Influence of the Severity of Osteogenesis Imperfecta on Cranial Measurements.

Osteogenesis Imperfecta (OI) is a disease that causes bone fragility and deformities, affecting both the cranial base and the craniocervical junction, and may lead to other neurological disorders. A retrospective cross-sectional study was carried out based on cephalometric analysis of the cranial base in a sample of patients with OI, in lateral skull radiographs and magnetic resonance imaging (MRI), comparing them with a sample of age-matched controls. When the different variables of the craniocervical junction were analyzed, significance was found in comparisons with the different age groups. All measurements of the variables studied stabilized as growth progressed. For most of the variables, the severity of the disease influences the measurements of the skull base, with statistically significant differences. Both age and severity of the disease are factors that directly influence the anatomy of the craniocervical junction in these patients and may serve as indicators in the early detection and prevention of other derived alterations.

Intraoperative Cortico-Cortical Evoked Potentials for Monitoring Language Function during Brain Tumor Resection in Anesthetized Patients.

BACKGROUND: Cortico-cortical evoked potentials (CCEPs) have been used to map the frontal (FLA) and parietal (PLA) cortical regions related to language function. However, they have usually been employed as a complementary method during sleep-awake surgery. METHODS: Five male and two female patients received surgery for tumors located near language areas. Six patients received general anesthesia and the sleep-awake method was used for patients with tumors located near the cortical language areas. We performed motor and somatosensory mapping with CCEPs to identify language areas and we monitored responses during surgery based on the mapping results. Electrocorticography was performed throughout the surgery. Single pulses of 1 ms duration at 5-20 mA were delivered by direct cortical stimulation using one grid at one region (e.g., FLA) and then recording using a second gird at another area (i.e., PLA). Next, reversed stimulation (from PLA to FLA) was performed. The charge density for electrical stimulation was computed. Sensibility, specificity, predictive positive values, and predicted negative values were also computed for warning alterations of CCEPs. RESULTS: Gross tumor resection was achieved in four cases. The first postsurgical day showed language alterations in three patients, but one year later six patients remained asymptomatic and one patient showed the same symptomatology as previously. Seizures were observed in two patients that were easily jugulated. CCEPs predicted warning events with high sensibility and specificity. Postsurgical language deficits were mostly transitory. Although the latency between frontal and parietal regions showed symmetry, the amplitude and the relationship between amplitude and latency were different for FLA than for PLA. The charge density elicited by CCEPs ranged from 442 to 1768 µC/cm2. CONCLUSIONS: CCEPs have proven to be a reliable neurophysiological technique for mapping and monitoring the regions associated with language function in a small group of anesthetized patients. The high correlation between warning events and postsurgical outcomes suggested a high sensitivity and specificity and CCEPs can be used systematically in patients under general anesthesia. Nevertheless, the small number of studied patients suggests considering these results cautiously.

Neurosurgical Treatment of Pain.

The aim of this review is to draw attention to neurosurgical approaches for treating chronic and opioid-resistant pain. In a first chapter, an up-to-date overview of the main pathophysiological mechanisms of pain has been carried out, with special emphasis on the details in which the surgical treatment is based. In a second part, the principal indications and results of different surgical approaches are reviewed. Cordotomy, Myelotomy, DREZ lesions, Trigeminal Nucleotomy, Mesencephalotomy, and Cingulotomy are revisited. Ablative procedures have a limited role in the management of chronic non-cancer pain, but they continues to help patients with refractory cancer-related pain. Another ablation lesion has been named and excluded, due to lack of current relevance. Peripheral Nerve, Spine Cord, and the principal possibilities of Deep Brain and Motor Cortex Stimulation are also revisited. Regarding electrical neuromodulation, patient selection remains a challenge.

Neuroanatomical and psychological considerations in temporal lobe epilepsy.

Temporal lobe epilepsy (TLE) is the most common form of focal epilepsy and is associated with a variety of structural and psychological alterations. Recently, there has been renewed interest in using brain tissue resected during epilepsy surgery, in particular 'non-epileptic' brain samples with normal histology that can be found alongside epileptic tissue in the same epileptic patients - with the aim being to study the normal human brain organization using a variety of methods. An important limitation is that different medical characteristics of the patients may modify the brain tissue. Thus, to better determine how 'normal' the resected tissue is, it is fundamental to know certain clinical, anatomical and psychological characteristics of the patients. Unfortunately, this information is frequently not fully available for the patient from which the resected tissue has been obtained - or is not fully appreciated by the neuroscientists analyzing the brain samples, who are not necessarily experts in epilepsy. In order to present the full picture of TLE in a way that would be accessible to multiple communities (e.g., basic researchers in neuroscience, neurologists, neurosurgeons and psychologists), we have reviewed 34 TLE patients, who were selected due to the availability of detailed clinical, anatomical, and psychological information for each of the patients. Our aim was to convey the full complexity of the disorder, its putative anatomical substrates, and the wide range of individual variability, with a view toward: (1) emphasizing the importance of considering critical patient information when using brain samples for basic research and (2) gaining a better understanding of normal and abnormal brain functioning. In agreement with a large number of previous reports, this study (1) reinforces the notion of substantial individual variability among epileptic patients, and (2) highlights the common but overlooked psychopathological alterations that occur even in patients who become "seizure-free" after surgery. The first point is based on pre- and post-surgical comparisons of patients with hippocampal sclerosis and patients with normal-looking hippocampus in neuropsychological evaluations. The second emerges from our extensive battery of personality and projective tests, in a two-way comparison of these two types of patients with regard to pre- and post-surgical performance.

