Probabilistic diffusion tractography of the optic radiations and visual function in preterm infants at term equivalent age.

Children born prematurely have a high incidence of visual disorders which cannot always be explained by focal retinal or brain lesions. The aim of this study was to test the hypothesis that visual function in preterm infants is related to the microstructural development of white matter in the optic radiations. We used diffusion tensor imaging (DTI) with probabilistic diffusion tractography to delineate the optic radiations at term equivalent age and compared the fractional anisotropy (FA) to a contemporaneous evaluation of visual function. Thirty-seven preterm infants (19 male) born at median (range) 28(+4) (24(+1)-32(+3)) weeks gestational age, were examined at a post-menstrual age of 42 (39(+6)-43) weeks. MRI and DTI were acquired on a 3 Tesla MR system with DTI obtained in 15 non-collinear directions with a b value of 750 s/mm(2). Tracts were generated from a seed mask placed in the white matter lateral to the lateral geniculate nucleus and mean FA values of these tracts were determined. Visual assessment was performed using a battery of nine items assessing different aspects of visual abilities. Ten infants had evidence of cerebral lesions on conventional MRI. Multiple regression analysis demonstrated that the visual assessment score was independently correlated with FA values, but not gestational age at birth, post-menstrual age at scan or the presence of lesions on conventional MRI. The occurrence of mild retinopathy of prematurity did not affect the FA measures or visual scores. We then performed a secondary analysis using tract-based spatial statistics to determine whether global brain white matter development was related to visual function and found that only FA in the optic radiations was correlated with visual assessment score. Our results suggest that in preterm infants at term equivalent age visual function is directly related to the development of white matter in the optic radiations.

Ventricular enlargement as a possible measure of Alzheimer's disease progression validated using the Alzheimer's disease neuroimaging initiative database.

Ventricular enlargement may be an objective and sensitive measure of neuropathological change associated with mild cognitive impairment (MCI) and Alzheimer's disease (AD), suitable to assess disease progression for multi-centre studies. This study compared (i) ventricular enlargement after six months in subjects with MCI, AD and normal elderly controls (NEC) in a multi-centre study, (ii) volumetric and cognitive changes between Apolipoprotein E genotypes, (iii) ventricular enlargement in subjects who progressed from MCI to AD, and (iv) sample sizes for multi-centre MCI and AD studies based on measures of ventricular enlargement. Three dimensional T(1)-weighted MRI and cognitive measures were acquired from 504 subjects (NEC n = 152, MCI n = 247 and AD n = 105) participating in the multi-centre Alzheimer's Disease Neuroimaging Initiative. Cerebral ventricular volume was quantified at baseline and after six months using semi-automated software. For the primary analysis of ventricle and neurocognitive measures, between group differences were evaluated using an analysis of covariance, and repeated measures t-tests were used for within group comparisons. For secondary analyses, all groups were dichotomized for Apolipoprotein E genotype based on the presence of an epsilon 4 polymorphism. In addition, the MCI group was dichotomized into those individuals who progressed to a clinical diagnosis of AD, and those subjects that remained stable with MCI after six months. Group differences on neurocognitive and ventricle measures were evaluated by independent t-tests. General sample size calculations were computed for all groups derived from ventricle measurements and neurocognitive scores. The AD group had greater ventricular enlargement compared to both subjects with MCI (P = 0.0004) and NEC (P < 0.0001), and subjects with MCI had a greater rate of ventricular enlargement compared to NEC (P = 0.0001). MCI subjects that progressed to clinical AD after six months had greater ventricular enlargement than stable MCI subjects (P = 0.0270). Ventricular enlargement was different between Apolipoprotein E genotypes within the AD group (P = 0.010). The number of subjects required to demonstrate a 20% change in ventricular enlargement was substantially lower than that required to demonstrate a 20% change in cognitive scores. Ventricular enlargement represents a feasible short-term marker of disease progression in subjects with MCI and subjects with AD for multi-centre studies.

Prevalence and risk factors for abdominal bloating and visible distention: a population-based study.

