Identificación Estable de Fuentes Asociadas a Focos Epilépticos Ubicadas sobre la Corteza / Stable Identification of Sources Associated with Epileptic Focus on the Cerebral Cortex

Resumen Objetivo: Presentar un algoritmo estable que determina, a partir de mediciones electroencefalográficas, los parámetros de fuentes de tipo dipolar asociadas a focos epilépticos ubicados sobre la superficie de la corteza cerebral. Metodología: Se utiliza un problema de contorno para establecer correlaciones entre la fuente y la medición. El problema se divide en dos subproblemas lineales y en cada uno de ellos, se utilizan el método de mínimos cuadrados y la regularización de Tikhonov para encontrar soluciones estables. Estos subproblemas son problemas mal planteados en el sentido de Hadamard, debido a la inestabilidad numérica que presentan, es decir, pequeños cambios en las mediciones pueden producir grandes variaciones en la solución de cada problema. El parámetro de regularización de Tikhonov fue elegido usando el método de la curva L. Para hallar la solución del problema de contorno se utiliza el método de las series de Fourier y el Método del Elemento Finito. Resultados: Se propuso un tipo de fuente para representar a los focos epilépticos en la corteza cerebral y un algoritmo estable para el problema de identificación de los parámetros de dichas fuentes. Se desarrollaron ejemplos sintéticos y programas en MATLAB para el caso de geometría simple bidimensional. Originalidad: La separación del problema original en dos subproblemas así como los ejemplos sintéticos son producto de esta investigación. Conclusión general: Se propuso un algoritmo estable que determina a los parámetros de fuentes de corriente dipolar definidas en la corteza cerebral.

Abstract Objective: To present a stable algorithm that determines, from electroencephalographic measurements, the parameters of dipolar sources associated with epileptic foci located on the cerebral cortex. Methodology: A boundary value problem is used to establish correlations between the sources and the measurements. The problem is divided into two linear subproblems and in each one, the method of Minimum Square and the Tikhonov regularization are used for finding stables solutions. These subproblems are an ill-posed problem in the Hadamard sense, which is due to the numerical instability, that is, small changes in the data can produce substantial variations in the solution of each problem. The Tikhonov regularization parameter was chosen using the L curve method. To find the solution of the boundary value problem are used the Fourier series method and the Finite Element Method. Results: A type of source that represents the epileptic foci on the cerebral cortex and a stable algorithm for finding the parameter of these sources were proposed. Synthetics examples and MATLAB programs were developed for the case of bidimensional geometry. Originality: The separation of the original problem into two subproblems and the synthetics examples are a product of this research. Conclusion: A stable algorithm was proposed for determining the parameters of the dipolar current defined on the cerebral cortex.

Late-onset achalasia after esophageal atresia repair.

The development of achalasia in a patient with a history of esophageal atresia (EA) is rare. Here, we report a patient who had undergone surgery for EA at birth and presented achalasia at 30 years of age. He was successfully treated with laparoscopic surgery.

Simplificación del problema inverso electroencefalográfico a una sola región homogénea con condición de Neumann nula / Simplification of the Inverse Electroencephalographic Problem to One Homogeneous Region with Null Neumann Condition

Objetivo: Presentar una simplificación del Problema Inverso Electroencefalográfico (PIE) del caso de varias capas conductoras a una región homogénea con condición de Neumann Nula. Metodología: Se divide el PIE en tres problemas, dos de los cuales se resuelven usando el potencial medido en el cuero cabelludo y con estas soluciones y el tercer problema se lleva a cabo la simplificación. Para validar la simplificación se genera un ejemplo sintético usando el modelo de esferas concéntricas. Resultados: Por medio de la simplificación la fuente se determina a partir de la ecuación de Poisson con una condición de Neumann nula y un dato adicional sobre la frontera de la región homogénea, el cual se obtiene de la medición. Esto es válido para regiones generales con fronteras suficientemente suaves. Adicionalmente, para el caso de esferas concéntricas, se plantea el PIE para el caso de una fuente dipolar (que representa a focos epilépticos) usando esta simplificación y la técnica de la función de Green. Conclusión: La simplificación presentada aquí permite analizar el PIE en una región lo cual simplifica su estudio teórico y numérico. En particular, puede ser útil para el análisis del problema de identificación de los parámetros de una fuente dipolar.