Surgical treatment of brainstem cavernous malformations: an international Delphi consensus.

OBJECTIVE: Indication for surgery in brainstem cavernous malformations (BSCMs) is based on many case series, few comparative studies, and no randomized controlled trials. The objective of this study was to seek consensus about surgical management aspects of BSCM. METHODS: A total of 29 experts were invited to participate in a multistep Delphi consensus process on the surgical treatment of BSCM. RESULTS: Twenty-two (76%) of 29 experts participated in the consensus. Qualitative analysis (content analysis) of an initial open-ended question survey resulted in 99 statements regarding surgical treatment of BSCM. By using a multistep survey with 100% participation in each round, consensus was reached on 52 (53%) of 99 statements. These were grouped into 4 categories: 1) definitions and reporting standards (7/14, 50%); 2) general and patient-related aspects (11/16, 69%); 3) anatomical-, timing of surgery-, and BSCM-related aspects (22/37, 59%); and 4) clinical situation-based decision-making (12/32, 38%). Among other things, a consensus was reached for surgical timing, handling of associated developmental venous anomalies, handling of postoperative BSCM remnants, assessment of specific anatomical BSCM localizations, and treatment decisions in typical clinical BSCM scenarios. CONCLUSIONS: A summary of typical clinical scenarios and a catalog of various BSCM- and patient-related aspects that influence the surgical treatment decision have been defined, rated, and interpreted.

Network Substrates of Centromedian Nucleus Deep Brain Stimulation in Generalized Pharmacoresistant Epilepsy.

Deep brain stimulation (DBS), specifically thalamic DBS, has achieved promising results to reduce seizure severity and frequency in pharmacoresistant epilepsies, thereby establishing it for clinical use. The mechanisms of action are, however, still unknown. We evidenced the brain networks directly modulated by centromedian (CM) nucleus-DBS and responsible for clinical outcomes in a cohort of patients uniquely diagnosed with generalized pharmacoresistant epilepsy. Preoperative imaging and long-term (2-11 years) clinical data from ten generalized pharmacoresistant epilepsy patients (mean age at surgery = 30.8 ± 5.9 years, 4 female) were evaluated. Volume of tissue activated (VTA) was included as seeds to reconstruct the targeted network to thalamic DBS from diffusion and functional imaging data. CM-DBS clinical outcome improvement (> 50%) appeared in 80% of patients and was tightly related to VTAs interconnected with a reticular system network encompassing sensorimotor and supplementary motor cortices, together with cerebellum/brainstem. Despite methodological differences, both structural and functional connectomes revealed the same targeted network. Our results demonstrate that CM-DBS outcome in generalized pharmacoresistant epilepsy is highly dependent on the individual connectivity profile, involving the cerebello-thalamo-cortical circuits. The proposed framework could be implemented in future studies to refine stereotactic implantation or the parameters for individualized neuromodulation.

Language hemispheric dominance analyzed with magnetic resonance DTI: correlation with the Wada test.

