The value of additional electrodes when stereo-electroencephalography is inconclusive.

OBJECTIVE: Stereo-electroencephalography (SEEG) is the preferred method for intracranial localization of the seizure-onset zone (SOZ) in drug-resistant focal epilepsy. Occasionally SEEG evaluation fails to confirm the pre-implantation hypothesis. This leads to a decision tree regarding whether the addition of SEEG electrodes (two-step SEEG - 2sSEEG) or placement of subdural electrodes (SDEs) after SEEG (SEEG2SDE) would help. There is a dearth of literature encompassing this scenario, and here we aimed to characterize outcomes following unplanned two-step intracranial EEG (iEEG). METHODS: All 225 adult SEEG cases over 8 years at our institution were reviewed to extract patient data and outcomes following a two-step evaluation. Three raters independently quantified benefits of additional intracranial electrodes. The relationship between two-step iEEG benefit and clinical outcome was then analyzed. RESULTS: Fourteen patients underwent 2sSEEG and nine underwent SEEG2SDE. In the former cohort, the second SEEG procedure was performed for these reasons-precise localization of the SOZ (36%); defining margins of eloquent cortex (21%); and broadening coverage in the setting of non-localizable seizure onsets (43% of cases). Sixty-four percent of 2sSEEG cases were consistently deemed beneficial (Light's κ = 0.80). 2sSEEG performed for the first two indications was much more beneficial than when onsets were not localizable (100% vs 17%, p = .02). In the SEEG2SDE cohort, SDEs identified the SOZ and enabled delineation of margins relative to eloquent cortex in all cases. SIGNIFICANCE: The two-step iEEG is useful if the initial evaluation is broadly concordant with the original electroclinical hypothesis, where it can clarify onset zones or delineate safe surgical margins; however, it provides minimal benefit when the implantation hypothesis is erroneous, and we recommend that 2sSEEG not be generally utilized in such cases. SDE implantation after SEEG minimizes the need for SDEs and is helpful in delineating surgical boundaries relative to ictal-onset zones and eloquent cortex.

Safety and efficacy of bihemispheric sampling via transmidline stereoelectroencephalography.

OBJECTIVE: Stereoelectroencephalography (SEEG) is designed to target distributed cortical networks responsible for electroclinical seizure syndrome and to enable localization of the site of seizure onset in patients with intractable epilepsy. When the preimplantation hypothesis invokes the bilateral mesial frontal lobes, sampling of several deep-seated cortical sites in both hemispheres is required. In this study, the authors have demonstrated the feasibility of sampling bihemispheric areas with intentional implantation of an SEEG electrode crossing the midline (SECM) for sampling the cortex on both sides of the interhemispheric fissure. METHODS: An analysis of 231 consecutive SEEG procedures over 8 years was used to identify instances of bihemispheric sampling by using the transmidline SEEG technique. RESULTS: The authors identified 53 SEEG cases, with a total of 126 electrodes that crossed the interhemispheric fissure; all were in the frontal lobes. Eighty-three electrodes targeted the cingulate gyrus (18 rostral, 43 anterior, and 22 middle), 31 targeted the posterior orbitofrontal region, 8 sampled the medial prefrontal cortex, and 4 targeted nodular heterotopia around the frontal horns. The ictal onset zone was localized to the frontal lobe in 16 cases. SECM isolated interictal and ictal activity in the contralateral hemisphere in 6 cases and independent bihemispheric seizure activity in 2 cases. No hemorrhagic or infectious complications were noted in any of these cases. CONCLUSIONS: Based on this extensive experience of bihemispheric sampling, the authors concluded that this technique is safe and effective. In this series, SECM showed contralateral interictal and/or ictal epileptiform activity in 8 (15%) cases, and 9 (16%) cases (with unilateral implantation) had sufficient data to discard contralateral involvement, contributing to support of the epileptogenic network. SECM may reduce the number of electrodes used to sample bilateral mesial frontal or orbitofrontal cortices, and such an approach may lower the risk of hemorrhage and costs.

Sensory Organ Investment Varies with Body Size and Sex in the Butterfly Pieris napi.

