Bedside Sonographic Duplex Technique as a Monitoring Tool in Patients after Decompressive Craniectomy: A Single Centre Experience.

BACKGROUND AND OBJECTIVES: Bedside sonographic duplex technique (SDT) may be used as an adjunct to cranial computed tomography (CCT) to monitor brain-injured patients after decompressive craniectomy (DC). The present study aimed to assess the value of SDT in repeated measurements of ventricle dimensions in patients after DC by comparing both techniques. MATERIALS AND METHODS: Retrospective assessment of 20 consecutive patients after DC for refractory intracranial pressure (ICP) increase following subarachnoid hemorrhage (SAH), bleeding and trauma which were examined by SDT and CCT in the context of routine clinical practice. Whenever a repeated CCT was clinically indicated SDT examinations were performed within 24 hours and correlated via measurement of the dimensions of all four cerebral ventricles. Basal cerebral arteries including pathologies such as vasospasms were also evaluated in comparison to selected digital subtraction angiography (DSA). RESULTS: Repeated measurements of all four ventricle diameters showed high correlation between CCT and SDT (right lateral r = 0.997, p < 0.001; left lateral r = 0.997, p < 0.001; third r = 0.991, p < 0.001, fourth ventricle r = 0.977, p < 0.001). SDT performed well in visualizing basal cerebral arteries including pathologies (e.g., vasospasms) as compared to DSA. CONCLUSIONS: Repeated SDT measurements of the dimensions of all four ventricles in patients after DC for refractory ICP increase delivered reproducible results comparable to CCT. SDT may be considered as a valuable bedside monitoring tool in patients after DC.

Systematic evaluation of stroke thrombectomy in clinical practice: The German Stroke Registry Endovascular Treatment.

BACKGROUND: Endovascular treatment has become standard of care for the treatment of acute ischemic stroke with large vessel occlusion. However, patients treated in clinical practice differ from the selected populations randomized in clinical trials. AIMS: The German Stroke Registry Endovascular Treatment (GSR-ET) aims at a systematic evaluation of outcome, safety, and process parameters of endovascular stroke treatment in standard of care in Germany. METHODS: The GSR-ET is an academic, independent, prospective, multicenter, observational registry study. Participating stroke centers from all over of Germany consecutively enroll patients transferred to the angiography suite with an intention to be treated with endovascular stroke treatment. Patients receive regular care. Data are collected as part of clinical routine. Baseline clinical and procedural information and clinical follow-up information after 90 days are recorded. Here, we present an analysis of baseline data of the first 1662 patients included in the GSR-ET. RESULTS: The registry was established in June 2015. By 31 December 2017, 1662 patients were enrolled in 23 active sites. Mean age was 72 ± 13 years, 50% were female, and median National Institutes of Health Stroke Scale on admission was 15 (IQR 10-19), 88% had anterior circulation occlusion. Median ASPECT score was 8 (IQR 7-10) prior to intervention. Fifty-nine percent of patients received intravenous thrombolysis prior to thrombectomy. Mean "onset-to-groin" time was 224 ± 176 min. CONCLUSIONS: Baseline characteristics of stroke patients undergoing thrombectomy in clinical practice differ from those in the randomized trials. The GSR-ET will provide valuable insights into practices of endovascular treatment in routine care of acute ischemic stroke. (GSR-ET ClinicalTrials.gov Identifier: NCT03356392.).

Cerebral Ventricular Dimensions After Decompressive Craniectomy: A Comparison Between Bedside Sonographic Duplex Technique and Cranial Computed Tomography.

BACKGROUND: The objective of this study was to assess and compare ventricle diameters in patients after decompressive craniectomy by using cranial computed tomography (CCT) versus sonographic duplex technique (SDT). METHODS: A total of 102 consecutive patients after decompressive craniectomy following brain infarct, bleeding and trauma were examined by CCT and SDT. SDT was performed within 24 h after repeated postinterventional control CCT and the correlation between both methods was assessed via measurement of dimensions of all four ventricles. In addition, midline shifts and overall cerebral anatomy was evaluated. RESULTS: A high correlation was found between CCT and SDT in measuring the diameters of all four ventricles (right lateral r = 0.978, p < 0.001; left lateral r = 0.975, p < 0.001; third r = 0.987, p < 0.001 and fourth ventricle r = 0.954, p < 0.001). Deviations of midline structure was observed in SDT as well as in CCT (r = 0.992, p < 0.001). CONCLUSION: SDT in patients after decompressive craniectomy may represent an additional bedside tool to assess the dimensions of the ventricular system, anatomical structures, e.g., subdural hygromas, hematomas, midline shifts, gyri and sulci. The measurement of the dimensions of all four ventricles by using SDT delivers accurate values and may be considered as an alternative to CCT or a trigger for CCT prior to further treatment.

