Publications by authors named "Mariana Bendersky"

12 Publications

  • Page 1 of 1

Functional anatomy of idiomatic expressions.

Brain Topogr 2021 Jul 4;34(4):489-503. Epub 2021 May 4.

ENyS (Studies in Neurosciences and Complex Systems), National Scientific and Technical Research Council (CONICET), National University A. Jauretche (UNAJ), El Cruce Hospital Néstor Kirchner, Avenue Calchaquí 5402, Florencio Varela, Buenos Aires, Argentina.

Idiomatic expressions (IE) are groups of words whose meaning is different from the sum of its components. Neural mechanisms underlying their processing are still debated, especially regarding lateralization, main structures involved, and whether this neural network is independent from the spoken language. To investigate the neural correlates of IE processing in healthy Spanish speakers.Twenty one native speakers of Spanish were asked to select one of 4 possible meanings for IE or literal sentences. fMRI scans were performed in a 3.0T scanner and processed by SPM 12 comparing IE vs. literal sentences. Laterality indices were calculated at the group level. IE activated a bilateral, slightly right-sided network comprising the pars triangularis and areas 9 and 10. In the left hemisphere (LH): the pars orbitalis, superior frontal, angular and fusiform gyrus. In the right hemisphere (RH): anterior insula, middle frontal, and superior temporal gyrus. This network reveals the importance of the RH, besides traditional LH areas, to comprehend IE. This agrees with the semantic coding model: the LH activates narrow semantic fields choosing one single meaning and ignoring others, and the RH detects distant semantic relationships, activating diffuse semantic fields. It is also in line with the configuration hypothesis: both meanings, literal and figurative, are executed simultaneously, until the literal meaning is definitively rejected and the figurative one is accepted. Processing IE requires the activation of fronto-temporal networks in both hemispheres. The results concur with previous studies in other languages, so these networks are independent from the spoken language. Understanding these mechanisms sheds light on IE processing difficulties in different clinical populations and must be considered when planning resective surgery.
View Article and Find Full Text PDF

Download full-text PDF

Source Listing
July 2021

Machine learning for filtering out false positive grey matter atrophies in single subject voxel based morphometry: A simulation based study.

J Neurol Sci 2021 01 6;420:117220. Epub 2020 Nov 6.

Pladema Institute - UNICEN/CONICET, Tandil, Buenos Aires, Argentina.

Single subject VBM (SS-VBM), has been used as an alternative tool to standard VBM for single case studies. However, it has the disadvantage of producing an excessively large number of false positive detections. In this study we propose a machine learning technique widely used for automated data classification, namely Support Vector Machine (SVM), to refine the findings produced by SS-VBM. A controlled set of experiments was conducted to evaluate the proposed approach using three-dimensional T1 MRI scans from control subjects collected from the publicly available IXI dataset. The scans were artificially atrophied at different locations and with different sizes to mimic the behavior of neurological disorders. Results empirically demonstrated that the proposed method is able to significantly reduce the amount of false positive clusters (p < 0.05), with no statistical differences in the true positive findings (p > 0.05). This evidence was observed to be consistent for different atrophied areas and sizes of atrophies. This approach could be potentially be applied to alleviate the intensive manual analysis that radiologists and clinicians have to perform to filter out miss-detections of SS-VBM, increasing its usability for image reading.
View Article and Find Full Text PDF

Download full-text PDF

Source Listing
January 2021

Development of a New Therapy-Oriented Classification of Intervertebral Vacuum Phenomenon With Evaluation of Intra- and Interobserver Reliabilities.

Global Spine J 2021 May 13;11(4):480-487. Epub 2020 Mar 13.

Institute of Orthopedics "Carlos E. Ottolenghi" 37533Hospital Italiano de Buenos Aires, Buenos Aires, Argentina.

Study Design: Diagnostic study, level of evidence III.

Objectives: Low back pain is a common cause of disability among elderly patients. Percutaneous discoplasty has been developed as a tool to treat degenerative disease when conservative management is not successful. Indications for this procedure include low back pain and the presence of vacuum phenomenon. The objective of this study was to describe a new classification of vacuum phenomenon based on computed tomography scan in order to improve the indications for percutaneous discoplasty.

