Preoperative 3-Dimensional Angiography Data and Intraoperative Real-Time Vascular Data Integrated in Microscope-Based Navigation by Automatic Patient Registration Applying Intraoperative Computed Tomography.

OBJECTIVE: To establish a workflow integrating preoperative 3-dimensional (3D) angiography data and intraoperative real-time vascular information in microscope-based navigation for aneurysm and arteriovenous malformation (AVM) surgery. METHODS: In 7 patients (3 with AVMs and 4 with aneurysms), preoperative 3D rotational angiography or computed tomography (CT) or magnetic resonance angiography data were navigated applying a 32-slice movable CT scanner for low-dose registration scanning. The 3D vasculature was segmented and visualized by microscope-based navigation along with navigated intraoperative real-time imaging data from indocyanin green angiography and duplex ultrasonography. RESULTS: Automatic registration applying intraoperative CT resulted in high accuracy (registration error, 0.80 ± 0.79 mm). The effective radiation dose of the registration CT scans (0.28-0.42 mSv) was only approximately one-sixth of a standard diagnostic head CT scan. The 3D vessel architecture could be visualized accurately in the operating microscope heads-up display and on the navigation screens in the same projection as the view angle of the surgeon, both facilitating orientation in 3D space, providing a better understanding of anatomy. In addition, intraoperative real-time modalities could be coregistered with high precision, providing further information during the course of the vascular procedure. CONCLUSIONS: Registration CT imaging facilitates integrating preoperative and intraoperative vascular image data with a low registration error and low radiation exposure for the patient, improving the understanding of 3D vascular anatomy during surgery with easier identification of feeding vessels in AVMs, and of the projection and configuration of aneurysms.

Regional Differences in Thrombectomy Rates : Secondary use of Billing Codes in the MIRACUM (Medical Informatics for Research and Care in University Medicine) Consortium.

BACKGROUND AND PURPOSE: Mechanical thrombectomy, in addition to intravenous (i.v.) thrombolysis is recommended for treatment of acute stroke in patients with large vessel occlusions (LVO) in the anterior circulation up to 6 h after symptom onset. We compared thrombectomy rates of eight university hospitals of the MIRACUM consortium to analyze the implementation of this guideline in clinical routine. METHODS: Anonymized billing data in a standardized format were loaded into a local i2b2 data warehouse by applying already existing extract, transform and load (ETL) routines. A locally executed uniform SQL (structured query language) query delivered aggregated site data for all inpatients with a discharge diagnosis of ischemic stroke (ICD-10 I63) containing counts for type of acute treatment, type of admission and age groups, which were centrally analyzed with R. RESULTS: From 2014 to 2016, the thrombectomy rate almost doubled from a mean of 4.7% to 9.6%, although significant differences between centers exist (range in 2016: 5.8-17%). The number of drip-and-ship procedures increased in 3 out of 8 centers. There was no evidence for a decrease in thrombectomy rates during weekends/holiday or among patients older than 80 years, but this age group is more likely to receive i.v. recombinant tissue plasminogen activator (rtPA). CONCLUSION: The observed increase of thrombectomy rates and drip-and-ship procedures without a significant difference between weekdays and weekends or patients of different ages is substantiating a rapid implementation of stroke guidelines within the analyzed neurovascular centers. The prototype of the MIRACUM Data Integration Center already contributes to health services research in Germany.

Inferior parietal and right frontal contributions to trial-by-trial adaptations of attention to memory.

The attention to memory theory (AtoM) proposes that the same brain regions might be involved in selective processing of perceived stimuli (selective attention) and memory representations (selective retrieval). Although this idea is compelling, given consistently found neural overlap between perceiving and remembering stimuli, recent comparisons brought evidence for overlap as well as considerable differences. Here, we present a paradigm that enables the investigation of the AtoM hypothesis from a novel perspective to gain further insight into the neural resources involved in AtoM. Selective attention in perception is often investigated as a control process that shows lingering effects on immediately following trials. Here, we employed a paradigm capable of modulating selective retrieval in a similarly dynamic manner as in such selective-attention paradigms by inducing trial-to-trial shifts between relevant and irrelevant memory representations as well as changes of the width of the internal focus on memory. We found evidence for an involvement of bilateral inferior parietal lobe and right inferior frontal gyrus in reorienting the attentional focus on previously accessed memory representations. Moreover, we could dissociate the right inferior from the parietal activation in separate contrasts, suggesting that the right inferior frontal gyrus plays a role in facilitating attentional reorienting to memory representations when competing representations have been activated in the preceding trial, potentially by resolving this competition. Our results support the AtoM theory, i.e. that ventral frontal and parietal regions are involved in automatic attentional reorienting in memory, and highlight the importance of further investigations of the overlap and differences between regions involved in internal (memory) and external (perceptual) attentional selection.

