Search

Purpose Noninvasive methods are desired to predict the treatment response to Stereotactic Radiosurgery (SRS) to improve individual tumor management. In a previous study, we demonstrated that Diffusion Tensor Imaging (DTI)-derived parameter maps significantly correlate to SRS response. This study aimed to analyze and compare the predictive value of intratumoral ADC and DTI parameters in patients with meningiomas undergoing radiosurgery. Methods MR images of 70 patients treated with Gamma Knife SRS for WHO grade I meningiomas were retrospectively reviewed. MR acquisition included pre- and post-treatment DWI and DTI sequences, and subtractions were calculated to assess for radiation-induced changes in the parameter values. Results After a mean follow-up period (FUP) of 52.7 months, 69 of 70 meningiomas were controlled, with a mean volume reduction of 34.9%. Whereas fractional anisotropy (FA) values of the initial exam showed the highest correlation to tumor volume change at the last FU (CC=-0.607), followed by the differences between first and second FU values of FA (CC=-0.404) and the first longitudinal diffusivity (LD) value (CC=-0.375), the correlation coefficients of all ADC values were comparably low. Nevertheless, all these correlations, except for ADC measured at the first follow-up, reached significance. Conclusion For the first time, the prognostic value of ADC maps measured in meningiomas before and at first follow-up after Gamma Knife SRS, was compared to simultaneously acquired DTI parameter maps. Quantities assessed from ADC maps present significant correlations to the volumetric meningioma response but are less effective than correlations with DTI parameters.

Purpose:This report presents the first investigation of the radiomics value in predicting the meningioma volumetric response to gamma knife radiosurgery (GKRS). Methods:The retrospective study included 93 meningioma patients imaged by three Tesla MRI. Tumor morphology was quantified by calculating 337 shape, first- and second-order radiomic features from MRI obtained before GKRS. Analysis was performed on original 3D MR images and after their laplacian of gaussian (LoG), logarithm and exponential filtering. The prediction performance was evaluated by Pearson correlation, linear regression and ROC analysis, with meningioma volume change per month as the outcome. Results:Sixty calculated features significantly correlated with the outcome. The feature selection based on LASSO and multivariate regression started from all available 337 radiomic and 12 non-radiomic features. It selected LoG-sigma-1-0-mm-3D_firstorder_InterquartileRange and logarithm_ngtdm_Busyness as the predictively most robust and non-redundant features. The radiomic score based on these two features produced an AUC = 0.81. Adding the non-radiomic karnofsky performance status (KPS) to the score has increased the AUC to 0.88. Low values of the radiomic score defined a homogeneous subgroup of 50 patients with consistent absence (0%) of tumor progression. Conclusion:This is the first report of a strong association between MRI radiomic features and volumetric meningioma response to radiosurgery. The clinical importance of the early and reliable prediction of meningioma responsiveness to radiosurgery is based on its potential to aid individualized therapy decision making.

To examine structural connectivity of white matter tracts in patients with Pantothenate Kinase-Associated Neurodegeneration (PKAN) dystonia and identify those ones which correlate negatively to severity of symptoms.In a group of 41 patients suffering from PKAN dystonia and an age- and gender-matched control group, white matter tractography was carried out, based on diffusion tensor imaging magnetic resonance data. Postprocessing included assessment of Quantitative Anisotropy (QA) using q-space diffeomorphic reconstruction in order to reduce influence of iron accumulation in globus pallidus of patients.Whole brain tractography presented significantly reduced QA values in patients (0.282 ± 0.056, as compared to controls (0.325 ± 0.046, p 0.001). 9 fiber clusters of tracts correlated negatively to the dystonia score of patients: the middle cerebellar peduncle and the tracts of both cerebellar hemispheres as well as corpus callosum, forceps minor, the superior cortico-striate tracts and the superior thalamic radiations of both cerebral hemispheres (False Discovery Rate FDR = 0.041).The finding of a reduced global structural connectivity within the white matter and of negative correlation of motor system-related tracts, mainly those between the basal ganglia, cortical areas and the cerebellum, fits well to the concept of a general functional disturbance of the motor system in PKAN.

