Novel method for restoration of anorectal function following spinal cord injury via nerve transfer in rats.

OBJECTIVES: Nerve transfer has been developed to restore partial function after serious nerve injuries, for example, restoring bladder control after spinal cord injury (SCI). Our aim here was to establish a preclinical proof-of-concept model using nerve transfer for restoring anorectal function after SCI. SETTING: We used laminectomy to model SCI, and bilateral spinal ventral and dorsal nerve root anastomosis to re-establish connectivity to the anorectal musculature. METHODS: Multidisciplinary methods were used to assess the anatomical and functional integrity of the alternative spinal-to-anorectal nerve circuit. Adult rats were used to establish the model. Bilateral anterior and posterior L5 nerve roots were surgically matched with anterior and posterior of S1 nerve roots by microscopic anastomosis to establish an artificial rectal reflex arc with complete sensory and motor pathways. Twelve weeks later, we used retrograde nerve tracing and neurohistomorphological analysis to assess anatomical integrity of the new artificial rectal reflex arc. Anorectal manometry was used to assess the function of the new nerve circuit. RESULTS: Retrograde tracing with recombinant attenuated pseudo rabies virus indicated that the new neural pathway was successfully established to the anorectal musculature after experimental SCI. Toluidine blue-stained sections of the anastomosis site revealed normal-appearing nerve fiber morphology and regeneration, and transmission electron microscopy revealed myelinated axons. Anorectal manometry revealed significant anorectal functional recovery. CONCLUSION: These results suggest that our model is a feasible first step in developing an alternative reflex pathway after laminectomy at L4 to S2 and shows promise for effective restoration of anorectal function.

Functional lesional neurosurgery for tremor-a protocol for a systematic review and meta-analysis.

INTRODUCTION: The recent introduction of incision-less lesional neurosurgery using Gamma Knife and MRI-guided focused ultrasound has revived interest in lesional treatment options for tremor disorders. Preliminary literature researches reveal that the consistency of treatment effects after lesional neurosurgery for tremor has not formally been assessed yet. Similarly, the efficacy of different targets for lesional treatment and incidence of persistent side effects of lesional neurosurgical interventions has not been comprehensively assessed. This work therefore aims to describe a suitable process how to review the existing literature on efficacy and persistent side effects of lesional neurosurgical treatment for tremor due to Parkinson's disease, essential tremor, multiple sclerosis and midbrain/rubral tremor. METHODS AND ANALYSIS: We will search electronic databases (Medline, Cochrane) and reference lists of included articles for studies reporting lesional interventions for tremor in cohorts homogeneous for tremor aetiology and intervention (technique and target). We will include cohorts with a minimum number of five subjects and follow-up of 2 months. One investigator will perform the initial literature search and two investigators then independently decide which references to include for final efficacy and safety analysis. After settling of disagreement, data will be extracted from articles using a standardised template. We will perform a random-effect meta-analysis calculating standardised mean differences (Hedge's g) for comparison in Forest plots and subgroup analysis after assessment of heterogeneity using I2 statistics. ETHICS AND DISSEMINATION: This study will summarise the available evidence on the efficacy of lesional interventions for the most frequent tremor disorders, as well as for the incidence rate of persisting side effects after unilateral lesional treatment. This data will be useful to guide future work on incision-less lesional interventions for tremor. SYSTEMATIC REVIEW REGISTRATION: This study has been registered with the PROSPERO database (no. CRD42016048049).

Functional Reconstruction of Motor and Language Pathways Based on Navigated Transcranial Magnetic Stimulation and DTI Fiber Tracking for the Preoperative Planning of Low Grade Glioma Surgery: A New Tool for Preservation and Restoration of Eloquent Networks.