Visualisation of the Bonebridge by means of CT and CBCT.

BACKGROUND: With the Bonebridge, a new bone-anchored hearing aid has been available since March 2012. The objective of the study was to analyse the visualisation of the implant itself as well as its impact on the representation of the bony structures of the petrosal bone in CT, MRI and cone beam CT (CBCT). METHODS: The Bonebridge was implanted unilaterally in two completely prepared human heads. The radiological imaging by means of CBCT, 64-slice CT, 1.5-T and 3.0-T MRI was conducted both preoperatively and postoperatively. The images were subsequently evaluated from both the ENT medical and nd radiological perspectives. RESULTS: As anticipated, no visualisation of the implant or of the petrosal bones could be realised on MRI because of the interactive technology and the magnet artefact. In contrast, an excellent evaluability of the implant itself as well as of the surrounding neurovascular structures (sinus sigmoideus, skull base, middle ear, inner ear, inner auditory canal) was exhibited in both the CT and in the CBCT. CONCLUSION: The Bonebridge can be excellently imaged with the radiological imaging technologies of CT and CBCT. In the process, CBCT shows discrete advantages in comparison with CT. No relevant restrictions in image quality in the evaluation of the bony structures of the petrosal bones could be seen.

Analysis of pneumatization and neurovascular structures of the sphenoid sinus using cone-beam tomography (CBT).

BACKGROUND: The sphenoid sinus is a frequent target of paranasal sinus surgery. Because of the high risk of injuring the surrounding structures (e.g. internal carotid artery, optical nerve) a preoperative imaging is absolutely necessary. PURPOSE: To analyze the possibilities of cone-beam computed tomography (CBCT), which is especially quite a new technique in ENT, in the evaluation of the sphenoid sinus, its surrounding structures, and the corresponding anatomical variations. MATERIAL AND METHODS: This was a retrospective, single-centre study of 580 patients (1160 sides = cases). The Accu-I-Tomo-F17 was used. Pneumatization of sphenoid sinus, course of internal artery, course of optical nerve, and dehiscence of the bony canals were evaluated. RESULTS: In the case of pneumatization a type I (completely missing or minimal sphenoid sinus) was found in two patients (0.3%), type II (posterior wall of sphenoid sinus is in front of the anterior wall of the sella) in 38 patients (6.6%), type III (posterior wall is between anterior and posterior wall of sella) in 332 patients (57,2%), type IVa (posterior wall is behind the posterior wall of sella without air dorsal the sella) in 104 patients (17.9%), and type IVb (similar to type IVa but with air dorsal the sella) in 104 patients (17.9%). In 1025 cases (89.5%) a smooth course of the internal carotid artery was found whereas a free course could be detected in 120 cases (10.5%). Defects of the bony canal of the optical nerve were found in 16.7% and of the internal carotid artery in 2.7% of the cases. The optical nerve showed a free course through the sphenoid in 151 cases (13.7%) and a smooth course in 1007 cases (87.0%). CONCLUSION: CBCT could evaluate all relevant anatomic structures and answer the questions of different anatomical variants. A modified classification of the pneumatization of the sphenoid sinus could be described. Frequencies of anatomical variations are in accordance with the current literature of CT research.

Controlling conflict from interfering long-term memory representations.

