Brain structural damage in Friedreich's ataxia.

OBJECTIVE: Neuropathological descriptions of the brain in Friedreich's ataxia (FRDA) were obtained before availability of the current molecular genetic tests for this disease. Voxel-based morphometry (VBM) enables an unbiased whole-brain quantitative analysis of differences in gray matter (GM) and white matter (WM) volume. METHODS: Using VBM, we assessed the brain structural damage in 22 patients with genetically confirmed FRDA and 25 healthy controls. The results were correlated with the disease duration and the severity of the patients' clinical deficits--evaluated using the International Cerebellar Ataxia Rating Scale and Inherited Ataxia Clinical Rating Scale. RESULTS: In patients with FRDA, VBM showed a symmetrical volume loss in dorsal medulla, infero-medial portions of the cerebellar hemispheres, the rostral vermis and in the dentate region. No volume loss in cerebral hemispheres was observed. The atrophy of the cerebellum and medulla correlated with the severity of the clinical deficit and disease duration. CONCLUSIONS: In patients with FRDA, significant GM and WM loss was observed only in the cerebellum and dorsal medulla. These structural changes correlate with the severity of the clinical deficit and disease duration.

Whole-brain histogram and voxel-based analyses of apparent diffusion coefficient and magnetization transfer ratio in celiac disease, epilepsy, and cerebral calcifications syndrome.

BACKGROUND AND PURPOSE: Diffusion and magnetization transfer (MT) techniques have been applied to the investigation with MR of epilepsy and have revealed changes in patients with or without abnormalities on MR imaging. We hypothesized that also in the coeliac disease (CD), epilepsy and cerebral calcifications (CEC) syndrome diffusion and MT techniques could reveal brain abnormalities undetected by MR imaging and tentatively correlated to epilepsy. MATERIALS AND METHODS: Diffusion and MT weighted images were obtained in 10 patients with CEC, 8 patients with CD without epilepsy and 17 healthy volunteers. The whole brain apparent diffusion coefficient (ADC) and MT ratio (MTR) maps were analyzed with histograms and the Statistical Parametric Mapping 2 (SPM2) software. We employed the non-parametric Mann-Whitney U test to assess differences for ADC and MTR histogram metrics. Voxel by voxel comparison of the ADC and MTR maps was performed with 2 tails t-test corrected for multiple comparison. RESULTS: A significantly higher whole brain ADC value as compared to healthy controls was observed in CEC (P = 0.006) and CD (P = 0.01) patients. SPM2 showed bilateral areas of significantly decreased MTR in the parietal and temporal subcortical white matter (WM) in the CEC patients. CONCLUSION: Our study indicates that diffusion and MT techniques are also capable of revealing abnormalities undetected by MR imaging. In particular patients with CEC syndrome show an increase of the whole brain ADC histogram which is more pronounced than in patients with gluten intolerance. IN CEC patients, voxel-based analysis demonstrates a localized decrease of the MTR in the parieto-temporal subcortical WM.

Morphometry and 1H-MR spectroscopy of the brain stem and cerebellum in three patients with fragile X-associated tremor/ataxia syndrome.

SUMMARY: Morphometry and spectroscopy were performed in 3 patients with fragile X-associated tremor/ataxia syndrome (FXTAS). The brain stem and cerebellum were atrophic and satisfied criteria for olivopontocerebellar atrophy in 2 patients. However, the vermis was relatively spared and the basis pontis maintained its oval shape. The only spectroscopic abnormality was a decrease of the pontine N-acetylaspartate/creatine ratio in 1 patient. Atrophy and metabolic changes in FXTAS differ to some extent from those of olivopontocerebellar atrophy.

Whole-brain histogram and voxel-based analyses of diffusion tensor imaging in patients with leukoaraiosis: correlation with motor and cognitive impairment.

