[Towards a positive physiological definition of the deep brain nuclei in humans]. / Hacia una definición fisiológica positiva de los núcleos cerebrales profundos en humanos.

INTRODUCTION: Using microelectrodes for recording purposes in deep brain stimulation (DBS) has proven to be very useful. Their efficiency can be improved by characterising the properties of extracellular action potentials (EAPs). PATIENTS AND METHODS: We analysed the records of nine patients who underwent surgery for epilepsy or aggressiveness under general anaesthesia. The properties of the EAPs of the centromedian, ventral intermediate, ventrocaudal and posteromedial hypothalamic nuclei of the thalamus have been determined. RESULTS: We have analysed 706 thalamic and 142 hypothalamic cells. The proportion of cell types was found to be specific to each cell nucleus. The most frequent cell type was P1P2N1 (59.5%), followed by N1P1N2 (23.1%). The first phase of the EAP is highly variable. The properties of the EAP phases of the same morphology differ greatly from one nucleus to another. CONCLUSIONS: We have shown that several deep brain nuclei have properties that are specific to the morphology of the EAPs. This will allow for improved localisation of these nuclei during DBS.

TITLE: Hacia una definición fisiológica positiva de los núcleos cerebrales profundos en humanos.Introducción. El registro con microelectrodos en la estimulación cerebral profunda (ECP) ha demostrado una gran utilidad. Es posible mejorar su eficiencia caracterizando las propiedades de los potenciales de acción extracelulares (PAE). Pacientes y métodos. Hemos analizado registros de nueve pacientes operados por epilepsia o agresividad bajo anestesia general. Se han determinado las propiedades de los PAE de los núcleos talámicos centromediano, ventral intermedio, ventrocaudal e hipotalámico posteromedial. Resultados. Hemos analizado 706 células talámicas y 142 hipotalámicas. La proporción de tipos celulares resultó específica de cada núcleo celular. El tipo celular más frecuente fue P1P2N1 (59,5%), seguido por N1P1N2 (23,1%). La primera fase del PAE es altamente variable. Las propiedades de las fases del PAE de la misma morfología difieren altamente entre núcleos. Conclusiones. Hemos demostrado que diversos núcleos cerebrales profundos tienen propiedades específicas de la morfología de los PAE. Esto permitirá una mejora en la localización de estos núcleos durante la ECP.

Deep brain stimulation in Parkinson's disease: analysis of brain fractional anisotropy differences in operated patients. / Estimulación cerebral profunda en la enfermedad de Parkinson: análisis de la anisotropía fraccional cerebral en pacientes intervenidos mediante estimulación cerebral profunda.

INTRODUCTION: Deep brain stimulation (DBS) of the subthalamic nucleus is currently an evidence-based therapeutic option for motor symptoms in patients with Parkinson's disease (PD), although other non-motor symptoms can be affected by stimulation. AIM: Our objective is to evaluate the global changes in the connectivity of the large-scale structural network in PD patients that have obtained a benefit from subthalamic DBS. SUBJECTS AND METHODS: Retrospective study of 31 subjects: 7 PD patients with subthalamic DBS (group A), 12 age and gender-matched non-operated PD (B) and 12 healthy controls (C). All subjects had undergone a 1.5 T brain MRI with DTI. DICOM images were processed with the FSL5.0 software and TBSS tool. RESULTS: The study group comprised 23 men and 8 women. No statistically significant differences in age, gender, scores on the HandY scale and mean follow-up between group A and B were found, and in age and gender between groups A and C. Statistical analysis revealed differences in the fractional anisotropy of the different groups in certain areas: bilateral corticospinal tract, anterior thalamic radiations, bilateral fronto-occipital fascicle, both superior longitudinal fascicles, and left inferior longitudinal fascicle. CONCLUSIONS: In our series, PD patients treated with bilateral subthalamic DBS showed a significantly higher fractional anisotropy in widespread areas of the cerebral white matter; suggesting that neuromodulation produces connectivity changes in different neural networks.

