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1.
Oral Dis ; 29(2): 343-368, 2023 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-33713052

RESUMO

OBJECTIVES: To determine the effectiveness of systemic pharmacotherapeutic interventions compared to placebo in burning mouth syndrome (BMS) randomized controlled trials (RCTs) based on the core outcome domains recommended by the Initiative on Methods, Measurement, and Pain Assessment in Clinical Trials (IMMPACT). METHODS: A systematic literature review of RCTs, concerning systemic pharmacotherapeutic interventions for BMS, published from January 1994 through October 2019, and meta-analysis was performed. RESULTS: Fourteen RCTs (n = 734 participants) were included. Of those, nine were eligible for the quantitative assessment due to the availability/homogeneity of data for at least one of the IMMPACT domains. Pain intensity was the only domain reported in all RCTs. Weighted mean changes in pain intensity, based on visual analogue scale (ΔVAS), were reported in three RCTs at 6 ± 2 weeks and only one RCT at 10+ weeks follow-ups. Quantitative assessment, based on ΔVAS, yielded very low evidence for the effectiveness of alpha-lipoic acid and clonazepam, low evidence for effectiveness of trazodone and melatonin, and moderate evidence for herbal compounds. CONCLUSIONS: Based on the RCTs studied, variable levels of evidence exist that suggest that select pharmacological interventions are associated with improved symptoms. However, the underreporting of IMMPACT domains in BMS RCTs restricts the multidimensional assessment of systemic interventions outcomes. Standardized outcome measures need to be applied to future RCTs to improve understanding of intervention outcomes.


Assuntos
Síndrome da Ardência Bucal , Humanos , Síndrome da Ardência Bucal/tratamento farmacológico
2.
Oral Dis ; 29(8): 3016-3033, 2023 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-35781729

RESUMO

OBJECTIVES: To assess the effectiveness of topical interventions in the management of burning mouth syndrome (BMS), based on the core outcome domains recommended by the Initiative on Methods, Measurement, and Pain Assessment in Clinical Trials (IMMPACT). METHODS: A systematic literature review of RCTs on topical interventions for the management of BMS, published in PubMed, Web of Science, PsycInfo, Cochrane Database/Central, and Google Scholar through May 2021 was performed. RESULTS: Eight RCTs (n = 358 study participants) were included in this study. Due to underreporting of IMMPACT domains, publication bias, high degree of heterogeneity between studies, meta-analysis was not undertaken. Based on changes in visual analogue pain scores (ΔVAS), the most reported outcome, the effectiveness of the topical interventions was demonstrated; however, it is low level of evidence. CONCLUSIONS: High levels of variability (interventions, outcomes, outcome measurement tools, and intervention effects evaluated), heterogeneity, publication bias, and underreporting of IMMPACT domains were observed across the RCTs. This systematic review highlights the need for application of standardized outcome measures to future RCTs. At the present time, there is lack of moderate-strong evidence on short- and long-term outcomes to support or refute the use of any particular topical intervention in managing BMS. Future RCTs with standardized outcome measures are needed.


Assuntos
Síndrome da Ardência Bucal , Humanos , Síndrome da Ardência Bucal/tratamento farmacológico , Medição da Dor , Qualidade de Vida
3.
Int J Surg Case Rep ; 83: 105977, 2021 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-34022762

RESUMO

INTRODUCTION: Schwannomas are a benign tumor of peripheral nerve sheath origin. Although most commonly arising in the extremities, head, and neck there have been rare cases of schwannomas presenting within or adjacent to the pancreas reported in the literature. PRESENTATION OF CASE: We present an asymptomatic and otherwise healthy 57-year-old male with an incidental peripancreatic mass measuring 3.5 × 3.7 cm found on abdominal computed tomography (CT). The patient underwent complete enucleation of the mass at our hospital. Pathological analysis of the excised specimen showed spindle shaped cells. Immunohistochemical staining was positive for S100 protein expression, confirming the definitive diagnosis of peripancreatic schwannoma. The patient's postoperative course was uneventful. DISCUSSION: Schwannoma is a commonly benign, encapsulated, and slowly growing tumor arising from myelin producing cells of peripheral nerves. A schwannoma presenting within or adjacent to solid abdominal viscera, such as the pancreas, may be challenging to diagnose preoperatively as it may mimic other lesions. Radiological appearance of schwannoma may be nonspecific and definitive diagnosis is reliant upon pathological analysis. The use of endoscopic ultrasound (EUS) with fine needle aspiration (FNA) may assist the clinician in preoperative diagnosis, however these interventions are not widely available. Accurate preoperative diagnosis of a peripancreatic schwannoma is of high importance as it may preclude unnecessary pancreatectomy or radical resection. CONCLUSION: Although rare, schwannoma should be part of the differential diagnosis of a cystic or solid appearing mass within or surrounding the pancreas. Total resection carries an excellent prognosis with little to no documented recurrence.

