Vilalta J

Valor predictivo de la clasificación de Knosp en el grado de resección quirúrgica de los macroadenomas invasivos: Estudio prospectivo de una serie de 23 casos

Resumen Objetivos Analizar y valorar el grado de reseccion y las complicaciones de la cirugia transesfenoidal en una serie de 23 casos de macroadenomas con invasion del seno cavernoso evaluados mediante la clasificacion de Knosp. Material, metodos y resultados Estudio prospectivo de 22 pacientes (23 operaciones) intervenidos en nuestro centro entre Mayo del 2002 y Diciembre del 2004 de macroadenomas hipofisarios con diferentes grados de invasion del seno cavernoso segun la clasificacion de Knosp15. Entre las variables del estudio se incluyeron los grados de invasion y de reseccion postoperatoria con un seguimiento radiologico medio a largo plazo de 15 meses. Nuestra serie consta de 15 varones y 7 mujeres, con una edad media de 48 anos (27 – 75 anos). Todos ellos presentaban macroadenomas con afectacion de uno o ambos senos cavernosos. De acuerdo con la clasificacion de Knosp 4 pacientes fueron grado 1, 2 grado 2, 1 grado 3 y 16 grado 4. En 20 casos se utilizo una via transesfenoidal clasica y en tres casos se hizo un abordaje transesfenoidal endoscopico. Segun la RMN postoperatoria los grados de reseccion fueron: completo o total en todos los pacientes con grados 1 y 2 y en solo 2 pacientes con grado 4; subtotal (>80%) en 1 paciente con grado 3 y en 6 pacientes con grado 4 y parcial ( Discusion y conclusiones Si bien unicamente la clasificacion radiologica de Knosp por si sola no puede predecir el comportamiento biologico del tumor o si la pared medial del seno cavernoso esta infiltrada o desplazada, en nuestra serie los tumores de grado 4 han sido los que han presentado un peor resultado de acuerdo al grado de reseccion. En los tumores que invaden el seno cavernoso, incluso en los casos donde la carotida esta englobada es posible realizar resecciones completas con una morbimortalidad aceptable.

Detección intraoperatoria de hipoxia cerebral isquémica mediante sensores de presión tisular de oxígeno

Resumen Objetivo e Importancia La deteccion de los eventos isquemicos intraoperatorios puede contribuir a la resolucion de su causa y a la prevencion del establecimiento definitivo de un infarto postquirurgico. Queremos ilustrar las posibilidades que ofrece la monitorizacion intraoperatoria de la presion tisular de oxigeno (PtiO2) en areas criticas durante un procedimiento neuroquirurgico vascular, resaltando su fiabilidad e inmediatez en la obtencion de informacion sobre el estado de oxigenacion tisular como marcador de isquemia del territorio vascular expuesto a riesgo. Presentacion clinica Presentamos el caso de un varon de 32 anos con una malformacion arteriovenosa (MAV) profunda situada en la region insular. El paciente habia sido tratado inicialmente mediante radiocirugia sin resultado satisfactorio. Intervencion La exeresis de la MAV se realizo a traves de un abordaje transilviano transinsular. La PtiO2 se monitorizo en el polo temporal (area de referencia) y en la region temporal posterior (area de riesgo). Ambas mantuvieron niveles de oxigenacion tisular parejos hasta la fase final de la reseccion de la MAV en la que, durante la hemostasia de un supuesto vaso aferente, se produjo una brusca caida de la tension de oxigeno en la region temporal posterior. En el postoperatorio se observo un infarto isquemico en este area. Conclusion La monitorizacion de la PtiO2 tiene una alta fiabilidad en la deteccion de hipoxia tisular intraoperatoria. Los datos que nos proporciona pueden servir para identificar precozmente estos acontecimientos y, en la medida de lo posible, solventar la situacion creada para prevenir la instauracion definitiva de un infarto isquemico.

Rapid Resolution of Brain Ischemic Hypoxia After Cerebral Revascularization in Moyamoya Disease

BACKGROUND In moyamoya disease (MMD), cerebral revascularization is recommended in patients with recurrent or progressive ischemic events and associated reduced cerebral perfusion reserve. Low-flow bypass with or without indirect revascularization is generally the standard surgical treatment. Intraoperative monitoring of cerebral partial pressure of oxygen (PtiO2) with polarographic Clark-type probes in cerebral artery bypass surgery for MMD-induced chronic cerebral ischemia has not yet been described. OBJECTIVE To describe basal brain tissue oxygenation in MMD patients before revascularization as well as the immediate changes produced by the surgical procedure using intraoperative PtiO2 monitoring. METHODS Between October 2011 and January 2013, all patients with a diagnosis of MMD were intraoperatively monitored. Cerebral oxygenation status was analyzed based on the Ptio2/PaO2 ratio. Reference thresholds of PtiO2/PaO2 had been previously defined as below 0.1 for the lower reference threshold (hypoxia) and above 0.35 for the upper reference threshold (hyperoxia). RESULTS Before STA-MCA bypass, all patients presented a situation of severe tissue hypoxia confirmed by a PtiO2/PaO2 ratio <0.1. After bypass, all patients showed a rapid and sustained increase in PtiO2, which reached normal values (PtiO2/PaO2 ratio between 0.1 and 0.35). One patient showed an initial PtiO2 improvement followed by a decrease due to bypass occlusion. After repeat anastomosis, the patients PtiO2 increased again and stabilized. CONCLUSION Direct anastomosis quickly improves cerebral oxygenation, immediately reducing the risk of ischemic stroke in both pediatric and adult patients. Intraoperative PtiO2 monitoring is a very reliable tool to verify the effectiveness of this revascularization procedure.

