A review of brain regions and associated post-concussion symptoms.

The human brain is an exceptionally complex organ that is comprised of billions of neurons. Therefore, when a traumatic event such as a concussion occurs, somatic, cognitive, behavioral, and sleep impairments are the common outcome. Each concussion is unique in the sense that the magnitude of biomechanical forces and the direction, rotation, and source of those forces are different for each concussive event. This helps to explain the unpredictable nature of post-concussion symptoms that can arise and resolve. The purpose of this narrative review is to connect the anatomical location, healthy function, and associated post-concussion symptoms of some major cerebral gray and white matter brain regions and the cerebellum. As a non-exhaustive description of post-concussion symptoms nor comprehensive inclusion of all brain regions, we have aimed to amalgamate the research performed for specific brain regions into a single article to clarify and enhance clinical and research concussion assessment. The current status of concussion diagnosis is highly subjective and primarily based on self-report of symptoms, so this review may be able to provide a connection between brain anatomy and the clinical presentation of concussions to enhance medical imaging assessments. By explaining anatomical relevance in terms of clinical concussion symptom presentation, an increased understanding of concussions may also be achieved to improve concussion recognition and diagnosis.

Measurements of Functional Network Connectivity Using Resting State Arterial Spin Labeling During Neurosurgery.

In neurosurgery, an exact delineation of functional areas is of great interest to spare important regions to ensure the best possible outcome for the patient (i.e., maximum removal while maintaining the highest possible quality of life). Preoperative imaging is routinely performed, including the visualization of not only structural but also functional information. During surgery, however, brain shift can occur, leading to an offset between the previously defined and the real position. Real-time imaging during the procedure is therefore desired to obtain this information while performing surgery. In this study 15 patients suffering from glioblastoma multiforme were included. These patients underwent structural and perfusion imaging using arterial spin labeling during the procedure. The latter has been used for gathering information about tumor residual perfusion. However, special postprocessing of this data allows for additional mapping of resting state networks and is intended to be used to gather deeper insights to aid the surgeon in planning the procedure. The data of each patient could be successfully postprocessed and used to map different resting state networks alongside the default mode network. On the basis of this study, it is feasible to use the information obtained from perfusion imaging to visualize not only vascular signal but also functional activation of resting state networks without acquiring any additional data besides the already available information. This may help guide the neurosurgeon in real time to adjust the surgical plan.

A comparison of arterial spin labeling and dynamic susceptibility perfusion imaging for resection control in glioblastoma surgery.

Resection control using magnetic resonance imaging during neurosurgical interventions increases confidence regarding the extent of tumor removal already during the procedure. In addition to morphological imaging, functional information such as perfusion might become an important marker of the presence and extent of residual tumor mass. The aim of this study was to implement arterial spin labeling (ASL) perfusion imaging as a noninvasive alternative to dynamic susceptibility contrast (DSC) perfusion imaging in patients suffering from intra-axial tumors for resection control already during surgery. The study included 15 patients suffering from glioblastoma multiforme in whom perfusion imaging using DSC and ASL was performed before, during, and after surgery. The data obtained from intraoperative scanning were analyzed by two readers blinded to any clinical information, and the presence of residual tumor mass was evaluated using a ranking scale. Similarity of results was analyzed using the intraclass correlation coefficient and Pearson's correlation coefficient. The results show that intraoperative ASL is as reliable as DSC when performing intraoperative perfusion imaging. According to the results of this study, intraoperative imaging using ASL represents an attractive alternative to contrast agent-based perfusion imaging.

Hematocrit and Serum Hemoglobin Do Not Influence Values in Computed Tomography Perfusion of Patients With Acute Ischemic Stroke.

OBJECTIVE: There is a correlation between both serum hemoglobin (HGB) and hematocrit (HCT) and attenuation values of vessels in noncontrast-enhanced computed tomography (NECT), which could influence calculated perfusion maps in CT perfusion. METHODS: We retrospectively included 45 patients, who presented with acute new neurological symptoms and underwent NECT and CT perfusion (128-row multi detector scanner, coverage: 6.9 cm craniocaudally; 80 kV; 200 mAs; temporal resolution: 2 seconds using 40 mL Ultravist 370 at a flow rate of 5 mL/s) on admission and a follow-up MRI within 1 week of admission. RESULTS: Hematocrit, HGB, and attenuation values did not differ between patients with stroke and controls. A statistically significant correlation was found between HCT and HGB and attenuation values in the internal carotid artery or middle cerebral artery on NECT (P < 0.05). No statistically significant correlation was observed between HCT and HGB and perfusion maps. CONCLUSIONS: Hematocrit and HGB do not influence calculated perfusion maps. There is no need for HCT/HGB-adjusted cerebral blood volume thresholds in stroke patients.