4.
Case Rep Surg ; 2020: 8850739, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33224549

RESUMO

A 71-year-old male, diagnosed with coronavirus disease 2019 (COVID-19), was admitted to the medical-surgical floor for supportive treatment. The patient received bag-mask ventilation (BMV) secondary to severe hypoxia and reendotracheal intubation in the hospital on day eleven. A chest X-ray following reintubation noted concern for intra-abdominal air. Significant abdominal distention and subsequent diagnostic imaging showed pneumoperitoneum and a possible perforation of the stomach. The patient underwent an exploratory laparotomy with omental patching for a gastric perforation. Amidst the height of the COVID-19 pandemic, several important findings have been made through the disease sequelae of this individual patient.

5.
Br J Cardiol ; 27(4): 34, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-35747220

RESUMO

The utility of computed tomography (CT) coronary angiography (CTCA) is underpinned by its excellent sensitivity and negative-predictive value for coronary artery disease (CAD), although it lacks specificity. Invasive coronary angiography (ICA) and invasive fractional flow reserve (FFR), are gold-standard investigations for coronary artery disease, however, they are resource intensive and associated with a small risk of serious complications. FFR-CT has been shown to have comparable performance to FFR measurements and has the potential to reduce unnecessary ICAs. The aim of this study is to briefly review FFR-CT, as an investigational modality for stable angina, and to share 'real-world' UK data, in consecutive patients, following the initial adoption of FFR-CT in our district general hospital in 2016. A retrospective analysis was performed of a previously published consecutive series of 157 patients referred for CTCA by our group in a single, non-interventional, district general hospital. Our multi-disciplinary team (MDT) recorded the likely definitive outcome following CTCA, namely intervention or optimised medical management. FFR-CT analysis was performed on 24 consecutive patients where the MDT recommendation was for ICA. The CTCA + MDT findings, FFR-CT and ICA ± FFR were correlated along with the definitive outcome. In comparing CTCA + MDT, FFR-CT and definitive outcome, in terms of whether a percutaneous coronary intervention was performed, FFR-CT was significantly correlated with definitive outcome (r=0.471, p=0.036) as opposed to CTCA + MDT (r=0.378, p=0.07). In five cases (21%, 5/24), FFR-CT could have altered the management plan by reclassification of coronary stenosis. FFR-CT of 60 coronary artery vessels (83%, 60/72) (mean FFR-CT ratio 0.82 ± 0.10) compared well with FFR performed on 18 coronary vessels (mean 0.80 ± 0.11) (r=0.758, p=0.0013). In conclusion, FFR-CT potentially adds value to MDT outcome of CTCA, increasing the specificity and predictive accuracy of CTCA. FFR-CT may be best utilised to investigate CTCAs where there is potentially prognostically significant moderate disease or severe disease to maximise cost-effectiveness. These data could be used by other NHS trusts to best incorporate FFR-CT into their diagnostic pathways for the investigation of stable chest pain.

7.
Case Rep Surg ; 2019: 9017863, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31093416

RESUMO

A 21-year-old African-American male presented to the emergency room with a sudden diffuse onset abdominal pain of one day duration. CT findings revealed mild telescoping of loops of small bowel and mesenteric fat in the left mid abdomen with no apparent masses. The patient underwent an exploratory laparoscopy revealing intussusception of the mid jejunum. As a fair amount of distention compromised safe navigation of the bowel, laparoscopic resection was not warranted at this time. Open approach allowed for segmental resection of the affected segment of the small bowel. This was followed by primary anastomosis. Pathological findings revealed focal reactive lymphoid hyperplasia with marked congestion in the lamina propria of the jejunum. The patient had an unremarkable postoperative period and recovered with no further complications.