In solitary insect pollinators such as butterflies, sensory systems must be adapted for multiple tasks, including nectar foraging, mate-finding, and locating host-plants. As a result, the energetic investments between sensory organs can vary at the intraspecific level and even among sexes. To date, little is known about how these investments are distributed between sensory systems and how it varies among individuals of different sex. We performed a comprehensive allometric study on males and females of the butterfly Pieris napi where we measured the sizes and other parameters of sensory traits including eyes, antennae, proboscis, and wings. Our findings show that among all the sensory traits measured, only antenna and wing size have an allometric relationship with body size and that the energetic investment in different sensory systems varies between males and females. Moreover, males had absolutely larger antennae and eyes, indicating that they invest more energy in these organs than females of the same body size. Overall, the findings of this study reveal that the size of sensory traits in P. napi are not necessarily related to body size and raises questions about other factors that drive sensory trait investment in this species and in other insect pollinators in general.

Validation of 3D fluoroscopy for image-guidance registration in depth electrode implantation for medically refractory epilepsy.

BACKGROUND: Frame registration is a critical step to ensure accurate electrode placement in stereotactic procedures such as stereoelectroencephalography (SEEG) and is routinely done by merging a computed tomography (CT) scan with the preoperative magnetic resonance (MR) examination. Three-dimensional fluoroscopy (XT) has emerged as a method for intraoperative electrode verification following electrode implantation and more recently has been proposed as a registration method with several advantages. METHODS: We compared the accuracy of SEEG electrode placement by frame registration with CT and XT imaging by analyzing the Euclidean distance between planned and post-implantation trajectories of the SEEG electrodes to calculate the error in both the entry (EP) and target (TP) points. Other variables included radiation dose, efficiency, and complications. RESULTS: Twenty-seven patients (13 CT and 14 XT) underwent placement of SEEG electrodes (319 in total). The mean EP and TP errors for the CT group were 2.3 mm and 3.3 mm, respectively, and 1.9 mm and 2.9 mm for the XT group, with no statistical difference (p = 0.75 and p = 0.246). The time to first electrode placement was similar (XT, 82 ± 10 min; CT, 84 ± 22 min; p = 0.858) and the average radiation exposure with XT (234 ± 55 mGy*cm) was significantly lower than CT (1245 ± 123 mGy*cm) (p < 0.0001). Four complications were documented with equal incidence in both groups. CONCLUSIONS: The use of XT as a method for registration resulted in similar implantation accuracy compared with CT. Advantages of XT are the substantial reduction in radiation dose and the elimination of the need to transfer the patient out of the room which may have an impact on patient safety and OR efficiency.

Association of intraneural perineurioma with neurofibromatosis type 2.

BACKGROUND: Neurofibromatosis type 2 (NF2) is a genetic disorder characterized by mutations of the NF2 tumor suppressor gene that predisposes patients to develop multiple tumors in the peripheral and central nervous system. The most common neoplasms associated with the disease are schwannomas and meningiomas. Both have been shown to contain abnormalities in chromosome 22 and the NF2 gene, suggesting a genetic component to their pathogenesis. Perineuriomas are rare benign tumors arising from the perineural cells. They are commonly classified as intraneural and soft tissue perineuriomas. Several studies have reported mutations in genes on chromosome 22 in both types of perineuriomas, and there are reports of soft tissue perineuriomas associated with NF2 gene mutations. Despite this, perineuriomas are not considered as part of the NF2 constellation of tumors. METHOD: The electronic medical records were searched for patients with a radiologic or pathologic diagnosis of intraneural perineurioma. Patients with clinical signs and genetic testing consistent with a diagnosis of NF2 were further evaluated. RESULTS: Of 112 patients meeting inclusion criteria, there were two cases of intraneural perineurioma in patients with NF2 treated at our institution (1.8%). We include a third patient treated at another facility for whom we performed a virtual consultation. CONCLUSIONS: The rarity of both NF2 and perineuriomas could explain the rarity of perineuriomas in the setting of NF2. Furthermore, there is divergent intraneural and soft tissue perineurioma somatic mutation pathogenesis, and there may be cytogenetic overlap between perineuriomas and multiple tumor syndromes. Our observed occurrence of intraneural perineurioma in the setting of NF2 in several patients provides further evidence of a potential link between the NF2 gene and the development of intraneural perineurioma.