Intraoperative resection control using arterial spin labeling - Proof of concept, reproducibility of data and initial results.

OBJECTIVES: Intraoperative magnetic resonance imaging is a unique tool for visualizing structures during resection and/or for updating any kind of neuronavigation that might be hampered as a result of brain shift during surgery. Advanced MRI techniques such as perfusion-weighted imaging have already proven to be important in the initial diagnosis preoperatively, but can also help to differentiate between tumor and surgically induced changes intraoperatively. Commonly used methods to visualize brain perfusion include contrast agent administration and are therefore somewhat limited. One method that uses blood as an internal contrast medium is arterial spin labeling (ASL), which might represent an attractive alternative. MATERIALS AND METHODS: Ten healthy volunteers were examined using three different scanners and coils within 1 h (3T Achieva MRI using 32-channel head coil, 1.5T Achieva MRI using a 6-channel head coil, 1.5 Intera Scanner using 2 surface coils, Philips, Best, The Netherlands) and quantitative CBF values were calculated and compared between the different setups. Additionally, in eight patients with glioblastoma multiforme, ASL was used pre-, intra-, and postoperatively to define tumor tissue and the extent of resection in comparison to structural imaging. RESULTS: A high correlation (r = 0.91-0.96) was found between MRI scanners and coils used. ASL was as reliable as conventional MR imaging if complete resection was already achieved, but additionally provided valuable information regarding residual tumor tissue in one patient. CONCLUSIONS: Intraoperative arterial spin-labeling is a feasible, reproducible, and reliable tool to map CBF in brain tumors and seems to give beneficial information compared to conventional intraoperative MR imaging in partial resection.

Parietal lobe critically supports successful paired immediate and single-item delayed memory for targets.

The parietal lobe is important for successful recognition memory, but its role is not yet fully understood. We investigated the parietal lobes' contribution to immediate paired-associate memory and delayed item-recognition memory separately for hits (targets) and correct rejections (distractors). We compared the behavioral performance of 56 patients with known parietal and medial temporal lobe dysfunction (i.e. early Alzheimer's Disease) to 56 healthy control participants in an immediate paired and delayed single item object memory task. Additionally, we performed voxel-based morphometry analyses to investigate the functional-neuroanatomic relationships between performance and voxel-based estimates of atrophy in whole-brain analyses. Behaviorally, all participants performed better identifying targets than rejecting distractors. The voxel-based morphometry analyses associated atrophy in the right ventral parietal cortex with fewer correct responses to familiar items (i.e. hits) in the immediate and delayed conditions. Additionally, medial temporal lobe integrity correlated with better performance in rejecting distractors, but not in identifying targets, in the immediate paired-associate task. Our findings suggest that the parietal lobe critically supports successful immediate and delayed target recognition memory, and that the ventral aspect of the parietal cortex and the medial temporal lobe may have complementary preferences for identifying targets and rejecting distractors, respectively, during recognition memory.

Clinical and Radiologic Outcomes in Adults and Children Treated with Pencil-Beam Scanning Proton Therapy for Low-Grade Glioma.

PURPOSE: We assessed clinical and radiologic outcomes in adults and children with low-grade glioma (LGG) of the brain treated with pencil-beam scanning (PBS) proton therapy (PT). MATERIALS AND METHODS: Between 1997 and 2014, 28 patients were treated with PBS PT, 20 (71%) of whom were younger than 18 years. Median age at start of PT was 12.3 years (range, 2.2-53.0 years). Nine patients (32%) underwent at least a subtotal resection; 12 (43%) underwent biopsy; and 7 (25%) were diagnosed radiographically. Twelve patients (43%) had grade II and 9 (32%) had grade I gliomas. Eleven patients (39%) received chemotherapy before PT. A median dose of 54 Gy (relative biologic effectiveness) was administered. Radiologic response to PT was determined using the Response Evaluation Criteria in Solid Tumors (RECIST). Eight domains of quality of life (QoL) for 16 pediatric patients were assessed prospectively by patients' parents using the pediatric QoL proxy questionnaire. Progression-free survival and overall survival (OS) were estimated by the Kaplan-Meier method. Median follow-up was 42.1 months for living patients. RESULTS: Ten patients (36%) developed local, clinical failure. Three patients (11%) died, all of tumor progression. Radiographic tumor response by RECIST was evaluable in 11 patients: 9 (82%) with stable disease, 1 (9%) with partial response, and 1 (9%) with complete response to PT. Three-year OS and progression-free survival were 83.4% and 56.0%, respectively. No ≥ grade III acute toxicities were observed. Grade III, late radiation necrosis developed in 1 patient (4%). No appreciable change in pediatric QoL proxy scores in children was noted in any of the 8 domains at any time point. CONCLUSION: Treatment with PBS PT is effective for LGG, with minimal acute toxicity and, in children, no appreciable decline in QoL. More patients and longer follow-up are needed to determine the long-term efficacy and toxicity of PT for LGG.