Remembering is more than an activation of a memory trace. As retrieval cues are often not uniquely related to one specific memory, cognitive control should come into play to guide selective memory retrieval by focusing on relevant while ignoring irrelevant information. Here, we investigated, by means of EEG and fMRI, how the memory system deals with retrieval interference arising when retrieval cues are associated with two material types (faces and spatial positions), but only one is task-relevant. The topography of slow EEG potentials and the fMRI BOLD signal in posterior storage areas indicated that in such situations not only the relevant but also the irrelevant material becomes activated. This results in retrieval interference that triggers control processes mediated by the medial and lateral PFC, which are presumably involved in biasing target representations by boosting the task-relevant material. Moreover, memory-based conflict was found to be dissociable from response conflict that arises when the relevant and irrelevant materials imply different responses. The two types of conflict show different activations in the medial frontal cortex, supporting the claim of domain-specific prefrontal control systems.

Memory-based decision-making with heuristics: evidence for a controlled activation of memory representations.

Many of our daily decisions are memory based, that is, the attribute information about the decision alternatives has to be recalled. Behavioral studies suggest that for such decisions we often use simple strategies (heuristics) that rely on controlled and limited information search. It is assumed that these heuristics simplify decision-making by activating long-term memory representations of only those attributes that are necessary for the decision. However, from behavioral studies alone, it is unclear whether using heuristics is indeed associated with limited memory search. The present study tested this assumption by monitoring the activation of specific long-term-memory representations with fMRI while participants made memory-based decisions using the "take-the-best" heuristic. For different decision trials, different numbers and types of information had to be retrieved and processed. The attributes consisted of visual information known to be represented in different parts of the posterior cortex. We found that the amount of information required for a decision was mirrored by a parametric activation of the dorsolateral PFC. Such a parametric pattern was also observed in all posterior areas, suggesting that activation was not limited to those attributes required for a decision. However, the posterior increases were systematically modulated by the relative importance of the information for making a decision. These findings suggest that memory-based decision-making is mediated by the dorsolateral PFC, which selectively controls posterior storage areas. In addition, the systematic modulations of the posterior activations indicate a selective boosting of activation of decision-relevant attributes.

Analysis of the fossa olfactoria using cone beam tomography (CBT).

CONCLUSION: A cone beam tomography (CBT) examination of the olfactory area with its different variants allows development of an individual anatomical-radiological risk profile of the ethmoid and the identification of so-called 'dangerous ethmoids.' OBJECTIVE: Preoperative imaging performed with high-resolution CBT is imperative for analysis of the risk of injuring the olfactory fossa during sinus surgery. This study aimed to analyze the relevant parameters. METHODS: This was a retrospective, single-center study of 141 patients. The Accu-I-Tomo F17 was used. Keros type, the point of the anterior ethmoid artery, and the angle between the lateral lamella and the cribriform plate (α(lc)) were evaluated. RESULTS: The Keros types were distributed as follows: type I, 13% (α(lc): 131°); type II, 64% (α(lc): 116°); type III, 23% (α(lc): 108°) (p < 0.001). The angle of the olfactory fossa and the position of the anterior ethmoid artery (free course: α(lc)=112° vs integrated into the skull base: α(lc)= 120°) was significantly different. DISCUSSION: Surgical procedures in Keros type III where the height of the lateral lamella is much longer than in type II or type I, with an angle of nearly 107° between the lateral lamella and the cribriform plate, are expected to be safer in comparison with Keros type II with 116° and Keros type I with 131°.

Frontal and parietal contributions to arithmetic fact retrieval: a parametric analysis of the problem-size effect.

The goal of the present study was to investigate the neuroanatomical basis of arithmetic fact retrieval. The rationale was that areas playing a crucial role in arithmetic fact retrieval should show a systematic increase of activation with increasing retrieval effort. To achieve this goal, we utilized the problem-size effect as this is known to be systematically related to retrieval effort. In contrast to many previous studies, we here took a parametric approach to account for the continuous increase of retrieval effort with problem size. BOLD signals were modeled with problem size as parametric regressor and negative slow waves of the EEG were categorized into six levels of problem size. The fMRI data showed that activation in the angular gyrus and ACC/SMA increased parametrically with problem size. The ERP data showed a systematic amplitude increase with increasing problem size, especially at fronto-central electrodes. Consistent with the fMRI data, source modeling localized this effect to the ACC. While these findings support previous notions about the crucial role of the angular gyrus during fact retrieval, they also provide evidence that the medial frontal cortex is involved when single-digit multiplications are solved. Thus, both parietal and frontal structures seem to be integral parts of a system that enables and controls arithmetic fact retrieval.