The almost-invisible perineurioma.

Intraneural perineurioma is a rare, benign slow-growing lesion arising from the perineurial cells that surrounds the peripheral nerve fibers. Typically it presents during childhood and young adulthood as a motor mononeuropathy. MRI plays an essential role in the diagnosis and localization of the lesion, which appears as a fusiform enlargement of the nerve fascicles that enhances intensely with gadolinium. Despite the typical clinical and radiological features, intraneural perineurioma remains largely underdiagnosed because of the lack of familiarity with this entity, but also as a result of technical limitations with conventional MRI that is typically performed as a screening test over a large field of view and without contrast sequences. The purpose of this article is to present the pitfalls and pearls learned from years of experience in the diagnosis and management of this relatively rare condition. Clinical suspicion and detailed neurological examination followed by high-quality electrophysiological studies (EPS) must lead to an adequate preimaging localization of the lesion and narrowing of the imaging area. The use of high-resolution (3-T) MRI combined with gadolinium administration will allow adequate visualization of the internal anatomy of the nerve and help in differentiating other causes of neuropathy. In cases where the lesion is not recognized but clinical suspicion is high, possible errors must be assessed, including the EPS localization, area of imaging, MRI resolution, and slice thickness.

Perineural spread of malignant melanoma from the mandible to the brachial plexus: case report.

Perineural spread is a well-known mechanism of dissemination of head and neck malignancies. There are few reports of melanoma involving the brachial plexus in the literature. To their knowledge, the authors report the first known case of perineural spread of malignant melanoma to the brachial plexus. Clinicoradiological and anatomopathological correlation is presented, highlighting the importance of peripheral nerve communications in perineural spread.

Expanding what is known of the anatomy of the spinal accessory nerve.

The spinal accessory nerve (SAN) is classically considered a motor nerve innervating the sternocleidomastoid and trapezius muscles. Its anatomical relevance derives from the high prevalence of lesions following head and neck surgeries. As expected, trapezius weakness and atrophy are the most common findings; however, it is also commonly accompanied by pain and other sensory deficits that have no clear explanation, suggesting other functions. We have recently seen two patients presenting with an unrecognized sign, that is, subclavicular/pectoral asymmetry secondary to the SAN lesion. Retrospectively, we reviewed other patients with similar findings in our case series and in the literature. We discuss the anatomical connections of the SAN with the superficial cervical plexus and propose an explanation for this finding. Of the 41 patients in our series, we identified this sign in all who had preoperative photographs. New insights on the anatomy and connections of the SAN may account for the diversity of symptoms and signs presented following an operative intervention as well as the variability of its severity.

Change in the balance of excitatory and inhibitory midline fiber crossing as an explanation for the hopping phenotype in EphA4 knockout mice.

Neuronal networks in the spinal cord termed central pattern generators (CPGs) are responsible for the generation of rhythmic movements, such as walking. The axon guidance molecule EphA4 has been suggested to play a role in the configuration of spinal CPG networks in mammals. In EphA4 knockout (EphA4-KO) mice, the normal alternating walking pattern is replaced by a rabbit-like hopping gait, which can be reproduced when locomotor-like activity is induced in the isolated spinal cord. This hopping phenotype has been explained by an abnormal midline crossing of ipsilateral axons. Here, we investigated the nature of this overcrossing in heterozygous EphA4 (EphA4(lacZ/+) ) mice that showed normal alternating gait and homozygous EphA4 (EphA4(lacZ/lacZ) ) mice with hopping gait. Localized lesions showed that the hopping phenotype is maintained by fibers crossing in the ventral commissure. Using transgenic mouse lines in which glutamatergic, GABAergic and glycinergic neurons are intrinsically labeled, we showed a significant increase in the number of crossing excitatory ß-galactosidase-positive neurons and a decrease in the number of inhibitory neurons crossing the midline in EphA4(lacZ/lacZ) mice compared with EphA4(lacZ/+) mice. These results show that the hopping phenotype is the result of a change in the balance between excitatory and inhibitory signals across the midline and that EphA4-positive neurons play an essential role in the mammalian CPG.

Risk-management and risk-analysis-based decision tools for attacks on electric power.

