Upper extremity training followed by lower extremity training with a brain-computer interface rehabilitation system.

Introduction: Brain-computer interfaces (BCIs) based on functional electrical stimulation have been used for upper extremity motor rehabilitation after stroke. However, little is known about their efficacy for multiple BCI treatments. In this study, 19 stroke patients participated in 25 upper extremity followed by 25 lower extremity BCI training sessions. Methods: Patients' functional state was assessed using two sets of clinical scales for the two BCI treatments. The Upper Extremity Fugl-Meyer Assessment (FMA-UE) and the 10-Meter Walk Test (10MWT) were the primary outcome measures for the upper and lower extremity BCI treatments, respectively. Results: Patients' motor function as assessed by the FMA-UE improved by an average of 4.2 points (p < 0.001) following upper extremity BCI treatment. In addition, improvements in activities of daily living and clinically relevant improvements in hand and finger spasticity were observed. Patients showed further improvements after the lower extremity BCI treatment, with walking speed as measured by the 10MWT increasing by 0.15 m/s (p = 0.001), reflecting a substantial meaningful change. Furthermore, a clinically relevant improvement in ankle spasticity and balance and mobility were observed. Discussion: The results of the current study provide evidence that both upper and lower extremity BCI treatments, as well as their combination, are effective in facilitating functional improvements after stroke. In addition, and most importantly improvements did not stop after the first 25 upper extremity BCI sessions.

Mapping of the central sulcus using non-invasive ultra-high-density brain recordings.

Brain mapping is vital in understanding the brain's functional organization. Electroencephalography (EEG) is one of the most widely used brain mapping approaches, primarily because it is non-invasive, inexpensive, straightforward, and effective. Increasing the electrode density in EEG systems provides more neural information and can thereby enable more detailed and nuanced mapping procedures. Here, we show that the central sulcus can be clearly delineated using a novel ultra-high-density EEG system (uHD EEG) and somatosensory evoked potentials (SSEPs). This uHD EEG records from 256 channels with an inter-electrode distance of 8.6 mm and an electrode diameter of 5.9 mm. Reconstructed head models were generated from T1-weighted MRI scans, and electrode positions were co-registered to these models to create topographical plots of brain activity. EEG data were first analyzed with peak detection methods and then classified using unsupervised spectral clustering. Our topography plots of the spatial distribution from the SSEPs clearly delineate a division between channels above the somatosensory and motor cortex, thereby localizing the central sulcus. Individual EEG channels could be correctly classified as anterior or posterior to the central sulcus with 95.2% accuracy, which is comparable to accuracies from invasive intracranial recordings. Our findings demonstrate that uHD EEG can resolve the electrophysiological signatures of functional representation in the brain at a level previously only seen from surgically implanted electrodes. This novel approach could benefit numerous applications, including research, neurosurgical mapping, clinical monitoring, detection of conscious function, brain-computer interfacing (BCI), rehabilitation, and mental health.

Brain-computer interface treatment for gait rehabilitation in stroke patients.

The use of Brain-Computer Interfaces (BCI) as rehabilitation tools for chronically ill neurological patients has become more widespread. BCIs combined with other techniques allow the user to restore neurological function by inducing neuroplasticity through real-time detection of motor-imagery (MI) as patients perform therapy tasks. Twenty-five stroke patients with gait disability were recruited for this study. Participants performed 25 sessions with the MI-BCI and assessment visits to track functional changes during the therapy. The results of this study demonstrated a clinically significant increase in walking speed of 0.19 m/s, 95%CI [0.13-0.25], p < 0.001. Patients also reduced spasticity and improved their range of motion and muscle contraction. The BCI treatment was effective in promoting long-lasting functional improvements in the gait speed of chronic stroke survivors. Patients have more movements in the lower limb; therefore, they can walk better and safer. This functional improvement can be explained by improved neuroplasticity in the central nervous system.

Characterization of High-Gamma Activity in Electrocorticographic Signals.

