Karl Egger

A widespread distinct pattern of cerebral atrophy in patients with alcohol addiction revealed by voxel-based morphometry

Background: Patients with alcohol addiction show a number of transient or persistent neurological and psychiatric deficits. The complexity of these brain alterations suggests that several brain areas are involved, although the definition of the brain alteration patterns is not yet accomplished. Aim: To determine brain atrophy patterns in patients with alcohol dependence. Methods: Voxel-based morphometry (VBM) of grey matter (GM) and white matter (WM) was performed in 22 patients with alcohol dependence and in 22 healthy controls matched for age and sex. Results: In patients with alcohol dependence, VBM of GM revealed a significant decrease in density (p<0.001) in the precentral gyrus, middle frontal gyrus, insular cortex, dorsal hippocampus, anterior thalamus and cerebellum compared with controls. Reduced density of WM was found in the periventricular area, pons and cerebellar pedunculi in patients with alcohol addiction. Conclusions: Our findings provide evidence that alcohol addiction is associated with altered density of GM and WM of specific brain regions. This supports the assumption that alcohol dependence is associated with both local GM dysfunction and altered brain connectivity. Also, VBM is an effective tool for in vivo investigation of cerebral atrophy in patients with alcohol addiction.

Imaging early practice effects in arithmetic.

A better understanding of learning processes in arithmetic in healthy adults can guide research into learning disabilities such as dyscalculia. The goal of the present functional magnetic resonance imaging study was to investigate the ongoing process of learning itself. No training was provided prior to the scanning session. Training consisted in a higher frequency of repetition for one set of complex multiplication problems (repeated) and a lower frequency for the other set (novel). Repeated and novel problems were presented randomly in an event-related design. We observed activation decreases due to training in fronto-parietal areas and the caudate nucleus, and activation increases in temporo-parietal regions such as the left angular gyrus. Training effects became significant after approximately eight repetitions of a problem and remained stable over the course of the experiment. The change in brain activation patterns observed was similar to the results of previous neuroimaging studies investigating training effects in arithmetic after a week of extensive training. The paradigm employed seems to be a suitably sensitive tool to investigate and compare learning processes on group level for different populations. Furthermore, on a more general level, the early and robust changes in brain activation in healthy adults observed here indicate that repeating stimuli can profoundly and quickly affect fMRI results.

Voxel based morphometry reveals specific gray matter changes in primary dystonia.

The present study assessed patterns of brain tissue alterations in different types of primary dystonia using voxel‐based morphometry (VBM). Nine patients with primary generalized dystonia (GD), 11 patients with primary cervical dystonia (CD), and 11 patients with primary focal hand dystonia (FHD) as well as 31 age and gender‐matched controls were included. When compared with healthy controls, patients with primary dystonia (n = 31) showed gray matter volume increase bilaterally in the globus pallidus internus, nucleus accumbens, prefrontal cortex, as well as unilaterally in the left inferior parietal lobe. This is the first study using VBM in patients with different types of primary dystonia, showing a common pattern of gray matter changes.

Pattern of brain atrophy in elderly patients with depression revealed by voxel-based morphometry

In this study, we explored to what extent brain abnormalities can be identified in specific brain structures of patients suffering from late onset depression. We examined the structural difference in regional gray and white matter volume between 14 community-dwelling patients suffering from geriatric depression and 20 age-matched non-depressed normal subjects by voxel-based morphometry (VBM) based on magnetic resonance imaging. All subjects also underwent an extensive neuropsychological assessment. Compared with control subjects, patients with depression were impaired in measures of verbal and visual memory, construction, executive ability, and information-processing speed. VBM of gray matter revealed a significant decrease of volume in the right rostral hippocampus, in the right amygdala and in the medial orbito-frontal cortex (gyrus rectus) bilaterally. In the correlation analysis of gray matter volume with the score of the geriatric depression scale, we observed a negative correlation with the medial orbito-frontal cortex (gyrus rectus) bilaterally. There were no differences in white matter volumes between patients with depression and healthy control subjects. The most important limitation of this study was sample size. A larger sample size may have improved detection of changes not reaching significance. Furthermore, our results may not be generalizable across depression severity or to hospitalized patients. The findings are consistent with our hypothesis that depression in the elderly is associated with local gray matter dysfunction.

Cortical atrophy in the cerebellar variant of multiple system atrophy: a voxel-based morphometry study.