Intraoperative monitoring of brain tissue oxygenation during arteriovenous malformation resection.

Background: In normal perfusion pressure breakthrough (NPPB) it is assumed that following arteriovenous malformation (AVM) resection, vasoparalysis persists in the margins of the lesion and that a sudden increase in cerebral blood flow (CBF) after AVM exclusion leads to brain swelling and postsurgical complications. However, the pathophysiology NPPB remains controversial. The aim of our study was to investigate the oxygenation status in tissue surrounding AVMs and in the distant brain using intraoperative monitoring of cerebral partial pressure of oxygen (PtiO2) to achieve a better understanding of NPPB pathophysiology. Methods: Patients with supratentorial AVMs were monitored intraoperatively using 2 polarographic Clark-type electrodes. To establish reference values, we also studied PtiO2 in a group of patients who underwent surgery to treat incidental aneurysms. Results: Twenty-two patients with supratentorial AVMs and 16 patients with incidentally found aneurysms were included. Hypoxic pattern was defined as PtiO2⩽15 mm Hg and/or PtiO2/PaO2 ratio ⩽0.10. Tissue hypoxia was detected in 63.6% of the catheters placed in the perinidal area and in 43.8% of catheters placed in a distant area. AVM excision significantly improved oxygenation both around the AVM and in the distant area. Conclusions: The PtiO2/PaO2 ratio is a better indicator than absolute PtiO2 in detecting tissue hypoxia in mechanically ventilated patients. Intraoperative monitoring showed tissue hypoxia in the margins of AVMs and in the distant ipsilateral brain as the most common finding. Surgical removal of AVMs induces a significant improvement in the oxygenation status in both areas.

Craniectomía descompresiva primaria en la hemorragia subaracnoidea aneurismática. Resultados de un estudio piloto en 11 casos

Resumen Introduccion A pesar de los avances cientificos y tecnicos de los ultimos anos, la hemorragia subaracnoidea aneurismatica (HSAa) sigue presentando una alta morbilidad y mortalidad. Este hecho, junto con los impresionantes resultados de la craneotomia descompresiva primaria (CDP) en el infarto maligno de la arteria cerebral media sugiere la posibilidad que la CDP sea una alternativa terapeutica a considerar en algunos pacientes con una HSAa. Presentamos nuestra experiencia de un estudio piloto en el que se utilizo la CDP en pacientes con HSAa en mal grado neurologico y hematoma intracerebral asociado. Pacientes y metodos Entre el 1 de marzo de 2002 y el 31 de abril de 2008, se trataron 342 pacientes con HSAa en nuestro hospital. De estos, 64 tenian una puntuacion de 4 o 5 de la escala de la WFNS (World Federation of Neurosurgical Societies). En el presente estudio prospectivo se analizan 11 pacientes en los que se realizo una CDP durante la misma cirugia de clipaje o/y evacuacion del hematoma asociado. Resultados En tres pacientes la CDP se realizo despues del tratamiento endovascular del aneurisma debido a la necesidad de evacuar el hematoma asociado. En los ocho pacientes restantes, la CDP se realizo durante el clipaje y la evacuacion del hematoma asociado. La evaluacion de los resultados de estos once pacientes se llevo a cabo al ano de la cirugia mediante la escala de resultados de Glasgow. La CDP fue eficaz en el control de presion intracraneal en los pacientes que sobrevivieron. Seis pacientes sobrevivieron, cuatro de ellos con un buen resultado neurologico. Sin embargo, dos de estos seis pacientes tuvieron un resultado desfavorable. De los cinco pacientes que no sobrevivieron, un paciente murio a causa de un hematoma subgalealepidural diferido como complicacion de la CDP, y los restantes cuatro pacientes fallecieron a causa de una hipertension intracraneal refractaria. Conclusiones La CDP puede ser una alternativa terapeutica en un grupo seleccionado de pacientes con HSAa con mal grado neurologico. Sin embargo, en la actualidad hay una falta de evidencia para apoyar unas recomendaciones claras para su uso.

Make Your Own Transpiring Tree.

In this paper we present a simple set-up that illustrates the mechanism of sap ascent in plants and demonstrates that it can easily draw water up to heights of a few meters. The set-up consists of a tube with the lower end submerged in water and the upper one connected to a filter supported by a standard filter-holder. The evaporation of water from the filter surface causes a tension large enough to pull the water up the column against gravity. The flow of water leaving the system was visualised by continuously weighing the water container with a balance. The set-up worked for at least 4 days before the water column broke, with typical flows of ∼10 mg min-1. Knowledge tests with second year university biology students prior to the activity indicated general ignorance not only of the mechanism of sap ascent but also of transpiration itself. After explaining the mechanism of sap ascent with the aid of the set-up all students were able to explain correctly the main aspects of the cohesion-tension theory. The pedagogical value of the set-up, both at the secondary and university levels, is discussed.