Clinical neuroradiology 32(2), 325-343 (2022). doi:10.1007/s00062-021-01093-3, Published by Urban & Vogel, München

Purpose To search for texture features of routine magnetic resonance imaging to predict tumor volume reduction and transient versus permanent tumor progression of vestibular schwannomas treated by Gamma Knife stereotactic radiosurgery. Materials and Methods Included were 23 patients with vestibular schwannomas treated in our center and followed over a period of 23.7–80.3 months (mean 42.7). Magnetic resonance imaging was performed on a 3-Tesla scanner and included T1-weighted images with and without contrast enhancement, T2-weighted, and fluid-attenuated inversion recovery images. Volumetric results were followed longitudinally over time and correlated to texture features as mean, minimum, maximum, standard deviation, skewness, and kurtosis of normalized signals taken from regions of interest covering the total tumor volume. Results In total, 14 tumors showed early progression during the first 5–18 months (2 cases permanent, 12 cases transient), whereas 9 tumors regressed immediately after SRS. Kurtosis of T2-weighted image intensity values turned out to predict progression best with a sensitivity and specificity of 71% and 78%. From all texture feature parameters, only the minimum of the normalized T2-weighted image intensity values correlated significantly to the final reduction of tumor volume per month (correlation coefficient = −0.634, P Conclusions Texture feature analysis helps to predict permanent versus transient enlargement and final volume reduction of schwannomas after SRS. Thus, alternative treatment strategies might be considered, mainly in large tumors, where further clinical deterioration cannot be excluded. To confirm these results, a prospective study including more cases and a longer follow-up period is necessary.

Hypofractionation has been recently considered as an alternative to improve stereotactic radiosurgery treatments of lesions close to the optic pathways. To estimate the intrinsic benefit from fractionation versus single-dose radiosurgery for perioptic lesions, the value of the alpha/beta ratio of the optic pathways needs to be known. Based on the linear quadratic (LQ) model, hypofractionation versus single-fraction SRS can be justified in cases where parts of the optic apparatus necessarily receive the full therapeutic peripheral dose, if there is a positive difference between α/s of the lesion and the α/s of the surrounding organs at risk. Furthermore, the knowledge of α/s ratios is required to calculate radiobiological dose parameters, such as the biologically effective dose (BED) and single fraction equivalent dose (SFED), and helps estimate normal tissue complication probability (NTCP), dose constraints, and retreatment doses. Only 3 alpha/beta ratios for the visual system have been published so far, varying between -0.6 and 3.06 Gy. The alpha/beta ratio of the optic pathways was estimated from a fraction equivalent plot based on a meta-analysis of 429 studies published between 2000 and June 2018. We included 15 studies with fraction sizes between 1 and 31, considering the following inclusion criteria: at least one well-documented RION case with detailed dosimetric analysis for the visual system, follow-up period (FUP) of at least 24 months, no tumor progression, no prior radiation. Additionally, we included results from our center on 68 hypofractionated treatments and 161 single-fraction SRS treatments for perioptic lesions. The fraction equivalent (FE) plot method revealed an alpha/beta ratio of the optic pathway of 1.03 Gy, confidence interval [-0.38–1.60]. Well-documented RION cases are rare in the literature; there is still not enough data to distinguish between alpha/beta ratios of the optic chiasm, the nerves, and the tracts. Optimized hypofractionation schedules were calculated for the treatment of meningiomas, chordomas, and brain metastases. Compared to single-fraction SRS, a significant intrinsic benefit from hypofractionation can be achieved, not only for perioptic malignant tumors, but for benign lesions as well, because of the very low alpha/beta ratio of the optic system of 1.03 Gy. An increased single fraction equivalent dose of up to 10% for perioptic meningiomas and of more than 25% for malignant tumors can be reached with optimized hypofractionated stereotactic radiosurgery schedules.