BACKGROUND: Surgery of low-grade gliomas (LGGs) in eloquent areas still presents a challenge. New technologies have been introduced to enable the performance of "functional", customized preoperative planning aimed at maximal resection, while reducing the risk of postoperative deficits. We describe our experience in the surgery of LGGs in eloquent areas using preoperative planning based on navigated transcranial magnetic stimulation (nTMS) and diffusion tensor imaging (DTI) tractography. METHODS: Sixteen patients underwent preoperative planning, using nTMS and nTMS-based DTI tractography. Motor and language functions were mapped. Preoperative data allowed for tailoring of the surgical strategy. The impact of these modalities on surgical planning was evaluated. Influence on functional outcome was analyzed in comparison with results in a historical control group. RESULTS: In 12 patients (75 %), nTMS added useful information on functional anatomy and surgical risks. Surgical strategy was modified in 9 of 16 cases (56 %). The nTMS "functional approach" provided a good outcome at discharge, with a decrease in postoperative motor and/or language deficits, as compared with controls (6 vs. 44 %; p = 0.03). CONCLUSIONS: The functional preoperative mapping of speech and motor pathways based on nTMS and DTI tractography provided useful information, allowing us to plan the best surgical strategy for radical resection; this resulted in improved postoperative neurological results.

The nondecussating pathway of the dentatorubrothalamic tract in humans: human connectome-based tractographic study and microdissection validation.

OBJECT The dentatorubrothalamic tract (DRTT) is the major efferent cerebellar pathway arising from the dentate nucleus (DN) and decussating to the contralateral red nucleus (RN) and thalamus. Surprisingly, hemispheric cerebellar output influences bilateral limb movements. In animals, uncrossed projections from the DN to the ipsilateral RN and thalamus may explain this phenomenon. The aim of this study was to clarify the anatomy of the dentatorubrothalamic connections in humans. METHODS The authors applied advanced deterministic fiber tractography to a template of 488 subjects from the Human Connectome Project (Q1-Q3 release, WU-Minn HCP consortium) and validated the results with microsurgical dissection of cadaveric brains prepared according to Klingler's method. RESULTS The authors identified the "classic" decussating DRTT and a corresponding nondecussating path (the nondecussating DRTT, nd-DRTT). Within each of these 2 tracts some fibers stop at the level of the RN, forming the dentatorubro tract and the nondecussating dentatorubro tract. The left nd-DRTT encompasses 21.7% of the tracts and 24.9% of the volume of the left superior cerebellar peduncle, and the right nd-DRTT encompasses 20.2% of the tracts and 28.4% of the volume of the right superior cerebellar peduncle. CONCLUSIONS The connections of the DN with the RN and thalamus are bilateral, not ipsilateral only. This affords a potential anatomical substrate for bilateral limb motor effects originating in a single cerebellar hemisphere under physiological conditions, and for bilateral limb motor impairment in hemispheric cerebellar lesions such as ischemic stroke and hemorrhage, and after resection of hemispheric tumors and arteriovenous malformations. Furthermore, when a lesion is located on the course of the dentatorubrothalamic system, a careful preoperative tractographic analysis of the relationship of the DRTT, nd-DRTT, and the lesion should be performed in order to tailor the surgical approach properly and spare all bundles.

Differential role of afferent and efferent renal nerves in the maintenance of early- and late-phase Dahl S hypertension.

Clinical data suggest that renal denervation (RDNX) may be an effective treatment for human hypertension; however, it is unclear whether this therapeutic effect is due to ablation of afferent or efferent renal nerves. We have previously shown that RDNX lowers arterial pressure in hypertensive Dahl salt-sensitive (S) rats to a similar degree observed in clinical trials. In addition, we have recently developed a method for selective ablation of afferent renal nerves (renal-CAP). In the present study, we tested the hypothesis that the antihypertensive effect of RDNX in the Dahl S rat is due to ablation of afferent renal nerves by comparing the effect of complete RDNX to renal-CAP during two phases of hypertension in the Dahl S rat. In the early phase, rats underwent treatment after 3 wk of high-NaCl feeding when mean arterial pressure (MAP) was ∼ 140 mmHg. In the late phase, rats underwent treatment after 9 wk of high NaCl feeding, when MAP was ∼ 170 mmHg. RDNX reduced MAP ∼ 10 mmHg compared with sham surgery in both the early and late phase, whereas renal-CAP had no antihypertensive effect. These results suggest that, in the Dahl S rat, the antihypertensive effect of RDNX is not dependent on pretreatment arterial pressure, nor is it due to ablation of afferent renal nerves.