Intralesional endoscopy of advanced lymphatic malformations of the head and neck: a new diagnostic approach and a potential therapeutic tool.

OBJECTIVES: To evaluate the morphologic properties of advanced lymphatic malformations of the head and neck and to investigate possible therapeutic interventions by intralesional endoscopy. DESIGN: This case study analyzes the outcome of intralesional endoscopy of lymphatic malformations of the head and neck and discusses the results of this approach. SETTING: Academic medical center. PATIENTS: Endoscopy was performed on 4 patients with cervicofacial lymphatic malformations. INTERVENTIONS: Endoscopy of lymphatic malformations. RESULTS: The endoscopic inspection and assessment of the lesions revealed detailed information about morphologic aspects like the structure of intralesional septa, internal vascularization, and intercystic correspondence and channel networks. Anatomic landmarks could be followed on their intralesional courses. CONCLUSIONS: Intralesional endoscopy of lymphatic malformations provides insight into the morphologic properties of the lesion and is a useful supplementary tool during conventional surgical intervention and for sclerosing therapy. The technique allows a detailed assessment of these lesions and opens a broad spectrum of therapeutic options.

Early side effects after embolization of a carotid body tumor using Onyx.

The case of a 20-year-old woman with a carotid body tumor of Shamblin class III is reported. Ten hours after preoperative direct intralesional embolization with 20 mL Onyx (ethylene-vinyl alcohol copolymer; Micro Therapeutics, Irvine, Calif), the patient showed symptoms of Horner syndrome and deficits of the hypoglossal and glossopharyngeal nerves. Intraoperative examination 12 hours after Onyx embolization revealed a massive swelling of the hypoglossal and glossopharyngeal nerves. The patient's tongue motility and glossopharyngeal function improved after surgery, but Horner syndrome was still present. Owing to the delayed occurrence of these adverse effects, the optimal time of surgical intervention after Onyx embolization should be discussed and perhaps expedited.

Neural correlates of generating visual nouns and motor verbs in a minimal phrase context.

The neural basis underlying the generation of nouns and verbs is still not completely understood. In classical generation tasks, specific features of the produced words can hardly be controlled. Therefore, the observed neural correlates of noun and verb production cannot be directly related to differences in specific features of the generated words. The present study seeks to address this issue by using a "minimal-phrase context" to elicit the activation of specific nouns and verbs. With this context, the to-be-generated words were highly constrained, and thus their semantic and other features (visual/action relatedness, word frequency, cloze probability, etc.) are well controlled. Thus, the present paradigm combines the advantages of classical word generation tasks (i.e., active semantic processing) with the advantages of tasks that allow for a high control of the experimental stimuli, such as passive viewing, reading, or lexical decision tasks. In an fMRI study, 17 participants generated verbs with strong motor and nouns with strong visual associations. Both noun and verb generation, compared to a rhyme generation baseline, elicited stronger activation in perisylvian language areas of the temporal and parietal cortex. In addition, stronger activation for nouns was found in the right middle/inferior temporal cortex. This activation supports the claim that noun generation is mediated by visual processing areas. Stronger activation for verb generation was found in the left superior temporal gyrus. Since this area is involved in motion perception, the results suggest that perceptual representations of movements mediate the generation of action verbs.

Orbital and periorbital vascular anomalies--an approach to diagnosis and therapeutic concepts.

CONCLUSION: A correct and universally accepted terminology based on the biologic behavior of orbital vascular anomalies is essential to avoid misleading diagnoses, to choose an adequate therapy regimen, and to compare different therapeutic approaches. The management of these diseases is multi-modal and an interdisciplinary challenge. BACKGROUND: There is persisting terminological and clinical confusion about vascular anomalies involving the orbit. Review of the literature reveals a diverse or misleading terminology and a lack of consensus for the treatment of vascular malformations or vascular tumors of the orbit. METHODS: This study comprised a detailed analysis of cases presenting with orbital vascular anomalies followed by an extensive review of the literature. RESULTS: Thirty-six patients were analyzed, among them 19 patients with peri- and/or intraorbital hemangiomas, 3 with intraorbital and 2 with periorbital venous malformations, 2 with orbital involvement of complex vascular malformations, and 10 with lymphatic malformations involving the orbit.