TITLE: Estimulación cerebral profunda en la enfermedad de Parkinson: análisis de la anisotropía fraccional cerebral en pacientes intervenidos mediante estimulación cerebral profunda.Introducción. La estimulación cerebral profunda (ECP) del núcleo subtalámico actualmente es una opción terapéutica basada en la evidencia para los síntomas motores en pacientes con enfermedad de Parkinson (EP), aunque otros síntomas no motores pueden verse afectados por la estimulación. Objetivo. Nuestro objetivo es evaluar los cambios globales en la conectividad de la red estructural a gran escala en pacientes con EP que han obtenido un beneficio de la ECP subtalámica. Sujetos y métodos. Estudio retrospectivo de 31 sujetos: siete pacientes con EP con ECP subtalámica (grupo A), 12 pacientes con EP no operados de la misma edad y sexo (B) y 12 controles sanos (C). Todos los sujetos se habían sometido a una resonancia magnética cerebral de 1,5 T con imagen del tensor de la difusión. Las imágenes DICOM se procesaron con el software FSL5.0 y la herramienta estadística espacial basada en el tracto. Resultados. El grupo de estudio estuvo compuesto por 23 hombres y ocho mujeres. No se encontraron diferencias estadísticamente significativas en edad, sexo, puntuación en la escala de Hoehn y Yahr y seguimiento medio entre el grupo A y B, y en edad y sexo entre los grupos A y C. El análisis estadístico reveló diferencias en la anisotropía fraccional de los diferentes grupos en ciertas áreas: tracto corticoespinal bilateral, radiaciones talámicas anteriores, fascículo frontooccipital bilateral, ambos fascículos longitudinales superiores y fascículo longitudinal inferior izquierdo. Conclusiones. En nuestra serie, los pacientes con EP tratados con ECP subtalámica bilateral mostraron una anisotropía fraccional significativamente mayor en áreas extensas de la sustancia blanca cerebral, lo que sugiere que la neuromodulación produce cambios de conectividad en diferentes redes neuronales.

[Bases of deep brain stimulation]. / Bases de la estimulación cerebral profunda.

INTRODUCTION: Deep brain stimulation is an effective therapy that is being used in an increasing number of indications. The mechanisms by which it exerts its therapeutic effect are still largely unknown, although there is increasing evidence of its influence at various levels. AIM: To review the existing literature on the mechanism of action of deep brain stimulation. DEVELOPMENT: Deep brain stimulation acts on brain tissue that is stimulated at various levels: molecular, cellular and neural networks. Spatial, temporal and electrical factors are involved in its effectiveness, but it mainly seems to perform its function by replacing anomalous firing patterns, which are present in certain neurological and psychiatric diseases. Other mechanisms, such as neuroprotection or neurogenesis, remain under study. CONCLUSIONS: Although many of the effects by which deep brain stimulation acts on the brain are still unknown, it seems to be a complex treatment, with large-scale effects, in which the correction of circuitopathies seems to prevail as the main mechanism.

TITLE: Bases de la estimulación cerebral profunda.Introducción. La estimulación cerebral profunda es una terapia eficaz que está siendo utilizada en un número creciente de indicaciones. Los mecanismos mediante los cuales ejerce efecto terapéutico aún se desconocen en su mayor parte, si bien cada vez se dispone de más datos sobre su influencia en diversos niveles. Objetivo. Revisar la bibliografía existente sobre el mecanismo de acción de la estimulación cerebral profunda. Desarrollo. La estimulación cerebral profunda actúa sobre el tejido cerebral estimulado en varios niveles, molecular, celular y de redes neuronales. En su efectividad intervienen factores espaciales, temporales y eléctricos, pero fundamentalmente parece ejercer su función mediante la sustitución de patrones de disparo anómalos, presentes en ciertas enfermedades neurológicas y psiquiátricas. Otros mecanismos, como la neuroprotección o la neurogénesis, permanecen en estudio. Conclusiones. Aunque aún se desconocen muchos efectos por los cuales la estimulación cerebral profunda actúa en el cerebro, parece un tratamiento complejo, con efectos a gran escala, en los que parece primar la corrección de circuitopatías como mecanismo principal.