To demonstrate that lesions of the visual pathways due to suprasellar tumors are accompanied by alterations of the visual cortex and to see if these alterations are reversible after treatment of tumors by gamma knife radiosurgery. In 36 patients with peri-optic tumors and defects of their visual fields and in an age-matched control group, magnetic resonance imaging was performed before and after treatment. T1 weighted images were evaluated by voxel-based morphometry and correlated to the degree of visual field defects. In patients, grey matter density and cortical thickness were reduced in all parts of the occipital cortex, reaching significance (p

OBJECTIVEThe goal of this study was to identify parameters from routine T1- and T2-weighted MR sequences and diffusion tensor imaging (DTI) that best predict the volumetric changes in a meningioma after treatment with Gamma Knife radiosurgery (GKRS).METHODSIn 32 patients with meningioma, routine MRI and DTI data were measured before GKRS. A total of 78 parameters derived from first-level texture analysis of the pretreatment MR images, including calculation of the mean, SD, 2.5th and 97.5th percentiles, and kurtosis and skewness of data in histograms on a voxel-wise basis, were correlated with lesion volume change after a mean follow-up period of 3 years (range 19.5–63.3 months).RESULTSSeveral DTI-derived parameters correlated significantly with a meningioma volume change. The parameter that best predicted the results of GKRS was the 2.5th percentile value of the smallest eigenvalue (L3) of the diffusion tensor (correlation coefficient 0.739, p ≤ 0.001), whereas among the non-DTI parameters, only the SD of T2-weighted images correlated significantly with a tumor volume change (correlation coefficient 0.505, p ≤ 0.05, after correction for family-wise errors using false-detection-rate correction).CONCLUSIONSDTI-derived data had a higher correlation to shrinkage of meningioma volume after GKRS than data from T1- and T2-weighted image sequences. However, if only routine MR images are available, the SD of T2-weighted images can be used to predict control or possible progression of a meningioma after GKRS.

Purpose To demonstrate deviations of functional connectivity within the motor system in dystonic patients suffering from Pantothenate Kinase Associated Neurodegeneration, a genetic and metabolic disease, which is characterized by a primary lesion in the globus pallidus. Material and methods Functional Magnetic Resonance Imaging data were measured during resting state in 12 patients suffering from a confirmed mutation of the PANK2 gene. In this region-of-interest based analysis, data were evaluated in respect to correlation of signal time course between basal ganglia, motor-related cortical regions and cerebellum, were related to clinical data and were compared to a control group of 20 healthy volunteers. Results During resting state, correlation coefficients within the motor system were significantly lower in patients than in controls (0.025 vs. 0.133, p, Highlights • For the first time, connectivity of fMRI signal during resting state of motor-related areas was measured in PKAN dystonia. • NBS analysis of networks showed two sub-networks, one between basal ganglia and another one between cortical areas. • Connectivity between both sub-networks was reduced in patients and correlated significantly to duration of disease. • Findings support the view of widespread network abnormalities in PKAN dystonia, not just confined to the globus pallidus.

Background and purpose The aim of this study was to look for deviations of cerebral perfusion in patients suffering from pantothenate kinase-associated neurodegeneration, where the globus pallidus is affected by severe accumulation of iron. Material and methods Under resting conditions, cerebral blood flow was measured by the magnetic resonance imaging technique of arterial spin labelling in cortical areas and basal ganglia in eight pantothenate kinase-associated neurodegeneration patients and 14 healthy age-matched control subjects and correlated to T2* time of these areas and – in patients – to clinical parameters. Results Despite highly significant differences of T2* time of the globus pallidus (20 vs 39 ms, p 0.05). Conclusion The absence of any obvious deviations of perfusion in the group of patients during a resting condition does not support the view that (non-functional) vascular pathology is a major pathogenic factor in pantothenate kinase-associated neurodegeneration in the younger age group. The findings underline the value of the arterial spin technique to measure cerebral blood flow in areas of disturbed susceptibility.

This article examines the relation between oxygen saturation and T2 star time in cyanotic congenital heart disease and its correlation to cerebral gray and white matter alterations. Magnetic resonance imaging was performed in 25 patients (mean age: 52.2 months) and 32 controls. Gray and white matter volumes, as well as fractional anisotropy and longitudinal diffusivity, were significantly reduced in patients. The reduction longitudinal diffusivity correlated to oxygen saturation and T2 star time of gray matter (p