BACKGROUND AND PURPOSE: Cerebral white matter changes, termed leukoaraiosis (LA), appearing as areas of increased signal intensity in T2-weighted MR images, are common in elderly subjects, but the possible correlation of LA with cognitive or motor deficit has not been established. We hypothesized that histogram and voxel-based analyses of whole-brain mean diffusivity (MD) and fractional anisotropy (FA) maps calculated from diffusion tensor imaging (DTI) could be more sensitive tools than visual scales to investigate the clinical correlates of LA. MATERIALS AND METHODS: Thirty-six patients of the Leukoaraiosis and Disability Study were evaluated with fluid-attenuated inversion recovery for LA extension, T1-weighted images for volume, and DTI for MD and FA. The extent of LA was rated visually. The normalized total, gray, and white matter brain volumes were computed, as well as the 25th percentile, 50th percentile, kurtosis, and skewness of the MD and FA maps of the whole brain. Finally, voxel-based analysis on the maps of gray and white matter volume, MD, and FA was performed with SPM2 software. Correlation analyses between visual or computerized data and motor or neuropsychologic scale scores were performed using the Spearman rank test and the SPM2 software. RESULTS: The visual score correlated with some MD and FA histogram metrics (P<.01). However, only the 25th and 50th percentiles, kurtosis, and skewness of the MD and FA histograms correlated with motor or neuropsychologic deficits. Voxel-based analysis revealed a correlation (P<.05 corrected for multiple comparisons) between a large cluster of increased MD in the corpus callosum and pericallosal white matter and motor deficit. CONCLUSIONS: These results are consistent with the hypothesis that histogram and voxel-based analyses of the whole-brain MD and FA maps are more sensitive tools than the visual evaluation for clinical correlation in patients with LA.

Brainstem neurodegeneration correlates with clinical dysfunction in SCA1 but not in SCA2. A quantitative volumetric, diffusion and proton spectroscopy MR study.

Magnetic resonance (MR) techniques enable in vivo measurement of the atrophy of the brainstem and cerebellum in spinocerebellar ataxia type 1 (SCA1) and 2 (SCA2) patients, which is accompanied by a decrease in the concentration of N-acetyl aspartate (NAA) or of the NAA/creatine ratio in the pons and cerebellum. Mean diffusivity (D) is emerging as an additional sensitive and quantitative MR parameter to investigate brain diseases. In order to explore differences between the MR features of SCA1 and SCA2 and correlate the MR and clinical findings in the two conditions, we examined 16 SCA1 patients, 12 SCA2 patients and 20 healthy control subjects. The MR protocol included T1-weighted 3D gradient echo sequences, single-voxel proton spectroscopy of the right cerebellar hemisphere (dentate and peridentate region) and of the pons with a PRESS sequence and an external reference quantitation method, and (in nine patients with SCA1 and nine patients with SCA2) diffusion-weighted echo-planar images with reconstruction of the D maps. The patients were evaluated with the Inherited Ataxia Clinical Rating Scale (IACRS). Compared with control subjects, the SCA1 and SCA2 patients showed a decrease (P < 0.01) in the volume of the brainstem and cerebellum and in the concentration of NAA in the pons and cerebellar hemisphere, whereas D of the brainstem and cerebellum was increased. No significant difference was observed between the SCA1 and SCA2 patient groups. No correlation between cerebellar volume and dentate and peridentate NAA concentration was found in SCA1 or SCA2 patients. The volume of the brainstem, D of the brainstem and cerebellum and the concentration of NAA in the pons were correlated (P < 0.05) with the IACRS score in SCA1 but not in SCA2. This discrepancy is in line with the clinical observation that the clinical deficit has a later onset and faster progression in SCA1 and an earlier onset and slower progression in SCA2, and suggests that neurodegeneration of the brainstem is a comparatively more rapid process in SCA1. In conclusion, our study indicates that SCA1 and SCA2 substantially exhibit the same MR features. The correlation in SCA1 between clinical severity and quantitative volumetric, diffusion MRI and proton MR spectroscopy findings in the brainstem indicates that these measurements might be employed for longitudinal studies and hopefully as surrogate markers in future pharmacological trials of this condition.

Progression of microstructural damage in spinocerebellar ataxia type 2: a longitudinal DTI study.