Methods: We developed a classification of vacuum phenomenon based on computed tomography scan images. We describe 3 types of vacuum based on the relationship between vacuum and the superior/inferior endplates and 2 subtypes based on the presence of significant subchondral sclerosis. A validation study was conducted selecting 10 orthopedic residents with spine surgery training to analyze 25 vacuum scenarios. Inter- and intraobserver reliabilities were assessed through the Fleiss's and Cohen's kappa statistics, respectively.

Results: The overall Fleiss's κ value for interobserver reliability was 0.85 (95% CI 0.82-0.86) in the first reading and 0.93 (95% CI 0.92-0.95) in the second reading. Cohen's κ for intraobserver reliability was 0.88 (95% CI 0.77-0.99).

Conclusion: The new classification has shown almost perfect inter- and intraobserver reliabilities for grading the vacuum phenomenon and could be an important tool to improve the indications for percutaneous cement discoplasty.
View Article and Find Full Text PDF

Download full-text PDF

Source Listing
May 2021

Percutaneous Cement Discoplasty for the Treatment of Advanced Degenerative Disc Conditions: A Case Series Analysis.

Global Spine J 2020 Sep 6;10(6):729-734. Epub 2019 Sep 6.

Hospital Italiano de Buenos Aires, Buenos Aires, Argentina.

Study Design: Retrospective analysis. Level of evidence III.

Objectives: To describe the results after a minimum 1-year follow-up in patients treated with percutaneous discoplasty (PD), a minimally invasive technique to treat low back pain in elderly patients with advanced degenerative disc disease. The procedure consists in improving stability by injecting bone cement in a severely degenerated pneumodisc. There are few reports in the literature about this technique.

Methods: Fifty-four patients with advanced disc disease with/without degenerative scoliosis treated with PD with at least 1 year follow-up were studied, variables included clinical (visual analogue scale [VAS] and Owestry Disability Index [ODI]) and radiological parameters (lumbar lordosis and Cobb angle), as well as hospital length of stay and complications.

Results: At 1-year postoperation, significant pain reduction (VAS: preoperative 7.8 ± 0.90; postoperative 4.4 ± 2.18) and improvement in the ODI (preoperative 62 ± 7.12; postoperative 36.2 ± 15.47) were observed with partial correction of radiological parameters (5° mean increase in lumbar lordosis and decrease in Cobb angle). Mean surgical time was 38 minutes, and the mean length of hospital stay was 1.2 days.

Conclusion: PD, currently not a very well-known technique, appears to be-at least in the short-term follow-up-an effective treatment option in selected cases with low back pain due to advanced degenerative disc disease.
View Article and Find Full Text PDF

Download full-text PDF

Source Listing
September 2020

Lumbosacral plexus root thickening: Establishing normal root dimensions using magnetic resonance neurography.

Clin Anat 2018 Sep 18;31(6):782-787. Epub 2018 Oct 18.

Department of Diagnostic Imaging, Raúl Carrea Foundation for Neurological Research, FLENI, Buenos Aires, Argentina.

Disorders affecting the lumbosacral plexus (LSP) can alter root diameter. Our aim was to determine normal LSP nerve root dimensions using magnetic resonance neurography (MRN). Eleven asymptomatic patients (ages: 18-53, mean: 34 years) underwent MRN of the LSP on a 3 T scanner with an 8-channel torso-PA coil. IDEAL T2-weighted images were acquired and nerve root dimensions were measured from the second lumbar (L2) to the first sacral (S1) vertebrae on the coronal plane, 5 mm from the dorsal root ganglion (DRG). Root size was recorded by three separate groups of radiologists with different levels of expertise. Additional LSP-MRN images were acquired from a fresh-frozen cadaver specimen using the same scanner and parameters identical to those described above. Subsequently, two experienced anatomists dissected and measured the LSP roots at exactly the same distance from the DRG, using an electronic caliper. Mean root size values recorded (± standard deviation) in the asymptomatic patients were as follows: L2: 3.12 mm (±0.92), L3: 4.29 mm (±0.95), L4: 5.13 mm (±0.79), L5: 5.29 mm (±0.9), and S1: 5.38 mm (±0.7). The correlation coefficients were 0.72 between the patient and cadaver MRN results and 0.79 between the patient and dissected cadaver MRN results. Inter-observer agreements were 0.73 among the radiologist groups and 0.87 between the anatomists conducting dissections. We believe MRN provides reliable assessments of LSP root thickness. More extensive studies should be conducted to confirm the results described here. Clin. Anat. 31:782-787, 2018. © 2018 Wiley Periodicals, Inc.
View Article and Find Full Text PDF