OBJECTIVEDiffusion tensor imaging (DTI) parameters are able to differentiate between meningioma subtypes. The hypothesis that there is a correlation between DTI parameters and the change in tumor size after Gamma Knife radiosurgery (GKRS) was analyzed.METHODSDTI parameters were measured using MRI before GKRS in 26 patients with meningiomas. The findings were correlated with the change in tumor size after treatment as measured at the last follow-up (range 12.5–45 months).RESULTSOnly those meningiomas that showed the highest fractional anisotropy (FA), the lowest spherical index of the tensor ellipsoid (Cs), and the lowest radial diffusivity (RD) either increased or remained stable in terms of volume, whereas all other meningiomas decreased in volume. The correlation between the DTI parameters (correlation values of −0.81 for FA, 0.75 for Cs, 0.66 for RD, and 0.66 for mean diffusivity) and the rate of volume change per month was significant (p ≤ 0.001). Other factors, including original tumor size, prescription dose, and patient age, did not correlate significantly.CONCLUSIONSMeningiomas that show high FA values—as well as low Cs, low RD, and low mean diffusivity values—do not respond as well to GKRS in comparison with meningiomas with low FA values. This finding might be due to their higher content level of fibrous tissue. In particular, the meningioma with the highest FA value (0.444) considerably increased in volume (by 32.3% after 37 months), whereas the meningioma with the lowest FA value (0.151) showed the highest rate of reduction (3.3% per month) in this study.

Objective To determine the impact of Zika virus (ZIKV) infection on brain structure and functional organization of severely affected adult patients with neurological complications that extend beyond Guillain-Barre Syndrome (GBS)-like manifestations and include symptoms of the central nervous system (CNS). Methods In this first case-control neuroimaging study, we obtained structural and functional magnetic resonance images in nine rare adult patients in the subacute phase, and healthy age- and sex-matched controls. ZIKV patients showed atypical descending and rapidly progressing peripheral nervous system (PNS) manifestations, and importantly, additional CNS presentations such as perceptual deficits. Voxel-based morphometry was utilized to evaluate gray matter volume, and resting state functional connectivity and Network Based Statistics were applied to assess the functional organization of the brain. Results Gray matter volume was decreased bilaterally in motor areas (supplementary motor cortex, specifically Frontal Eye Fields) and beyond (left inferior frontal sulcus). Additionally, gray matter volume increased in right middle frontal gyrus. Functional connectivity increased in a widespread network within and across temporal lobes. Interpretation We provide preliminary evidence for a link between ZIKV neurological complications and changes in adult human brain structure and functional organization, comprising both motor-related regions potentially secondary to prolonged PNS weakness, and nonsomatomotor regions indicative of PNS-independent alternations. The latter included the temporal lobes, particularly vulnerable in a range of neurological conditions. While future studies into the ZIKV-related neuroinflammatory mechanisms in adults are urgently needed, this study indicates that ZIKV infection can lead to an impact on the brain.

Background and Importance Transtegmental brain herniation into the petrous bone is a rare cause of rhinoliquorrhea. Our case presents a combination of several typical clinical and imaging findings illustrating the ongoing etiologic discussion of such cerebrospinal fluid (CSF) fistulas. Clinical Presentation A 53-year-old man presented with nasal discharge after a strong effort to suppress coughing. Imaging revealed a transtegmental herniation of parts of the inferior temporal gyrus into the petrous bone and in addition a combination of signs of chronically increased intracranial pressure and a hyperpneumatization of the petrous bone. The fistula was closed by a middle cranial fossa approach. Conclusion The case illustrates the two main predisposing factors for development of petrous bone CSF fistulas: increased intracranial pressure and thinning of the tegmental roof due to extensive development of air cells. Because the CSF leakage repair does not change the underlying cause, patients have to be informed about the possibility of developing increased intracranial pressure and recurrences of brain herniations at other sites.

To quantify involvement of globus pallidus and two midbrain nuclei (substantia nigra and red nucleus) in Pantothenate Kinase-Associated Neurodegeneration (PKAN). We performed T2 and T2* weighted imaging with calculation of the corresponding relaxation times on a subset of 5 patients from a larger group of 20 patients with PKAN from the southwest part of the Dominican Republic. Examinations were carried out on a 3T scanner and included a multi-echo spin-echo as well as a multi-echo gradient echo sequence. Results were compared to a control group of 19 volunteers. T2 and T2* weighted sequences showed abnormal signal reduction in the globus pallidus of all patients. On T2* weighted imaging, abnormal signal in the substantia nigra could reliably be detected in 75% of cases, but differentiation from normal was less reliable in T2 weighted scans. Correspondingly, relaxation times differed from normal with very high significance (p