Triceps motor branch transfer for isolated traumatic pediatric axillary nerve injuries.

OBJECT: Transfer of the triceps motor branch has been used for treatment of isolated axillary nerve palsy in the adult population. However, there are no published data on the effectiveness of this procedure in the pediatric population with traumatic injuries. The authors reviewed demographics and outcomes in their series of pediatric patients who underwent this procedure. METHODS: Six patients ranging in age from 10 to 17 years underwent triceps motor branch transfer for the treatment of isolated axillary nerve injuries between 4 and 8 months after the inciting injury. Deltoid muscle strength was evaluated using the modified British Medical Research Council (MRC) grading system. Shoulder abduction at last follow-up was measured. RESULTS: The mean duration of follow-up was 38 months. The average postoperative MRC grading of deltoid muscle strength was 3.6 ± 1.3. The median MRC grade was 4. One patient who did not achieve an MRC grade of 3 suffered multiple injuries from high-velocity trauma. Unlike in the adult population, age, body mass index of the patient, and delay from injury to surgery were not significant factors affecting the outcome of the procedure. CONCLUSIONS: In the pediatric population with traumatic injuries, isolated axillary nerve injury treated with triceps motor branch transfer can result in good outcomes.

High-resolution direct microstimulation mapping of spinal cord motor pathways during resection of an intramedullary tumor.

Despite the use of advanced microsurgical techniques, resection of intramedullary tumors may result in significant postoperative deficits because of the vicinity or invasion of important functional tracts. Intraoperative monitoring of somatosensory evoked potentials and transcranial electrical motor evoked potentials has been used previously to limit such complications. Electromyography offers an opportunity for the surgeon to map the eloquent tissue associated with the tumor using intraoperative motor fiber stimulation. Similar to the use of cortical simulation in the resection of supratentorial gliomas, this technique can potentially advance the safety of intramedullary spinal cord tumor resection. The authors describe the use of intraoperative motor fiber tract stimulation to map the corticospinal tracts associated with an intramedullary tumor. This technique led to protection of these tracts during resection of the tumor.

Tailoring neurophysiological strategies with clinical context enhances resection and safety and expands indications in gliomas involving motor pathways.

BACKGROUND: Resection of motor pathway gliomas requires the intraoperative recognition of essential cortical-subcortical motor structures. The degree of involvement of motor structures is variable, and increases as result of treatments patients are submitted to. Intraoperative neurophysiology offers various stimulation modalities, which efficiency is based on the ability to recognize essential sites with the highest possible resolution in most clinical conditions. Two stimulation paradigms evolved for intraoperative guidance of motor tumors removal: the 60 Hz-technique [low frequency (LF)] and the pulse-technique [high frequency-(HF)], delivered by bipolar or monopolar probe respectively. Most surgical teams rely on to either of the 2 techniques. The key point is the integration of the choice of the stimulation modality with the clinical context. METHODS: In 591 tumors involving the corticospinal tract, the use of HF and LF was tailored to the clinical context defined by patient clinical history and tumor features (by imaging). The effect was evaluated on the feasibility of mapping, the impact on immediate and permanent morbidity, the extent of resection, and the number of patients treated. RESULTS: By integrating the choice of the probe and the stimulation protocol with patient clinical history and tumor characteristics, the best probe-frequency match was identified for the different sets of clinical conditions. This integrative approach allows increasing the extent of resection and patient functional integrity, and greatly expands the number of patients who could benefit from surgery. CONCLUSIONS: The integration of stimulation modalities with clinical context enhances the extent and safety of resection and expands the population of patients who could benefit from surgical treatment.

Renal sympathetic nerve ablation for treatment-resistant hypertension.