Dissociable contributions of left and right dorsolateral prefrontal cortex in planning.

It is well established that the mid-dorsolateral prefrontal cortex (dlPFC) plays a critical role in planning. Neuroimaging studies have yielded predominantly bilateral dlPFC activations, but the existence and nature of functionally specific contributions of left and right dlPFC have remained elusive. In recent experiments, 2 independent parameters have been identified which substantially determine planning: 1) the degree of interdependence between consecutive steps (search depth) and 2) the degree to which the configuration of the goal state renders the order of single steps either clearly evident or ambiguous (goal hierarchy). Thus, search depth affects the actual mental generation and evaluation of action sequences, whereas goal hierarchy reflects the extraction of goal information from an encountered problem. Here, both parameters were independently manipulated in an event-related functional magnetic resonance imaging study using the Tower of London task. Results revealed a double dissociation as indicated by a significant crossover interaction of hemisphere and task parameter: in left dlPFC, activations were stronger for higher demands on goal hierarchy than on search depth, whereas the reversed result emerged in right dlPFC. In conclusion, often observed bilateral patterns of dlPFC activation in complex tasks may reflect the concomitant operation of specific cognitive processes that show opposing lateralizations.

Remote effects of hippocampal damage on default network connectivity in the human brain.

In the healthy human brain the hippocampus is known to work in concert with a variety of cortical brain regions. It has recently been linked to the default network of the brain, with the precuneus being its core hub. Here we studied the remote effects of damage to the hippocampus on functional connectivity patterns of the precuneus. From 14 epilepsy patients with selective, unilateral hippocampal sclerosis and 8 healthy control subjects, we acquired functional MRI data during performance of an object-location memory task. We assessed functional connectivity of a functionally defined region in the precuneus, which showed the typical properties of the default network: significant task-related deactivation, which was reduced in patients compared to control subjects. In control subjects, a largely symmetrical pattern of functional coherence to the precuneus emerged, including canonical default network areas such as ventral medial prefrontal cortex, inferior parietal cortex, and the hippocampi. Assessment of group differences within the default network areas revealed reduced connectivity to the precuneus in ipsilesional middle temporal gyrus and hippocampus in left hippocampal sclerosis patients compared to controls. Furthermore, left hippocampal sclerosis patients showed lower connectivity than right hippocampal sclerosis patients in left middle temporal gyrus, ventral medial prefrontal cortex, and left amygdala. We report remote effects of unilateral hippocampal damage on functional connectivity between distant brain regions associated with the default network of the human brain. These preliminary results underline the impact of circumscribed pathology on functionally connected brain regions.

Reduced interhemispheric hippocampal BOLD signal coupling related to early epilepsy onset.

In order to investigate the factors influencing interhemispheric hippocampal connectivity we used fMRI to assess the time course of hippocampal activity during a spatial memory task. Data were obtained from 14 patients with unilateral hippocampal sclerosis and focal unilateral medial temporal lobe epilepsy. Correlation coefficients between left and right hippocampal BOLD signal fluctuations were determined in each patient as a measure for interhemispheric hippocampal coupling. On the group level a non-parametric Spearman correlation analysis was performed to assess relations of hippocampal connectivity to age, age at epilepsy onset, disease duration, and task performance. In all except for one patient correlation coefficients between left and right hippocampal time courses reached significance. Interhippocampal connectivity exhibited the strongest correlation to age at onset, i.e. patients with later onset showed greater connectivity. It was negatively correlated with disease duration, but not with age. Our findings underline the malicious effect of epileptic seizures on brain structures inevitably engaged with core cognitive functions. The results suggest that a measure of interhemispheric interplay - even at a coarse time-scale - might reflect the functional status of brain structures.

Testing the diagnostic value of electrical ear canal stimulation in cochlear implant candidates by functional magnetic resonance imaging.