Spontaneous dissections of the anterior cerebral artery: a meta-analysis of the literature and three recent cases.

INTRODUCTION: Spontaneous dissections of intracranial arteries are rare, but important causes of stroke, especially in younger patients. Dissections of the anterior cerebral artery (ACA) have been reported only very rarely in the European and North American populations but might be more prevalent than previously thought. METHODS: This paper describes the presenting pattern of the disease, the clinical and imaging findings, as well as endovascular therapeutical options with respect to a meta-analysis of cases reported in the literature. Additionally, own observations in three recent representative cases are discussed. RESULTS: Overall, 80 cases from recent literature were included to the meta-analysis. The median age was 51 (35-82) years. Ischemia alone was described in 58 cases (73 %), subarachnoid hemorrhage (SAH) in 8 cases (10 %), and a combination of both in 14 cases (17 %). Radiological diagnosis including use of thin-layered 3T-MRI vessel wall imaging with black blood technique was verified by double lumen, by a string sign or string and pearl sign, or by a vessel wall hematoma in 23 (32 %), 62 (89 %), and 14 (20 %) cases, respectively. Interventional or surgical treatment was performed in 7 cases. A good clinical recovery was achieved in 77 % of cases. CONCLUSION: Dissections of the ACA mostly cause ischemia, but can cause SAH or a combination of both in a relatively young population. Detailed neuroradiological diagnosis including 3T-MRI vessel wall imaging is required as a double lumen, isolated stenosis due to vessel wall hematoma, or the secondary development of a pseudoaneurysm might occur. Interventional therapy is the primary therapy for these vascular complications.

Neuropsychological Markers of Medial Perirhinal and Entorhinal Cortex Functioning are Impaired Twelve Years Preceding Diagnosis of Alzheimer's Dementia.

Neurofibrillary pathology in Alzheimer's dementia (AD) is associated with cognitive impairments and cortical thinning, and begins in medial perirhinal cortex (mPRC) before entering entorhinal cortex (ERC). Thus, mPRC dysfunction (e.g., semantic object memory impairments) may predate or accompany ERC (i.e., episodic memory) dysfunction in the preclinical course of typical AD. We developed formulae estimating mPRC and ERC integrity (i.e., cortical thickness) using common neuropsychological tests in 31 healthy individuals and 58 early AD patients. These formulae estimated the longitudinal courses of mPRC and ERC functioning in independent groups of 28 optimally healthy individuals who developed AD (NC-AD) over 2.8-13.4 years and 28 pairwise-matched, stable, healthy individuals (NC-NC). Mixed models demonstrated significantly worse NC-AD than NC-NC estimated mPRC and ERC functioning at the earliest observation, 12 years preceding diagnosis, and a significant decline 4 years preceding the AD diagnosis. These findings demonstrate that specific neuropsychological impairments occur early in the course of preclinical AD and that tasks measuring mPRC functioning may serve as additional, powerful markers of preclinical AD.

Cortical thinning of parahippocampal subregions in very early Alzheimer's disease.

The stereotypical pattern of neurofibrillary tangle spreading in the earliest stages of typical Alzheimer's dementia (AD) predicts that medial perirhinal cortex (mPRC) atrophy precedes entorhinal cortex (ERC) atrophy, whereas the status of the parahippocampal cortex (PHC) remains unclear. Atrophy studies have focused on more advanced rather than early AD patients, and usually segment the entire PRC as opposed to the mPRC versus lateral PRC (lPRC). The present study therefore determined the extent of ERC, mPRC, lPRC, and PHC atrophy in very early AD (mean Mini-Mental State Examination score = 26) patients and its presumed prodrome amnestic mild cognitive impairment (mean Mini-Mental State Examination score = 28) compared to demographically matched controls. PHG structures were manually segmented (blinded rater) and cortical thicknesses extracted. ERC and mPRC were similarly atrophied in both patient groups. The lPRC was atrophied in the AD group only. Thus, atrophic changes in very early AD broadly map onto the pattern of neurofibrillary tangle spreading and suggest that mPRC, ERC, and lPRC, but not PHC-associated functional impairments, characterize very early-stage AD.