Digital volume tomography (DVT) measurements of the olfactory cleft and olfactory fossa.

CONCLUSION: Preoperative imaging is important, because of the small size of the cribriform plate, different anatomical variants of the olfactory fossa in varied patients and unequal width of the cribriform plate in the anterior and posterior third. OBJECTIVE: Digital volume tomography (DVT) is a rather new imaging technique for the diagnosis of diseases of paranasal sinuses. This technology is dedicated to the evaluation of the distinctive structures of the anterior skull base due to the high resolution of the DVT. Based on the Keros classification this anatomic area was analyzed radiologically and also in relation to the uncinate process. METHODS: The investigation was performed on 111 patients. The Accu-I-tomo F17 was used. Patients with total nasal polyposis and patients who had undergone sinus surgery were excluded from the study. RESULTS: Keros type I was found in 11.25% of the patients, type II in 68.05% and type III in 20.7%. Significant asymmetry of the olfactory fossa was identified in nine patients (8.1%). The width of the olfactory cleft varied from 0 to 3.25 mm. No relation between Keros type and a particular onset of the uncinate process to orbit, skull base or middle turbinate could be detected.

Dissociating the solution processes of small, large, and zero multiplications by means of fMRI.

The present study investigated the neuroanatomical basis of different solution processes in single-digit multiplication by means of fMRI. Sixteen participants silently produced the solution of three distinct types of multiplication, i.e., problems involving zero (e.g., 3*0), small (e.g., 2*4), or large operands (e.g., 8*7). Zero and small problems are assumed to be solved by rule application and fact retrieval, respectively, and problems with large operands sometimes involve backup strategies when direct retrieval is not sufficient. Small problems, when compared with a high-level baseline not requiring any kind of calculation, activated a network of parietal, subcortical, and frontal areas. This activation pattern supports the hypothesis that arithmetic fact retrieval is mediated by a verbal processing loop including the angular gyrus and the basal ganglia. Problems with larger operands showed increased activation in the anterior cingulate cortex, SMA, and the left inferior frontal gyrus, which could reflect increased conflict during the fact-retrieval process, but also higher demands for controlling and coordinating multiple processing steps when a problem cannot be solved by direct retrieval. Zero problems, in comparison to multiplications with small operands, activated the caudate nucleus and the right inferior frontal cortex, showing that rule application is separable from fact retrieval on a neuroanatomical level, too.

Digital volume tomography (DVT) as a diagnostic modality of the anterior skull base.

CONCLUSION: Because of high resolution and the relatively lower costs in comparison with modern helical CT scanners, digital volume tomography (DVT) can be recommended in the diagnosis of the nasal cavity and paranasal sinuses. OBJECTIVES: DVT is an advancement of panoramic tomography and is based on the principles of rotational tomography. It enables high resolution visualization of osseous structures. The slices can be displayed in three orthogonal planes that can be changed in angle arbitrarily. Data volumes of up to 12×17 cm can be examined with a new generation of the DVT. The aim of this study was to point out the potential of DVT in the anterior skull base. SUBJECTS AND METHODS: DVT scans with a cylindrical size of 10 cm in diameter and 10 cm in height were performed in 23 patients. The identification of surgical key landmarks (uncinate process, middle turbinate, ethmoidal bulla, agger nasi cells, Haller cells, frontal recess, anterior ethmoidal artery in its relationship to the skull base, the cribiform plate of the sphenoidal sinus in relation to the optic nerve, and the internal carotid artery) was evaluated. RESULTS: Display of the essential surgical key landmarks was possible in all patients.

The human dorsal action control system develops in the absence of vision.

The primate dorsal pathway has been proposed to compute vision for action. Although recent findings suggest that dorsal pathway structures contribute to somatosensory action control as well, it is yet not clear whether or not the development of dorsal pathway functions depends on early visual experience. Using functional magnetic resonance imaging, we investigated the pattern of cortical activation in congenitally blind and matched blindfolded sighted adults while performing kinesthetically guided hand movements. Congenitally blind adults activated similar dorsal pathway structures as sighted controls. Group-specific activations were found in the extrastriate cortex and the auditory cortex for congenitally blind humans and in the precuneus and the presupplementary motor area for sighted humans. Dorsal pathway activity was in addition observed for working memory maintenance of kinesthetic movement information in both groups. Thus, the results suggest that dorsal pathway functions develop in the absence of vision. This favors the idea of a general mechanism of movement control that operates regardless of the sensory input modality. Group differences in cortical activation patterns imply different movement control strategies as a function of visual experience.