Prior to cochlear implant (CI) surgery in children, the integrity of the auditory pathway is sometimes assessed by electrical ear canal stimulation (ECS). However, the evaluation of reactions as auditory is subjective. To test the prognostic value of ECS, functional magnetic resonance imaging (fMRI) was performed during ECS vicariously in 18 adult CI candidates. Activation of the primary auditory cortex was detected in 9 of 16 cases when auditory sensations during ECS occurred, and tended to be more bilaterally distributed in CI candidates than in normal-hearing controls. ECS sensations only tended to correlate with fMRI activations. However, solely frequency discrimination during electrical stimulation predicted CI outcome, but neither other auditory sensations nor fMRI activations did so satisfactorily, which limits the diagnostic value of these measures. Instead, preoperative residual hearing (nonamplified and amplified) was a robust predictor for CI benefit.

Thinking around the corner: the development of planning abilities.

The ability to plan and search ahead is essential for problem solving in most situations in everyday life. To investigate the development of planning and related processes, a sample of four- and five-year-old children was examined in a variant of the Tower of London, a frequently used neuropsychological assessment tool of planning abilities. The applied problems either required searching ahead for optimal solution or were solvable by pure step-by-step forward processing. Furthermore, the ambiguity of subgoal ordering was varied. Results revealed an age-related effect of search depth: the four-year olds' planning accuracy was particularly decreased in problems demanding search ahead, while five-year olds mastered both problem types equally well. Interestingly, this interaction between age and search depth could not be accounted for by measures of working memory and inhibition. Differential effects of age were also found for subgoal ordering with respect to initial planning and movement execution times. In sum, planning abilities showed considerable development during late kindergarten age that appeared to be specifically associated with the integration and back-validation of the anticipated consequences of internally modeled actions. The present study demonstrates that a careful consideration of problem structure may greatly enhance the insights gained from the application of a routinely used assessment tool, the Tower of London. This may be especially advantageous when addressing specific subpopulations such as children or clinical samples.

Occurrence of a germinoma 22 years after resection of a mature cerebral teratoma.

We present the rare case of a 31-year-old man who developed a germinoma 22 years after resection of a mature teratoma of the pineal region. The initial stereotactic biopsy showed a granulomatous inflammation, but no malignant cells. The correct diagnosis could only be confirmed in a second cerebral biopsy, allowing for proper treatment with radiation therapy. The need to consider metachronous germinoma in this setting is discussed.

Differential effect of side of temporal lobe epilepsy on lateralization of hippocampal, temporolateral, and inferior frontal activation patterns during a verbal episodic memory task.

The encoding of verbal stimuli elicits left-lateralized activation patterns within the medial temporal lobes in healthy adults. In our study, patients with left- and right-sided temporal lobe epilepsy (LTLE, RTLE) were investigated during the encoding and retrieval of word-pair associates using functional magnetic resonance imaging. Functional asymmetry of activation patterns in hippocampal, inferior frontal, and temporolateral neocortical areas associated with language functions was analyzed. Hippocampal activation patterns in patients with LTLE were more right-lateralized than those in patients with RTLE (P<0.05). There were no group differences with respect to lateralization in frontal or temporolateral regions of interest (ROIs). For both groups, frontal cortical activation patterns were significantly more left-lateralized than hippocampal patterns (P<0.05). For patients with LTLE, there was a strong trend toward a difference in functional asymmetry between the temporolateral and hippocampal ROIs (P=0.059). A graded effect of epileptic activity on laterality of the different regional activation patterns is discussed.

Hippocampal functional connectivity reflects verbal episodic memory network integrity.

Using functional magnetic resonance imaging during a verbal memory task, we investigated correlations of signal fluctuations within the hippocampus and ipsilateral frontal as well as temporal areas in temporal lobe epilepsy patients. Declarative memory abilities were additionally examined before and after temporal lobe epilepsy surgery. A significant difference exists in functional connectivity between patients whose mnemonic functions deteriorated and those who remained stable or improved. Univariate analyses showed significantly higher preoperative coupling between the hippocampus and Brodmann area 22 for the group that decreased in verbal learning. We suggest greater coupling to reflect higher functional network integrity. Postoperatively reduced learning ability in patients with higher preoperative coupling underlines the importance of hippocampal interaction with cortical areas for successful memory formation.

Functional neuroimaging of emotional learning and autonomic reactions.