Introduction: Electrocorticographic (ECoG) high-gamma activity (HGA) is a widely recognized and robust neural correlate of cognition and behavior. However, fundamental signal properties of HGA, such as the high-gamma frequency band or temporal dynamics of HGA, have never been systematically characterized. As a result, HGA estimators are often poorly adjusted, such that they miss valuable physiological information. Methods: To address these issues, we conducted a thorough qualitative and quantitative characterization of HGA in ECoG signals. Our study is based on ECoG signals recorded from 18 epilepsy patients while performing motor control, listening, and visual perception tasks. In this study, we first categorize HGA into HGA types based on the cognitive/behavioral task. For each HGA type, we then systematically quantify three fundamental signal properties of HGA: the high-gamma frequency band, the HGA bandwidth, and the temporal dynamics of HGA. Results: The high-gamma frequency band strongly varies across subjects and across cognitive/behavioral tasks. In addition, HGA time courses have lowpass character, with transients limited to 10 Hz. The task-related rise time and duration of these HGA time courses depend on the individual subject and cognitive/behavioral task. Task-related HGA amplitudes are comparable across the investigated tasks. Discussion: This study is of high practical relevance because it provides a systematic basis for optimizing experiment design, ECoG acquisition and processing, and HGA estimation. Our results reveal previously unknown characteristics of HGA, the physiological principles of which need to be investigated in further studies.

Primary neurolymphomatosis of the trigeminal nerve.

We report a case of a primary malignant lymphoma of the trigeminal nerve that was associated with facial pain. A 65-year-old man was examined at another hospital for unilateral facial pain. Carbamazepine was prescribed, but his symptoms did not improve. Magnetic resonance imaging (MRI) revealed swelling of the trigeminal nerve and a mass lesion in Meckel's cave. The patient was referred to our hospital at this point. Gadolinium-enhanced MRI and F18-Fluorodeoxyglucose-position emission tomography suggested a likely malignant tumour and a biopsy was performed. Histopathological examination showed diffuse a large B cell lymphoma. The patient was treated with high-dose methotrexate (HD-MTX) and radiotherapy. Despite responding well to initial treatment, the patient relapsed, with lymphoma observed throughout the body. He died of pneumonia 18 months after the initial diagnosis. Facial pain is a symptom that is commonly managed in general practice. If symptoms do not improve, repeated imaging studies, including contrast MRI, is warranted. This is the first reported case of primary neurolymphomatosis (NL) of the trigeminal nerve associated with facial pain alone. Furthermore, HD-MTX and radiotherapy may be considered for the management of primary NL of a cranial nerve.

Portable rehabilitation system with brain-computer interface for inpatients with acute and subacute stroke: A feasibility study.

The feasibility and safety of brain-computer interface (BCI) systems for patients with acute/subacute stroke have not been established. The aim of this study was to firstly demonstrate the feasibility and safety of a bedside BCI system for inpatients with acute/subacute stroke in a small cohort of inpatients. Four inpatients with early-phase hemiplegic stroke (7-24 days from stroke onset) participated in this study. The portable BCI system showed real-time feedback of sensorimotor rhythms extracted from scalp electroencephalograms (EEGs). Patients attempted to extend the wrist on their affected side, and neuromuscular electrical stimulation was applied only when the system detected significant movement intention-related changes in EEG. Between 120 and 200 training trials per patient were successfully and safely conducted at the bedside over 2-4 days. Our results clearly indicate that the proposed bedside BCI system is feasible and safe. Larger clinical studies are needed to determine the clinical efficacy of the system and its effect size in the population of patients with acute/subacute post-stroke hemiplegia.

Brain Computer Interface Treatment for Motor Rehabilitation of Upper Extremity of Stroke Patients-A Feasibility Study.