Cortical activation patterns during long-term memory retrieval of visually or haptically encoded objects and locations.

The present study used functional magnetic resonance imaging to delineate cortical networks that are activated when objects or spatial locations encoded either visually (visual encoding group, n=10) or haptically (haptic encoding group, n=10) had to be retrieved from long-term memory. Participants learned associations between auditorily presented words and either meaningless objects or locations in a 3-D space. During the retrieval phase one day later, participants had to decide whether two auditorily presented words shared an association with a common object or location. Thus, perceptual stimulation during retrieval was always equivalent, whereas either visually or haptically encoded object or location associations had to be reactivated. Moreover, the number of associations fanning out from each word varied systematically, enabling a parametric increase of the number of reactivated representations. Recall of visual objects predominantly activated the left superior frontal gyrus and the intraparietal cortex, whereas visually learned locations activated the superior parietal cortex of both hemispheres. Retrieval of haptically encoded material activated the left medial frontal gyrus and the intraparietal cortex in the object condition, and the bilateral superior parietal cortex in the location condition. A direct test for modality-specific effects showed that visually encoded material activated more vision-related areas (BA 18/19) and haptically encoded material more motor and somatosensory-related areas. A conjunction analysis identified supramodal and material-unspecific activations within the medial and superior frontal gyrus and the superior parietal lobe including the intraparietal sulcus. These activation patterns strongly support the idea that code-specific representations are consolidated and reactivated within anatomically distributed cell assemblies that comprise sensory and motor processing systems.

How moving objects become animated: the human mirror neuron system assimilates non-biological movement patterns.

The so-called mirror neuron system (MNS) responds when humans observe actions performed by a member of their own species. This activity is understood as an internal motor representation of the observed movement pattern. By contrasting meaningless human hand movements with meaningless artificial movements of objects in space, we tested the claim that exclusively movements belonging to the human motor repertoire have direct access to the MNS. Eighteen participants observed video clips of moving hands and objects while the hemodynamic response was recorded with functional magnetic resonance imaging. Second-level analysis of the hemodynamic response revealed substantially overlapping activation patterns for both types of movements including relevant structures of the MNS (bilateral premotor and parietal areas, occipito-temporal junction, postcentral gyrus and the right superior temporal sulcus). This suggests that perceptual processing of moving hands and objects recruits similar and overlapping cortical networks. Direct comparison of the two movement types revealed stronger activations for hand movements mainly in structures of the MNS suggesting an "expertise effect". Overall, our results provide evidence that observing movements not explicitly belonging to the human motor repertoire can activate the human MNS, most likely because an association with a biological movement is evoked.

Motor learning affects visual movement perception.

In the present study we investigated whether imitation of artificial movement trajectories of meaningless objects has an effect on how these trajectories are later perceptually processed within the human brain. During observation of a sequence of artificial object movements 10 participants (experimental group) actively imitated the trajectories during motor training and 10 participants (control group) solved a working memory task without motor training. The haemodynamic responses were recorded before and after the intervention while participants observed the movements and either had to detect colour changes of one of the objects (colour task, motor-irrelevant) or had to judge whether the movement pattern could be imitated with the hands (simulation judgement task, motor-relevant). The between-group comparison of the post-intervention haemodynamic responses revealed stronger activity for the motor training than for the control group during the simulation judgement task. This activity appeared in motor-related areas (supplementary motor area and inferior parietal lobe) and in the occipito-temporal area. During the colour task, the motor training group showed stronger activity in the occipital lobe. The control group did not reveal any stronger activity than the motor training group for either task. The results suggest that motor training has task-specific effects on neural processes that are involved in perception of movements. Furthermore, they indicate that motor-related areas are triggered by observed artificial object movements, but only if a motor-relevant task is pursued.