This article provides a selective overview of the functional neuroimaging literature with an emphasis on emotional activation processes. Emotions are fast and flexible response systems that provide basic tendencies for adaptive action. From the range of involved component functions, we first discuss selected automatic mechanisms that control basic adaptational changes. Second, we illustrate how neuroimaging work has contributed to the mapping of the network components associated with basic emotion families (fear, anger, disgust, happiness), and secondary dimensional concepts that organise the meaning space for subjective experience and verbal labels (emotional valence, activity/intensity, approach/withdrawal, etc.). Third, results and methodological difficulties are discussed in view of own neuroimaging experiments that investigated the component functions involved in emotional learning. The amygdala, prefrontal cortex, and striatum form a network of reciprocal connections that show topographically distinct patterns of activity as a correlate of up and down regulation processes during an emotional episode. Emotional modulations of other brain systems have attracted recent research interests. Emotional neuroimaging calls for more representative designs that highlight the modulatory influences of regulation strategies and socio-cultural factors responsible for inhibitory control and extinction. We conclude by emphasising the relevance of the temporal process dynamics of emotional activations that may provide improved prediction of individual differences in emotionality.

Gender-related differences in lateralization of hippocampal activation and cognitive strategy.

Gender-related differences in brain activation patterns and their lateralization associated with cognitive functions have been reported in the field of language, emotion, and working memory. Differences have been hypothesized to be due to different cognitive strategies. The aim of the present study was to test whether lateralization of brain activation in the hippocampi during memory processing differs between the sexes. We acquired functional magnetic resonance imaging data from healthy female and male study participants performing a spatial memory task and quantitatively assessed the lateralization of hippocampal activation in each participant. Hippocampal activation was significantly more left lateralized in women, and more right lateralized in men. Correspondingly, women rated their strategy as being more verbal than men did.

Precuneus is involved in allocentric spatial location encoding and recognition.

Using a declarative memory paradigm, the anatomical correlates of spatial location encoding and retrieval in the healthy human brain as reflected by BOLD fMRI were investigated. During encoding, subjects were instructed to view and keep in mind different locations of an object on a platform seen from different viewpoints in virtual 3D. In retrieval trials, subjects had to recognize previously learned object locations. Comparing activation patterns associated with encoding and recognition on a voxel-by-voxel basis, we found regions in the precuneus bilaterally activated by both processes. To our knowledge, this is the first study that directly compared human brain activation patterns associated with allocentric encoding and retrieval of spatial locations in virtual 3D. Our results provide further information concerning the role of the precuneus in declarative memory processes, pointing to precuneus involvement in encoding and retrieval of spatial locations.

Enhanced visualization of blurred gray-white matter junctions in focal cortical dysplasia by voxel-based 3D MRI analysis.

PURPOSE: Focal cortical dysplasia (FCD), a frequent cause of partial epilepsy, is often associated with blurring of the gray-white matter junction in magnetic resonance images (MRI). To improve the recognition and delineation of FCD we developed a novel voxel-based image post-processing method for enhanced visualization of blurred gray-white matter junctions. METHODS: Using standard algorithms of statistical parametric mapping software (SPM99) a T1-weighted MRI volume data set is normalized and segmented. The distribution of gray and white matter is analyzed on a voxelwise basis and compared with a normal database. Based on this analysis, a three-dimensional feature map is created which highlights brain areas with blurred gray-white matter transition. This method was applied to the MRI data of 25 epilepsy patients with histologically proven FCD. RESULTS: In 18/25 patients the new feature maps clearly showed that the dysplastic lesions were accompanied by blurring of the gray-white matter junction. Combined with a formerly published method of voxel-based 3D MRI analysis, 21/25 FCD lesions were shown to be associated with either blurring or abnormal extension of gray matter beyond the normal cortical ribbon, including four cases with lesions not or incompletely recognized on conventional MRI. CONCLUSIONS: The MRI post-processing presented here improves the visualization of FCD and may increase the diagnostic yield of MRI. Thereby, it provides a valuable additional diagnostic tool in the presurgical evaluation of epilepsy patients.

The reliability of fMRI activations in the medial temporal lobes in a verbal episodic memory task.