OBJECTIVE: Language lateralization is a major concern in some patients with pharmacoresistant epilepsy who will face surgery; in these patients, hemispheric dominance testing is essential to avoid further complications. The Wada test is considered the gold standard examination for language localization, but is invasive and requires many human and material resources. Functional MRI and tractography with diffusion tensor imaging (DTI) have demonstrated that they could be useful for locating language in epilepsy surgery, but there is no evidence of the correlation between the Wada test and DTI MRI in language dominance. METHODS: The authors performed a retrospective review of patients who underwent a Wada test before epilepsy surgery at their institution from 2012 to 2017. The authors retrospectively analyzed fractional anisotropy (FA), number and length of fibers, and volume of the arcuate fasciculus and uncinate fasciculus, comparing dominant and nondominant hemispheres. RESULTS: Ten patients with temporal lobe epilepsy were reviewed. Statistical analysis showed that the mean FA of the arcuate fasciculus in the dominant hemisphere was higher than in the nondominant hemisphere (0.369 vs 0.329, p = 0.049). Also, the number of fibers in the arcuate fasciculus was greater in the dominant hemisphere (881.5 vs 305.4, p = 0.003). However, no differences were found in the FA of the uncinate fasciculus or number of fibers between hemispheres. The length of fibers of the uncinate fasciculus was longer in the dominant side (74.4 vs 50.1 mm, p = 0.05). Volume in both bundles was more prominent in the dominant hemisphere (12.12 vs 6.48 cm3, p = 0.004, in the arcuate fasciculus, and 8.41 vs 4.16 cm3, p = 0.018, in the uncinate fasciculus). Finally, these parameters were compared in patients in whom the seizure focus was situated in the dominant hemisphere: FA (0.37 vs 0.30, p = 0.05), number of fibers (114.4 vs 315.6, p = 0.014), and volume (12.58 vs 5.88 cm3, p = 0.035) in the arcuate fasciculus were found to be statistically significantly higher in the dominant hemispheres. Linear discriminant analysis of FA, number of fibers, and volume of the arcuate fasciculus showed a correct discrimination in 80% of patients (p = 0.024). CONCLUSIONS: The analysis of the arcuate fasciculus and other tract bundles by DTI could be a useful tool for language location testing in the preoperative study of patients with refractory epilepsy.

Prediction of Memory Impairment in Epilepsy Surgery by White Matter Diffusion.

OBJECTIVE: To analyze the relationship between cognitive performance and white matter integrity in patients with temporal lobe epilepsy (TLE) to establish radiologic criteria to help with patient selection for surgery. METHODS: The study included 19 adults with temporal lobe epilepsy. A tractography analysis of fractional anisotropy and mean diffusivity (MD) of the following fascicles was performed: arcuate fascicle, cingulum, fornix, inferior fronto-occipital fascicle, inferior longitudinal fascicle, parahippocampal fibers of the cingulum, and uncinate fascicle. The Wechsler Memory Scale-Third Edition neuropsychological test was performed to evaluate short- and long-term verbal (Logical Memory I and II subtests) and nonverbal (Visual Reproduction I and II subtests) memory. Relationships between memory scores and diffusion were calculated. RESULTS: Lower Logical Memory I subtest scores were correlated with lower MD of the right inferior fronto-occipital fascicle, while lower Logical Memory II subtest scores were related to higher values of fractional anisotropy in bilateral cingulum, right uncinate, and right parahippocampal fibers of the cingulum and lower MD in left cingulum fascicle. Finally, lower values in Visual Reproduction I subtest scores were associated with lower values in MD in right cingulum and inferior fronto-occipital fascicles. CONCLUSIONS: Structural changes of some white matter tracts were associated with deterioration of both short- and long-term memory. These alterations were more associated with verbal memory than with nonverbal memory. These changes mainly consist of an increase in fractional anisotropy and a decrease in MD, which could be interpreted as reorganization phenomena. Diffusion tensor imaging could be a useful tool for cognitive assessment in surgical candidates with temporal lobe epilepsy who are not suitable for neuropsychological testing or in whom their results do not lead to definitive conclusions.

Prediction of Laterality in Temporal Lobe Epilepsy Using White Matter Diffusion Metrics.

BACKGROUND: Diagnostic methods of the epileptogenic area continue to be a challenge in epilepsy surgery research. We hypothesized that temporal lobe epilepsy (TLE) will result in white matter changes that can be detected using diffusion tensor imaging. Measurement of white matter diffusivity will therefore be useful for presurgical assessment. METHODS: Twelve patients with TLE who had undergone temporal lobectomy and amygdalohippocampectomy were included. In 6 patients, magnetic resonance imaging (MRI) showed evidence of mesial temporal sclerosis (m-TLE), whereas the 6 remaining MRI studies were informed without any abnormality (nl-TLE). All had excellent outcomes from surgery. Patients were compared with 12 age- and sex-matched controls. Five pairs of white matter fiber tracts were traced, and fiber tract fractional anisotropy and mean diffusivity were calculated. RESULTS: There were several alterations in diffusion parameters in white matter tracts, both ipsilateral and on the contralateral side, these alterations were more pronounced in the hemisphere ipsilateral to the epileptogenic focus. m-TLE patients had more alterations on ipsilateral side than nl-TLE patients, but similar alterations on contralateral side and bilateral fornix. The discriminant function analysis successfully lateralized all the patients with left TLE, 83.3% of the patients with right TLE, and all nl-TLE. CONCLUSIONS: Our results suggest that there are alterations in diffusion parameters in white matter tracts both in m-TLE and nl-TLE patients. Diffusion tensor imaging could be a useful presurgical tool to help establish the laterality of TLE, including patients with "normal" MRI. Further studies with a larger number of patients would be necessary to confirm these results.