Incident data about disruptions to the electric power grid provide useful information that can be used as inputs into risk management policies in the energy sector for disruptions from a variety of origins, including terrorist attacks. This article uses data from the Disturbance Analysis Working Group (DAWG) database, which is maintained by the North American Electric Reliability Council (NERC), to look at incidents over time in the United States and Canada for the period 1990-2004. Negative binomial regression, logistic regression, and weighted least squares regression are used to gain a better understanding of how these disturbances varied over time and by season during this period, and to analyze how characteristics such as number of customers lost and outage duration are related to different characteristics of the outages. The results of the models can be used as inputs to construct various scenarios to estimate potential outcomes of electric power outages, encompassing the risks, consequences, and costs of such outages.

Activity of Renshaw cells during locomotor-like rhythmic activity in the isolated spinal cord of neonatal mice.

In the present study, we examine the activity patterns of and synaptic inputs to Renshaw cells (RCs) during fictive locomotion in the newborn mouse using visually guided recordings from GABAergic cells expressing glutamic acid decarboxylase 67-green fluorescent protein (GFP). Among the GFP-positive neurons in the lumbar ventral horn, RCs were uniquely identified as receiving ventral root-evoked short-latency EPSPs that were markedly reduced in amplitude by nicotinic receptor blockers mecamylamine or tubocurarine. During locomotor-like rhythmic activity evoked by bath application of 5-HT and NMDA, 50% of the recorded RCs fired in-phase with the ipsilateral L2 flexor-related rhythm, whereas the rest fired in the extensor phase. Each population of RCs fired throughout the corresponding locomotor phase. All RCs received both excitatory and inhibitory synaptic inputs during the locomotor-like rhythmic activity. Blocking nicotinic receptors with mecamylamine markedly reduced the rhythmic excitatory drive, indicating that these rhythmic inputs originate mainly from motor neurons (MNs). Inhibitory synaptic inputs persisted in the presence of the nicotinic blocker. Part of this inhibitory drive and remaining excitatory drive could be from commissural interneurons because the present study also shows that RCs receive direct crossed inhibitory and excitatory synaptic inputs. However, rhythmic synaptic inputs in RCs were also observed in hemicord preparations in the presence of mecamylamine. These results show that, during locomotor activity, RC firing properties are modulated not only by MNs but also by the ipsilateral and contralateral locomotor networks.

Extubación temprana (fast-track) en neuroanestesia: ¿Una alternativa segura? / Extubación early (fast-track) in neuroanestesia: A sure alternative?

Las técnicas de transito rápido (fast y track) han impactado la práctica de la disciplina, desde áreas tan diversas como cardioanestesia a anestesia ambulatoria sin quedar fuera de este movimiento la neuroanestesia. Teniendo en este contexto una repercusión aun mayor, fundamentada en que la evaluación de la condición neurológica en un paciente despierto, es el método mejor y menos costoso de neuromonitoreo disponible; pero a pesar de la premisa anterior la aplicación de este tipo de protocolos en neurocirugía debe ser vista como un trabajo en equipo, para que la ejecución de la técnica no sea detrimente para el resultado final. Por eso durante esta revisión pretendemos evaluar el papel del fast y track en neuroanestesia, teniendo en cuenta las repercusiones fisopatològicas y por ende los pros y contras del despertar temprano vs. tardío; generando las bases para la elaboración de un posible plan anestésico para tránsito rápido, por que finalmente la emergencia anestésica y extubación temprana en neuroanestesia es deseable y posible en la mayoría de los casos, lo cual es esencial para detectar complicaciones postoperatorias a la llegada a recuperación...

Role of EphA4 and EphrinB3 in local neuronal circuits that control walking.

Local circuits in the spinal cord that generate locomotion are termed central pattern generators (CPGs). These provide coordinated bilateral control over the normal limb alternation that underlies walking. The molecules that organize the mammalian CPG are unknown. Isolated spinal cords from mice lacking either the EphA4 receptor or its ligand ephrinB3 have lost left-right limb alternation and instead exhibit synchrony. We identified EphA4-positive neurons as an excitatory component of the locomotor CPG. Our study shows that dramatic locomotor changes can occur as a consequence of local genetic rewiring and identifies genes required for the development of normal locomotor behavior.