Hypertension is a major risk factor for increased cardiovascular events with accelerated sympathetic nerve activity implicated in the pathogenesis and progression of disease. Blood pressure is not adequately controlled in many patients, despite the availability of effective pharmacotherapy. Novel procedure- as well as device-based strategies, such as percutaneous renal sympathetic nerve denervation, have been developed to improve blood pressure in these refractory patients. Renal sympathetic denervation not only reduces blood pressure but also renal as well as systemic sympathetic nerve activity in such patients. The reduction in blood pressure appears to be sustained over 3 years after the procedure, which suggests absence of re-innervation of renal sympathetic nerves. Safety appears to be adequate. This approach may also have potential in other disorders associated with enhanced sympathetic nerve activity such as congestive heart failure, chronic kidney disease and metabolic syndrome. This review will focus on the current status of percutaneous renal sympathetic nerve denervation, clinical efficacy and safety outcomes and prospects beyond refractory hypertension.

Fast presurgical functional mapping using task-related intracranial high gamma activity.

OBJECT: Electrocorticography (ECoG) is a powerful tool for presurgical functional mapping. Power increase in the high gamma band has been observed from ECoG electrodes on the surface of the sensory motor cortex during the execution of body movements. In this study the authors aim to validate the clinical usage of high gamma activity in presurgical mapping by comparing ECoG mapping with traditional direct electrical cortical stimulation (ECS) and functional MRI (fMRI) mapping. METHODS: Seventeen patients with epilepsy participated in an ECoG motor mapping experiment. The patients executed a 5-minute hand/tongue movement task while the ECoG signal was recorded. All 17 patients also underwent extraoperative ECS mapping to localize the motor cortex. Eight patients also participated in a presurgical fMRI study. The high gamma activity on ECoG was modeled using the general linear model (GLM), and the regions showing significant gamma power increase during the task condition compared with the rest condition were localized. The maps derived from GLM-based ECoG mapping, ECS, and fMRI were then compared. RESULTS: High gamma activity in the motor cortex can be reliably modulated by motor tasks. Localization of the motor regions achieved with GLM-based ECoG mapping was consistent with the localization determined by ECS. The maps also appeared to be highly localized compared with the fMRI activations. Using the ECS findings as the reference, GLM-based ECoG mapping showed a significantly higher sensitivity than fMRI (66.7% for ECoG, 52.6% for fMRI, p<0.05), while the specificity was high for both techniques (>97%). If the current-spreading effect in ECS is accounted for, ECoG mapping may produce maps almost identical to those produced by ECS mapping (100% sensitivity and 99.5% specificity). CONCLUSIONS: General linear model-based ECoG mapping showed a superior performance compared to traditional ECS and fMRI mapping in terms of efficiency and accuracy. Using this method, motor functions can be reliably mapped in less than 5 minutes.

Clinical application of motor pathway mapping using diffusion tensor imaging tractography and intraoperative direct subcortical stimulation in cerebral glioma surgery: a prospective cohort study.

BACKGROUND: Glioma surgery in eloquent areas remains a challenge because of the risk of postoperative motor deficits. OBJECTIVE: To prospectively evaluate the efficiency of using a combination of diffusion tensor imaging (DTI) tractography functional neuronavigation and direct subcortical stimulation (DsCS) to yield a maximally safe resection of cerebral glioma in eloquent areas. METHODS: A prospective cohort study was conducted in 58 subjects with an initial diagnosis of primary cerebral glioma within or adjacent to the pyramidal tract (PT). The white matter beneath the resection cavity was stimulated along the PT, which was visualized with DTI tractography. The intercept between the PT border and DsCS site was measured. The sensitivity and specificity of DTI tractography for PT mapping were evaluated. The efficiency of the combined use of both techniques on motor function preservation was assessed. RESULTS: Postoperative analysis showed gross total resection in 40 patients (69.0%). Seventeen patients (29.3%) experienced postoperative worsening; 1-month motor deficit was observed in 6 subjects (10.3%). DsCS verified a high concordance rate with DTI tractography for PT mapping. The sensitivity and specificity of DTI were 92.6% and 93.2%, respectively. The intercepts between positive DsCS sites and imaged PTs were 2.0 to 14.7 mm (5.2 ± 2.2 mm). The 6-month Karnofsky performance scale scores in 50 postoperative subjects were significantly increased compared with their preoperative scores. CONCLUSION: DTI tractography is effective but not completely reliable in delineating the descending motor pathways. Integration of DTI and DsCS favors patient-specific surgery for cerebral glioma in eloquent areas.