Basic Principles and Clinical Applications of Magnetic Resonance Spectroscopy in Neuroradiology.

Magnetic resonance spectroscopy is a powerful tool to assist daily clinical diagnostics. This review is intended to give an overview on basic principles of the technology, discuss some of its technical aspects, and present typical applications in daily clinical routine in neuroradiology.

Intraoperative perfusion magnetic resonance imaging: Cutting-edge improvement in neurosurgical procedures.

The goal in brain tumor surgery is to remove the maximum achievable amount of the tumor, preventing damage to "eloquent" brain regions as the amount of brain tumor resection is one of the prognostic factors for time to tumor progression and median survival. To achieve this goal, a variety of technical advances have been introduced, including an operating microscope in the late 1950s, computer-assisted devices for surgical navigation and more recently, intraoperative imaging to incorporate and correct for brain shift during the resection of the lesion. However, surgically induced contrast enhancement along the rim of the resection cavity hampers interpretation of these intraoperatively acquired magnetic resonance images. To overcome this uncertainty, perfusion techniques [dynamic contrast enhanced magnetic resonance imaging (DCE-MRI), dynamic susceptibility contrast magnetic resonance imaging (DSC-MRI)] have been introduced that can differentiate residual tumor from surgically induced changes at the rim of the resection cavity and thus overcome this remaining uncertainty of intraoperative MRI in high grade brain tumor resection.

Perturbation of the left inferior frontal gyrus triggers adaptive plasticity in the right homologous area during speech production.

The role of the right hemisphere in aphasia recovery after left hemisphere damage remains unclear. Increased activation of the right hemisphere has been observed after left hemisphere damage. This may simply reflect a release from transcallosal inhibition that does not contribute to language functions. Alternatively, the right hemisphere may actively contribute to language functions by supporting disrupted processing in the left hemisphere via interhemispheric connections. To test this hypothesis, we applied off-line continuous theta burst stimulation (cTBS) over the left inferior frontal gyrus (IFG) in healthy volunteers, then used functional MRI to investigate acute changes in effective connectivity between the left and right hemispheres during repetition of auditory and visual words and pseudowords. In separate sessions, we applied cTBS over the left anterior IFG (aIFG) or posterior IFG (pIFG) to test the anatomic specificity of the effects of cTBS on speech processing. Compared with cTBS over the aIFG, cTBS over the pIFG suppressed activity in the left pIFG and increased activity in the right pIFG during pseudoword vs. word repetition in both modalities. This effect was associated with a stronger facilitatory drive from the right pIFG to the left pIFG during pseudoword repetition. Critically, response became faster as the influence of the right pIFG on left pIFG increased, indicating that homologous areas in the right hemisphere actively contribute to language function after a focal left hemisphere lesion. Our findings lend further support to the notion that increased activation of homologous right hemisphere areas supports aphasia recovery after left hemisphere damage.

Endovascular treatment of cervical artery dissection: ten case reports and review of the literature.

PURPOSE: The role of endovascular treatment in cases of cervical artery dissection (CeAD) is debatable. With an increasing number of endovascular therapies such as endovascular recanalization and embolization the number of complications such as iatrogenic dissection is also rising. We report our experience with endovascular stenting in the treatment of patients presenting with CeAD. METHODS: We included all consecutive patients with CeAD (n = 168) treated in our hospital between 2001 and 2010 for our retrospective study. Patients with CeAD were considered eligible for stenting: (1) in iatrogenic dissections and (2) in noniatrogenic dissections if they suffered from recurrent ischemic events despite antithrombotic treatment. RESULTS: During our observation period 10 out of 168 patients presenting with CeAD were selected for stenting. Several types of stents were used. Stenting was technically successful in 8 but unsuccessful in 2 patients with complete arterial occlusion. Stent-related clinically apparent complications occurred in 3 of the 10 patients. All were transient. During a mean follow-up of 47 (±24.8) months none of the patients had new cerebrovascular ischemic events. CONCLUSION: In our patient sample stenting due to dissection is a rare procedure performed in less than 10% of CAD patients. It should be considered as a feasible rescue treatment in cases of impending stroke despite optimal antithrombotic therapy.

Sellar and supra-sellar glioblastoma masquerading as a pituitary macroadenoma.

