Excessive Astrocytic GABA Causes Cortical Hypometabolism and Impedes Functional Recovery after Subcortical Stroke.

Glucose hypometabolism in cortical structures after functional disconnection is frequently reported in patients with white matter diseases such as subcortical stroke. However, the molecular and cellular mechanisms have been poorly elucidated. Here we show, in an animal model of internal capsular infarct, that GABA-synthesizing reactive astrocytes in distant cortical areas cause glucose hypometabolism via tonic inhibition of neighboring neurons. We find that reversal of aberrant astrocytic GABA synthesis, by pharmacological inhibition and astrocyte-specific gene silencing of MAO-B, reverses the reduction in cortical glucose metabolism. Moreover, induction of aberrant astrocytic GABA synthesis by cortical injection of putrescine or adenovirus recapitulates cortical hypometabolism. Furthermore, MAO-B inhibition causes a remarkable recovery from post-stroke motor deficits when combined with a rehabilitation regimen. Collectively, our data indicate that cortical glucose hypometabolism in subcortical stroke is caused by aberrant astrocytic GABA and MAO-B inhibition and that attenuating cortical hypometabolism can be a therapeutic approach in subcortical stroke.

Three-axis Modification of Coordinates Enables Accurate Stereotactic Targeting in Non-human Primate Brains of Different Sizes.

The brain grows with age in non-human primates (NHPs). Therefore, atlas-based stereotactic coordinates cannot be used directly to target subcortical structures if the size of the animal's brain differs from that used in the stereotactic atlas. Furthermore, growth is non-uniform across different cortical regions, making it difficult to simply apply a single brain-expansion ratio. We determined the skull reference lines that best reflect changes in brain size along the X, Y, and Z axes and plotted the changes in reference-line length against the changes in body weight. The skull reference lines had a linear relationship with body weight. However, comparison of skull reference lines with body weight confirmed the non-uniform skull growth during postnatal development, with skull growth more prominent in the X and Y axes than the Z axis. Comparing the differences between the atlas-based lengths and those calculated empirically from plot-based linear fits, we created craniometric indices that can be used to modify stereotactic coordinates along all axes. We verified the accuracy of the corrected stereotactic targeting by infusing dye into internal capsule in euthanized and preserved NHP brains. Our axis-specific, craniometric-index-adjusted stereotactic targeting enabled us to correct for targeting errors arising from differences in brain size. Histological verification showed that the method was accurate to within 1 mm. Craniometric index-adjusted targeting is a simple and relatively accurate method that can be used for NHP stereotactic surgery in the general laboratory, without the need for high-resolution imaging.

Simplified adaptor for stereotactic surgery in non-human primates.

BACKGROUND: It is challenging for researchers performing stereotactic procedures to transition from small animals to non-human primate (NHP) experiments. The NHP stereotactic atlas is based on ear-bar zero (EBZ), which is an anatomical reference frame that is not visible during surgery. Most current NHP stereotactic systems require high-cost MRI or CT imaging and complex computer processing to determine the stereotactic coordinates, limiting the procedure to those with significant expertise. NEW METHOD: We have designed a simplified adaptor consisting of a circular arc for coronal tilt, a carrier for electrodes or cannulas, and an anchor to attach the adaptor to a conventional stereotactic frame. Our adaptor allows easy identification of the EBZ with the help of an anchor notch, and provides digital distance sensors without the need for imaging data or computer processing. Our system enables the use of trajectories that avoid injury to important structures and vessels. RESULTS: We tested the accuracy of our system using simulated targeting with phantoms, and demonstrated sub-millimeter accuracy. Infusion of methylene blue also showed satisfactory staining in target structures deep in the brain. COMPARISON WITH EXISTING METHODS: This system does not require high-cost imaging and extra training to determine EBZ. Once EBZ is set automatically by the system itself, targeting is similar to that in small animal stereotactic procedure. CONCLUSION: Our simple adaptor will aid researchers who plan to conduct experiments involving stereotactic surgery in NHPs.

Automated Pressure-Controlled Discography in Patients Undergoing Anterior Lumbar Interbody Fusion for Discogenic Back Pain.