Objective: To give a simplification of the Inverse Electroencephalographic Problem (IEP) from the case of multilayer conductive medium to the case of a homogeneous region with null Neumann condition. Methodology: IEP is divided in three problems, two of which are resolved using the measurements of potential on the scalp and with these solutions and the third problem the simplification is carried out. In order to validate the simplification a synthetic example is generated using the model of concentric spheres. Results: Through of simplification, the source is determined from the Poisson equation with null Neumann condition and an additional data on the boundary of the homogeneous region, which is obtained from the measurement. This is valid for regions with smooth boundary. Additionally, in the case of concentric spheres, it is statement the identification problem for dipolar sources (representing epileptic focus) using this simplification and Green function. Conclusion: The simplification presented here allows us to analyze the inverse problem in one region, which simplifies the theoretical and numerical study. In particular it may be useful to analyze the problem of parameter identification of a dipolar source.

[New treatment protocols and follow-up in patients with exudative age-related macular degeneration]. / Nuevas pautas de tratamiento y seguimiento en pacientes con degeneración macular asociada a la edad exudativa.

Intravitreal ranibizumab (Lucentis®) injections are the treatment of choice in patients with exudative macular degeneration. In the last few years, several treatment and follow-up strategies have been evaluated with the aim of optimizing the safety and efficacy of this drug. In routine clinical practice, the Pro Re Nata (PRN) and treat-and-extend protocols or variants of the FUSION regimen have been used. PRN protocols are based on regular patient follow-up and on retreatment when there is evidence of reactivation of the lesion, basically determined by loss of visual acuity and persistent or recurrent macular fluid on optical coherence tomography. Treat-and-extend or FUSION protocols are based on early retreatment of the lesion before reactivation occurs with the aim of avoiding the irreversible visual loss that can occur in disease recurrences. There is no ideal treatment and follow-up protocol that could be used as an alternative to the monthly regimen and be applied and reproduced in all patients. Consequently, intravitreal ranibizumab therapy should be individualized in each patient.

Normal values in ambulatory oesophageal pH monitoring at two levels in Spain.

AIM: Upper oesophageal pH monitoring may play a significant role in the study of extra-oesophageal GERD, but limited normal data are available to date. Our aim was to develop a large series of normal values of proximal oesophageal acidification. METHODS: 155 healthy volunteers (74 male) participated in a multi-centre national study including oesophageal manometry and 24 hours oesophageal pH monitoring using two electrodes individually located 5 cm above the LOS and 3 cm below the UOS. RESULTS: 130 participants with normal manometry completed all the study. Twelve of them were excluded for inadequate pH tests. Twenty-seven subjects had abnormal conventional pH. The remaining 91 subjects (37 M; 18-72 yrs age range) formed the reference group for normality. At the level of the upper oesophagus, the 95th percentile of the total number of reflux events was 30, after eliminating the meal periods 22, and after eliminating also the pseudo-reflux events 18. Duration of the longest episodes was 5, 4 and 4 min, respectively (3.5 min in upright and 0.5 min in supine). The upper limit for the percentage of acid exposure time was 1.35, 1.05 and 0.95%, respectively. No reflux events were recorded in the upper oesophagus in 8 cases. CONCLUSION: This is the largest series of normal values of proximal oesophageal reflux that confirm the existence of acid reflux at that level in healthy subjects, in small quantity and unrelated to age or gender. Our data support the convenience of excluding pseudo-reflux events and meal periods from analysis.

Intravitreal ranibizumab for choroidal neovascularization secondary to pathologic myopia: 12-month results.

