0.31 SD at 4 minutes, P = .073) in women paralleled by a trend in a stronger positive correlation between itch intensity and blood oxygen level–dependent (BOLD) activity in brain structures identified during itch in comparison with men (rs in women: .46, P = .08, rs in men: .07, P = .79). The erythema and wheal following histamine skin pricking were (non‐significantly) larger in men, indicating that higher mean itch intensities on the right volar forearm in women may not be explained by more intense flares. The comparison of the activation patterns between the sexes revealed increased activity in men compared to women in the left middle temporal gyrus (temporooccipital part)/lateral occipital cortex. Thus, our findings indicate that histaminergic itch perception and central itch processing differ between the sexes under standardised conditions.

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Section: Discussionsupporting

confidence: 90%

Section: Discussioncontrasting

confidence: 84%

Section: Discussionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Assessment of the impact of sex in intensity, skin flares and central processing of histaminergic itch—A pilot study

Mueller

Reinhardt

et al. 2019

Experimental Dermatology

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The Dysfunction of the Cerebellum and Its Cerebellum-Reward-Sensorimotor Loops in Chronic Spontaneous Urticaria

et al. 2018

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Chronic spontaneous urticaria (CSU) is a common itchy skin disease. Despite its prevalence, the neuropathology of CSU is uncertain. In this study, we explored resting state functional connectivity (rs-FC) changes in CSU, as well as how the symptom changes following intervention can modulate rs-FC. Forty patients and 40 healthy controls (HCs) were recruited. Following an intervention, 32 patients participated in a second scan approximately 6 weeks after the first scan. Compared with healthy controls, CSU subjects exhibited higher regional homogeneity (ReHo) values in the cerebellum, which were positively associated with urticaria activity scores over 7 days (UAS7) at baseline. After an intervention accompanied with clinical improvement, we found that ReHo values decreased at the cerebellum and increased at the bilateral primary somatosensory cortex (SI)/primary motor cortex (MI)/supplementary motor area (SMA). Using the cerebellum as a seed, CSU subjects exhibited increased rs-FC with reward regions when compared with HCs and exhibited decreased rs-FC at the right orbitofrontal cortex and right sensorimotor region following the intervention. The improvement rate values were positively associated with reduced rs-FC values in the two regions. Using the cluster of SI/MI/SMA as a seed, CSU patients exhibited decreased rs-FC with the left putamen, caudate, accumbens, and thalamus following the intervention. These results demonstrate the altered cerebellar activity and cerebellum-reward-sensorimotor loops in CSU.

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Delusions of Parasitosis: An Update

Reich

Kwiatkowska

Pacan³

2019

Dermatol Ther (Heidelb)

100

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Delusional parasitosis, also known as delusional infestation or Ekbom syndrome, is a relatively infrequent psychotic disorder characterized by an unwavering false belief that there is a parasitic infestation of the skin, despite the absence of any medical evidence that could support this claim. Delusional parasitosis can be categorized into primary, secondary, and organic forms. Sometimes, close relatives also experience identical delusions. This phenomenon was reported to occur in 5–15% of cases, and is known as shared psychotic disorder–delusional parasitosis with folie à deux. Patients with delusional parasitosis frequently seek help from many physicians. Close multidisciplinary cooperation between clinicians is often key to shortening the time taken to diagnose this disorder. Initiation of psychopharmacological therapy is a challenge, as many patients refuse any psychiatric treatment because of the stigma associated with mental illness and because of their firm belief that they have a parasitic infestation, not a psychiatric condition. For many patients, a sense of a lack of understanding leads to isolation and the development of depression symptoms, which is why it is crucial to earn the trust of such patients while taking care of them.

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Functional magnetic resonance imaging in dermatology: The skin, the brain and the invisible

Cited by 32 publications

References 147 publications

Assessment of the impact of sex in intensity, skin flares and central processing of histaminergic itch—A pilot study

Assessment of the impact of sex in intensity, skin flares and central processing of histaminergic itch—A pilot study

The Dysfunction of the Cerebellum and Its Cerebellum-Reward-Sensorimotor Loops in Chronic Spontaneous Urticaria

Delusions of Parasitosis: An Update

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