¿Es posible obtener información de la presión intracraneal a partir de la actividad electroencefalográfica? / Is it possible to extract intracranial pressure information based on the EEG activity?

Introducción. El electroencefalograma (EEG) permite obtener información directa de la actividad bioeléctrica del cerebro y es una herramienta fundamental para la evaluación de la condición neurológica del paciente. En los últimos años ha comenzado a emplearse también para obtener indirectamente información sobre la hemodinámica cerebral y las variables que intervienen en la autorregulación del flujo sanguíneo cerebral. Objetivo. Estudiar la posible relación entre la actividad electroencefalográfica y la presión intracraneal (PIC) en pacientes con traumatismo craneoencefálico y hemorragia subaracnoidea ingresados en cuidados intensivos. Pacientes y métodos. Se incluyó a 21 pacientes (10 mujeres) mayores de 18 años con traumatismo craneoencefálico o hemorragia subaracnoidea que requerían monitorización de la PIC y a los que se les registró el EEG de forma continua. Se determinó la causalidad de Granger entre la PIC con respecto a las variables espectrales del EEG para ventanas temporales de 10 minutos durante la estancia en cuidados intensivos. Resultados. La causalidad de Granger mostró una alta correlación entre la PIC con las bandas del EEG. En la mayoría de los pacientes existe una causalidad de Granger significativa en la dirección del EEG hacia la PIC en gran parte del tiempo de monitorización, de forma que las variables del EEG precedían a la PIC. Conclusiones. El presente trabajo expone la relación temporal subyacente entre la dinámica de la PIC y la actividad bioeléctrica cerebral registrada mediante EEG en pacientes con traumatismo craneoencefálico y hemorragia subaracnoidea. El potencial uso de esta relación podría permitir estimar la PIC de manera no invasiva

Introduction. The capability of the electroencephalography (EEG) of recording the bioelectrical activity of the brain has made of it a fundamental tool for the evaluation of the patient’s neurological condition. In recent years, moreover, it has also begun to be used in obtaining information for other kind of variables, as the ones related with the cerebral hemodynamics Aim. To study the potential relationship between the EEG activity and the intracranial pressure (ICP) in patients suffering from traumatic brain injury and subarachnoid hemorrhage, during their stay at the intensive care unit. Patients and methods. Twenty-one adult patients (10 women) were included in the present observational prospective cohort study. They suffered from either traumatic brain injury or subarachnoid hemorrhage, requiring continuous EEG and ICP monitoring. In every patient, Granger causality between spectral functions of the EEG and the ICP was evaluated. Temporal windows of 10 minute were used to evaluate whether a causal relationship between those variables exist or not. In all of the cases, several days of continuous recording and assessment were performed. Results. In most patients and during most of the time, Granger causality turns out to be significant in the direction from the EEG to the ICP, meaning that the EEG dynamics actually leads the ICP dynamics. Conclusions. The present work provides useful information and shed light in discovering a hidden relationship between the ICP and EEG dynamics. The potential use of this relationship could lead to develop a medical device to measure ICP in a non-invasive fashion

Evolución morfométrica de descompresión obtenida tras corpectomía. Dirigiéndonos hacia abordajes posteriores / Morphometrical evaluation of decompression obtained through corpectomy. Heading towards to posterior approaches

Introducción: Hemos analizado la descompresión obtenida mediante corpectomía dorsal o dorsolumbar medida a través del ángulo de Cobb y el área del canal medular antes y después de la cirugía. Además, se ha comparado la evolución de la técnica entre los primeros 5 años del estudio y los 5 posteriores. Material y método: Se realizó un estudio retrospectivo de los pacientes operados entre 2005-2015 en nuestro centro mediante abordajes anteriores y posteriores. Resultados: Se intervinieron 24 pacientes y observamos una mejoría significativa entre los valores preoperatorios y postoperatorios en el análisis morfométrico (corrección de 4,18° de cifosis y un aumento del área del canal medular de 130,8mm2 con una significación de p<0,001 en ambos casos) y mejoría clínica (45,8% de los pacientes presentaron mejoría en la escala ASIA y una mejoría media de 13 puntos en el Karnofsky, p<0,001). Sin embargo, no se observa correlación entre los parámetros clínicos y morfométricos. También hemos observado que en los últimos 5 años del estudio los abordajes posteriores se utilizaron con mayor frecuencia y con buenos resultados. Conclusiones: La corpectomía dorsal permite una descompresión espinal significativa, con mejoría de la función neurológica sin que se correlacione con las mediciones de la descompresión. Gracias a las mejoras técnicas, las técnicas mínimamente invasivas (abordajes posteriores y técnicas MISS) permiten unos buenos resultados funcionales que son similares a los obtenidos con técnicas anteriores