Testigos de Jehova con placenta previa total: alternativas de manejo / Placenta praevia in Jehovah's witness patients: two different therapeutics approaches

La mortalidad materna a nivel local esta determinada por fenómenos hemorrágicos mayores. Las pacientes con placenta previa total representan un grupo de altísimo riesgo para desarrollar el síndrome. Describimos dos casos de pacientes con placenta previa total que a su vez son Testigos de Jehová. Se describen dos aproximaciones terapéuticas diferentes para el ahorro de producto sanguíneo en esta subpoblación, discutiendo además la información entregada en el contexto de la nueva tendencia de esta comunidad religiosa sobre el uso o no de producto sanguíneo

Borreliosis: la enfermedad de Lyme y otras dermatosis posiblemente asociadas / Borreliosis: Lyme's disease and other possibly associated diseases

Objetivo: actualizar el rol de las borrelias, en relación con varios cuadros nosológicos de interés dermatológico de etiología oscura, que han sido estudiados recientemente y deben ser más conocidos por los dermatólogos prácticos. Se analiza la enfermedad de Lyme y se discuten brevemente la esclerodermia localizada, liquen escleroso y atrófico, fasceítis eosinofílica, atrofodermia de Pasini y Pierini, granuloma anular, paniculitis septal, nódulos fibrosos subcutáneos, enfermedad de Jessner-Kanof, la hemiotrofia facial de Parry-Romberg y el linfoma B cutáneo primario que parecen asociarse con borrelias. La enfermedad de Lyme es un cuadro infeccioso sistémico, causado por espiroquetas del género Borrelia, transmitidas al hombre por garrapatas de género Ixodes. Tiene diversas manifestaciones cutáneas a lo largo de cada una de las etapas por las que atraviesa el proceso, por ejemplo el eritema migrans y el linfocitoma cutis (LC) en el estadío temprano y la acrodermatitis crónica atrofiante (ACA) en el estadío tardío. Se acompaña de síntomas principalmente neurológicos y reumatológicos. Existe tratamiento antibiótico útil, con dixiciclina, amoxicilina o eritromicina. Respecto a las otras enfermedades enumeradas, la terapia antibiótica anti-borrelia es todavía de valor discutible. Conclusión: si las diferentes entidades asociadas con borrelias son marcadores cutáneos de la enfermedad de Lyme o simplemente hallazgos coincidentes, es algo que aún está por determinarse

Borreliosis: la enfermedad de Lyme y otras dermatosis posiblemente asociadas / Borreliosis: Lymes disease and other possibly associated diseases

Objetivo: actualizar el rol de las borrelias, en relación con varios cuadros nosológicos de interés dermatológico de etiología oscura, que han sido estudiados recientemente y deben ser más conocidos por los dermatólogos prácticos. Se analiza la enfermedad de Lyme y se discuten brevemente la esclerodermia localizada, liquen escleroso y atrófico, fasceítis eosinofílica, atrofodermia de Pasini y Pierini, granuloma anular, paniculitis septal, nódulos fibrosos subcutáneos, enfermedad de Jessner-Kanof, la hemiotrofia facial de Parry-Romberg y el linfoma B cutáneo primario que parecen asociarse con borrelias. La enfermedad de Lyme es un cuadro infeccioso sistémico, causado por espiroquetas del género Borrelia, transmitidas al hombre por garrapatas de género Ixodes. Tiene diversas manifestaciones cutáneas a lo largo de cada una de las etapas por las que atraviesa el proceso, por ejemplo el eritema migrans y el linfocitoma cutis (LC) en el estadío temprano y la acrodermatitis crónica atrofiante (ACA) en el estadío tardío. Se acompaña de síntomas principalmente neurológicos y reumatológicos. Existe tratamiento antibiótico útil, con dixiciclina, amoxicilina o eritromicina. Respecto a las otras enfermedades enumeradas, la terapia antibiótica anti-borrelia es todavía de valor discutible. Conclusión: si las diferentes entidades asociadas con borrelias son marcadores cutáneos de la enfermedad de Lyme o simplemente hallazgos coincidentes, es algo que aún está por determinarse (AU)