Utility of presurgical navigated transcranial magnetic brain stimulation for the resection of tumors in eloquent motor areas.

OBJECT: Navigated transcranial magnetic stimulation (nTMS) is a newly evolving technique. Despite its supposed purpose (for example, preoperative central region mapping), little is known about its accuracy compared with established modalities like direct cortical stimulation (DCS) and functional MR (fMR) imaging. Against this background, the authors performed the current study to compare the accuracy of nTMS with DCS and fMR imaging. METHODS: Fourteen patients with tumors in or close to the precentral gyrus were examined using nTMS for motor cortex mapping, as were 12 patients with lesions in the subcortical white matter motor tract. Moreover, preoperative fMR imaging and intraoperative mapping of the motor cortex were performed via DCS, and the outlining of the motor cortex was compared. RESULTS: In the 14 cases of lesions affecting the precentral gyrus, the primary motor cortex as outlined by nTMS correlated well with that delineated by intraoperative DCS mapping, with a deviation of 4.4 ± 3.4 mm between the two methods. In comparing nTMS with fMR imaging, the deviation between the two methods was much larger: 9.8 ± 8.5 mm for the upper extremity and 14.7 ± 12.4 mm for the lower extremity. In 13 of 14 cases, the surgeon admitted easier identification of the central region because of nTMS. The procedure had a subjectively positive influence on the operative results in 5 cases and was responsible for a changed resection strategy in 2 cases. One of 26 patients experienced nTMS as unpleasant; none found it painful. CONCLUSIONS: Navigated TMS correlates well with DCS as a gold standard despite factors that are supposed to contribute to the inaccuracy of nTMS. Moreover, surgeons have found nTMS to be an additional and helpful modality during the resection of tumors affecting eloquent motor areas, as well as during preoperative planning.

Return of spinal reflex after spinal cord surgery for brachial plexus avulsion injury.

Motor but not sensory function has been described after spinal cord surgery in patients with brachial plexus avulsion injury. In the featured case, motor-related nerve roots as well as sensory spinal nerves distal to the dorsal root ganglion were reconnected to neurons in the ventral and dorsal horns of the spinal cord by implanting nerve grafts. Peripheral and sensory functions were assessed 10 years after an accident and subsequent spinal cord surgery. The biceps stretch reflex could be elicited, and electrophysiological testing demonstrated a Hoffman reflex, or Hreflex, in the biceps muscle when the musculocutaneous nerve was stimulated. Functional MR imaging demonstrated sensory motor cortex activities on active as well as passive elbow flexion. Quantitative sensory testing and contact heat evoked potential stimulation did not detect any cutaneous sensory function, however. To the best of the authors' knowledge, this case represents the first time that spinal cord surgery could restore not only motor function but also proprioception completing a spinal reflex arch.

[Renal denervation a new treatment option in resistant arterial hypertension]. / Die renale Denervation als neue Behandlungsmöglichkeit der therapierefraktären arteriellen Hypertonie.

Resistant hypertension is defined as blood pressure that remains above therapeutic goal despite the use of 3 antihypertensive drugs including a diuretic. After exclusion of secondary causes and medical in compliance, the estimated prevalence of resistant arterial hypertension ranges from 4% to 19% in hypertensive patients. Treatment requires a multimodal therapeutic approach. Hyperactivation of the sympathetic nervous system plays a key role in the genesis of hypertension. Targeting renal sympathetic nerves, percutaneous catheter-based renal denervation is a new therapeutic option for the treatment of resistant arterial hypertension in selected drug resistant patients.

A role of diffusion tensor imaging fiber tracking in deep brain stimulation surgery: DBS of the dentato-rubro-thalamic tract (drt) for the treatment of therapy-refractory tremor.