AIMS: To determine the efficacy and safety of intravitreal ranibizumab in the treatment of choroidal neovascularization (CNV) secondary to pathologic myopia (PM). METHODS: Prospective, consecutive, non-randomized, interventional case series of 23 eyes of 23 patients with CNV secondary to PM treated with intravitreal ranibizumab as needed, after the first injection (PRN: Pro Re Nata). Patients were followed-up monthly with best-corrected visual acuity (BCVA), biomicroscopy, fluorescein angiography, and optical coherence tomography. RESULTS: There were 23 eyes of 23 patients, and the mean age was 51.08 (SD=17.40) years. One patient was lost during the follow-up. At the 12-month follow-up, the mean VA improved by 9.53 letters (P<0.05). In all, 69% of patients increased at least one line, and 34.7% increased three or more lines. There were no cases of moderate vision loss (>3 lines) or severe vision loss (>6 lines). Favourable outcomes were obtained in all subgroups. Patients received an average of 1.52 injections. No serious ocular complications were noted. CONCLUSIONS: The 12-month results of this consecutive series of 23 patients suggests that a small number of injections of intravitreal ranibizumab may be safe and effective for both preventing and restoring visual loss in patients with CNV secondary to PM. Further studies to evaluate the safety and efficacy are justified.

Unusual upper gastrointestinal diseases associated with achalasia: laparoscopic approach.

BACKGROUND: As a result of the high success rate associated with the laparoscopic approach for achalasia, surgery for the disease has become the treatment of choice in recent years. With the greater number of patients undergoing surgery, surgeons may encounter other upper gastroesophageal illnesses associated with achalasia, and these may require evaluation for simultaneous surgical treatment. This study aimed to evaluate the incidence of gastroesophageal diseases associated with achalasia, and to determine the possibility for simultaneous management using the laparoscopic approach. METHODS: From January 1999 to May 2006, 81 patients were referred from the Service of Gastroenterology to the Service of General and Digestive Surgery as candidates for the surgical management of achalasia. Data for this group were recorded prospectively in laparoscopic surgery databases at the Hospital Sant Pau and the Hospital de Igualada. A total of 78 patients underwent laparoscopic Heller myotomy with gastric fundoplication. RESULTS: In 8 of 81 patients, nine additional gastroesophageal diseases (11.1%) were found: three cases of pseudoachalasia (3.7%), three cases of paraesophageal hiatal hernia (3.7%), two cases of esophageal diverticulum (2.5%), and one case of gastric volvulus (1.2%). Pseudoachalasia was diagnosed for three patients. The diagnosis was made preoperatively for one of these patients. For the other two patients, an adenocarcinoma arising from the gastroesophageal junction was diagnosed during the laparoscopy. In three cases, a paraesophageal hiatal hernia was found and treated by laparoscopic Heller myotomy, sac excision, hiatal closure, and posterior fundoplication. Esophageal diverticulectomy was performed for one patient. Another patient presented with an organoaxial gastric volvulus associated with achalasia, for which laparoscopic Heller myotomy, posterior fundoplication, and anterior gastropexy were performed. The median follow-up period was 39 months, with no recurrence. CONCLUSIONS: Despite their infrequency, several gastroesophageal diseases may be found in association with achalasia. Laparoscopic surgery may be useful for the diagnosis and/or treatment of both diseases.

Evolving European guidance on the medical management of neovascular age related macular degeneration.

BACKGROUND: Until recently, only two options were available for the treatment of choroidal neovascularisation (CNV) associated with age related macular degeneration (AMD)-thermal laser photocoagulation and photodynamic therapy with verteporfin (PDT-V). However, new treatments for CNV are in development, and data from phase III clinical trials of some of these pharmacological interventions are now available. In light of these new data, expert guidance is required to enable retina specialists with expertise in the management of AMD to select and use the most appropriate therapies for the treatment of neovascular AMD. METHODS: Consensus from a round table of European retina specialists was obtained based on best available scientific data. Data rated at evidence levels 1 and 2 were evaluated for laser photocoagulation, PDT-V, pegaptanib sodium, and ranibizumab. Other treatments discussed are anecortave acetate, triamcinolone acetonide, bevacizumab, rostaporfin (SnET2), squalamine, and transpupillary thermotherapy. RESULTS: PDT-V is currently recommended for subfoveal lesions with predominantly classic CNV, or with occult with no classic CNV with evidence of recent disease progression and a lesion size

Recurrence of Helicobacter pylori infection after several eradication therapies: long-term follow-up of 1000 patients.