The test-retest reliability of activation patterns elicited by encoding and recognition of word-pair associates within the whole brain and a predefined medial temporal region of interest (ROI) was investigated. Twenty healthy right-handed subjects were studied within two sessions, either on the same day or 210-308 days later. Three quantitative measures of reliability were calculated for the contrasts encoding and recognition versus a control condition within the ROI and also for the whole brain: A group correlational analysis between the lateralization indices of the first and second session, correlations of the individual SPM(t) maps of the first and the second run, and overlap ratios between both sessions. For the ROI, correlational analysis of lateralization indices during both encoding trials was significant. Eighty percent of the individual positive correlation coefficients of SPM(t) maps during encoding, and 75% during recognition reached significance. The mean percentage of overlapping voxels was 18% during encoding and 19% during recognition. The reproducibility measures evaluated for the whole brain demonstrated significantly higher values compared to the ROI. For the group that stayed inside the scanner, better whole brain test-retest reliability was observed, and no influence of the memory process (encoding or recognition) on reproducibility was found.

Rapid and fully automated visualization of subdural electrodes in the presurgical evaluation of epilepsy patients.

For rapid visualization of subdural electrodes with respect to cortical and subcortical structures, we describe a novel and fully automated method based on coregistration, normalization, optional cerebellum masking, and volume rendering of 3D MR imaging data taken before and after implantation. The key step employs the skull-stripped preimplantation image as a mask to also remove the skull in the postimplantation image. The extracted brain is presented in 3D with the electrodes directly visible by their susceptibility artifacts. Compared with alternative methods, ours is based on freely available software and does not require manual intervention.

The brain tumor board: lessons to be learned from an interdisciplinary conference.

BACKGROUND: The aim of this study is to analyze the work of the interdisciplinary Brain Tumor Board (BTB) which was established at Freiburg University Hospital in 1998. PATIENTS AND METHODS: From January 1998 to December 2003, a total of 1,516 patients were discussed in 259 meetings of the BTB. The protocols of the BTB were analyzed retrospectively. RESULTS: In 79% of the patients, the diagnosis was based on histological findings or a typical radiological appearance of a lesion, or both. This group was composed of 4 subgroups: 28% benign skull base tumors (19% meningiomas, 4% pituitary adenomas, 3% acoustic schwannomas, 2% others), 24% primary brain tumors of glial origin (8% glioblastomas, 12% gliomas other than glioblastomas, 5% oligoastrocytomas or oligodendrogliomas), 19% brain metastases, and 8% other brain or skull base tumors. In 13% of the cases, the exact diagnosis was still unknown when the patient was presented. 8% of the presentations were motivated by nontumorous interdisciplinary problems (e.g. arterio-venous malformations). The recommendations given by the BTB included: 23% further diagnostic procedures (11% non-invasive examinations, 12% stereotactic biopsies), 57% active antitumoral therapy (22% resection, 17% fractionated radiotherapy, 13% radiosurgery, 5% chemotherapy, <1% embolization), 20% no treatment (14% watchful waiting, 6% supportive care). 91% of the BTB recommendations were realized within 3 months. CONCLUSION: Interdisciplinary care seems to be particularly necessary in patients with benign skull base tumors, gliomas and brain metastases. Decisions made in a small interdisciplinary group of experts have a high potential of subsequently being realized.

Activation of cortical areas in music execution and imagining: a high-resolution EEG study.

Neuroimaging studies have shown that execution of a musical sequence on an instrument activates bilateral frontal opercular regions, in addition to bilateral sensorimotor and supplementary motor areas. During imagining activation of the same areas without primary sensorimotor areas was shown. We recorded EEG from 58 scalp positions to investigate the temporal sequence and the time course of activation of these areas while violin players prepared to execute, executed, prepared to imagine, or imagined a musical sequence on a violin. During the preparation for the sequence in three of seven musicians investigated the bilateral frontal opercular regions became active earlier than the motor areas and in one of them simultaneously with the motor areas. In two of the musicians a rather variable pattern of activation was observed. The frontal opercular regions were also strongly involved throughout the period of music execution or imagining. The supplementary motor area was involved in both preparation for the sequence and during execution and imagining of the sequence. The left primary sensorimotor area was involved in the preparation and termination of the musical sequence for both execution and imagining. The right sensorimotor area was strongly involved in the preparation for and during the execution of the sequence. We conclude that the bilateral frontal opercular regions are crucial in both preparation for and during music execution and imagining. They may have "mirror neurone" properties that underlie observation or imagining of one's own performance. The motor areas are differentially activated during the preparation and execution or imagining the sequence.