Hypometabolism of the posterior cingulate cortex (PCC) in early Alzheimer's disease (AD) is thought to arise in part due to AD-specific neuronal damage to the hippocampal formation. Here, we explored the association between microstructural alterations within the hippocampus and whole-brain glucose metabolism in subjects with AD, also in relation to episodic memory impairment.Twenty patients with early AD (Mini-Mental State Examination 25.7 ± 1.7) were studied with [(18)F]fluorodeoxyglucose (FDG) positron emission tomography and diffusion tensor imaging. Episodic memory performance was assessed using the free delayed verbal recall task (DVR). Voxel-wise relative FDG uptake was correlated to diffusivity indices of the hippocampus, followed by extraction of FDG uptake values from significant clusters. Linear regression analysis was performed to test for unique contributions of diffusivity and metabolic indices in the prediction of memory function.Diffusivity in the left anterior hippocampus negatively correlated with FDG uptake primarily in the left anterior hippocampus, parahippocampal gyrus and the PCC (p0.005). The same correlation pattern was found for right hippocampal diffusivity (p0.05). In linear regression analysis, left anterior hippocampal diffusivity and FDG uptake from the PCC cluster were the only significant predictors for performance on DVR, together explaining 60.6% of the variance. We found an inverse association between anterior hippocampal diffusivity and PCC glucose metabolism, which was in turn strongly related to episodic memory performance in subjects with early AD.These findings support the diaschisis hypothesis of AD and implicate a dysfunction of structures along the hippocampal output pathways as a significant contributor to the genesis of episodic memory impairment.

Abnormal microstructural integrity and glucose metabolism of the hippocampus are common in subjects with Alzheimer’s disease (AD) that typically manifest as episodic memory impairment. The above-tissue alterations can be captured in vivo using diffusion tensor imaging (DTI) and positron emission tomography with [18F]fluorodeoxyglucose (FDG-PET). Here, we explored relationships between the above neuroimaging and cognitive markers of early AD-specific hippocampal damage. Twenty patients with early AD (MMSE 25.7 ± 1.7) were studied using DTI and FDG-PET. Episodic memory performance was assessed using the free delayed verbal recall task (DVR). In the between-modality correlation analysis, FDG uptake was strongly associated with diffusivity in the left anterior hippocampus only (r = −0.81, p < 0.05 Bonferroni’s corrected for multiple tests). Performance on DVR significantly correlated with left anterior (r = −0.80, p < 0.05) and left mean (r = −0.72, p < 0.05) hippocampal diffusivity, while the correlation with left anterior FDG uptake did not reach statistical significance (r = 0.52, n.s.). DTI-derived diffusivity of the anterior hippocampus might be a sensitive early marker of hippocampal dysfunction as reflected at the synaptic and cognitive levels. This neurobiological distinction of the anterior hippocampus might be related to the disruption of the perforant pathway that is known to occur early in the course of AD.

PURPOSE: The measurement of the CBF is a non-standardized procedure and there are no reliable gold standards. This abstract shows a capillary-based perfusion-phantom for CE-DSC-MRI. It has equivalent flow properties to those within the tissue capillary system of the human brain and allows the validation of the Siemens Perfusion (MR) software. MATERIALS AND METHODS: The perfusion phantom consists of a dialyzer for the simulation of the capillary system, a feeding tube for simulation of the AIF and a pulsatile pump for simulation of the heart. Using this perfusion phantom, the exact determination of the gold standard CBF due to the well-known geometry of the phantom is easy. It was validated based on different perfusion measurements. These measurements were investigated with standard software (Siemens Perfusion MR). The software determined the CBF within the capillary system. Based on this CBF, a comparison to the gold standard was made with several different flow speeds. After AIF selection, a total of 726 CBF data points were automatically extracted by the software. RESULTS: This results in a comparison of the gold standard CBF to these 726 CBF values. Therefore, a reproducible and reliable deviation estimation between gold standard CBF and measured CBF using the software was computed. It can be shown that the deviation between gold standard and software-based evaluation ranges between 1 and 31 %. CONCLUSION: There is no significance for any correlation between flow speed and amount of deviation. The mean measured CBF is 11.4 % higher than the gold standard CBF (p-value < 0.001). Using this kind of perfusion-phantom, the validation of different software systems allows reliable conclusions about their quality.