[Deep brain stimulation in drug-resistant epilepsy]. / Estimulación cerebral profunda en la epilepsia farmacorresistente.

INTRODUCTION: Deep brain stimulation (DBS) in drug-resistant epilepsy has been applied to several brain targets. However, its exact mechanism of action is not known, and the diversity of targets makes it difficult to know the degree of evidence that supports its use. DEVELOPMENT: A review of the literature on DBS for drug-resistant epilepsy was conducted. The efficacy of DBS in drug-resistant epilepsy seems to be mediated by a desynchronisation of neuronal activity at the epileptogenic focus or a modulation of the «circuitopathies¼ that exist in epilepsy, depending on the target. In DBS multiple cortical and subcortical structures have been used, but class I evidence exists only for DBS of the anterior nucleus of the thalamus. CONCLUSIONS: DBS in epilepsy is still under investigation, with class I evidence for DBS of the anterior nucleus of the thalamus. The rest of the targets have yielded variable results that must be confirmed with randomised designs in larger series.

TITLE: Estimulación cerebral profunda en la epilepsia farmacorresistente.Introducción. La estimulación cerebral profunda (ECP) en la epilepsia farmacorresistente se ha aplicado en varias dianas cerebrales. Sin embargo, su mecanismo de acción no se conoce con exactitud, y la diversidad de dianas hace difícil conocer el grado de evidencia que apoya su utilización. Desarrollo. Se realiza una revisión bibliográfica sobre la ECP para la epilepsia farmacorresistente. La eficacia de la ECP en la epilepsia farmacorresistente parece mediada por una desincronización de la actividad neuronal en el foco epileptógeno o una modulación de las circuitopatías que existen en la epilepsia, dependiendo de la diana. En la ECP se han utilizado múltiples estructuras corticales y subcorticales, pero solamente la ECP del núcleo anterior del tálamo tiene una evidencia de clase I. Conclusiones. La ECP en la epilepsia es aún objeto de investigación, con evidencia de clase I en la ECP del núcleo anterior del tálamo. El resto de las dianas ha arrojado resultados variables que deben confirmarse con diseños aleatorizados en series de mayor tamaño.

[Bilateral two-stage implantation for deep brain stimulation in the treatment of bilateral idiopathic Parkinson's disease: clinical outcomes]. / Implantacion bilateral en dos tiempos para estimulacion cerebral profunda en el tratamiento de la enfermedad de Parkinson idiopatica bilateral: resultados clinicos.

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 and Yahr, and the Schwab and 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 and 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 and England scale in the pre-operative period and at six months was 39%. Two patients suffered post-operative 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 randomised study in patients who underwent bilateral surgery in one and two stages in order to confirm these results.

TITLE: Implantacion bilateral en dos tiempos para estimulacion cerebral profunda en el tratamiento de la enfermedad de Parkinson idiopatica bilateral: resultados clinicos.Objetivo. La implantacion bilateral simultanea de electrodos en el nucleo subtalamico para la enfermedad de Parkinson idiopatica (EPI) se asocia a una duracion elevada de la intervencion, alteraciones del lenguaje y confusion posquirurgica; ademas, existe evidencia de mejoria ipsilateral tras la estimulacion del nucleo subtalamico. Para optimizar el manejo perioperatorio se realiza un estudio prospectivo con estimulacion cerebral profunda (ECP) en el nucleo subtalamico en dos procedimientos unilaterales consecutivos. Pacientes y metodos. Estudio prospectivo de 41 pacientes con EPI bilateral, con implantacion de ECP en dos fases quirurgicas unilaterales. Se analizan sus resultados clinicos segun las escalas Unified Parkinson's Disease Rating Scale (UPDRS), Hoehn y Yahr, y Schwab y England, asi como sus complicaciones. Resultados. La edad media fue de 61 ± 7 años, 23 hombres. Cinco pacientes (12%) no fueron intervenidos del nucleo subtalamico contralateral por buen control. La media en la UPDRS motora y la Hoehn y Yahr en off farmacologico preoperatorio fue de 44 ± 14 y 3, respectivamente, y de 19 ± 8 y 1,8 a los seis meses de seguimiento. La mejoria media en la escala de Schwab y England en el preoperatorio y a los seis meses fue del 39%. Dos pacientes tuvieron confusion postoperatoria, y uno, disartria transitoria. Conclusiones. La ECP bilateral en dos etapas unilaterales fue una opcion eficaz y con escasas complicaciones en nuestra serie de pacientes con EPI. El 10% de los pacientes no preciso electrodos contralaterales. Seria necesario un estudio aleatorizado en pacientes sometidos a cirugia bilateral en uno y dos tiempos para confirmar estos resultados.