STUDY DESIGN: Retrospective cohort study. OBJECTIVE: To compare the clinical outcomes of patients undergoing anterior lumbar interbody fusion (ALIF) with or without automated pressure-controlled discography (APCD) before the procedure. METHODS: Patients (n = 36) who underwent ALIF for lumbar discogenic back pain between 2008 and 2013 and were followed for more than 6 months were enrolled in this study. APCD was performed to identify discogenic back pain. Preoperative x-rays, computed tomography images, and magnetic resonance images were obtained. The intervertebral disc height, type of Modic change, grade of disc degeneration, and fusion rate were determined. Additionally, the presence or absence of high-intensity zone and vacuum disc were checked preoperatively. Clinical evaluation was performed by visual analog scale (0 = no pain, 10 = worst pain imaginable), Oswestry Disability Index (ODI), and 36-Item Short Form Health Survey before surgery and every 6 months postoperatively. RESULTS: The average patient age was 53.3 years (range, 31-73 years). The mean follow-up durations were 19.7 months. Seventeen patients (the APCD-ALIF group) underwent ALIF after APCD, and 19 patients underwent ALIF without APCD. The APCD-ALIF group had significantly improved clinical outcomes compared with the control group (visual analog scale score 1.8 ± 1.6 vs. 3.3 ± 2.4; P = 0.039: ODI score 6.7 ± 6.3 vs. 12.1 ± 6.8; P = 0.019). The surgical improvement rate was significantly associated with ODI score (P = 0.005). CONCLUSIONS: The results of this study confirm that APCD aids surgical outcomes of ALIF in patients with suspected lumbar discogenic pain. We recommend performing APCD before ALIF to confirm lumbar discogenic pain.

Capsular stroke modeling based on somatotopic mapping of motor fibers.

Recently, several capsular stroke models have been reported with different targets of destruction. This study was performed to establish an accurate internal capsule (IC) target for capsular stroke modeling in rats. We injected adeno-associated virus serotype 5 (AAV)-CaMKII-EYFP into forelimb motor cortex and AAV-CaMKII-mCherry into hindlimb motor cortex (n = 9) to anterogradely trace the pyramidal fibers and map their somatotopic distribution in the IC. On the basis of the neural tracing results, we created photothrombotic infarct lesions in rat forelimb and hindlimb motor fiber (FMF and HMF) areas of the IC (n = 29) and assessed motor behavior using a forelimb-use asymmetry test, a foot-fault test, and a single-pellet reaching test. We found that the FMFs and HMFs were primarily distributed in the inferior portion of the posterior limb of the IC, with the FMFs located largely ventral to the HMFs but with an area of partial overlap. Photothrombotic lesions in the FMF area resulted in persistent motor deficits. In contrast, lesions in the HMF area did not result in persistent motor deficits. These results indicate that identification of the somatotopic distribution of pyramidal fibers is critical for accurate targeting in animal capsular stroke models: only infarcts in the FMF area resulted in long-lasting motor deficits.

Circumscribed Capsular Infarct Modeling Using a Photothrombotic Technique.

Recent increase in the prevalence rate of white matter stroke demands specific research in the field. However, the lack of a pertinent animal model for white matter stroke has hampered research investigations. Here, we describe a novel method for creating a circumscribed capsular infarct that minimizes damage to neighboring gray matter structures. We used pre-surgery neural tracing with adeno-associated virus-green fluorescent protein (AAV-GFP) to identify somatotopic organization of the forelimb area within the internal capsule. The adjustment of light intensity based on different optical properties of gray and white matter contributes to selective destruction of white matter with relative preservation of gray matter. Accurate positioning of optical-neural interface enables destruction of entire forelimb area in the internal capsule, which leads to a marked and persistent motor deficit. Thus, this technique produces highly replicable capsular infarct lesions with a persistent motor deficit. The model will be helpful not only to study white matter stroke (WMS) at the behavioral, circuit, and cellular levels, but also to assess its usefulness for development of new therapeutic and rehabilitative interventions.

Near-infrared stimulation on globus pallidus and subthalamus.

Near-infrared stimulation (NIS) is an emerging technique used to evoke action potentials in nervous systems. Its efficacy of evoking action potentials has been demonstrated in different nerve tissues. However, few studies have been performed using NIS to stimulate the deep brain structures, such as globus pallidus (GP) and subthalamic nucleus (STN). Male Sprague-Dawley rats were randomly divided into GP stimulation group (n=11) and STN stimulation group (n=6). After introducing optrodes stereotaxically into the GP or STN, we stimulated neural tissue for 2 min with continuous near-infrared light of 808 nm while varying the radiant exposure from 40 to 10 mW. The effects were investigated with extracellular recordings and the temperature rises at the stimulation site were also measured. NIS was found to elicit excitatory responses in eight out of 11 cases (73%) and inhibitory responses in three cases in the GP stimulation group, whereas it predominantly evoked inhibitory responses in seven out of eight cases (87.5%) and an excitatory response in one case in STN stimulation group. Only radiation above 20 mW, accompanying temperature increases of more than 2°C, elicited a statistically significant neural response (p<0.05). The responsiveness to NIS was linearly dependent on the power of radiation exposure.