Background While functional MRI and PET studies have shown altered task-related brain activity in PKAN, we want to find such differences also in the resting state (RS). Here we used ICA based analysis to investigate RS fMRI data to compare connectivity of 11 well known networks (Auditory, Cerebellum, Default Mode Network (DMN), Exectutive Control, Fronto-parietal 1, Fronto-parietal 2, Salience, Sensorimotor, Visual1, Visual2, Visual3 network) between patients with PKAN and healthy controls suggesting deficits in related neuropsychological functions. Methods We obtained RS fMRI series (3T, 3x3x3mm resolution, 45 slices, TR 2s, 300 volumes) in 17 PKAN patients but 3 were discarded because of excessive movement, (mean age 17.2a±7.1) on stable medication and 15 healthy controls (22.5a±8.3). Subjects were asked to lie in the scanner keeping eyes closed with no further specific instructions. Data were pre-processed; we applied FSL MELODIC (pICA) yielding IC, we used FIX to auto-classify ICA components which represent artifacts and an automated routine to select for each subject the component matching the anatomical definition of resting state networks. SPM12 was used for second level analysis, we used two sample t-test to compare networks functional connectivity between groups. In addition, we used multiple regression to correlate RS networks activity components with Dystonia score. Results Our method reliably identified all networks in every control and patients. We found significant differences in the anatomical pattern of areas. Patients showed decreased functional connectivity in comparison to healthy controls in portions of Fronto-parietal 1, Fronto-parietal 2 and Visual1 networks; in addition, patients showed increased functional connectivity in comparison to healthy controls in portions of Cerebellum, DMN, Executive Control, Salience and Visual1 networks. Finally, significant correlation was found between dystonia score and functional connectivity of Cerebellum, Fronto-parietal1, Fronto-parietal2, Salience, Sensorimotor and Visual2 networks. Discussion Well known resting state networks were reliable identified from RS fMRI in PKAN patients. The differences in anatomical distribution point to possible alterations in functional connectivity in PKAN, which suggests disruption in cerebellum, DMN, fronto-parietal, salience and visual activity. Correlations with dystonia suggest a direct relation to motor items, which would support a clinical significance of altered RS networks activity.

Recent neuroanatomical and functional neuroimaging studies indicate that the anterior part of the hippocampus, rather than the whole structure, may be specifically involved in episodic memory. In the present work, we examined whether anterior structural measurements are superior to other regional or global measurements in mapping functionally relevant degenerative alterations of the hippocampus in Alzheimer's disease (AD). Twenty patients with early AD (MMSE 25.7+/-1.7) and 18 healthy controls were studied using magnetic resonance and diffusion-tensor imaging. Using a regions-of-interest analysis, we obtained volumetric and diffusivity measures of the hippocampal head and body-tail-section as well as of the whole hippocampus. Detailed cognitive evaluation was based on the CERAD battery. All volumetric measures as well as diffusivity of the hippocampus head were significantly (p0.01) altered in patients as compared to controls. In patients, increased left head diffusivity significantly (p0.01) correlated with performance on free delayed verbal recall test (DVR) (r=-0.74, p=0.0002) and with the CERAD global score. Reduced volume of the left body-tail was also associated with performance on DVR (r=0.62, p=0.004). Stepwise regression analyses revealed that increased left head diffusivity was the only predictor for performance on DVR (R(2)=52%, p0.0005). These findings suggest that anterior hippocampus diffusivity is more closely related to verbal episodic memory impairment than other regional or global structural measures. Our data support the hypothesis of functional differentiation in general and the specific role of the anterior hippocampus in episodic memory in particular. Diffusivity measurements might be highly sensitive to functionally relevant degenerative alterations of the hippocampus.