BACKGROUND AND PURPOSE: The ability of DTI to track the progression of microstructural damage in patients with inherited ataxias has not been explored so far. We performed a longitudinal DTI study in patients with spinocerebellar ataxia type 2. MATERIALS AND METHODS: Ten patients with spinocerebellar ataxia type 2 and 16 healthy age-matched controls were examined twice with DTI (mean time between scans, 3.6 years [patients] and 3.3 years [controls]) on the same 1.5T MR scanner. Using tract-based spatial statistics, we analyzed changes in DTI-derived indices: mean diffusivity, axial diffusivity, radial diffusivity, fractional anisotropy, and mode of anisotropy. RESULTS: At baseline, the patients with spinocerebellar ataxia type 2, as compared with controls, showed numerous WM tracts with significantly increased mean diffusivity, axial diffusivity, and radial diffusivity and decreased fractional anisotropy and mode of anisotropy in the brain stem, cerebellar peduncles, cerebellum, cerebral hemisphere WM, corpus callosum, and thalami. Longitudinal analysis revealed changes in axial diffusivity and mode of anisotropy in patients with spinocerebellar ataxia type 2 that were significantly different than those in the controls. In patients with spinocerebellar ataxia type 2, axial diffusivity was increased in WM tracts of the right cerebral hemisphere and the corpus callosum, and the mode of anisotropy was extensively decreased in hemispheric cerebral WM, corpus callosum, internal capsules, cerebral peduncles, pons and left cerebellar peduncles, and WM of the left paramedian vermis. There was no correlation between the progression of changes in DTI-derived indices and clinical deterioration. CONCLUSIONS: DTI can reveal the progression of microstructural damage of WM fibers in the brains of patients with spinocerebellar ataxia type 2, and mode of anisotropy seems particularly sensitive to such changes. These results support the potential of DTI-derived indices as biomarkers of disease progression.

Longitudinal evaluation of leukoaraiosis with whole brain ADC histograms.

FLAIR and diffusion-weighted MRI were obtained twice (mean interval 20 +/- 4 months) in 10 patients with leukoaraiosis. At follow-up, visual extension of leukoaraiosis was unchanged, whereas the median of whole brain apparent diffusion coefficient (WB-ADC) histogram was increased (p= 0.008) and brain volume index (BVI) was decreased (p = 0.006). WB-ADC histogram and BVI are sensitive to leukoaraiosis and might be considered for monitoring progression of the disease.

Regional distribution and clinical correlates of white matter structural damage in Huntington disease: a tract-based spatial statistics study.

BACKGROUND AND PURPOSE: HD entails damage of the WM. Our aim was to explore in vivo the regional volume and microstructure of the brain WM in HD and to correlate such findings with clinical status of the patients. MATERIALS AND METHODS: Fifteen HD gene carriers in different clinical stages of the disease and 15 healthy controls were studied with T1-weighted images for VBM and DTI for TBSS. Maps of FA, MD, and λ∥ and λ⊥ were reconstructed. RESULTS: Compared with controls, in addition to neostriatum and cortical GM volume loss, individuals with HD showed volume loss in the genu of the internal capsule and subcortical frontal WM bilaterally, the right splenium of the corpus callosum, and the left corona radiata. TBSS revealed symmetrically decreased FA in the corpus callosum, fornix, external/extreme capsule, inferior fronto-occipital fasciculus, and inferior longitudinal fasciculus. Areas of increased MD were more extensive and included arciform fibers of the cerebral hemispheres and cerebral peduncles. Increase of the λ∥ and a comparatively more pronounced increase of the λ⊥ underlay the decreased FA of the WM in HD. Areas of WM atrophy, decreased FA, and increased MD correlated with the severity of the motor and cognitive dysfunction, whereas only the areas with increased MD correlated with disease duration. CONCLUSIONS: Microstructural damage accompanies volume decrease of the WM in HD and is correlated with the clinical deficits and disease duration. MR imaging-based measures could be considered as a biomarker of neurodegeneration in HD gene carriers.