INTRODUCTION: Numerous recent publications have explored Brain Computer Interfaces (BCI) systems as rehabilitation tools to help subacute and chronic stroke patients recover upper extremity movement. Recent work has shown that BCI therapy can lead to better outcomes than conventional therapy. BCI combined with other techniques such as Functional Electrical Stimulation (FES) and Virtual Reality (VR) allows to the user restore the neurological function by inducing the neural plasticity through improved real-time detection of motor imagery (MI) as patients perform therapy tasks. METHODS: Fifty-one stroke patients with upper extremity hemiparesis were recruited for this study. All participants performed 25 sessions with the MI BCI and assessment visits to track the functional changes before and after the therapy. RESULTS: The results of this study demonstrated a significant increase in the motor function of the paretic arm assessed by Fugl-Meyer Assessment (FMA-UE), ΔFMA-UE = 4.68 points, P < 0.001, reduction of the spasticity in the wrist and fingers assessed by Modified Ashworth Scale (MAS), ΔMAS-wrist = -0.72 points (SD = 0.83), P < 0.001, ΔMAS-fingers = -0.63 points (SD = 0.82), P < 0.001. Other significant improvements in the grasp ability were detected in the healthy hand. All these functional improvements achieved during the BCI therapy persisted 6 months after the therapy ended. Results also showed that patients with Motor Imagery accuracy (MI) above 80% increase 3.16 points more in the FMA than patients below this threshold (95% CI; [1.47-6.62], P = 0.003). The functional improvement was not related with the stroke severity or with the stroke stage. CONCLUSION: The BCI treatment used here was effective in promoting long lasting functional improvements in the upper extremity in stroke survivors with severe, moderate and mild impairment. This functional improvement can be explained by improved neuroplasticity in the central nervous system.

Tailor-Made Surgery Based on Functional Networks for Intractable Epilepsy.

Normal and pathological networks related to seizure propagation have got attention to elucide complex seizure semiology and contribute to diagnosis and surgical monitoring in epilepsy treatment. Since focal and generalized epileptogenic syndromes abnormalities might involve multiple foci and large-scale networks, we applied electrophysiolpgy (cortco-cortico evoked potential; CCEP), and tractography to make detailed diagnosis for complex syndrome. All 14 epilepsy patients with no or little abnormality on images investigations underwent subdural grid implantation for epilepsy diagnosis. To perform quick network analysis, we recorded and analyzed high gamma activity (HGA) of epileptogenic activity and CCEPs to identify pathological activity distribution and network connectivity. [Results] Pathological CCEPs showed two negative deflections consisting of early (>40 ms) and late (>150 ms) components in electrically stable circumstance at bed side and early CCEPs appeared in 57% of the patients. On the basis of the CCEP findings, tractography detected anatomical connections. Early components of pathological CCEPs diminished after complete disconnection of tractoography-based fibers between the foci in seven of eight cases. One case with residual pathological CCEPs showed poorer outcome. Thirteen (92.8%) patients with or without CCEPs who underwent network surgery had favorable prognosis except for a case with wide traumatic epilepsy. Intraoperative CCEP measurements and HGA mapping enabled visualization of pathological networks and clinical impotence as a biomarker to improve functional prognosis. HGA/CCEP recording should shed light on pathological and complex propagation for epilepsy surgery.

Time-Variant Linear Discriminant Analysis Improves Hand Gesture and Finger Movement Decoding for Invasive Brain-Computer Interfaces.

Invasive brain-computer interfaces yield remarkable performance in a multitude of applications. For classification experiments, high-gamma bandpower features and linear discriminant analysis (LDA) are commonly used due to simplicity and robustness. However, LDA is inherently static and not suited to account for transient information that is typically present in high-gamma features. To resolve this issue, we here present an extension of LDA to the time-variant feature space. We call this method time-variant linear discriminant analysis (TVLDA). It intrinsically provides a feature reduction stage, which makes external approaches thereto obsolete, such as feature selection techniques or common spatial patterns (CSPs). As well, we propose a time-domain whitening stage which equalizes the pronounced 1/f-shape of the typical brain-wave spectrum. We evaluated our proposed architecture based on recordings from 15 epilepsy patients with temporarily implanted subdural grids, who participated in additional research experiments besides clinical treatment. The experiments featured two different motor tasks involving three high-level gestures and individual finger movement. We used log-transformed bandpower features from the high-gamma band (50-300 Hz, excluding power-line harmonics) for classification. On average, whitening improved the classification performance by about 11%. On whitened data, TVLDA outperformed LDA with feature selection by 11.8%, LDA with CSPs by 13.9%, and regularized LDA with vectorized features by 16.4%. At the same time, TVLDA only required one or two internal features to achieve this. TVLDA provides stable results even if very few trials are available. It is easy to implement, fully automatic and deterministic. Due to its low complexity, TVLDA is suited for real-time brain-computer interfaces. Training is done in less than a second. TVLDA performed particularly well in experiments with data from high-density electrode arrays. For example, the three high-level gestures were correctly identified at a rate of 99% over all subjects. Similarly, the decoding accuracy of individual fingers was 96% on average over all subjects. To our knowledge, these mean accuracies are the highest ever reported for three-class and five-class motor-control BCIs.