In the past years, claims of cognitive and attentional function of the cerebellum have first been raised but were later refuted. One reason for this controversy might be that attentional deficits only occur when specific cerebellar structures are affected. To further elucidate this matter and to determine which cerebellar regions might be involved in deficits of covert visual attention, we used new brain imaging tools of lesion mapping that allow a direct comparison with control patients. A total of 26 patients with unilateral right-sided cerebellar infarcts were tested on a covert visual attention task. Eight (31%) patients showed markedly slowed responses, especially in trials in which an invalid cue necessitated reorienting of the focus of attention for target detection. Compared with the 18 patients who performed within the range of healthy control subjects, only the impaired patients had lesions of cerebellar vermal structures such as the pyramid. We suggest that these midcerebellar regions are indirectly involved in covert visual attention via oculomotor control mechanisms. Thus, specific cerebellar structures do influence attentional orienting, whereas others do not.

Inattention and impulsivity are the most prominent clinical features of attention deficit hyperactivity disorder (ADHD) in adulthood. Structural and functional neuroimaging studies of subjects with ADHD have demonstrated abnormalities in several brain areas, including fronto-striatal and fronto-cerebellar networks. Mostly, these studies were based on volumetric measurements and have been conducted in children. We investigated white matter (WM) integrity and correlation with measures of attention and impulsivity in adult patients with ADHD adopting diffusion tensor imaging (DTI). N = 37 (21 males) never-medicated adult patients with ADHD combined subtype and N = 34 (16 males) healthy controls were investigated. ADHD diagnosis (DSM-IV) was assessed with clinical interviews and rating scales, subjects also underwent a large neuropsychological test battery including tests of attention and impulsivity. DTI was acquired, and group differences of fractional anisotropy (FA) and mean diffusivity (MD) as well as correlation analyses with measures of attentional performance and impulsivity were calculated using voxel-based analyses. In adult patients with ADHD, we found reduced FA as well as higher MD bilaterally in orbitomedial prefrontal WM and in the right anterior cingulate bundle, while elevated FA was present bilaterally in temporal WM structures. Measures of attention were correlated with DTI parameters in the right superior longitudinal fasciculus, whereas measures of impulsivity were correlated with FA in right orbitofrontal fibre tracts. This is the first DTI study demonstrating disturbed structural connectivity of the frontal-striatal circuitry in adult patients with ADHD. Moreover, a direct correlation between WM integrity and measures of attention and impulsivity is shown.

A 65-year-old man had an embolic stroke of both posterior cerebral arteries in 2002. Two years later he noted rapid improvement of the residual bilateral inferior quadrant anopia whenever he took 25 mg sildenafil. The improvement of scotomas was verified by visual field examinations and persisted reproducibly for 3–7 days. An overlay of a subtraction of functional magnetic resonance imaging (MRI) during visual stimulation before and after medication onto a T1-weighted MRI of the patient revealed additional activations along the margins of the old cerebral infarctions. These findings and the additional results of a perfusion MRI suggest that phosphodiesterase 5 inhibitors may prove beneficial in the rehabilitative course after ischemic strokes.

The definition of neuropathic pain has recently been revised by an expert committee of the Neuropathic Pain Special Interest Group of the International Association for the Study of Pain (NeuPSIG) as "pain arising as direct consequence of a lesion or disease affecting the somatosensory system," and a grading system of "definite," "probable," and "possible" neuropathic pain has been introduced. This open case series of 5 outpatients (3 men, 2 women; mean age 48 +/- 12 years) demonstrates how the grading system can be applied, in combination with appropriate confirmatory testing, to diagnosis neuropathic conditions in clinical practice. The proposed grading system includes a dynamic algorithm that enhances the physician's ability to determine with a greater level of certainty whether a pain condition is neuropathic. Its clinical use should be further validated in prospective studies.