INTRODUCTION: Deep brain stimulation (DBS) can alleviate tremor of various origins. A number of regions are targeted. In recent work our group was able to show the involvement of the dentato-rubro-thalamic tract (drt) in tremor control with fiber tracking techniques. Here we report for the first time the successful use of magnetic resonance tractography in combination with traditional landmark-based targeting techniques to perform the implantation of a bilateral DBS system in a patient with dystonic head tremor. METHODS: We report on a 37-year-old female with long-standing pure head tremor from myoclonus dystonia. She was identified as a candidate for thalamic DBS. The use of head fixation in a stereotactic frame would blur target symptoms (head tremor) during surgery and was therefore avoided. Her dentate-rubro-thalamic tracts were visualized with preoperative diffusion tensor imaging (DTI) and tractography, and then directly targeted stereotactically with DBS electrodes. RESULTS: Three months after implantation, tremor control was excellent (>90%). A close evaluation of the active electrode contact positions revealed clear involvement of the drt. CONCLUSION: This is the first time that direct visualization of fiber tracts has been employed for direct targeting and successful movement disorder tremor surgery. In the reported case, additional knowledge about the position of the drt, which previously has been shown to be a structure for modulation to achieve tremor control, led to a successful implantation of a DBS system, although there was a lack of intra-operatively testable tremor symptoms. In concordance with studies in optogenetic neuromodulation, fiber tracts are the emerging target structures for DBS. The routine integration of DTI tractography into surgical planning might be a leading path into the future of DBS surgery and will add to our understanding of the pathophysiology of movement disorders. Larger study populations will have to prove these concepts in future research.

Tratamiento de los tumores cerebrales intrínsecos de áreas motoras elocuentes. Resultados de un protocolo basado en la navegación, tractografía y monitorizaciónneurofisiológica de estructuras corticales y subcorticales / Treatment of intrinsic brain tumors located in motor eloquent areas. results of a protocol based in navegation, tractography and neurophysiological monitoring of cortical and subcortical structures

Objetivos. El papel actual del tratamiento microquirúrgicode los tumores cerebrales intrínsecos se basaen alcanzar la máxima resección volumétrica del tumorminimizando la morbilidad postoperatoria. El propósitodel trabajo es estudiar los beneficios de un protocolodiseñado para tratar tumores localizados en áreaselocuentes motoras, en el que se incluye la navegación yla estimulación de tractos motores subcorticales.Material y métodos. Se han incluido 17 pacientescon tumores corticales y subcorticales de área motoratratados quirúrgicamente. Para la planificación preoperatoriase fusionaron en el sistema de navegaciónestudios anatómicos, de resonancia funcional motora(RNM-f) y los tractos subcorticales generados porestudios de tensor de difusión (DTI). La monitorizaciónintraoperatoria incluía el mapeo motor por estimulacióncortical y subcortical directa (ECD y EsCD) e identificacióndel surco central por inversión de la onda N20con electrodos corticales multipolares. La localizaciónde los puntos con respuesta positiva a la ECD o EsCD secorrelacionaba con las áreas corticales o tractos funcionalesmotores definidos en los estudios preoperatoriosgracias al navegador.Resultados. La resección volumétrica tumoral mediafue del 89.1±14.2% del volumen tumoral calculado enlos estudios preoperatorios, con resección total (≥100%)en doce pacientes. En el preoperatorio había focalidadneurológica deficitaria motora en el 58.8% de lospacientes, que aumentó al 76.5% a las 24 horas de lacirugía y se redujo a los 30 días al 41.1%. Hubo una (..) (AU)

Objectives. The role of the microsurgical managementof intrinsic brain tumors is to maximize the volumetricresection of the tumoral tissue minimizing thepostoperative morbidity. The purpose of our paper hasbeen to study the benefits of an original protocol developedfor the microsurgical treatment of tumors locatedin eloquent motor areas where the navigation and electricalstimulation of motor subcortical pathways havebeen implemented.Materials and methods. A total of 17 patients operatedon for resection of cortical or subcortical tumors inmotor areas were included in the series. Preoperativeplanning for multimodal navigation was done integratinganatomic studies, motor functional MRI (f-MRI)and subcortical pathways volumes generated by diffusiontensor imaging (DTI). Intraoperative neuromonitorizationincluded motor mapping by direct corticaland subcortical electrical stimulation (CS and sCS) andlocalization of the central sulcus using cortical multipolarelectrodes and the N20 wave inversion technique.The location of all cortical and subcortical stimulatedpoints with positive motor response was stored in thenavigator and correlated with the cortical or subcorticalmotor functional structures defined preoperatively.Results. The mean tumoral volumetric resection (..) (AU)

Histological modifications of the rat prostate following transection of somatic and autonomic nerves.