Multispectrum Indocyanine Green Videography for Visualizing Brain Vascular Pathology.

OBJECTIVE: Currently, neurosurgical vascular surgery frequently uses indocyanine green (ICG)-videography (VG) to evaluate the blood flow in brain vessels. Although ICG-VG delineates intravascular ICG fluorescence as a high-intensity signal in gray-scale with dark background, it is hard to identify anatomical structures, including vasculature or surgical devices simultaneously. This report developed combination of a near-infrared (NIR) camera with particular sensitivity and an optical filter to observe the blood-flow conditions and anatomical structures. METHODS: To overcome the specific issues of ICG-VG, we applied a high-sensitivity camera with a 980-nm NIR component to delineate anatomical and fluorescence images, detecting signals between 830 and 1000 nm simultaneously during operation. We used a diluted ICG phantom to evaluate fluorescence signal changes by changing wavelength of the emission light. For clinical use, we used a high-sensitivity NIR camera with a high-pass filter on a surgical microscope. The new NIR system detected signals between 770 and 1000 nm, and the lighting system illuminated objects mainly at 980-nm wavelength. Both images with the blood flow and anatomical structures were projected to the smart glasses in real time. RESULTS: In the phantom experiment, we found that the emission light with wide band widths (575-800 nm) evoked various intensities of ICG fluorescence. This new NIR system allowed us to observe ICG fluorescence and anatomical structures without image fusion or time-delay. The both information of anatomy and fluorescence was projected on wearable smart glasses. Furthermore, the new NIR system detected ICG-fluorescence signals for a longer duration than the original camera, which allowed us to achieve careful and detailed observation of more vasculature and fine vessels. CONCLUSIONS: This study proposes a new NIR system and emphasizes simultaneous observation of anatomy and fluorescence signals during operation. It paves the way for further possibilities in the development of optical systems. To understand the natural phenomena and combination of different scientific and clinical fields, it might be important to understand and combine not only fluorescence, but also natural science, optics, and background pathology. This simple system would be available for neuroendoscope and robotic surgery.

Real-time spectrum quantification of tumor-related fluorescence during neurosurgery: A preliminary report.

OBJECTIVES: The fluorescent dye, 5-aminolevulinic acid (5-ALA), is currently applied for fluorescence-guided resections of high-grade gliomas. Present limitations of this technique are qualitative and subjective analyses, which show little of the background structures. This paper describes the intraoperative quantitative analysis of fluorescence intensity, hot-spot enhancement by frame averaging, and observation of surrounding structures by using 1000-nm lighting in real time. PATIENTS AND METHODS: A sample of diluted protoporphyrin IX (PpIX) in a bottle and 37 samples from nine patients with brain lesions were involved in this study. In this preliminary study, we determined appropriate conditions for image averaging and filters and selected the most sensitive spectrometer. In addition, we utilized a 1000-nm lighting system to visualize surrounding structures with no interference from PpIX fluorescence. RESULTS: The novel system permitted the real-time quantitative analysis of PpIX fluorescence in operative fields by illuminating structures with 1000-nm-lighting. The real-time quantification provided subjective evaluations for surgical decision-making. We found good correlations between the fluorescence and PpIX contents in brain tissue. Furthermore, 1000-nm lighting visualized the anatomical structures and PpIX fluorescence simultaneously. CONCLUSION: The combination of spectroscopy and a 1000-nm lighting system could enable surgeons to create a spectrogram of targets of interest while observing background structures. The spectrometer that we selected is highly sensitive to PpIX fluorescence and enables us to perform intraoperative real-time tissue mapping. By using a real-time system, we can perform quantitative and objective evaluations to achieve maximal tumor resection.

Subarachnoid Hemorrhage with Concurrent Dural and Perimedullary Arteriovenous Fistulas at Craniocervical Junction: Case Report and Literature Review.