Magnetization transfer MR imaging demonstrates degeneration of the subcortical and cortical gray matter in Huntington disease.

BACKGROUND AND PURPOSE: GM is typically affected in HD since the presymptomatic stage. Our aim was to investigate with MT MR imaging the microstructural changes of the residual brain subcortical and cortical GM in carriers of the HD gene and to preliminarily assess their correlation with the clinical features. MATERIALS AND METHODS: Fifteen HD gene carriers with a range of clinical severity and 15 age- and sex-matched healthy controls underwent MT MR imaging on a 1.5T scanner. The MT ratio was measured automatically in several subcortical and cortical GM regions (striatal nuclei; thalami; and the neocortex of the frontal, temporal, parietal, and occipital lobes) by using FLS tools. RESULTS: The MT ratio was significantly (P < .05 with Bonferroni correction for multiple comparison) decreased in all subcortical structures except the putamen and decreased diffusely in the cerebral cortex of HD carriers compared with controls. Close correlation was observed between the subcortical and cortical regional MT ratios and several clinical variables, including disease duration, motor disability, and scores in timed neuropsychological tests. CONCLUSIONS: MT imaging demonstrates degeneration of the subcortical and cortical GM in HD carriers and might serve, along with volumetric assessment, as a surrogate marker in future clinical trials of HD.

Early structural changes in individuals at risk of familial Alzheimer's disease: a volumetry and magnetization transfer MR imaging study.

Presenilin 1 (PS1) mutation carriers provide the opportunity to asses early features of neurodegeneration in familial Alzheimer's disease (AD). Gray matter (GM) regional volume loss and decrease of magnetization transfer ratio (MTR) consistent with microstructural changes have been reported in sporadic AD. We performed a regional volumetric and MTR analysis in carriers of PS1 mutations. Six non-demented mutated PS1 carriers (5 with memory deficits) and 14 healthy subjects were examined with high resolution T1-weighted images for volumetry and with T2* weighted images for MTR. Cortical GM volume and MTR values were derived. Compared to healthy controls, the GM volume of the left temporal and inferior parietal cortex and the MTR of the temporal cortex bilaterally were significantly decreased in PS1 gene carriers. In the latter, the temporal lobe MTR showed a trend for correlation with memory and executive function scores. Early neurodegeneration in non-demented subjects at risk for familial AD may be associated with atrophy and decreased MTR in the temporal cortex.

A whole-brain analysis in de novo Parkinson disease.

BACKGROUND AND PURPOSE: Widespread cerebral changes are observed in advanced stages of Parkinson disease (PD), suggesting that PD is a multisystem disorder. We investigated with MR imaging whether global brain changes are present in early clinical stages of PD and correlated the findings with the type of clinical presentation. MATERIALS AND METHODS: T1-weighted images and mean diffusivity and fractional anisotropy (FA) maps calculated from diffusion tensor imaging (DTI) were obtained in 27 patients with de novo drug-naïve PD, who were classified according to the clinical features in tremor-dominant type (n = 13), akinetic-rigid type (n = 11), and mixed type (n = 3). Sixteen healthy subjects provided control data. With SIENAX software, total brain, gray matter (GM), and white matter (WM) volumes were computed from T1-weighted images, whereas brain histograms were obtained from mean diffusivity and FA maps. RESULTS: Total brain, GM and WM volumes were not significantly different in patients as a whole or subgroups and controls. As compared with controls, patients with PD as a whole and patients with the akinetic-rigid type showed an increase (P

Paroxysmal arousal in epilepsy associated with cingulate hyperperfusion.

A patient with nocturnal frontal lobe epilepsy characterized by paroxysmal motor attacks during sleep had brief paroxysmal arousals (PAs), complex episodes of nocturnal paroxysmal dystonia, and epileptic nocturnal wandering since childhood. Ictal SPECT during an episode of PA demonstrated increased blood flow in the right anterior cingulate gyrus and cerebellar cortex with hypoperfusion in the right temporal and frontal associative cortices.