[New thalamic potential associated with somatosensory evoked potentials]. / Nuevo potencial talamico asociado con potenciales evocados somatosensoriales.

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 drug-resistant 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.

TITLE: Nuevo potencial talamico asociado con potenciales evocados somatosensoriales.Introduccion. La respuesta del talamo durante el estudio con potenciales evocados somatosensoriales (PESS) no esta suficientemente comprendida. Caso clinico. Varon de 30 años intervenido con sedacion completa mediante estimulacion cerebral profunda en el nucleo centromediano por epilepsia farmacorresistente. Durante la intervencion se registraron las respuestas de los nucleos talamicos mediante cuatro microelectrodos a los PESS. Estas respuestas se pueden descomponer en tres tipos: potenciales de campo local (PCL), oscilaciones rapidas de baja amplitud (ORB) y oscilaciones lentas de gran amplitud (OLG). Las ORB estan muy extendidas por gran parte de las regiones registradas (> 5 mm) y en los cuatro electrodos simultaneamente. Sin embargo, las OLG estan localizadas en un unico punto del registro y estan intimamente asociadas con los PCL. Ademas, el analisis de wavelets muestra un componente espectral y un tiempo de aparicion diferentes. Conclusiones. Aunque se ha considerado la presencia de ORB como indicador de la presencia del talamo sensorial, su amplia extension por diferentes nucleos talamicos sugiere que se trata de una respuesta poco especifica a los PESS. Sin embargo, la localizacion espacial restringida de los OLG y su asociacion con PCL sugiere que estos potenciales de nueva descripcion son los marcadores de la presencia del talamo sensorial. Su identificacion puede resultar muy util en estimulacion cerebral profunda talamica en pacientes despiertos y, especialmente, en los que precisen sedacion.

[Tumours in the pineal region in the paediatric age. Reports of 23 cases and a review of the literature]. / Tumores de la region pineal en la edad pediatrica. Presentacion de 23 casos y revision de la bibliografia.

INTRODUCTION: Tumours in the pineal region are located at a meeting point of several neurovascular structures that are difficult to reach surgically and for which the possibility of resection is limited; as a result the management of these lesions usually requires associated adjunctive treatment with radiotherapy and/or chemotherapy. PATIENTS AND METHODS: This study is a retrospective analysis of the epidemiological, clinical, neuroimaging and pathological characteristics of 23 patients with tumours in the pineal region who were treated between the years 1997 and 2010 in the Hospital Infantil Niño Jesús. The factors involved in the prognosis of this cohort following surgical or adjunctive treatment are also discussed. RESULTS: Subjects included in the study were 6 girls and 17 boys with ages ranging from 4 months to 18 years. It was found that the initial symptoms in 95% of the patients were signs of acute or subacute hydrocephalus, which required the placement of a ventriculoperitoneal shunt (82%). A histological sample of the tumour tissue was collected in all cases. Biopsy samples were taken in the case of five patients and 18 underwent surgery involving a craniotomy. Germinoma (eight cases) and mature teratoma (one case) were the tumours with the longest survival times; non-germinomatous tumours (three cases), those of the pineal parenchyma (four cases) and gliomas (five cases) presented the highest rates of recurrence and a poorer prognosis. CONCLUSIONS: The study of tumour markers can be used to guide the diagnosis of certain tumours of the pineal region. At present, the recommended procedure involves taking a histological sample of the tumour in order to establish an accurate diagnosis and a specific oncological treatment.