Humans are able to stabilize the images of moving targets on the retina by means of smooth pursuit eye movements. After the pontine level, all smooth pursuit pathways pass through the cerebellum. Previous animal studies gave evidence that two specific lesion sites within the cerebellum cause smooth pursuit disorders: those of the flocculus/paraflocculus and the vermis including lobule VI, VII, the uvula and the deep cerebellar nuclei. To date, there have been only a few lesion studies in patients with smooth pursuit disorders that do not allow direct comparison with a control group. In the present study, new lesion mapping techniques determined which cerebellar structures were involved in patients with deficits of smooth pursuit eye movements, slow phase of optokinetic nystagmus (OKN) and fixation suppression of vestibulo-ocular reflex, i.e. in eye movements that are considered to belong to the smooth pursuit system. The aim was to elucidate whether there is an anatomical and clinical link between these different eye movement disorders. Seventeen patients with acute, mainly unilateral cerebellar infarctions and an intact gain of the smooth pursuit system were compared with 11 patients with cerebellar lesions and deficient gain of sinusoidal smooth pursuit eye movements by means of lesion-mapping imaging. In addition, lesion analyses were conducted in subgroups with impaired fixation suppression of vestibulo-ocular reflex and deficient gain of the slow phase of the OKN. The uvula and partly the vermal pyramid were found to be the structures commonly damaged in patients with deficient gain of the horizontal sinusoidal smooth pursuit eye movement, of the slow phase of the OKN and impaired fixation suppression of vestibulo-ocular reflex; and were less involved in patients with intact smooth pursuit system. The present data give evidence for an anatomical link between sinusoidal smooth pursuit eye movements, fixation suppression of vestibulo-ocular reflex and the slow phases of OKN implying that the uvula and the vermal pyramid are important structures for generating slow phases within the smooth pursuit network in humans.

Neurologic hallmarks of Fabry disease (FD) include small fiber neuropathy as well as cerebral micro- and macroangiopathy with premature stroke. Cranial MRI shows progressive white matter lesions (WML) at an early age, increased signal intensity in the pulvinar, and tortuosity and dilatation of the larger vessels. To unravel the most promising imaging tool for the detection of CNS involvement in FD we compared the diagnostic utility of the different MR imaging findings.Twenty-five clinically affected patients with FD (age 36.5 +/- 11.0) and 20 age-matched controls were investigated by structural MRI, MR angiography, and diffusion tensor imaging (DTI). Individual WML volumes, global mean diffusivity (MD), and mean cerebral artery diameters were determined.Using receiver operating characteristic analyses, enlarged diameters of the following cerebral arteries significantly separated patients with FD from controls: middle cerebral artery: area under curve (AUC) = 0.75, p = 0.005; posterior cerebral artery: AUC = 0.69, p = 0.041; carotid artery: 0.69, p = 0.041; basilar artery: AUC = 0.96, p0.0005. A total of 87% of the individuals were correctly classified by basilar artery diameters (sensitivity 95%, specificity 83%). WML volumes and global MD values did not significantly separate patients from controls.With an accuracy of 87%, basilar artery diameters were superior to all other MR measures for separating patients with Fabry disease (FD) from controls. Future studies should adopt basilar artery measurements for early detection and monitoring of brain involvement in FD. Moreover, further investigations should reveal if the dilated vasculopathy in FD could be a screening marker to detect FD in a cohort of other cerebrovascular diseases, especially in cryptogenic stroke.

Earlier functional imaging studies on the processing of vestibular information mainly focused on cortical activations due to stimulation of the horizontal semicircular canals in right-handers. Two factors were found to determine its processing in the temporo-parietal cortex: a dominance of the non-dominant hemisphere and an ipsilaterality of the neural pathways. In an investigation of the role of these factors in the vestibular otoliths, we used vestibular evoked myogenic potentials (VEMPs) in a fMRI study of monaural saccular-otolith stimulation. Our aim was to (1) analyze the hemispheric dominance for saccular-otolith information in healthy left-handers, (2) determine if there is a predominance of the ipsilateral saccular-otolith projection, and (3) evaluate the impact of both factors on the temporo-parieto-insular activation pattern. A block design with three stimulation and rest conditions was applied: (1) 102 dB-VEMP stimulation; (2) 65 dB-control-acoustic stimulation, (3) 102 dB-white-noise-control stimulation. After subtraction of acoustic side effects, bilateral activations were found in the posterior insula, the superior/middle/transverse temporal gyri, and the inferior parietal lobule. The distribution of the saccular-otolith activations was influenced by the two factors but with topographic disparity: whereas the inferior parts of the temporo-parietal cortex were mainly influenced by the ipsilaterality of the pathways, the upper parts reflected the dominance of the non-dominant hemisphere. This is in contrast to the processing of acoustic stimulation, which showed a predominance of the contralateral pathways. Our study proves the importance of the hemispheric preponderance also in left-handers, which is of relevance in the superior parts of the insula gyrus V, the inferior parietal lobule, and the superior temporal gyri.