Download full-text PDF

Source Listing
September 2018

Percutaneous cement discoplasty for the treatment of advanced degenerative disk disease in elderly patients.

Eur Spine J 2018 Mar 23. Epub 2018 Mar 23.

Orthopaedic and Traumatology Department, Institute of Orthopedics "Carlos E. Ottolenghi", Hospital Italiano de Buenos Aires, Potosi, 4215, Buenos Aires, Argentina.

Purpose: The authors describe a percutaneous technique to treat advanced degenerative disk disease in elderly patients.

Method: A step-by-step technical description based on our experience in selected cases.

Result: Postoperative imaging results are presented as well as indications and recommendations.

Conclusion: Percutaneous discoplasty can result as an alternative minimal invasive strategy for the treatment of advanced degenerative disk disease.
View Article and Find Full Text PDF

Download full-text PDF

Source Listing
March 2018

Intraoperative monitoring for spinal radiculomedullary artery aneurysm occlusion treatment: What, when, and how long?

Surg Neurol Int 2017 6;8:211. Epub 2017 Sep 6.

Department of Neurosurgery, Hospital Italiano de Buenos Aires, Argentina.

Background: Spinal radiculomedullary artery aneurysms are extremely rare. Treatment should be tailored to clinical presentation, distal aneurysm flow, and lesion anatomical features. When a surgical occlusion is planned, it is necessary to evaluate whether intraoperative monitoring (IOM) should be considered as an indispensable tool to prevent potential spinal cord ischemia.

Methods: We present a patient with symptoms and signs of spinal subarachnoid hemorrhage resulting from the rupture of a T4 anterior radiculomedullary aneurysm who underwent open surgical treatment under motor evoked potential (MEP) monitoring.

Results: Due to the aneurysmal fusiform shape and preserved distal flow, the afferent left anterior radiculomedullary artery was temporarily clipped; 2 minutes after the clamping, the threshold stimulation level rose higher than 100 V, and at minute 3, MEPs amplitude became attenuated over 50%. This was considered as a warning criteria to leave the vessel occlusion. The radiculomedullary aneurysm walls were reinforced and wrapped with muscle and fibrin glue to prevent re-bleeding. The patient awoke from general anesthesia without focal neurologic deficit and made an uneventful recovery with complete resolution of her symptoms and signs.

Conclusion: This paper attempts to build awareness of the possibility to cause or worsen a neurological deficit if a radiculomedullary aneurysm with preserved distal flow is clipped or embolized without an optimal IOM control. We report in detail MEP monitoring during the occlusion of a unilateral T4 segmental artery that supplies an anterior radiculomedullary artery aneurysm.
View Article and Find Full Text PDF

Download full-text PDF

Source Listing
September 2017

Monitoring lumbar plexus integrity in extreme lateral transpsoas approaches to the lumbar spine: a new protocol with anatomical bases.

Eur Spine J 2015 May 13;24(5):1051-7. Epub 2015 Feb 13.

III Normal Anatomy Department, School of Medicine, University of Buenos Aires, Paraguay 2155, 1211, Buenos Aires, Argentina,

Unlabelled: XLIF is an increasingly popular procedure that requires traversing the psoas, with the potential risk of injuring the lumbar plexus nerves. Intraoperative neurophysiological monitoring (IOM) is, therefore, critical in this kind of procedures; nevertheless, there were some reports of neural damage.