8.
Oral Dis ; 25 Suppl 1: 122-140, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31140700

RESUMO

OBJECTIVES: To determine the frequency of use of the core outcome domains published by the Initiative on Methods, Measurement, and Pain Assessment in Clinical Trials (IMMPACT) in burning mouth syndrome (BMS) randomized controlled trials (RCTs). METHODS: This systematic review, conducted as part of the World Workshop on Oral Medicine VII (WWOM VII), was performed by searching the literature for studies published in PubMed, Web of Science, PsycINFO, Cochrane Database/Cochrane Central, and Google Scholar from January 1994 (when the first BMS definition came out) through October 2017. RESULTS: A total of 36 RCTs (n = 2,175 study participants) were included and analyzed. The overall reporting of the IMMPACT core and supplemental outcome domains was low even after the publication of the IMMPACT consensus papers in 2003 and 2005 (mean before IMMPACT consensus publication = 2.6 out of 6; mean after IMMPACT publication = 3.8 out of 6). Use of validated assessment tools recommended by the IMMPACT consensus was scarce (1.9 out of 6). None of the RCTs reviewed cited the IMMPACT consensus papers. CONCLUSIONS: The underreporting of IMMPACT outcome domains in BMS RCTs is significant. Raising awareness regarding the existence of standardized outcome domains in chronic pain research is essential to ensure more accurate, comparable, and consistent interpretation of RCT findings that can be clinically translatable.


Assuntos
Síndrome da Ardência Bucal/terapia , Dor Crônica/terapia , Medicina Bucal , Guias de Prática Clínica como Assunto , Ensaios Clínicos Controlados Aleatórios como Assunto , Congressos como Assunto , Gerenciamento Clínico , Humanos , Manejo da Dor/métodos , Medição da Dor , Guias de Prática Clínica como Assunto/normas , Qualidade de Vida , Resultado do Tratamento
9.
Oral Dis ; 25 Suppl 1: 141-156, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30785661

RESUMO

OBJECTIVE: To conduct a systematic review analyzing disease definitions and diagnostic criteria used in randomized controlled trials (RCTs) involving burning mouth syndrome (BMS). METHODS: A systematic search conducted in PubMed, Web of Science, PsycINFO, Cochrane Database/Cochrane Central, and Google Scholar that included RCTs on BMS published between 1994 and 2017 was performed. RESULTS: Considerable variability in BMS disease definitions and diagnostic criteria used created substantial heterogeneity in the selection of participants and weakened the rigor of the 36 RCTs identified. The analyzed RCTs routinely under-reported the methods used to rule in or out study participants and the number of individuals excluded from BMS RCTs. CONCLUSIONS: Our findings indicate that a large proportion of participants enrolled in these studies may have had an underlying condition that could have explained their BMS symptoms. Thus, outcomes of therapeutic interventions from these BMS RCTs should be interpreted with caution due to heterogeneous disease definitions and diagnostic criteria. In order to improve the quality of clinical trials, future research should focus on establishing consensus for a single definition of BMS that includes specific inclusion and exclusion criteria that should be used to select study participants for clinical trials.


Assuntos
Síndrome da Ardência Bucal , Ensaios Clínicos Controlados Aleatórios como Assunto , Síndrome da Ardência Bucal/diagnóstico , Congressos como Assunto , Humanos
10.
Open Heart ; 5(2): e000817, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30018778