It is known that hormones influence significantly the prostate tissue. However, we reported that mating induces an increase in androgen receptors, revealing a neural influence on the gland. These data suggested that somatic afferents (scrotal and genitofemoral nerves) and autonomic efferents (pelvic and hypogastric nerves) could regulate the structure of the prostate. Here we assessed the role of these nerves in maintaining the histology of the gland. Hence, afferent or efferent nerves of male rats were transected. Then, the ventral and dorsolateral regions of the prostate were processed for histology. Results showed that afferent transection affects prostate histology. The alveoli area decreased and increased in the ventral and dorsolateral prostate, respectively. The epithelial cell height increased in both regions. Efferent denervation produced dramatic changes in the prostate gland. The tissue lost its configuration, and the epithelium became scattered and almost vanished. Thus, afferent nerves are responsible for spinal processes pertaining to the trophic control of the prostate, activating its autonomic innervation. Hence, our data imply that innervation seems to be synergic with hormones for the healthy maintenance of the prostate. Thus, it is suggested that some prostate pathologies could be due to the failure of the autonomic neural pathways regulating the gland.

Histological modifications of the rat prostate following transection of somatic and autonomic nerves

It is known that hormones influence significantly the prostate tissue. However, we reported that mating induces an increase in androgen receptors, revealing a neural influence on the gland. These data suggested that somatic afferents (scrotal and genitofemoral nerves) and autonomic efferents (pelvic and hypogastric nerves) could regulate the structure of the prostate. Here we assessed the role of these nerves in maintaining the histology of the gland. Hence, afferent or efferent nerves of male rats were transected. Then, the ventral and dorsolateral regions of the prostate were processed for histology. Results showed that afferent transection affects prostate histology. The alveoli area decreased and increased in the ventral and dorsolateral prostate, respectively. The epithelial cell height increased in both regions. Efferent denervation produced dramatic changes in the prostate gland. The tissue lost its configuration, and the epithelium became scattered and almost vanished. Thus, afferent nerves are responsible for spinal processes pertaining to the trophic control of the prostate, activating its autonomic innervation. Hence, our data imply that innervation seems to be synergic with hormones for the healthy maintenance of the prostate. Thus, it is suggested that some prostate pathologies could be due to the failure of the autonomic neural pathways regulating the gland.

Sabe-se que os hormônios influenciam significativamente o tecido prostático. Entretanto, nós demonstramos que o acasalamento induz um aumento nos receptores androgênicos, revelando uma influência neural sobre a glândula. Esses dados sugerem que os aferentes somáticos (nervos escrotal e genito-femural) e os eferentes autonômicos (nervos pélvicos e hipo-gástricos) poderiam regular a estrutura da próstata. Neste trabalho, avaliou-se a função destes nervos na manutenção da histologia da glândula. Dessa forma, os nervos aferentes e eferentes de ratos machos foram seccionados As regiões ventral e dorsolateral da próstata foram processadas para histologia. Os resultados mostraram que a transecção aferente afeta a histologia da próstata. A área alveolar diminuiu e aumentou na próstata dorsal e dorsolateral, respectivamente. A altura da célula epitelial aumentou em ambas as regiões. A desenervação eferente produziu alterações dramáticas na glândula prostática. O tecido perdeu a sua configuração e o epitélio tornou-se difuso e quase desapareceu. Assim, os nervos aferentes são responsáveis por processos espinhais que pertencem ao controle trófico da próstata, ativando sua inervação autonômica. Dessa forma, nossos dados sugerem que a inervação parece ser sinérgica com os hormônios para a manutenção saudável da próstata. Assim, sugere-se que algumas patologias prostáticas poderiam ser ocasionadas devido a falhas nas vias neurais autonômicas que regulam esta glândula.