Purpose: To determine the effectiveness of a new protocol for IOM during XLIF.

Materials And Methods: This prospective, nonrandomized, institutional review board-approved study enrolled adult patients of both sexes undergoing XLIF at the Italian Hospital of Buenos Aires between 2012 and 2014. Preoperative and immediate postoperative neurological examinations were carried out, paying special attention to lumbar plexus motor and sensory territories. IOM included EMG and transpsoas stimulation, considering the territories of every motor and sensory branch of the lumbar plexus.

Results: 107 patients (133 lumbar levels) were evaluated. Reproducible responses were obtained in the collateral and terminal branches of the lumbar plexus, which were well preserved. No patient (0%) had new motor postoperative deficits. Nineteen (17.75%) patients had minor and transient sensory symptoms, lasting less than a month. One patient (0.93%) had longer duration of sensory complaints (3 months).

Conclusion: A detailed IOM of lumbar plexus branches can determine in real time the proximity of intrapsoas nerves during XLIF.
View Article and Find Full Text PDF

Download full-text PDF

Source Listing
May 2015

Identifying the trigeminal nerve branches for transovale radiofrequency thermolesion: "no pain, no stress".

Neurosurgery 2012 Jun;70(2 Suppl Operative):259-63

Intraoperative Neurophysiology Department, Hospital Italiano de Buenos Aires, Buenos Aires, Argentina.

Background: Radiofrequency thermorhizotomy of the trigeminal nerve is a known treatment of trigeminal neuralgia. Analysis of verbal responses to electric stimulation of the trigeminal rootlets has been the only method available to localize the affected branch, but patient discomfort may lead to unreliable verbal responses, resulting in increased morbidity or even therapeutic failure. Orthodromically elicited evoked potentials of the trigeminal nerve have also been used, but their application is tedious and results may vary.

Objective: To develop an electrophysiological method for intraoperative localization of the trigeminal nerve branches.

Methods: A series of 55 patients under general anesthesia during radiofrequency thermorhizotomy were studied. The trigeminal nerve root was stimulated through the foramen ovale with the RF electrode. Antidromic responses were recorded from the 3 divisions of the trigeminal nerve in the face. Effectiveness rate, pain relief, recurrence, complications, and patient comfort after the procedure were analyzed.

Results: Reproducible and easily obtained antidromic responses were clearly recorded in every subdivision of the trigeminal nerve in all patients. Ninety-four percent of patients experienced immediate pain relief after the procedure. The recurrence rate was 12.72%, and the surgical morbidity was 20%.

Conclusion: This method proved to be useful to determine the exact localization of individual subdivisions of the trigeminal nerve in anesthetized patients, making this procedure safer and more comfortable for them.
View Article and Find Full Text PDF

Download full-text PDF

Source Listing
June 2012

Prenatal cerebral magnetic resonance imaging.

J Neurol Sci 2008 Dec 28;275(1-2):37-41. Epub 2008 Aug 28.

III Normal Human Anatomy Department, Medical School, Buenos Aires University. Paraguay 2155, Buenos Aires, Argentina.

Unlabelled: Ultrasonography (USG) is the preferred screening method for fetal brain examination. It has some technical limitations and a relatively low sensibility and specificity for many central nervous system (CNS) malformations. Fetal cerebral magnetic resonance imaging (MRI) offers better resolution and sensibility, with scarce limitations.

Objectives: To determine the fetal age according to cortical maturation as seen in MRI, correlating these data with those obtained by means of USG measurements; to correlate USG pathological findings with the MRIs and to determine how the sequence of cortical maturation varies in abnormal brains.

Materials And Methods: 50 pregnant women were submitted to USG and fetal brain MRI. Fifteen carried out normal pregnancies. In the remaining 35, the USG, the clinical assessment or both, raised the suspicion of a CNS malformation. Facts studied were: the gestational age calculated by USG, analysis of the cortical gyral development by MRI (cortical age), the presence of CNS abnormalities and the correlation between the cortical maturation and the presence of CNS pathologies. Statistical analysis included the Student's t test for paired samples, the Pearson's correlation coefficient (r) and linear regression curves.