Introduction: We analysed the decompression obtained by dorsal or dorsolumbar corpectomy measured by Cobb angle and the spinal area prior to and after surgery and compared the evolution of the technique over the last five years of the study. Material and method: A retrospective review of patients operated between 2005 and 2015 through anterior or posterior approaches was performed. Results: 24 patients were studied and a significant improvement was observed between the preoperative and postoperative morphometrical measurement (4.18° correction of the kyphosis and an increase of 130.8mm2 in the spinal canal, p<.001 in both cases) and in clinical parameters (45.8% of patients improved in ASIA, and Karnofsky showed 13 points of improvement, p<.001 in both cases). However, there was no correlation between clinical and morphological parameters. We also observed that in the last five years of the study posterior approaches were more frequently used with good results. Conclusions: Dorsal corpectomy allows significant spinal decompression, with neurological improvement but this does not correlate with the measurement of decompression. Thanks to technical improvements, less invasive techniques (posterior approaches and MISS) allow good clinical results, which are similar to those obtained by anterior techniques

Intrachiasmatic craniopharyngioma: Assessment of visual outcome with optical coherence tomography after complete surgical removal.

BACKGROUND: Optic chiasm invasion by a craniopharyngioma (CP) is exceptional. Surgical treatment of intrachiasmatic CPs associates a high risk of chiasm injury, which should be properly addressed before surgery. CASE DESCRIPTION: We present a 46-year-old woman admitted to the hospital with low visual acuity (0.1 in the right eye and 0.5 in the left) and a severe defect in her visual fields, in addition to headaches, diabetes insipidus, and a long-term depressive disorder. Her visual deficit progressed from a right homonymous temporal inferior quadrantanopia to an almost complete loss of vision in both eyes that only spared the upper nasal quadrants. Brain MRI showed a rounded third ventricle tumor with a potbelly expansion of the optic chiasm, suggesting chiasm invasion by the tumor. Optical coherence tomography (OCT) showed the thinning of the retinal nerve fiber layer (RNFL) in the superior and temporal wedges of the right eye and in the temporal wedge of the left one. The tumor was completely removed by employing a frontotemporal craniotomy and a translamina terminalis approach. Histological analysis showed a squamous-papillary CP. Postoperatively, a significant worsening of the visual defect was evidenced on the perimetry, which was related to a marked RNFL atrophy measured with OCT, as compared to the preoperative study. The poor long-term visual outcome in this patient correlated well with the results of postoperative OCT. CONCLUSIONS: Preoperative analysis of retinal atrophy with optic coherence tomography allows a reliable assessment of the patient's visual outcome in CPs involving the optic chiasm.

Potential EEG biomarkers of sedation doses in intensive care patients unveiled by using a machine learning approach.

OBJECTIVE: Sedation of neurocritically ill patients is one of the most challenging situation in ICUs. Quantitative knowledge on the sedation effect on brain activity in that complex scenario could help to uncover new markers for sedation assessment. Hence, we aim to evaluate the existence of changes of diverse EEG-derived measures in deeply-sedated (RASS-Richmond agitation-sedation scale -4 and -5) neurocritically ill patients, and also whether sedation doses are related with those eventual changes. APPROACH: We performed an observational prospective cohort study in the intensive care unit of the Hospital de la Princesa. Twenty-six adult patients suffered from traumatic brain injury and subarachnoid hemorrhage were included in the present study. Long-term continuous electroencephalographic (EEG) recordings (2141 h) and hourly annotated information were used to determine the relationship between intravenous sedation infusion doses and network and spectral EEG measures. To do that, two different strategies were followed: assessment of the statistical dependence between both variables using the Spearman correlation rank and by performing an automatic classification method based on a machine learning algorithm. MAIN RESULTS: More than 60% of patients presented a correlation greater than 0.5 in at least one of the calculated EEG measures with the sedation dose. The automatic classification method presented an accuracy of 84.3% in discriminating between different sedation doses. In both cases the nodes' degree was the most relevant measurement. SIGNIFICANCE: The results presented here provide evidences of brain activity changes during deep sedation linked to sedation doses. Particularly, the capability of network EEG-derived measures in discriminating between different sedation doses could be the framework for the development of accurate methods for sedation levels assessment.

Morphometrical evaluation of decompression obtained through corpectomy. Heading towards to posterior approaches. / Evolución morfométrica de descompresión obtenida tras corpectomía. Dirigiéndonos hacia abordajes posteriores.