BACKGROUND: The association between a dural arteriovenous fistula (dAVF) and perimedullary arteriovenous fistula (AVF) is rarely observed at the craniocervical junction (CCJ). We present a case of subarachnoid hemorrhage (SAH) with concurrent dAVF and perimedullary AVF at the CCJ. Here, we describe the cause of bleeding and the process of determining whether it was a varix or an arterial aneurysm. CASE DESCRIPTION: A 69-year-old man with SAH visited the emergency department. A dAVF at the CCJ was detected on digital subtraction angiography (DSA). However, after 3 weeks, when the DSA was repeated, a perimedullary AVF and varix were identified. We performed an endovascular treatment, but because the perimedullary AVF remained, we performed a direct surgery. The patient was discharged without weakness, but this left abducens nerve palsy remained. CONCLUSIONS: In recent reports, SAH caused by concurrent dAVF and perimedullary AVF raised the possibility of an arterial aneurysm. However, in this case, the possibility of venous bleeding was high and a varix rather than an aneurysm was observed. On the basis of the reported cases, concurrent dAVF and perimedullary AVF at the CCJ is a "middle-flow arteriovenous shunt" that may induce a varix or an arterial aneurysm.

Preoperative Predictors and Prognosticators After Microsurgical Clipping of Poor-Grade Subarachnoid Hemorrhage: A Retrospective Study.

BACKGROUND: Contrary to expectations, some patients with poor-grade subarachnoid hemorrhage (SAH) show favorable outcomes. However, the factors predictive of good prognosis are unclear. The purposes of this study were to identify factors related to poor-grade SAH and to analyze preoperative prognostic factors. METHODS: We included 186 patients with SAH who underwent surgical clipping or conservative treatment immediately after SAH diagnosis. Physiologic, radiographic, and blood examination data were collected retrospectively. Factors related to poor World Federation of Neurological Societies (WFNS) grade (WFNS IV and V) and poor outcome (modified Rankin Scale scores 3-6) were analyzed. RESULTS: The patients (mean age, 61.6 years) included 134 women (72%). Seventy patients (38.2%) had poor WFNS scores. On multivariate analysis, age ≥70 years (adjusted odds ratio [OR], 3.73), midline shift (OR, 4.89), and the absence of cerebrospinal fluid in the high-convexity cortical sulci (OR, 5.47) and ambient cistern (OR, 4.83) were predictive of poor WFNS scores. Age ≥70 years (OR, 8.36), WFNS grade 5 (OR, 15.35), intracerebral hematoma (OR, 3.32), and Evans index (EI) ≥0.3 (OR, 4.40) were predictive of poor outcome. Body mass index (OR, 0.87), intraventricular hemorrhage (OR, 3.86), glycated hemoglobin level (OR, 2.78), and age ≥70 years (OR, 4.12) were predictive of EI ≥0.3. CONCLUSIONS: Poor outcomes correlated with older age, brain-destructive hemorrhage, and EI ≥0.3. The EI reflects both hydrocephalus and the patient's frailty. Radiographic signs of poor-grade SAH were not correlated with poor outcome, suggesting that early decompressive surgery may improve outcome.

Treatment of Fourth Ventricle Arachnoid Cyst via Anterior Hone of Lateral Ventricle Using Flexible Endoscope.

BACKGROUND: Arachnoid cysts are common anomalies in the intracranial region. However, an intraventricular arachnoid cyst is rare, and occurrence within the fourth ventricle is especially uncommon; only 16 cases have been described in the literature. Arachnoid cysts in the fourth ventricle may cause obstructive hydrocephalus or cerebellar ataxia or cranial nerve palsy. Treatment of a fourth ventricular arachnoid cyst is complete or partial resection via a midline suboccipital approach. Recently, endoscopic fenestration has become the procedure of choice in the treatment of arachnoid cysts in supratentorial locations, but as yet there has been no report of treating a fourth ventricle arachnoid cyst using a flexible endoscope. CASE DESCRIPTION: We present the case of a 43-year-old man who suffered a recurrence of an arachnoid cyst in the fourth ventricle that had been partially excised 8 years previously using midline suboccipital craniectomy. Because of concerns of adhesions following the previous craniectomy, we decided to perform endoscopic treatment via the anterior horn of the lateral ventricle. CONCLUSIONS: As per our knowledge, this is the first case reporting the treatment of an arachnoid cyst of the fourth ventricle using a flexible endoscope via the anterior horn of the lateral ventricle. This method can be used to treat arachnoid cysts of the fourth ventricle.