Results: In the control group, fetal age highly correlated with the cortical age estimated by MRI. In the abnormal group, a wide variety of pathologies could be found, with higher sensibility and specificity than USG when applying MRI techniques. Cortical age did not correlate with the gestational age in this group; moreover, its estimation could not be achieved in severely malformed brains.

Discussion: MRI allows a detailed study of the CNS before birth. It proved to be more reliable and specific than USG, with fewer technical limitations. Cortical maturation can be accurately assessed by this method in normal or slightly abnormal fetuses. However, USG is better than MRI for diagnosing skull bony defects.
View Article and Find Full Text PDF

Download full-text PDF

Source Listing
December 2008

Normal anatomy of the developing fetal brain. Ex vivo anatomical-magnetic resonance imaging correlation.

J Neurol Sci 2006 Dec 14;250(1-2):20-6. Epub 2006 Aug 14.

Science and Technology Department, (UBACYT) Buenos Aires University, Paraguay 2155, Buenos Aires, Argentina.

Fetal brain Magnetic Resonance Imaging (MRI) is a new technique of growing interest, with a high potential to detect prenatal central nervous system abnormalities. This requires an accurate knowledge of the normal morphological sequence of brain development. In this paper we studied the cortical development of post-mortem normal fetal brains, correlating MRI estimations of fetal age with in vitro anatomical and anthropometric measurements. Ten post-mortem fetal heads were submitted to MRI. Maturational state of sulci and gyri and gray-white matter differentiation were analysed in the MRIs and by dissection of the brains. The findings were correlated with the previously estimated ages of the fetuses, which varied between 17 and 38 weeks. Consistency between methods was assessed employing intraclass correlation coefficient and Bland-Altman plots, with a 95% confidence interval. Estimations of fetal age obtained by MRI were very similar to those achieved by anthropometric measurements or by considering anatomical parameters. Gyral development proved to be more precise than gray-white matter differentiation for this purpose. Fetal MRI proved to be as reliable as the macroscopic anatomical examination for depicting normal cortical developmental sequence and age, suggesting that this technique may be a suitable option for achieving precise information about the morphology of human brains along the gestational period.
View Article and Find Full Text PDF

Download full-text PDF

Source Listing
December 2006

Magnetic resonance imaging identifies cytoarchitectonic subtypes of the normal human cerebral cortex.

J Neurol Sci 2003 Jul;211(1-2):75-80

Science and Technology Department, (UBACYT) Buenos Aires University, Paraguay 2155, Buenos Aires, Argentina.

Background: Magnetic Resonance Imaging (MRI) allows a detailed "in vivo" macroscopic study of the human brain; previously, it has been demonstrated that Fluid Attenuated Inversion Recovery (FLAIR) sequence shows higher signal intensity of cortices belonging to limbic structures.

Purpose: To measure and compare signal intensities (SI) of cytoarchitectonically different cortical regions.

Methods: In 22 adult subjects, without psychiatric or neurological diseases, FLAIR sequence was performed in coronal slices, perpendicular to the main hippocampal axis. Signal intensity was measured, with a region-of-interest (ROI) function, in 12 different cortical regions. We compared these values and grouped the cortices into five groups: (1) limbic cortices, (2) paralimbic agranular cortices, (3) paralimbic granular cortices, (4) parietal-type neopallium, (5) frontal-type neopallium. A t-test for comparison of paired samples was performed, considering p
Results: We found statistically significant differences amongst the different groups, with the exception of groups 1 and 2, which did not show differences between them. No statistically significant differences were found among cortices belonging to the same group.

Conclusion: Structural characteristics of the cerebral cortex cause changes in its signal intensity. Magnetic resonance imaging (FLAIR sequence) allows discrimination of different cytoarchitectonic areas of the human cerebral cortex.
View Article and Find Full Text PDF

Download full-text PDF

Source Listing
July 2003