[Frontal aneurysmal bone cyst. A case report and review of the literature]. / Quiste oseo aneurismatico frontal. Caso clinico y revision de la bibliografia.

INTRODUCTION: Cranial aneurysmal bone cyst (ABC) is a rare pathological finding that is usually diagnosed in young patients. It is defined as a benign lesion made up of intervillous spaces limited by connective bone tissue septa and osteoclast-type giant cells; these histological characteristics are common to extracranial ABC. Clinically, in most patients, they manifest as cranial tumours which may be painful and vary in size. About 100 cases of cranial ABC have been reported in the literature. We present a literature review of the cases of frontal ABC reported to date, including one that was recently treated in our own service. CASE REPORT: A 29-year-old female, with no history of traumatic brain injury, who was examined due to the presence of a fixed, painless frontal cranial lesion on the right-hand side. The results of a radiological study revealed the presence of a lytic cranial lesion with well-delimited edges and marginal sclerosis; peripheral and linear contrast enhancement was also observed in the magnetic resonance imaging of the brain. The patient was submitted to a surgical intervention and the entire lesion was removed. There were no incidents in the post-operative period and the definitive pathological diagnosis was cranial ABC. CONCLUSIONS: Cranial ABC is a pathological condition with well-defined histological and radiological characteristics, despite the fact that its aetiopathogenesis is still not fully understood. Complete excision of the tumour is considered to be the preferred treatment, which often leads to full recovery of the patient and also offers a good long-term prognosis.

[Cavernous haemangioma of the skull]. / Hemangioma cavernoso intraóseo craneal.

INTRODUCTION: Cavernous haemangiomas are benign tumours that rarely affect the skull. A correct suspicion diagnosis is seldom obtained when typical radiological signs are lacking. In this way a definite diagnosis is only obtained after a surgical procedure in most cases. CASE REPORT: A 52-year-old female presented a painless, slow-growing tumoration in her right forehead. Skull CT showed an osteolytic lesion located within the right frontal bone. On suspicion of a metastatic origin of the lesion, a systemic research for a primary tumour was performed without significative findings. Finally, en bloc resection of the lesion was performed followed by cranioplasty. Microscopically, the lesion proved to be a cavernous haemangioma of the frontal bone. CONCLUSION: Despite their low frequency, cavernous haemangiomas must be included in the differential diagnosis of slow-growing osteolytic lesions located within the skull. The elective treatment of this tumours includes a complete resection by craniectomy, with safe bony margins.

[Cystic hemangioblastoma of the junction of the medulla and upper spinal cord associated to von Hippel-Lindau disease. Two case reports and a review of the literature]. / Hemangioblastoma quistico de la union bulbomedular asociado a enfermedad de von Hippel-Lindau. Presentacion de dos casos y revision de la bibliografia.

INTRODUCTION: Hemangioblastomas are very highly vascularised benign tumours that can present either sporadically or in association with von Hippel-Lindau syndrome in 20% of cases. Only 5-20% of hemangioblastomas are located in the brainstem, and those that occur at the junction of the medulla and upper spinal cord are the ones that are less commonly diagnosed. CASE REPORTS: Two young patients were diagnosed with von Hippel-Lindau disease after beginning with a cystic hemangioblastoma at the junction of the medulla and upper spinal cord as the first pathological manifestation. Both of them underwent a suboccipital craniotomy and the two lesions were completely removed without any kind of post-operative neurological deficits. One of the patients required a reintervention some years later due to a new recurrence of a symptomatic hemangioblastoma in the dorsal medulla. The genetic study conducted in both patients confirmed the presence of a mutation in the VHL gene, which is responsible for the syndrome they were suffering from. CONCLUSIONS: The presence of cystic hemangioblastomas of the junction of the medulla and upper spinal cord associated to von Hippel-Lindau disease is very rare. Despite the technical difficulties involved in removing them, the incorporation of the latest neuroimaging and microsurgery techniques has made it possible to significantly reduce the morbidity and mortality rate associated to the surgical treatment of such patients.