AIM: To study the incidence of Helicobacter pylori recurrence, its chronological aspects, and the variables that might influence it. METHODS: A total of 1000 patients in whom H. pylori had been eradicated were prospectively studied. Therapies were classified as low and high efficacy regimens. Four to eight weeks after completion of therapy, 13C-urea-breath-test was performed, and it was repeated yearly up to 5 years. In some patients, endoscopy with biopsies was also performed to confirm H. pylori eradication. RESULTS: A total of 1000 patients were included, giving 2744 patient-years of follow-up. Seventy-one H. pylori recurrences were observed (2.6% per patient-year). Probability of being H. pylori-negative at 1 year was 94.7%, and at 5 years 90.7%. In the multivariate analysis, low age (OR: 1.84; 95% CI: 1.04-3.26) and low efficacy therapies (OR: 2.5; 1.23-5.04) correlated with 1-year H. pylori recurrence. Differences were observed when Kaplan-Meier curves were compared depending on age and therapy regimen. CONCLUSION: Risk of posteradication H. pylori recurrence is higher during the first year, which suggests that most recurrences during this period are recrudescence and not true reinfections. H. pylori recurrence is more frequent in younger patients and in those treated with low efficacy therapies, but is exceptional if high efficacy therapies are used, in which case post-therapy eradication can be safely confirmed at 4 weeks with 13C-urea-breath-test.

Indications, diagnostic tests and Helicobacter pylori eradication therapy. Recommendations by the 2nd Spanish Consensus Conference.

The results of the 2nd Spanish Consensus Conference for appropriate practice regarding indications for eradication, diagnostic tests, and therapy regimens for Helicobacter pylori infection are summarized. The Conference was based on literature searches in Medline, abstracts from three international meetings, and abstracts from national meetings. Results were agreed upon and approved by the whole group. Results are supplemented by evidence grades and recommendation levels according to the classification used in the Clinical Practice Guidelines issued by Cochrane Collaboration. Convincing indications (peptic ulcer, duodenal erosions with no history of ASA or NSAIDs, MALT lymphoma), and not so convincing indications (functional dyspepsia, patients receiving low-dose ASA for platelet aggregation, gastrectomy stump in patients operated on for gastric cancer, first-degree relatives of patients with gastric cancer, lymphocytic gastritis, and Ménétrier s disease) for H. pylori eradication are discussed. Diagnostic recommendations for various clinical conditions (peptic ulcer, digestive hemorrhage secondary to ulcer, eradication control, patients currently or recently receiving antibiotic or antisecretory therapy), as well as diagnostic tests requiring biopsy collection (histology, urease fast test, and culture) when endoscopy is needed for clinical diagnosis, and non-invasive tests requiring no biopsy collection (13C-urea breath test, serologic tests, and fecal antigen tests) when endoscopy is not needed are also discussed. As regards treatment, first-choice therapies (triple therapy using a PPI and two antibiotics), therapy length, quadruple therapy, and a number of novel antibiotic options as "rescue" therapy are prioritized, the fact that prolonging PPI therapy following effective eradication is unnecessary for patients with duodenal ulcer but not for all gastric ulcers is documented, the fact that cultures and antibiograms are not needed for all eradicating therapies is indicated, and finally the test and treat strategy is considered adequate, however only under certain circumstances.

Contrast sensitivity as an outcome measure in patients with subfoveal choroidal neovascularisation due to age-related macular degeneration.

PURPOSE: Although visual acuity is the most frequently used primary outcome measure in clinical trials of treatments for choroidal neovascularisation (CNV) due to age-related macular degeneration (AMD), contrast sensitivity may provide valuable additional information. This paper reviews the evidence for using contrast sensitivity as a measure of visual function and as an outcome measure in clinical trials in patients with subfoveal CNV due to AMD. METHODS: Medline database searches were performed to retrieve relevant articles on contrast sensitivity. In addition, articles were included from the authors' knowledge of the literature and from the reference lists of retrieved articles. RESULTS: The published literature demonstrates that contrast sensitivity is an important measure of visual function in patients with subfoveal CNV due to AMD. Most clinical trials of treatments for CNV due to AMD have reported visual acuity as the primary outcome. However, there is evidence that treatment (such as verteporfin therapy) may also provide additional benefits in terms of contrast sensitivity. These benefits may not be completely characterised by measurement of visual acuity alone. CONCLUSIONS: The inclusion of contrast sensitivity as an outcome measure in studies of patients with CNV due to AMD may provide a more complete understanding of the effects of treatment on visual function and the likely benefits for patients.