Comparison of functional and histological outcomes after intralesional, intracisternal, and intravenous transplantation of human bone marrow-derived mesenchymal stromal cells in a rat model of spinal cord injury.

BACKGROUND: Few studies have compared methods of stem cell transplantation. The aim of the present study was to determine the optimal method of delivery of therapeutic stem cells in spinal cord injury (SCI). We compared functional and histologic outcomes after administration of human bone marrow stromal cells (BMSCs) by intralesional (ILT), intracisternal (ICT), and intravenous transplantation (IVT). METHOD: A rat model of spinal cord injury was produced by dropping a 10-g weight, 2 mm in diameter, onto the exposed spinal cords of animals from a height of 25 mm. In each treatment group, 24 animals were randomly assigned for functional assessment and 24 for histologic examination. BMSCs (3 × 10(5), ILT; 1 × 10(6), ICT; 2 × 10(6), IVT) were transplanted 1 week after SCI in numbers determined in previous studies. Basso-Beattie-Bresnahan scoring was performed in all animals weekly for 6 weeks. Spinal cord specimens were obtained from eight animals in each group 2, 4, and 6 weeks after SCI. Viable BMSCs were counted in six sagittal sections from each spinal cord. RESULTS: All three treatment groups showed improved functional recovery compared to controls beginning 2 weeks after stem cell injection (P < 0.01). The ICT group showed the best functional recovery, followed by the ILT and IVT groups, respectively (P < 0.01). Histological analysis showed the largest number of viable BMSCs in the ILT group, followed by the ICT and IVT groups, respectively (P < 0.01). CONCLUSIONS: ICT may be the safest and most effective method for delivering stem cells and improving functional outcome in SCI when no limits are placed on the number of cells transplanted. As research on enhancing engraftment rates advances, further improvement of functional outcome can be expected.

Bilateral perisylvian ulegyria: an under-recognized, surgically remediable epileptic syndrome.

PURPOSE: Interest in the association of epilepsy and pseudobulbar palsy was rekindled since the identification through magnetic resonance imaging (MRI) of bilateral perisylvian polymicrogyria (PMG). Seizures are often intractable, but resective epilepsy surgery has not been recommended. However, a similar clinical picture can be encountered in patients with bilateral perisylvian destructive lesions, which fit the description of ulegyria (ULG). We report a series of patients with epilepsy and pseudobulbar palsy due to bilateral perisylvian ULG (BP-ULG), show that hippocampal sclerosis (HS) is often associated and highlight the fact that in this entity, unlike in malformative bilateral perisylvian PMG, seizures may be surgically treated. METHODS: The motor, cognitive, epileptologic, and imaging features of 12 patients with perisylvian ULG followed at three institutions are described. For patients with refractory seizures, we detail extracranial and intracranial electrographic recordings, surgical strategies, histopathologic analyses of the resected tissue, and outcome of surgical treatment. Descriptive statistics were used for quantitative and categorical variables. Student's t-test was used to compare means, and a p < 0.05 was considered significant. KEY FINDINGS: Pseudobulbar palsy and mental retardation were present in all patients with symmetrical BP-ULG. Five had refractory seizures. There was no relationship between the severity of the pseudobulbar palsy or of the mental retardation and the degree of seizure control with medication. The five patients in whom seizures were refractory to medication had significantly earlier age of onset and longer duration of epilepsy (p < 0.05). Dual pathology with associated unilateral HS was present in four. One patient with dual pathology had a temporolimbic electroclinical picture and had an anterior temporal lobectomy (ATL) based upon noninvasive evaluation. The other four had ictal semiology suggesting involvement of both temporolimbic and perisylvian cortex. Intracranial electroencephalography (EEG) showed concomitant seizure onset in the anterior temporal region and in the ipsilateral ULG in three of the four with dual pathology and in the ulegyric cortex in the one without HS. Resection guided by a combination of semiology, MRI, and extra and intracranial EEG led to complete seizure control in two and almost complete seizure control (Engel class II) in two other patients. The only surgical failure was an isolated ATL in a patient with dual pathology, and concomitant seizure onset in both lesions according to semiology and intracranial EEG. SIGNIFICANCE: Our findings suggest that BP-ULG mimics the clinical features of bilateral perisylvian PMG. In patients with refractory seizures, recognition of this entity should lead to consideration of resective surgery despite the bilateral ULG.

A case of angiocentric glioma with unusual clinical and radiological features.