A few number of suprasellar gliomas have been reported thus far of which, some of them developed several years after radiation therapy for pituitary adenomas or craniopharyngiomas. Herein, we report a case of sellar glioblastoma with suprasellar extension with no prior radiation history who mimicked clinical and radiologic findings of a pituitary macroadenoma.

Increased facilitatory connectivity from the pre-SMA to the left dorsal premotor cortex during pseudoword repetition.

Previous studies have demonstrated that the repetition of pseudowords engages a network of premotor areas for articulatory planning and articulation. However, it remains unclear how these premotor areas interact and drive one another during speech production. We used fMRI with dynamic causal modeling to investigate effective connectivity between premotor areas during overt repetition of words and pseudowords presented in both the auditory and visual modalities. Regions involved in phonological aspects of language production were identified as those where regional increases in the BOLD signal were common to repetition in both modalities. We thus obtained three seed regions: the bilateral pre-SMA, left dorsal premotor cortex (PMd), and left ventral premotor cortex that were used to test 63 different models of effective connectivity in the premotor network for pseudoword relative to word repetition. The optimal model was identified with Bayesian model selection and reflected a network with driving input to pre-SMA and an increase in facilitatory drive from pre-SMA to PMd during repetition of pseudowords. The task-specific increase in effective connectivity from pre-SMA to left PMd suggests that the pre-SMA plays a supervisory role in the generation and subsequent sequencing of motor plans. Diffusion tensor imaging-based fiber tracking in another group of healthy volunteers showed that the functional connection between both regions is underpinned by a direct cortico-cortical anatomical connection.

Thin-slice reconstructions of nonenhanced CT images allow for detection of thrombus in acute stroke.

BACKGROUND AND PURPOSE: The purpose of this study was to investigate whether thin-slice image reconstructions of cranial nonenhanced CT scans could be used to significantly increase sensitivity for detecting intraluminal thrombus in patients with acute ischemic stroke due to proximal occlusion of the middle cerebral artery. METHODS: In a prospective case series, the raw data of nonenhanced CT scans from 54 patients presenting with acute ischemic stroke and proven vascular obliteration of the middle cerebral artery were collected along with the same data from patients not having a stroke but the same sex and age. All raw data were reconstructed with a slice thickness of 5 mm and as thin slices with a thickness of 0.625 mm. Three observers independently evaluated the 5-mm nonenhanced CT reconstructions and 5-mm maximum intensity projections of the thin slices and rated the likelihood of a clot obliterating the middle cerebral artery trunk or first-order branches using a 5-point scale. The results were evaluated in comparison with base data using receiver operating curve analysis. Interobserver agreement was measured using Cohen κ for every pair of observers. RESULTS: The area under the curve for the receiver operating curve analysis for the thick slices ranged from 0.63 to 0.67, whereas for the maximum intensity projection images of the thin slice reconstructions, receiver operating curve analysis revealed areas under the curve between 0.94 and 0.97. Interobserver agreement was higher for thin-slice (κ, 0.69-0.83) versus thick-slice nonenhanced CT reconstructions (κ, 0.38-0.45). CONCLUSIONS: Thin-slice reconstructions of standard cranial nonenhanced CT raw data allow for more sensitive and reliable detection of clots occluding the proximal middle cerebral artery.

Temporal changes in magnetic resonance imaging characteristics of Gliadel wafers and of the adjacent brain parenchyma.

Carmustine is used in the treatment of glioblastomas as locally applied chemotherapy in the form of biodegradable wafers, which are lined on the walls of the resection cavity at the end of the resection, to increase local concentrations and decrease systemic toxicity. A total of 44 patients with glioblastoma with gross macroscopic tumor removal were included. MRIs were performed at various times postoperatively (within 24 hours, 1 week, 1 month, 2 months, 3 months, 6 months, 9 months, and 1 year). MR protocols included a T2-, diffusion-weighted, and T1-weighted sequences with and without intravenous administration of gadolinium. On T1, the wafers change from their initial hypointense to an isointense appearance after a period during which they appear to be hypointense, with a hyperintense rim most prominent less than 1 month postoperatively. On T2 they change from a hypointense to an isointense appearance. Restricted diffusivity reshaping the silhouette of the wafer's surface at the rim of the resection cavity can be found as early as day 1 postoperatively; however, 1 month after implantation, they all show areas of restricted diffusion, which may remain up to 1 year. Contrast enhancement at the rim of the resection cavity can already be found at day 1 postoperatively, with a peak shortly after 1 month after surgery. These changes can easily be mistaken for an abscess and hamper the early differentiation between residual tumor tissue and normal postoperative changes. However, early changes in either appearance do not predict overall survival or the progression free interval.