A quantitative method for evaluating cortical responses to electrical stimulation.

BACKGROUND: Electrical stimulation of the cortex using subdurally implanted electrodes can causally reveal structural connectivity by eliciting cortico-cortical evoked potentials (CCEPs). While many studies have demonstrated the potential value of CCEPs, the methods to evaluate them were often relatively subjective, did not consider potential artifacts, and did not lend themselves to systematic scientific investigations. NEW METHOD: We developed an automated and quantitative method called SIGNI (Stimulation-Induced Gamma-based Network Identification) to evaluate cortical population-level responses to electrical stimulation that minimizes the impact of electrical artifacts. We applied SIGNI to electrocorticographic (ECoG) data from eight human subjects who were implanted with a total of 978 subdural electrodes. Across the eight subjects, we delivered 92 trains of approximately 200 discrete electrical stimuli each (amplitude 4-15 mA) to a total of 64 electrode pairs. RESULTS: We verified SIGNI's efficacy by demonstrating a relationship between the magnitude of evoked cortical activity and stimulation amplitude, as well as between the latency of evoked cortical activity and the distance from the stimulated locations. CONCLUSIONS: SIGNI reveals the timing and amplitude of cortical responses to electrical stimulation as well as the structural connectivity supporting these responses. With these properties, it enables exploration of new and important questions about the neurophysiology of cortical communication and may also be useful for pre-surgical planning.

Quantitative Blood Flow Assessment by Multiparameter Analysis of Indocyanine Green Video Angiography.

BACKGROUND: Measurements of quantitative blood flow are crucial during brain vascular surgery. Indocyanine green video angiography (ICG-VAG) is an accepted method of blood flow visualization; however, quantitative techniques have not yet been established. Thus, the aim of this study was to further develop ICG analysis for visualizing intraoperative flow changes. METHODS: We conducted basic experiments and clinical investigations to establish a relationship between ICG-VAG and measured blood flow. We evaluated several parameters and identified optimal indicators that precisely reflect blood (or fluid) flow. Both in vitro and in vivo studies were performed to calculate the interval between baseline and the intensity peak (Grad) and to measure actual flow rate. RESULTS: Grad and actual flow rate showed good exponential correlation, with R2 values of 0.90 in vitro and 0.82 in vivo. In a representative patient (case 3), we performed intraoperative flow analysis using FlowInsight, which identified a marked elevation in Grad on the brain surface. Because this observation is predictive of brain hyperperfusion, we used these data to carefully manage blood pressure postoperatively. CONCLUSIONS: Grad is the optimum parameter for estimating flow conditions. Although ICG-VAG provides only visual profiles of blood circulation in the brain, this procedure has the potential to be widely used in clinical situations. ICG-based flow measurement can be used to identify normal and abnormal blood flow conditions, such as graft flow and vascular pathology. The novelty of this technique is that the fluorescence intensity of Grad enables surgeons to quantitatively measure real blood flow.

Evaluation of Microsurgery for Managing Giant or Complex Cerebral Aneurysms: A Retrospective Study.