INTRODUCTION: We analysed the decompression obtained by dorsal or dorsolumbar corpectomy measured by Cobb angle and the spinal area prior to and after surgery and compared the evolution of the technique over the last five years of the study. MATERIAL AND METHOD: A retrospective review of patients operated between 2005 and 2015 through anterior or posterior approaches was performed. RESULTS: 24 patients were studied and a significant improvement was observed between the preoperative and postoperative morphometrical measurement (4.18° correction of the kyphosis and an increase of 130.8mm2 in the spinal canal, p<.001 in both cases) and in clinical parameters (45.8% of patients improved in ASIA, and Karnofsky showed 13 points of improvement, p<.001 in both cases). However, there was no correlation between clinical and morphological parameters. We also observed that in the last five years of the study posterior approaches were more frequently used with good results. CONCLUSIONS: Dorsal corpectomy allows significant spinal decompression, with neurological improvement but this does not correlate with the measurement of decompression. Thanks to technical improvements, less invasive techniques (posterior approaches and MISS) allow good clinical results, which are similar to those obtained by anterior techniques.

Identifying causal relationships between EEG activity and intracranial pressure changes in neurocritical care patients.

OBJECTIVE: To explore and assess the relationship between electroencephalography (EEG) activity and intracranial pressure (ICP) in patients suffering from traumatic brain injury (TBI) and subarachnoid hemorrhage (SAH) during their stay in an intensive care unit. APPROACH: We performed an observational prospective cohort study of adult patients suffering from TBI or SAH. Continuous EEG-ECG was performed during ICP monitoring. In every patient, variables derived from the EEG were calculated and the Granger causality (GC) methodology was employed to assess whether, and in which direction, there is any relationship between EEG and ICP. MAIN RESULTS: One-thousand fifty-five hours of continuous multimodal monitoring were analyzed in 21 patients using the GC test. During 37.88% of the analyzed time, significant GC statistic was found in the direction from the EEG activity to the ICP, with typical lags of 25-50 s between them. When recordings were adjusted by sedation-perfusion and/or bolus-and handling, these percentages hardly changed. SIGNIFICANCE: Long-lasting, continuous and simultaneous EEG and ICP recordings from TBI and SAH patients provide highly rich and useful information, which has allowed for uncovering a strong relationship between both signals. The use of this relationship could lead to developing a medical device to measure ICP in a non-invasive way.

Validation of Grading Scores and Outcome Prognostic Factors in Intracranial Meningiomas in Elderly Patients.

OBJECTIVE: Meningiomas are the most frequent benign intracranial tumors and they are becoming more frequent because of the aging population and advances in diagnostics and neurosurgical treatment. Therefore, there will be an increase of this disease in the coming years. METHODS: We performed a retrospective analysis of patients older than 70 years who underwent surgery for intracranial meningiomas, and we established risk factors related to outcome, morbidity, and mortality. We compared 3 previously described scores (Geriatric Scoring System [GSS], Clinico-Radiological Grading System [CRGS], and Sex, Karnofsky, ASA, Location and Edema [SKALE] score). RESULTS: We identified 110 patients older than 70 years. In the univariate analysis, postoperative Karnofsky Performance Status (KPS) was related to the presence of edema (P = 0.036), tumor size (P = 0.043), previous neurologic impairment (P = 0.012), and preoperative American Society of Anesthesiologists (ASA) physical status classification (P = 0.029). In the multivariable logistic regression model, ASA classification (odds ratio, 0.324; P = 0.04) and preoperative KPS (odds ratio, 1.042; P = 0.05) were also statistically significant. In all cases, better survival curves in the Kaplan-Meier survival test appear in patients with lower scores (CRGS, P = 0.015; GSS, P = 0.014; SKALE, P < 0.001). Also, morbidity measured as postoperative KPS correlated with these scores (CRGS, P < 0.001; SKALE, P < 0.001; GSS, P < 0.001). However, only SKALE correlated with perioperative morbidity, mortality, and 1-year mortality. CONCLUSIONS: Meningioma resection in patients older than 70 years is safe, with an acceptable rate of mortality and morbidity. Patients who should undergo surgery must be selected in relation to their comorbidities, such as ASA classification or preoperative KPS. However, SKALE could be a useful tool as an initial approach.

Image guidance in transdiscal fixation for high-grade spondylolisthesis in adults with correct spinal balance.