This study aimed to determine in vivo the atrophy patterns in clinically established cerebellar variant of multiple‐system atrophy (MSA‐C) using voxel‐based morphometry (VBM). Thirteen patients with MSA‐C (12 probable, 1 possible) and 13 healthy controls matched for age and sex were included. High‐resolution MR images were acquired with a 1.5 T scanner. Images were normalized onto a study‐specific template, segmented into the tissue compartments, modulated with the Jacobian determinants, and finally smoothed with a Gaussian kernel filter of 10 mm. The general linear model was used to assess statistical differences in gray and white matter. Infratentorial atrophy was observed in the cerebellar hemispheres, vermis, mesencephalon, and pons of MSA‐C patients. Supratentorial volume loss was found in orbitofrontal and mid‐frontal regions as well as in temporomesial and insular areas of both hemispheres. A negative correlation was observed between a cerebellar ataxia score and the volume of cerebellar hemispheres, peduncles, and pons. To compare this atrophy pattern to that of spinocerebellar ataxia (SCA2), which was previously reported by our group, a conjunction analysis was assessed. We observed a volume loss shared by both disorders comprising the cerebellum, vermis, pons, mesencephalon, orbitofrontal, mid‐frontal, and temporomesial cortex of both hemispheres as well as the left insular cortex.

Are Numbers Special? Comparing the Generation of Verbal Materials From Ordered Categories (Months) to Numbers and Other Categories (Animals) in an fMRI Study

Months, days of the week, and numbers differ from other verbal concepts because they are ordered in a sequence, whereas no order is imposed on members of other categories, such as animals or tools. Recent studies suggest that numbers activate a representation of their quantity within the intraparietal sulcus (IPS) automatically, that is, in tasks that do not require the processing of quantity. It is unclear, however, whether ordered verbal materials in general and not only numbers activate the IPS in such tasks. In the present functional magnetic resonance imaging study word generation of months, numbers, and animals were compared. Word generation of numbers and nonnumerical materials from an ordered category (months) activated the IPS more strongly than generating items from a not‐ordered category such as animals or the verbal control conditions. An ROI analysis of three subregions within the anterior IPS revealed that the most anterior and lateral of these regions, human intraparietal area hIP2, shows a greater sensitivity to ordered materials than the other two areas, hIP1 and hIP3. Interestingly, no difference in activation was observed within the IPS between numbers and months suggesting that the activation of the IPS might not be modulated by the additional quantity information carried by numbers. Hum Brain Mapp, 2008.

Diffusion-weighted imaging in Huntington's disease

Huntingtons disease (HD) is an autosomal dominant progressive neurodegenerative disorder that results from an expanded trinucleotide (CAG) repeat on the huntingtin gene. Neurodegeneration in HD affects most prominently the basal ganglia. Therefore, diffusivity was obtained in the basal ganglia and thalamus of 29 patients with early HD and 27 healthy volunteers by means of the trace of the diffusion tensor (Trace(D)). Putaminal, caudate, pallidal, and thalamic Trace(D) values were increased in patients with HD compared with controls. Increased diffusivity in the putamen and caudate nucleus correlated with global functional impairment, CAG repeat length, as well as bicaudate ratio. Diffusion‐weighted imaging appears to be a promising surrogate marker for disease severity in HD. Sensitivity to change remains to be established longitudinally.

Differentiation of neurodegenerative parkinsonian syndromes by volumetric magnetic resonance imaging analysis and support vector machine classification.

Clinical differentiation of parkinsonian syndromes is still challenging.

Manual MRI morphometry in Parkinsonian syndromes

Background: Several morphometric magnetic resonance imaging parameters may serve for differential diagnosis of parkinsonism. The objective of this study was to identify which performs best in clinical routine.

Neurocognition and brain structure in pediatric patients with type 1 diabetes

Recent findings suggest that in addition to severe hypoglycemia, chronic hyperglycemia may also hamper the cognitive development of patients with type 1 diabetes. Executive and memory dysfunctions mediated by frontoparietal and temporal brain structures are frequently reported to be associated with type 1 diabetes. However, most studies investigating pediatric patients with diabetes focus on either brain function or brain structure. The current study combines neuropsychological and structural brain imaging methods (i.e., voxel-based-morphometry) to study the neurofunctional integrity of frontoparietal brain areas. We investigated 30 children with type 1 diabetes and 19 healthy controls. Children with diabetes were divided into two groups representing better (HbA1c ≤ 7.9%) and worse (HbA1c ≥ 8.0%) glycemic con- trol. Our findings were threefold: First, results revealed significant group differences with respect to neuropsychological performance (i.e. response accuracies on a marker task tapping frontoparietal brain functions). Second, structural imaging disclosed significant group differences between patients and controls regarding gray matter volume in frontal (anterior cingulate) and occipital (cuneus, bordering precuneus) brain regions and regarding white matter in middle temporal and occipital gyri as well as in the ventromedial temporal lobe (uncus). Third, disease duration, age at diagnosis and white matter volume in a hippocampal region-of-interest (but not HbA1c levels, intelligence, total gray/white matter or other white/gray matter regions-of-interest) explained 56% of neuropsycholo- gical performance variance. Taken together, our findings are among the first to provide evidence of a direct link between brain function and brain structure in pediatric patients with type 1 diabetes.