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Itch is a sensation defined as the urge to scratch. The central mechanisms of itch are being increasingly studied. These studies are usually based on experimental itch induction methods, which can be classified into the following categories: histamine‐induced, induction by other non‐histamine chemicals (e.g. cowhage), physically induced (e.g. electrical) and mentally induced (e.g. audio‐visual). Because pain has been more extensively studied, some extrapolations to itch can be proposed and verified by experiments. Recent studies suggest that the itch‐processing network in the brain could be disrupted in certain diseases. This disruption could be related to the implication of new regions or the exclusion of already engaged brain regions from itch‐processing network in the brain. [ABSTRACT FROM AUTHOR]

Background: Despite the prevalence of psoriasis, the processing of itch in psoriasis and its impact on the central nervous system (CNS) remain unclear. Objective: We studied the influence of psoriasis on the CNS using magnetic resonance imaging techniques (fMRI and DTI, respectively) to investigate whether mentally induced itch can modify the functional connectivity or the white matter microstructure of the brain. Methods: Fourteen patients with chronic psoriasis and 15 healthy controls were recruited. Itch was mentally induced in subjects by videos showing others scratching themselves. Results: The observation of functional connectivity during the viewing the video revealed an interconnected network of brain regions that are more strongly coupled in psoriasis patients than in healthy controls. This network links the cerebellum, the thalami, the anteroposterior cingulum, the inferior parietal lobules, the middle temporal poles and the parahippocampal, hippocampal, lingual and supramarginal gyri. We also found connections with the right precuneus and both left insula and superior temporal gyrus. The DTI analysis showed that chronic itch affects the microstructure of white matter, including the anterior thalamic radiations, the superior and inferior longitudinal fasciculi, the corticospinal tracts, the cingulum, the external capsules, the inferior frontal‐occipital fasciculi and both minor and major forceps. Conclusion: Our results indicate that there could exist a network which is more interconnected in psoriasis patients. Among two building blocks of this network, the subnetwork encoding the perception and control of itch sensation is more affected than the subnetwork representing mentalizing and empathy. With an approach consisting of measuring microstructural changes at a local level in the brain, we also contradict the findings obtained with global measures which stated that chronic psoriasis cannot alter the anatomy of the brain. This confirms that itchy pathophysiological conditions have similar effects on functional and structural connectivity as those observed in chronic pain. [ABSTRACT FROM AUTHOR]

Summary: Magnetic resonance imaging (MRI) and computed tomography (CT) scans were used to analyse, respectively, the soft tissues and the bones of the heads of four common dolphins and three harbour porpoises. This imaging study was completed by an examination of anatomical sections performed on two odontocete heads (a subadult common dolphin and a subadult harbour porpoise). The three complementary approaches allowed to illustrate anatomical differences in the echolocation systems of the common dolphin and the harbour porpoise. We captured images confirming strong differences of symmetry of the melon and of its connexions to the MLDB (Monkeys Lips/Dorsal Bursae) between the common dolphin and the harbour porpoise. The melon of the common dolphin is asymmetrically directly connected to the right bursae cantantes at its right side, whereas the melon of the harbour porpoise is symmetrical, and separated from the two bursae cantantes by a set of connective tissues. Another striking difference comes from the bursae cantantes themselves, less deeply located in the head of the common dolphin than in the harbour porpoise. [ABSTRACT FROM AUTHOR]

Background Magnetic resonance imaging ( MRI) is rarely used for the exploration of skin, even if studies have validated both feasibility of skin MRI and its interest for anatomical, physiological, and biochemical study of the skin. The purpose of this study is to explore moisturizing of the different skin layers using 3-T scan. Methods An MRI of the heel's skin was performed using a 23 mm coil diameter on a 3T scan with a FFE (Fast Field Echo) 3D T1-weighted sequence and a TSE (Turbo Spin Echo) calculation T2-weighted sequence (pixels size of respectively 60 and 70 μm). This study was conducted on 35 healthy volunteers, who were scanned before applying moisturizer topic and 1 h after applying it. Region of interest in the stratum corneum, the epidermis and the dermis were generated on the T2 mapping. The thickness of each layer was measured. The T1 sequence allowed accurate cross-examination repositioning to ensure the comparability of the measurements. Results Among the 35 cases, two were excluded from the analysis because of movement artifacts. Measurements before and after moisturizer topic application displayed a T2 increase of 48.94% ( P < 0.0001) in the stratum corneum and of 5.45% ( P < 0.0001) in the epidermis yet without significant difference in the dermis. There was no significant link between the thickness of the stratum corneum and the T2 increase. However, there was a strong correlation between the thickness of the stratum corneum and the thickness of the epidermis ( P < 0.001; rhô=0.72). Conclusion High-resolution MRI allows fine exploration of anatomical and physiological properties of the skin and can further be used to extend the studies of skin hydration. [ABSTRACT FROM AUTHOR]

Magnetic resonance imaging ( MRI) was used to scan the head of a common dolphin ( Delphinus delphis) in order to visualize the different adipose tissues involved in echolocation functioning and to precisely delineate their anatomical topology. MRI scans were performed on the head taken from a freshly stranded carcass and repeated after a 2-week freezing time followed by thawing. The main fatty organs of the head, that is the melon, the mandibula bulba, the bursae cantantes, and their different connections with surrounding tissues were identified and labelled. The nasal sacs, other organs of echolocation, were also identified and labelled thanks to different MRI acquisitions. The shape, the location, the type of MRI signal of each organ and of their different connections were successfully analysed on all images, and then, the images of the head fresh or after thawing were compared. No impacts of the freezing/thawing cycle on the fatty tissues of the head were identified. Different parts were distinguished in the melon on the basis of the MRI signal emitted, corresponding most likely to the internal and external melon already identified by other analytical approaches, and linked to differences in lipid composition. MRI is shown here to be a useful tool to study the functional anatomy of the organs responsible for echolocation in odontocetes, with a particularly high level of precision. [ABSTRACT FROM AUTHOR]

Background: Hippocampus is selectively susceptible to ischemic damage and it could be, in some conditions, considered as a border zone of brain ischemia. Results: We illustrate this concept with three cases of hippocampal diffusion-weighted imaging (DWI) restrictions secondary to a carotid artery dissection with an ipsilateral fetal posterior cerebral artery (PCA) in two cases and to global brain hypoperfusion consequent to a cardiac arrest in the last case. Conclusion: The hypoperfusion induced by a cardiac arrest or an internal carotid dissection with an incomplete circle of Willis promotes hippocampal ischemia in the territories of the anterior choroidal artery and the longitudinal terminal segments of the hippocampal arteries. [ABSTRACT FROM AUTHOR]

A letter to the editor is presented in response to the article on subinsular vascular lesions in the January 2007 issue.

We describe a 46-month-old child presenting with developmental delay, mild facial dysmorphism, micropenis, strabismus and striking multiple cysts of the corpus callosum who was found to have a de novo interstitial 3.1 Mb 15q24.1q24.2 microdeletion using a 244 K microarray-based comparative genomic hybridization (array-CGH). The cystic lesions were located in the anterior half of the corpus callosum and did not take up gadolinium contrast. There was no other brain abnormality, and the gyral pattern and myelination were normal. There was no history of infectious disease or vascular injury and a metabolic disease was ruled out. Such cystic lesions of the corpus callosum are exceptional in the pediatric literature. Although these brain abnormalities have not been described in other reports with 15q24 microdeletion, we believe that they might be related to the cytogenetic abnormality since the work-up for other causes was negative. We suggest that a chromosomal rearrangement should be ruled out when such corpus callosum lesions are identified.