Angiocentric glioma was recently recognized as a distinct clinicopathological entity in the 2007 World Health Organization classification of tumors of the central nervous system. Typically, it presents with seizure in children and young adults. However, our patient did not have a history of seizure. Seizure did not occur up to 6 months after operation. Although it usually does not have calcification brain magnetic resonance imaging in our patient showed T1-hyperintense and T2-hypointense signals with calcification.

Pathophysiologic characteristics of balloon cells in cortical dysplasia.

OBJECTS: Balloon cells are histopathological hallmarks of cortical malformations, i.e., focal cortical dysplasia (FCD) of the Taylor type or the cortical tubers of tuberous sclerosis, and they are believed to be the epileptogenic substrate and cause therapeutic drug resistant epilepsy in man. This study was carried out to investigate the developmental histogenesis and epileptogenesis of balloon cells in FCD. MATERIALS AND METHODS: We used an immunohistochemical approach to examine the expressions of primitive neuroepithelial cell antigens (CD34, nestin, and vimentin), ionotrophic glutamate receptor subunits (NR1, NR2A/B, GluR1, GluR2, GluR3, GluR4, and GluR5/6/7), and P-glycoprotein in balloon cells from FCD and normal cerebral cortex epileptogenic lesions. CONCLUSION: Balloon cells presented in clusters or as scattered cells throughout FCD lesions involving the gray and white matter. We found the balloon cells to be classifiable into three subtypes based on glial fibrillary acidic protein (GFAP) and neurofilament protein (NF-L) immunohistochemistry, i.e., as neuronal, astrocytic, and uncommitted. Immunopositivity for nestin, CD34, and vimentin in balloon cells of FCD suggests that they may be derived from the abnormal development and differentiation of neural stem cells. Moreover, it appears that epileptogenesis in cortical dysplasia is partly caused by the upregulations of some glutamate receptor subunit proteins (NR1, NR2A/B, GluR1, and GluR3) in balloon cells and dysplastic neurons. We speculate that the presence of the drug resistance protein P-glycoprotein in balloon cells might explain medically refractory epilepsy in FCD.

Radiofrequency neurotomy of cervical medial branches for chronic cervicobrachialgia.

Chronic neck and arm pain or cervicobrachialgia commonly occurs with the degeneration of cervical spine. Authors investigated the usefulness of radiofrequency (RF) neurotomies of cervical medial branches in patients with cervicobrachialgia and analyzed the factors which can influence the treatment outcome. Demographic data, types of pain distribution, responses of double controlled blocks, electrical stimulation parameters, numbers and levels of neurotomies, and surgical outcomes were evaluated after mean follow-up of 12 months. Pain distribution pattern was not significantly correlated with the results of diagnostic blocks. Average stimulation intensity was 0.45 V, ranging from 0.3 to 0.69, to elicit pain response in cervical medial branches. The most common involvement of nerve branches was C4 (89%), followed by C5 (82%), C6 (75%), and C7 (43%). Among total of 28 patients, nineteen (68%) reported successful outcome according to outcome criteria after 6 months of followup (p=0.001), and eight (42%) of 19 patients reported complete relief (100%) of pain. Four patients showed recurrence of pain between 6 and 12 months. It was therefore concluded that cervical medial branch neurotomy is considered useful therapeutic modality for the management of cervicobrachialgia in selected patients, particularly in degenerative zygapophyseal disorders.

Upregulation of glutamate receptors in rat cerebral cortex with neuronal migration disorders.

Neuronal migration disorders (NMDs) constitute the main pathologic substrate of medically intractable epilepsy in human. This study is designed to investigate the changes in expression of glutamate receptor subtypes on radiation-induced NMD in rats. The lesion was produced by intrauterine irradiation (240 cGy) on E17 rats, and then 10 weeks old rats were used for the study. The pathologic and immuno-histochemical findings for glutamate receptor subunit proteins on NMD cortex were correlated with development of behavioral seizures and EEG abnormality. Spontaneous seizures uncommonly occurred in NMD rats (5%); however, clinical stages of seizures were significantly increased in NMD rats by an administration of kainic acid. Brains taken from irradiated rats revealed gross and histopathologic features of NMD. Focal cortical dysplasia was identified by histopathology and immunohistochemistry with neurofilament protein (NF-M/H). Significantly strong NR1 and NR2A/B immunoreactivities were demonstrated in cytomegalic and heterotopic neurons of NMD rats. The results of the present study indicate that epileptogenesis of NMD might be caused by upregulation of glutamate receptor expression in dysplastic neurons of the rat cerebral cortex with NMDs.