Injuries to the Immature Optic Radiation Show Correlated Thinning of the Macular Ganglion Cell Layer.

Injuries to the immature optic radiation (OR) are associated with thinning of the retinal nerve fiber layer and corresponding visual field (VF) defects. The aim of the current study was to seek evidence for causal retrograde trans-synaptic degeneration by exploring the correspondence between the localization and extension of the injury to the OR and the structure of the macular ganglion cell complex, and the relation to VF function. Seven adults (age range 18-35) with visual dysfunction secondary to white-matter damage of immaturity and six healthy adults (age range 22-33) underwent magnetic resonance imaging (MRI). Fiber tractography was used to generate the geniculate projections to the dorsal and ventral striate cortex, delineated by retinotopic functional MRI mapping. The structure of the macular ganglion cell complex was measured with optical coherence tomography. The tractography showed overlaps between the dorsal and ventral geniculo-striate projections. However, in four patients with inferior VF defects, the dorsal projections were to a large extent traversing the space normally solely occupied by ventral projections. This is consistent with structural changes to the OR and suggests of re-organization upon injury. Diffusion parameters were significantly different between patients and controls, and most pronounced in the dorsal geniculo-striate projections, with a pattern indicating primary injury. The macular ganglion cell complex was significantly thinner in the patients and most pronounced in the superior sectors; a pattern particularly evident in the four patients with inferior VF defects. The ratio of the mean thickness of the macular ganglion cell complex in the superior and inferior sectors significantly correlated with the axial and mean diffusivities in the contra- and ipsilateral dorsal striate projections. The results suggest a causal link between injuries to the superior portion of the immature OR and secondary thinning in the macular ganglion cell complex, resulting in inferior VF defects.

Risk of Meningioma after CT of the Head.

Purpose To investigate the association between exposure to head computed tomography (CT) and subsequent risk of meningioma. Materials and Methods The study was approved by the local ethics committee. A cohort of 26 370 subjects was retrospectively collected from a radiology archive of CT examinations of the head performed from 1973 through 1992. For comparison, an age- and sex-matched cohort of 96 940 subjects who were not exposed to CT (unexposed cohort) was gathered. The risk of meningioma was assessed by using data from the Swedish Cancer Registry; however, one-third of patients with meningioma had to be excluded because they either had a prevalent meningioma or other brain tumor at the first CT examination or had undergone radiation treatment to the head. Hazard ratios (HRs) were calculated from time of exposure to the occurrence of meningioma or death or until December 31, 2010, with logistic regression. Results Comparison of exposed and unexposed cohorts showed that there was no statistically significant increase in the risk of meningioma after exposure to CT of the head (HR: 1.49; 95% confidence interval: 0.97, 2.30; P = .07). If incident cases at the time of the first CT examination were not excluded, the risk of meningioma would have been falsely increased (HR: 2.28; 95% confidence interval: 1.56, 3.33; P = .0001). Conclusion When prevalent cases of meningioma at first exposure to CT of the head are excluded, no statistically significant increase in risk of meningioma was found among exposed subjects compared with unexposed control subjects. © RSNA, 2017.

Damage to the immature optic radiation causes severe reduction of the retinal nerve fiber layer, resulting in predictable visual field defects.

PURPOSE: The aim of the present study was to seek evidence of a relationship between damage to the optic radiation (OR) in the immature brain and subsequent development of the retinal nerve fiber layer (RNFL) and associated visual manifestations. METHODS: Seven cases (2 males and 5 females ranging in age from 18 to 35 years old) were selected from a large cohort of individuals with known white matter damage of immaturity (WMDI), who had presented with visual dysfunction. They underwent magnetic resonance imaging (MRI), including diffusion-weighted MRI. Visual function was evaluated by best-corrected visual acuity and visual field (VF) testing using Goldmann perimetry and Humphrey field analyzer (HFA). RNFL thickness was measured by optical coherence tomography. RESULTS: A homogeneous lesion pattern with bilateral WMDI predominantly in the superior posterior periventricular white matter was seen in all subjects. However, as shown by white matter fiber tractography, only cases with injuries to the superior portion of the OR had corresponding inferior VF defects. In the individuals showing structural abnormalities in the OR, a commensurate reduction in the peripapillary RNFL was seen. The RNFL loss was most pronounced in the subjects suffering from the more extensive lesions, and it followed the pattern of OR damage in the sense that damage in the superior portion of the OR gave a reduced RNFL thickness in the superior part of the peripapillary RNFL. CONCLUSIONS: Primary injuries in the immature OR are associated with reduced RNFL thickness, and examination of the RNFL may be a helpful predictor of VF defects.

Location of gliomas in relation to mobile telephone use: a case-case and case-specular analysis.

The energy absorbed from the radio-frequency fields of mobile telephones depends strongly on distance from the source. The authors' objective in this study was to evaluate whether gliomas occur preferentially in the areas of the brain having the highest radio-frequency exposure. The authors used 2 approaches: In a case-case analysis, tumor locations were compared with varying exposure levels; in a case-specular analysis, a hypothetical reference location was assigned for each glioma, and the distances from the actual and specular locations to the handset were compared. The study included 888 gliomas from 7 European countries (2000-2004), with tumor midpoints defined on a 3-dimensional grid based on radiologic images. The case-case analyses were carried out using unconditional logistic regression, whereas in the case-specular analysis, conditional logistic regression was used. In the case-case analyses, tumors were located closest to the source of exposure among never-regular and contralateral users, but not statistically significantly. In the case-specular analysis, the mean distances between exposure source and location were similar for cases and speculars. These results do not suggest that gliomas in mobile phone users are preferentially located in the parts of the brain with the highest radio-frequency fields from mobile phones.

Autism spectrum disorder and underlying brain mechanism in the oculoauriculovertebral spectrum.

As part of a multidisciplinary study, the rate of autism spectrum disorder (ASD), learning disability (LD), and brain abnormalities was examined in 20 participants (12 males, 8 females; age range 8mo-17y, mean age 8y 1mo) diagnosed as falling within the oculoauriculovertebral spectrum (OAV). A neuropsychiatric examination was performed, including standardized autism diagnostic interviews. Two individuals met diagnostic criteria for autism, one for autistic-like condition, and five for autistic traits. Four patients had mild LD, three severe LD, two profound LD, and two borderline intellectual functioning. Neuroimaging indicated cerebral abnormalities in more than half of the patients. Abnormalities of white/grey matter were found in more than half of examined individuals; enlargement of ventricles in more than a third. Results indicate that at least a subgroup of ASD may be associated with errors in early embryonic brain development. Awareness of the coexistence of OAV/ASD is important in habilitation care of individuals with OAV.

Visual field defects in prematurely born patients with white matter damage of immaturity: a multiple-case study.

PURPOSE: White matter damage of immaturity may affect visual, motor and cognitive functions. This multiple-case study presents standardized perimetry results in six teenagers and young adults born prematurely with visual dysfunction due to white matter damage of immaturity of pre- or perinatal origin. METHODS: Six subjects, aged 13-25 years, born at a gestational age of 28-34 weeks, with white matter damage of immaturity documented by MRI, and optic disc appearances documented by fundus photography, were examined with manual and computerized quantitative perimetry. RESULTS: All subjects had subnormal visual field (VF) function, although the depth and extension of the VF defects differed between subjects. The inferior VF function was more deviant than the superior in all cases. The concordance between the VF defects detected with the different techniques was good, although the static computerized techniques revealed slightly more abnormality. CONCLUSION: White matter damage of immaturity may affect the VF. The lower VF is often more affected than the upper. The abnormalities can be demonstrated by both manual and computerized perimetry.