OBJECTIVE: Surgical or endovascular treatment for giant or complex aneurysms is challenging. The aims of this study were to evaluate clinical outcomes and factors affecting the prognosis of giant or complex aneurysms and to better establish the role of microsurgery in the management strategy. METHODS: One hundred fifty-nine patients with surgically treated complex aneurysms were included. Thirty-two patients (20.1%) had giant aneurysms (≥25 mm) and 57 (35.8%) had large aneurysms (≥15 mm). Poor outcome was defined as modified Rankin Scale scores of 3-6. RESULTS: The mean aneurysm size was 17.0 mm (range, 1.6-47.5 mm). One hundred and sixteen aneurysms (80.0%) were in the anterior circulation and 43 (27.0%) were in the posterior circulation. One hundred and thirty-eight (86.8%) aneurysms were completely occluded without residual aneurysms. Nineteen (11.9%) had minor aneurysm remnants; 2 (1.3%) had incomplete occlusion. Two patients (1.3%) with giant basilar artery (BA) trunk aneurysms experienced rupture of the treated aneurysm and died. Bypass surgery was combined with microsurgery in 148 patients (93.1%). Perforating artery infarction was observed postoperatively in 42 patients (26.4%), and poor outcome was observed in 29 (18.2%). Male sex (P = 0.016; adjusted odds ratio [OR], 4.524 [1.949-10.500]), perforating artery infarction (P < 0.001; adjusted OR, 13.625 [5.329-34.837]), and BA aneurysm location (P = 0.003; adjusted OR, 56.333 [6.830-464.657]) were significantly related to poor outcome. The aneurysm size (P = 0.017; adjusted OR, 1.064 [1.021-1.107]), C1 aneurysm location (P = 0.042; adjusted OR, 2.591 [0.986-6.811]), and BA aneurysm location (P = 0.033; adjusted OR, 12.956 [3.197-52.505]) were significantly related to perforating artery infarction. CONCLUSIONS: Microsurgery with bypass is effective for many different complex aneurysms, except BA aneurysms.

Disconnection of the pathological connectome for multifocal epilepsy surgery.

OBJECTIVERecent neuroimaging studies suggest that intractable epilepsy involves pathological functional networks as well as strong epileptogenic foci. Combining cortico-cortical evoked potential (CCEP) recording and tractography is a useful strategy for mapping functional connectivity in normal and pathological networks. In this study, the authors sought to demonstrate the efficacy of preoperative combined CCEP recording, high gamma activity (HGA) mapping, and tractography for surgical planning, and of intraoperative CCEP measures for confirmation of selective pathological network disconnection.METHODSThe authors treated 4 cases of intractable epilepsy. Diffusion tensor imaging-based tractography data were acquired before the first surgery for subdural grid implantation. HGA and CCEP investigations were done after the first surgery, before the second surgery was performed to resect epileptogenic foci, with continuous CCEP monitoring during resection.RESULTSAll 4 patients in this report had measurable pathological CCEPs. The mean negative peak-1 latency of normal CCEPs related to language functions was 22.2 ± 3.5 msec, whereas pathological CCEP latencies varied between 18.1 and 22.4 msec. Pathological CCEPs diminished after complete disconnection in all cases. At last follow-up, all of the patients were in long-term postoperative seizure-free status, although 1 patient still suffered from visual aura every other month.CONCLUSIONSCombined CCEP measurement, HGA mapping, and tractography greatly facilitated targeted disconnection of pathological networks in this study. Although CCEP recording requires technical expertise, it allows for assessment of pathological network involvement in intractable epilepsy and may improve seizure outcome.

Facephenes and rainbows: Causal evidence for functional and anatomical specificity of face and color processing in the human brain.

Neuroscientists have long debated whether some regions of the human brain are exclusively engaged in a single specific mental process. Consistent with this view, fMRI has revealed cortical regions that respond selectively to certain stimulus classes such as faces. However, results from multivoxel pattern analyses (MVPA) challenge this view by demonstrating that category-selective regions often contain information about "nonpreferred" stimulus dimensions. But is this nonpreferred information causally relevant to behavior? Here we report a rare opportunity to test this question in a neurosurgical patient implanted for clinical reasons with strips of electrodes along his fusiform gyri. Broadband gamma electrocorticographic responses in multiple adjacent electrodes showed strong selectivity for faces in a region corresponding to the fusiform face area (FFA), and preferential responses to color in a nearby site, replicating earlier reports. To test the causal role of these regions in the perception of nonpreferred dimensions, we then electrically stimulated individual sites while the patient viewed various objects. When stimulated in the FFA, the patient reported seeing an illusory face (or "facephene"), independent of the object viewed. Similarly, stimulation of color-preferring sites produced illusory "rainbows." Crucially, the patient reported no change in the object viewed, apart from the facephenes and rainbows apparently superimposed on them. The functional and anatomical specificity of these effects indicate that some cortical regions are exclusively causally engaged in a single specific mental process, and prompt caution about the widespread assumption that any information scientists can decode from the brain is causally relevant to behavior.