Multimodal navigation in the functional microsurgical resection of intrinsic brain tumors located in eloquent motor areas: role of tractography.

OBJECT: Nowadays the role of microsurgical management of intrinsic brain tumors is to maximize the volumetric resection of the tumoral tissue, minimizing the postoperative morbidity. The purpose of this paper was to study the benefits of an original protocol developed for the microsurgical treatment of tumors located in eloquent motor areas where the navigation and electrical stimulation of motor subcortical pathways have been implemented. METHODS: A total of 17 patients who underwent resection of cortical or subcortical tumors in motor areas have been included in the series. The preoperative planning for multimodal navigation was done by integrating anatomical studies, motor functional MR (fMR) imaging, and subcortical pathway volumes generated by diffusion tensor (DT) imaging. Intraoperative neuromonitoring included motor mapping by direct cortical stimulation (CS) and subcortical stimulation (sCS), and localization of the central sulcus by using cortical multipolar electrodes and the N20 wave inversion technique. The location of all cortically and subcortically stimulated points with positive motor response was stored in the navigator and correlated with the cortical and subcortical motor functional structures defined preoperatively. RESULTS: The mean tumoral volumetric resection was 89.1 +/- 14.2% of the preoperative volume, with a total resection (> or = 100%) in 8 patients. Preoperatively a total of 58.8% of the patients had some kind of motor neurological deficit, increasing 24 hours after surgery to 70.6% and decreasing to 47.1% at 1 month later. There was a great correlation between anatomical and functional data, both cortically and subcortically. A total of 52 cortical points submitted to CS had positive motor response, with a positive correlation of 83.7%. Also, a total of 55 subcortical points had positive motor response; in these cases the mean distance from the stimulated point to the subcortical tract was 7.3 +/- 3.1 mm. CONCLUSIONS: The integration of anatomical and functional studies allows a safe functional resection of the brain tumors located in eloquent areas. Multimodal navigation allows integration and correlation among preoperative and intraoperative anatomical and functional data. Cortical motor functional areas are anatomically and functionally located preoperatively thanks to MR and fMR imaging and subcortical motor pathways with DT imaging and tractography. Intraoperative confirmation is done with CS and N20 inversion wave for cortical structures and with sCS for subcortical pathways. With this protocol the authors achieved a good volumetric resection in cortical and subcortical tumors located in eloquent motor areas, with an increase in the incidence of neurological deficits in the immediate postoperative period that significantly decreased 1 month later. Ongoing studies must define the safe limits for functional resection, taking into account the intraoperative brain shift. Finally, it must be demonstrated whether this protocol has any long-term benefit for patients by prolonging the disease-free interval, the time to recurrence, or the survival time.

Intraoperative neurophysiology of the motor system in children: a tailored approach.

INTRODUCTION: Intraoperative neurophysiology has moved giant steps forward over the past 15 years thanks to the advent of techniques aimed to reliably assess the functional integrity of motor areas and pathways. INTRAOPERATIVE NEUROPHYSIOLOGICAL TECHNIQUES: Motor evoked potentials recorded from the muscles and/or the spinal cord (D-wave) after transcranial electrical stimulation allow to preserve the integrity of descending pathways, especially the corticospinal tract (CT), during brain and spinal cord surgery. Mapping techniques allow to identify the motor cortex through direct cortical stimulation and to localize the CT at subcortical levels during brain and brainstem surgery. These techniques are extensively used in adult neurosurgery and, in their principles, can be applied to children. However, especially in younger children, the motor system is still under development, making both mapping and monitoring techniques more challenging. In this paper, we review intraoperative neurophysiological techniques commonly used in adult neurosurgery and discuss their application to pediatric neurosurgery, in the light of preliminary experience from our and other centers. The principles of development and maturation of the motor system, and especially of the CT, are reviewed focusing on clinical studies with transcranial magnetical stimulation.