OBJECTIVE Spondylolisthesis is a prevalent spine disease that recent studies estimate could be detected in 9% of the population. High-grade spondylolisthesis (HGS), however, is much less frequent, which makes it difficult to develop a general recommendation for its treatment. Posterior transdiscal fixation was proposed in 1994 for HGS, and the use of spine navigation could make this technique more accessible and reduce the morbidity associated with the procedure. The purpose of this study was to present a case series involving adult patients with HGS and correct spinal alignment who were treated with transdiscal pedicle screw placement guided with neuronavigation and compare the results to those achieved previously without image guidance. METHODS The authors reviewed all cases in which adult patients with correct spinal alignment were treated for HGS with posterior transdiscal instrumentation placement guided with navigation between 2014 and 2016 at their institution. The authors compared preoperative and postoperative spinopelvic parameters on standing radiographs as well as Oswestry Disability Index (ODI) scores and visual analog scale (VAS) scores for low-back pain. Follow-up CT and MRI studies and postoperative radiographs were evaluated to identify any screw malplacement or instrumentation failure. Any other intraoperative or postoperative complications were also recorded. RESULTS Eight patients underwent posterior transdiscal navigated instrumentation placement during this period, with a mean duration of follow-up of 16 months (range 9-24 months). Six of the patients presented with Meyerding grade III spondylolisthesis and 2 with Meyerding grade IV. In 5 cases, L4-S1 instrumentation was placed, while in the other 3 cases, surgery consisted of transdiscal L5-S1 fixation. There was no significant difference between preoperative and postoperative spinopelvic parameters. However, there was a statistically significant improvement in the mean VAS score for low-back pain (6.5 ± 1.5 vs 4 ± 1.7) and the mean ODI score (49.2 ± 19.4 vs 37.7 ± 22) (p = 0.01 and p = 0.012, respectively). Six patients reduced their use of pain medication. There were no intraoperative or postoperative complications during the hospital stay, and as of the most recent follow-up, no complications related to pseudarthrosis or hardware failure had been observed. CONCLUSIONS Treatment with posterior transdiscal pedicle screws with in situ fusion achieved good clinical and radiological outcomes in patients with HGS and good sagittal spinal balance. The use of navigation and image guidance was associated with improved results in this technique, including a reduction in postoperative and intraoperative complications related to screw malplacement, pseudarthrosis, and instrumentation failure.

Implantación bilateral en dos tiempos para estimulación cerebral profunda en el tratamiento de la enfermedad de Parkinson idiopática bilateral: resultados clínicos / Bilateral two-stage implantation for deep brain stimulation in the treatment of bilateral idiopathic Parkinson's disease: clinical outcomes

Objetivo. La implantación bilateral simultánea de electrodos en el núcleo subtalámico para la enfermedad de Parkinson idiopática (EPI) se asocia a una duración elevada de la intervención, alteraciones del lenguaje y confusión posquirúrgica; además, existe evidencia de mejoría ipsilateral tras la estimulación del núcleo subtalámico. Para optimizar el manejo perioperatorio se realiza un estudio prospectivo con estimulación cerebral profunda (ECP) en el núcleo subtalámico en dos procedimientos unilaterales consecutivos. Pacientes y métodos. Estudio prospectivo de 41 pacientes con EPI bilateral, con implantación de ECP en dos fases quirúrgicas unilaterales. Se analizan sus resultados clínicos según las escalas Unified Parkinson's Disease Rating Scale (UPDRS), Hoehn y Yahr, y Schwab y England, así como sus complicaciones. Resultados. La edad media fue de 61 ± 7 años, 23 hombres. Cinco pacientes (12%) no fueron intervenidos del núcleo subtalámico contralateral por buen control. La media en la UPDRS motora y la Hoehn y Yahr en off farmacológico preoperatorio fue de 44 ± 14 y 3, respectivamente, y de 19 ± 8 y 1,8 a los seis meses de seguimiento. La mejoría media en la escala de Schwab y England en el preoperatorio y a los seis meses fue del 39%. Dos pacientes tuvieron confusión postoperatoria, y uno, disartria transitoria. Conclusiones. La ECP bilateral en dos etapas unilaterales fue una opción eficaz y con escasas complicaciones en nuestra serie de pacientes con EPI. El 10% de los pacientes no precisó electrodos contralaterales. Sería necesario un estudio aleatorizado en pacientes sometidos a cirugía bilateral en uno y dos tiempos para confirmar estos resultados (AU)

Aims. Simultaneous bilateral implantation of electrodes in the subthalamic nucleus for idiopathic Parkinson’s disease (IPD) is associated with long surgery time, language disorders and post-operative confusion. Moreover, there is evidence of ipsilateral improvement after stimulation of the subthalamic nucleus. In order to optimise perioperative management a prospective study is conducted with deep brain stimulation (DBS) in the subthalamic nucleus in two consecutive unilateral procedures. Patients and methods. We conducted a prospective study of 41 patients with bilateral IPD, with DBS implantation in two unilateral surgical phases. Its clinical outcomes are analysed according to the Unified Parkinson’s Disease Rating Scale (UPDRS), the Hoehn & Yahr, and the Schwab & England scales, together with their complications. Results. The mean age was 61 ± 7 years old, 23 males. Five patients (12%) did not undergo surgery of the contralateral subthalamic nucleus due to good control. The mean on the motor UPDRS and the Hoehn & Yahr in preoperative pharmacological off was 44 ± 14 and 3, respectively, and 19 ± 8 and 1.8 at six months’ follow-up. The mean improvement on the Schwab & England scale in the pre-operative period and at six months was 39%. Two patients suffered postoperative confusion, and one of them had transient dysarthria. Conclusions. Bilateral DBS in two unilateral stages was an effective option with few complications in our series of patients with IPD. 10% of the patients did not require contralateral electrodes. It would be necessary to conduct a randomized study in patients who underwent bilateral surgery in one and two stages in order to confirm these results (AU)

Review of Cortical Bone Trajectory: Evidence of a New Technique.

