Structural and functional motor cortex asymmetry in unilateral lower limb amputation with phantom limb pain.

OBJECTIVE: The role of motor cortex reorganization in the development and maintenance of phantom limb pain (PLP) is still unclear. This study aims to evaluate neurophysiological and structural motor cortex asymmetry in patients with PLP and its relationship with pain intensity. METHODS: Cross-sectional analysis of an ongoing randomized-controlled trial. We evaluated the motor cortex asymmetry through two techniques: i) changes in cortical excitability indexed by transcranial magnetic stimulation (motor evoked potential, paired-pulse paradigms and cortical mapping), and ii) voxel-wise grey matter asymmetry analysis by brain magnetic resonance imaging. RESULTS: We included 62 unilateral traumatic lower limb amputees with a mean PLP of 5.9 (SD = 1.79). We found, in the affected hemisphere, an anterior shift of the hand area center of gravity (23 mm, 95% CI 6 to 38, p = 0.005) and a disorganized and widespread representation. Regarding voxel-wise grey matter asymmetry analysis, data from 21 participants show a loss of grey matter volume in the motor area of the affected hemisphere. This asymmetry seems negatively associated with time since amputation. For TMS data, only the ICF ratio is negatively correlated with PLP intensity (r = -0.25, p = 0.04). CONCLUSION: There is an asymmetrical reorganization of the motor cortex in patients with PLP, characterized by a disorganized, widespread, and shifted hand cortical representation and a loss in grey matter volume in the affected hemisphere. This reorganization seems to reduce across time since amputation. However, it is not associated with pain intensity. SIGNIFICANCE: These findings are significant to understand the role of the motor cortex reorganization in patients with PLP, showing that the pain intensity may be related with other neurophysiological factors, not just cortical reorganization.

Cortical plasticity in phantom limb pain: A fMRI study on the neural correlates of behavioral clinical manifestations.

The neural mechanism of phantom limb pain (PLP) is related to the intense brain reorganization process implicating plasticity after deafferentation mostly in sensorimotor system. There is a limited understanding of the association between the sensorimotor system and PLP. We used a novel task-based functional magnetic resonance imaging (fMRI) approach to (1) assess neural activation within a-priori selected regions-of-interested (motor cortex [M1], somatosensory cortex [S1], and visual cortex [V1]), (2) quantify the cortical representation shift in the affected M1, and (3) correlate these changes with baseline clinical characteristics. In a sample of 18 participants, we found a significantly increased activity in M1 and S1 as well as a shift in motor cortex representation that was not related to PLP intensity. In an exploratory analyses (not corrected for multiple comparisons), they were directly correlated with time since amputation; and there was an association between increased activity in M1 with a lack of itching sensation and V1 activation was negatively correlated with PLP. Longer periods of amputation lead to compensatory changes in sensory-motor areas; and itching seems to be a protective marker for less signal changes. We confirmed that PLP intensity is not associated with signal changes in M1 and S1 but in V1.

Ineffectiveness of information and access to health services: vulnerability to human papillomavirus.

AIM: To examine situations of vulnerability to human papillomavirus in the social representations of young women. BACKGROUND: Human papillomavirus is one of the most frequent sexually transmitted infections among women and constitutes a serious health problem among youth. This problem is embedded in psychosocial issues that promote situations of vulnerability and affect attitudes and behaviour in relation to prevention. METHODS: Qualitative study based on the theory of social representations, conducted among 64 female students in a high school in the city of Rio de Janeiro, Brazil. The study used personal semi-structured interviews, with a lexical analysis by Alceste 2010 software. FINDINGS: The inefficacy of information on the human papillomavirus pointed out individual and social vulnerabilities, and showed relationships between the difficulty of access and the perception of low quality in public health services, which also promotes institutional vulnerability. DISCUSSION: The representation of vulnerability to human papillomavirus infection is associated, not only with individual behaviours related to sexuality and gender identity but also to social and institutional conditions involving insufficient information and low quality of and ineffective access to public health services. CONCLUSION: Situations of vulnerability of young women to human papillomavirus infection influence ways of thinking and acting, when they generate feelings and behaviours that put them at risk. The social representations provided knowledge about how the participants appropriated consensual and reified universes in relation to vulnerability, influencing care and awareness of prevention. IMPLICATION FOR NURSING AND HEALTH POLICY: Situations of vulnerability, whether individual, social or institutional, warrant the attention of nurses and should be prioritized as public health policy goals to reduce the number of cases of human papillomavirus infection among younger women.

Toward an understanding of the epithelial requirement for osteogenesis in scleral mesenchyme of the embryonic chick.

Explants of scleral tissue from chick embryos of H.H. stage 29-36 (6-10 days of incubation) were used to determine if the epithelial-mesenchymal interaction which initiates scleral bone formation is cell contact, extracellular matrix, or diffusion mediated. Transfilter tissue recombinations, in which explanted interacting tissues are associated across interposing Nuclepore filters of various pore sizes and thicknesses, were performed with scleral mesenchyme and epithelium. When filters with pore sizes which would allow the passage of cell processes and diffusible substances were used, osteogenesis was initiated in the scleral mesenchyme. When cell processes were blocked with thicker filters or smaller pore sizes, bone formation still occurred, indicating that a diffusible substance mediates this tissue interaction. Further support for a diffusion-mediated interaction came from transfilter experiments using dialysis membranes to discriminate the size of the molecule(s), and Millipore filters to determine the distance over which these molecules travel. These experiments revealed that the scleral epithelial diffusible factor has a molecular weight of between 3500 and 6000 daltons, and acts over distances between 150 and 300 microns.

Cancer mortality in Rio de Janeiro.

Cancer mortality data for 1979-81 are presented for the state of Rio de Janeiro, Brazil. The population in 1980 was over 11 million, and more than 30,000 deaths (11% of the total) were certified as being due to cancer during the 3-year period. Death certification was fairly complete, and for two-thirds there was complementary medical evidence of the certified cause of death. Cancers of the stomach, lung and female breast accounted for one-third of all cancers, and cancers of the oesophagus and liver ranked 4th and 5th, respectively, among both sexes combined. Lung cancer mortality was higher in both sexes (ASR 27.9 in males, 6.1 in females) than elsewhere in Brazil. Mortality from liver cancer (ASR 5.9 in males, 4.5 in females) was more than 8 times higher than in the city of São Paulo. Cervix cancer mortality was only one-third of that of Fortaleza, a rural state. The results confirm large regional differences in the pattern of cancer mortality within Brazil.