BACKGROUND: Abdominal bloating and visible distention are common yet poorly understood symptoms. Epidemiological data distinguishing visible distention from bloating are not available. We aimed to evaluate the prevalence and potential risk factors for abdominal bloating and visible distention separately in a representative US population, and their association with other functional gastrointestinal disorders (FGIDs). METHODS: The validated Talley Bowel Disease Questionnaire was mailed to a cohort selected at random from the population of Olmsted County, Minnesota. The complete medical records of responders were abstracted; 2259 subjects (53% females; mean age 62 years) provided bloating and distention data. RESULTS: The age and sex-adjusted (US White 2000) overall prevalence per 100 for bloating was 19.0 [95% confidence interval (CI), 16.9 to 21.2] vs 8.9 (95% CI, 7.2 to 10.6) for visible distention. Significantly increased odds for bloating alone and separately for distention (vs neither) were detected in females, and in those with higher overall Somatic Symptom Checklist (SSC) scores and higher scores of each individual SSC item. Further, females [odds ratio (OR), 1.5; 95% CI, 1.0 to 2.1], higher SSC score (OR, 1.4; 95% CI, 1.1 to 1.8), constipation-predominant irritable bowel syndrome (OR, 2.3; 95% CI, 1.3 to 4.1), dyspepsia (OR, 1.9; 95% CI, 1.1 to 3.2), and gastro-intestinal symptom complex overlap (OR, 1.7; 95% CI, 1.1 to 2.7) significantly increased odds for distention over bloating alone. CONCLUSIONS: Bloating and distention are common and have similar risk factors; somatisation probably plays a role.

Cranial magnetic resonance imaging and school performance in very low birth weight infants in adolescence.

AIM: To determine whether neurological deficits are associated with structural anomalies of the brain in very low birthweight (VLBW) infants with subsequent learning disorders but without cerebral palsy, or whether other factors, such as poor early growth, are responsible. METHODS: Eighty seven VLBW infants and eight term controls who had been examined at school between the ages of 12 and 13 years, had cranial magnetic resonance imaging (MRI) scans at 15-17 years of age. RESULTS: Thirty seven (42.5%) of the VLBW children had abnormalities reported on their scans (two porencephaly, 28 periventricular leucomalacia, 24 ventricular dilatation, and 15 thinning of the corpus callosum). No significant differences in intelligence quotient, motor clumsiness, or frequency of attention deficit / hyperactivity disorder were observed between those children with MRI lesions and those with normal scans. Quantitative measurements showed the VLBW infants had smaller brains, and a relatively smaller corpus callosum compared with controls. No association between brain measurements and school performance was observed among the VLBW infants. CONCLUSIONS: The difficulties experienced by VLBW children at school are unlikely to be the result of perinatal brain injury, but they might to be attributable to the effects of poor postnatal growth.

Early language ability as a function of ventricular dilatation associated with intraventricular hemorrhage.

This study examined the impact of right and left lateral ventricle dilatation on early language function associated with intraventricular hemorrhage (IVH). Because language is controlled primarily by the left cerebral hemisphere, it was hypothesized that language ability would be related to extent of left side dilatation more than to right. The relations of the number of other common complications of prematurity and socioeconomic status to language also were explored, and their independent contributions to the variance in the outcome were determined. The receptive and expressive language abilities of 45 low birth weight preterms, 18 of whom suffered IVH, were evaluated at a mean age of 16 months. Correlational analyses indicated that left, but not right, ventricle dilatation was inversely related to the expressive language measure. Partial correlations, holding the effects of medical complications and socioeconomic status constant, indicated that the impact of left ventricle dilatation was independent of these variables. Number of medical complications also had an independent relation to expressive language outcome that was equivalent to that of the left ventricle dilatation. Implications of these findings are discussed.

Altered rectal perception in irritable bowel syndrome is associated with symptom severity.

BACKGROUND & AIMS: Diverging results exist regarding the connection between altered visceral perception and gastrointestinal (GI) symptoms, as well as the effects of psychological status on visceral sensitivity. We sought to investigate different aspects of rectal perception in irritable bowel syndrome (IBS) and the association with GI and psychological symptoms. METHODS: We included 109 patients with IBS meeting Rome II criteria (77 women; age range, 20-71 years) and 29 healthy controls (21 women; age range, 20-68 years). They underwent rectal balloon distentions determining sensory thresholds for discomfort and pain, the perceived intensity of unpleasantness, and the viscerosomatic referral area. The fifth percentile (thresholds) and 95th percentile (unpleasantness and referral area) in controls were used to define altered perception. Questionnaires were used to assess severity of IBS-related GI symptoms and psychological symptoms. RESULTS: When combining the 3 aspects of perception, 67 patients (61%) had altered rectal perception. These patients, compared with normosensitive patients, more frequently reported moderate or severe pain (73% vs 44%; P < .01), bloating (73% vs 36%; P < .0001), diarrhea (47% vs 21%; P < .01), satiety (39% vs 13%; P < .01), and clinically significant anxiety (31% vs 12%; P < .05). In a multivariate analysis, only pain and bloating remained associated with altered rectal perception. CONCLUSIONS: Altered rectal perception is common in IBS and seems to be one important pathophysiologic factor associated with GI symptom severity in general and pain and bloating in particular. It is not just a reflection of the psychological state of the patient.