Variabilidad en las indicaciones quirúrgicas de las lesiones intradurales postraumáticas

Resumen Introduccion El tratamiento de las lesiones focales intradurales continua siendo motivo de controversia. Esto es especialmente importante en la decision de evacuar contusiones cerebrales. Presentamos los resultados de un estudio prospectivo y observacional, cuyo objetivo ha sido analizar la variabilidad en las indicaciones quirurgicas de lesiones focales intradurales postraumaticas en un servicio de neurocirugia perteneciente a un hospital universitario, dotado de una unidad especializada en neurotraumatologia. Material y metodos Entre el 1 de mayo y el 31 de diciembre de 2001, se incluyeron 32 pacientes con un traumatismo craneoencefalico (TCE) cerrado, con lesiones focales intradurales. Estos pacientes constituyen la aportacion que nuestro centro realizo en el estudio multicentrico y observacional sobre el manejo de lesiones intradurales dirigido por el European Brain Injury Consortium (EBIC). Resultados Las lesiones intradurales de volumen > 25 cc. se evacuaron de forma inmediata al diagnostico. Nueve de los 13 pacientes con lesiones Conclusiones A pesar que el reducido numero de casos incluidos no nos permiten generalizar las conclusiones, en nuestro centro no se evidencia una variabilidad significativa en las indicaciones quirurgicas de lesiones > 25 cc. Sin embargo, existen discrepancias en las indicaciones quirurgicas de las lesiones con volumen

Prognosis of patients in coma after acute subdural hematoma due to ruptured intracranial aneurysm.

Acute subdural hematomas (aSDH) secondary to intracranial aneurysm rupture are rare. Most patients present with coma and their functional prognosis has been classically considered to be very poor. Previous studies mixed good-grade and poor-grade patients and reported variable outcomes. We reviewed our experience by focusing on patients in coma only and hypothesized that aSDH might worsen initial mortality but not long-term functional outcome. Between 2005 and 2013, 440 subarachnoid hemorrhage (SAH) patients were admitted to our center. Nineteen (4.3%) were found to have an associated aSDH and 13 (2.9%) of these presented with coma. Their prospectively collected clinical and outcome data were reviewed and compared with that of 104 SAH patients without aSDH who presented with coma during the same period. Median aSDH thickness was 10mm. Four patients presented with an associated aneurysmal cortical laceration and only one had good recovery. Overall, we observed good long-term outcomes in both SAH patients in coma with aSDH and those without aSDH (38.5% versus 26.4%). Associated aSDH does not appear to indicate a poorer long-term functional prognosis in SAH patients presenting with coma. Anisocoria and brain herniation are observed in patients with aSDH thicknesses that are smaller than those observed in trauma patients. Despite a high initial mortality, early surgery to remove the aSDH results in a good outcome in over 60% of survivors. Aneurysmal cortical laceration appears to be an independent entity which shows a poorer prognosis than other types of aneurysmal aSDH.

Monitorización intraoperatoria de la presión tisular de oxígeno: aplicaciones en neurocirugía vascular

Ischemic lesions related to surgical procedures are a major cause of postoperative morbidity in patients with cerebral vascular disease. There are different systems of neuromonitoring to detect intraoperative ischemic events, including intraoperative monitoring of oxygen tissue pressure (PtiO2). The aim of this article was to describe, through the discussion of 4 cases, the usefulness of intraoperative PtiO2 monitoring during vascular neurosurgery. In presenting these cases, we demonstrate that monitoring PtiO2 is a reliable way to detect early ischemic events during surgical procedures. Continuous monitoring of PtiO2 in an area at risk allows the surgeon to resolve the cause of the ischemic event before it evolves to an established cerebral infarction.

Water potential regulation, stomatal behaviour and hydraulic transport under drought : deconstructing the iso/anisohydric concept

In this review, we address the relationship between stomatal behaviour, water potential regulation and hydraulic transport in plants, focusing on the implications for the iso/anisohydric classification of plant drought responses at seasonal timescales. We first revise the history of the isohydric concept and its possible definitions. Then, we use published data to answer two main questions: (1) is greater stomatal control in response to decreasing water availability associated with a tighter regulation of leaf water potential (ΨL ) across species? and (2) is there an association between tighter ΨL regulation (~isohydric behaviour) and lower leaf conductance over time during a drought event? These two questions are addressed at two levels: across species growing in different sites and comparing only species coexisting at a given site. Our analyses show that, across species, a tight regulation of ΨL is not necessarily associated with greater stomatal control or with more constrained assimilation during drought. Therefore, iso/anisohydry defined in terms of ΨL regulation cannot be used as an indicator of a specific mechanism of drought-induced mortality or as a proxy for overall plant vulnerability to drought.