This article summarizes recent evidence on the cortical bone trajectory (CBT) obtained from published anatomical, biomechanical, and clinical studies. CBT was proposed by Santoni in 2009 as a new trajectory that can improve the fixation of pedicle screws in response to screw loosening in osteoporotic patients. Recently, research interest has been growing with increasing numbers of published series and frequent reports of new applications. We performed an online database search using the terms "cortical bone trajectory," "pedicle screw," "CBT spine," "CBT fixation," "MISS CBT," and "traditional trajectory." The search included the PubMed, Ovid MEDLINE, Cochrane, and Google Scholar databases, resulting in an analysis of 42 articles in total. These covered three aspects of CBT research: anatomical studies, biomechanical parameters, and clinical cases or series. Compared to the traditional trajectory, CBT improves pullout strength, provides greater stiffness in cephalocaudal and mediolateral loading, and shows superior resistance to flexion/extension; however, it is inferior in lateral bending and axial rotation. CBT seems to provide better immediate implant stability. In clinical studies, CBT has shown better perioperative results for blood loss, length of stay in hospital, and surgery time; similar or better clinical postoperative scores; and similar comorbidity, without any major fixation system complications due to instrumentation failure or screw misplacement. In addition, advantages such as less lateral exposure allow it to be used as a minimally invasive technique. However, most of the clinical studies were retrospective case series or case-control studies; prospective evidence on this technique is scarce, making a definitive comparison with the traditional trajectory difficult. Nevertheless, we can conclude that CBT is a safe technique that offers good clinical results with similar biomechanical and perioperative parameters to those of the traditional trajectory. In addition, new applications can improve its results and make it useful for additional pathologies.

Nuevo potencial talámico asociado con potenciales evocados somatosensoriales / New thalamic potential associated with somatosensory evoked potentials

Introducción. La respuesta del tálamo durante el estudio con potenciales evocados somatosensoriales (PESS) no está suficientemente comprendida. Caso clínico. Varón de 30 años intervenido con sedación completa mediante estimulación cerebral profunda en el núcleo centromediano por epilepsia farmacorresistente. Durante la intervención se registraron las respuestas de los núcleos talámicos mediante cuatro microelectrodos a los PESS. Estas respuestas se pueden descomponer en tres tipos: potenciales de campo local (PCL), oscilaciones rápidas de baja amplitud (ORB) y oscilaciones lentas de gran amplitud (OLG). Las ORB están muy extendidas por gran parte de las regiones registradas (> 5 mm) y en los cuatro electrodos simultáneamente. Sin embargo, las OLG están localizadas en un único punto del registro y están íntimamente asociadas con los PCL. Además, el análisis de wavelets muestra un componente espectral y un tiempo de aparición diferentes. Conclusiones. Aunque se ha considerado la presencia de ORB como indicador de la presencia del tálamo sensorial, su amplia extensión por diferentes núcleos talámicos sugiere que se trata de una respuesta poco específica a los PESS. Sin embargo, la localización espacial restringida de los OLG y su asociación con PCL sugiere que estos potenciales de nueva descripción son los marcadores de la presencia del tálamo sensorial. Su identificación puede resultar muy útil en estimulación cerebral profunda talámica en pacientes despiertos y, especialmente, en los que precisen sedación (AU)

Introduction. The response of the thalamus during the study with somatosensory evoked potentials (SSEP) is not sufficiently understood. Case report. A 17-year-old man undergoing surgery for deep brain stimulation in the centromedian nucleus for drugresistant epilepsy under complete sedation. During the intervention, the responses to SSEPs of the thalamic nuclei were recorded by means of four microelectrodes. These responses can be decomposed into three types: local field potentials (LFP), low amplitude fast oscillations (LFO), and high amplitude slow oscillations (HSO). LFO are widespread in much of the registered regions. However, HSOs are located at a single point in the registry and are closely associated with LFPs. Conclusions. Although the presence of LFO has been considered as an indicator of the presence of the sensory thalamus, its wide extension by different thalamic nuclei suggests that it is an unspecific response to SSEPs. However, the restricted spatial location of HSO and their association with LFP suggest that these newly described potentials are the markers for the presence of the sensory thalamus. Their identification may prove very useful in thalamic deep brain stimulation either in awake patients or especially in those requiring sedation (AU)