[Hematuria during pregnancy caused by bladder tumour. Report of 2 cases]. / Hematuria durante la gestación debida a tumor vesical. Presentación de 2 casos.

Tumours of the urinary bladder are rare in pregnancy. We report two such cases presenting with gross hematuria, but one of them was initially mistaken as vaginal bleeding. Patients age was 41 and 27 years old, at 26 and 18 weeks of gestation respectively. Diagnoses were made with cystoscopy and sonography. Tocolytics agents were employed. Both of the tumours were managed succesfully by transurethral electroresection. Raquianesthesia was employed in both. There were no adverse effects on the pregnacies. Transurethral resection is a safe procedure during pregnancy. The pathology diagnoses were inverted papilloma in the first case and papillary urothelial neoplasm of low malignant potential in the other one. The literature is reviewed.

Helicobacter pylori eradication versus one-year maintenance therapy: effect on relapse and gastritis outcome.

OBJECTIVE: The aim of this study was to determine ulcer healing and H. pylori eradication rates obtained with triple therapy (omeprazole, amoxicillin and clarithromycin). Ulcer relapsing rate one year after eradication was also assessed. Maintenance therapy with placebo was compared with ranitidine therapy and the effect of eradication on histological variables of the gastric mucosa was studied. METHODS: A prospective, double-blind parallel study was performed in 85 patients endoscopically diagnosed of duodenal ulcer H. pylori positive. Patients were randomized to a 7-days triple therapy (group A) or omeprazole plus antibiotic placebo (group B). All patients were treated only with omeprazole for the next three weeks. Patients with ulcer healing after treatment were entered in a one-year follow up phase with ranitidine placebo (group A) or ranitidine (group B). Endoscopy and biopsies were performed at baseline, after treatment (5 weeks) and after 12 months of follow-up or when relapsing symptoms appeared. RESULTS: Healing rate was 90.2% in group A and 85.7% in group B. Eradication rate was 78% in group A and 0% in group B. Out of 37 healed patients in group A, eradication was achieved in 29 and only one relapse was found (3.4%). Three out of eight patients with healing but without eradication relapsed at 12 months (35%) (p < 0.05). Histopathological results showed statistically significant differences (p < 0.05) between eradicated and non eradicated patients in terms of severity of inflammation and intestinal metaplasia, but not in terms of atrophy. CONCLUSIONS: H. pylori eradication is useful to prevent ulcer relapse and to improve gastric mucosa status.

Criteria used by general practitioners in prescribing prokinetic or antisecretory drugs in patients with functional dyspepsia.

OBJECTIVE: To analyze the clinical factors considered by general practitioners for the prescription of prokinetic or antisecretory drugs in patients with functional dyspepsia (FD), and to assess therapeutic outcomes and factors predicting effectiveness. DESIGN: Multicentric, prospective and observational study. PATIENTS: 1,021 patients with FD were included. One hundred and thirty-two (132) were excluded from the analysis because they were taking ASA or NSAID. Patients were classified according to their predominant symptoms as reflux, ulcer, dysmotility or non-specific. At the physician discretion, treatment with alkali drugs was prescribed to 38 patients, prokinetic drugs to 574, antisecretory drugs to 123 and a combined therapy to 154. One month later, patient self-perception of symptomatic improvement was evaluated in patients treated with prokinetic drugs and antisecretory drugs. RESULTS: 85% of the patients reported symptomatic improvement after one month of treatment. Patients with non-specific FD had lower improvement rates regardless of the drug used (prokinetic or antisecretory) (77%) compared to all the other types (p = 0.03). Prescription of prokinetics was associated to female gender (OR: 0.43; 95% CI: 0.28-0.66) and early satiety (OR: 2.5; 95% CI: 1.6-4.1). A longer symptomatic evolution (OR 0.92: 95% CI: 0.88-0.97) was the only independent predictive factor of a poor response to prokinetic drugs. CONCLUSIONS: Among patients with FD attended by general practitioners, female gender and early satiety symptom were associated to the prescription of prokinetic drugs. Early symptomatic effectiveness rates for prokinetic or antisecretory drugs alike were high (85%). Patients with non-specific dyspepsia or long symptomatic evolution showed less favorable symptomatic response to prokinetic drugs.