RESUMO

Introduction: CT coronary angiography (CTCA) has excellent sensitivity but lacks specificity when compared with invasive coronary angiography (ICA) particularly in patients with a high coronary calcium burden. CTCA has been shown in large trials to decrease the requirement for diagnostic ICA and provide diagnostic clarity. We describe the methodology used to provide a standardised CTCA service established in a District General Hospital, which may assist other hospitals aiming to develop a cardiac CT service. Methods: Scan request forms, authorisation and patient instruction were recorded. Patient preparation prior to CTCA as well as exclusion and inclusion criteria were documented. Scans were interpreted using a multidisciplinary team (MDT) approach in order to organise follow-up, medication and further investigation. Results: Over 6 months, 157 consecutive scans were performed. CTCA was completed in 88% (n=138/157) and considered of diagnostic quality in 82% (n=129/157). The median radiation dose was 3.42 mSv. Overall, 64% of patients had evidence of coronary calcium. Following MDT review, 72% (n=113/157) of patients were discharged without requiring invasive angiography. 15% (n=24/157) of patients went on to have invasive angiography showing non-obstructive disease and 13% (20/157) of patients underwent percutaneous coronary intervention (11%) or bypass surgery (1%). Discussion: Appropriate referrals, patient preparation and scan quality remain significant factors in running a CTCA service. Despite this, the vast majority of patients can be discharged on the basis of the CTCA alone. An MDT approach is key to the delivery of a cardiac CT service.

11.
Oral Surg Oral Med Oral Pathol Oral Radiol ; 123(2): 194-204.e10, 2017 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-27989710

RESUMO

OBJECTIVE: The aim of this study was to identify factors associated with death in relation to dental care. STUDY DESIGN: A systematic review was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. PubMed, Dental and Oral Sciences Source, Web of Science, and the Cochrane database were searched, and the references of all retrieved articles were analyzed. Studies were included if death had occurred within 90 days of the dental appointment, and if the patient's age, procedure, and information regarding cause or time of death were provided. Factors associated with death were assessed by multivariate analyses and logistic regression. RESULTS: Fifty-six publications, including retrospective studies and case reports/series that reported 148 fatalities, were analyzed. On average, 2.6 deaths were reported per year. The leading cause of deaths was anesthesia/sedation/medication-related complications (n = 70). Other causes were cardiovascular events (n = 31), infection (n = 19), airway-respiratory complications (n = 18), bleeding (n = 5), and others (n = 5). Age (P < .0001), disease severity (P < .02), disease stability (P < .006), dental provider characteristics (P < .05), level of consciousness/sedation (P < .02), and drug effects (P < .03) had significant associations with death. CONCLUSIONS: Reports of death were rare; however, specific risk factors associated with dentistry were identified. A better understanding of these factors is important for the development of guidelines that help prevent fatalities in dentistry.


Assuntos
Assistência Odontológica/mortalidade , Humanos , Fatores de Risco
12.
Med Dosim ; 39(2): 139-45, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-24661778

RESUMO

With traditional photon therapy to treat large postoperative pancreatic target volume, it often leads to poor tolerance of the therapy delivered and may contribute to interrupted treatment course. This study was performed to evaluate the potential advantage of using passive-scattering (PS) and modulated-scanning (MS) proton therapy (PT) to reduce normal tissue exposure in postoperative pancreatic cancer treatment. A total of 11 patients with postoperative pancreatic cancer who had been previously treated with PS PT in University of Pennsylvania Roberts Proton Therapy Center from 2010 to 2013 were identified. The clinical target volume (CTV) includes the pancreatic tumor bed as well as the adjacent high-risk nodal areas. Internal (iCTV) was generated from 4-dimensional (4D) computed tomography (CT), taking into account target motion from breathing cycle. Three-field and 4-field 3D conformal radiation therapy (3DCRT), 5-field intensity-modulated radiation therapy, 2-arc volumetric-modulated radiation therapy, and 2-field PS and MS PT were created on the patients' average CT. All the plans delivered 50.4Gy to the planning target volume (PTV). Overall, 98% of PTV was covered by 95% of the prescription dose and 99% of iCTV received 98% prescription dose. The results show that all the proton plans offer significant lower doses to the left kidney (mean and V18Gy), stomach (mean and V20Gy), and cord (maximum dose) compared with all the photon plans, except 3-field 3DCRT in cord maximum dose. In addition, MS PT also provides lower doses to the right kidney (mean and V18Gy), liver (mean dose), total bowel (V20Gy and mean dose), and small bowel (V15Gy absolute volume ratio) compared with all the photon plans and PS PT. The dosimetric advantage of PT points to the possibility of treating tumor bed and comprehensive nodal areas while providing a more tolerable treatment course that could be used for dose escalation and combining with radiosensitizing chemotherapy.


Assuntos
Neoplasias Pancreáticas/radioterapia , Terapia com Prótons/métodos , Doses de Radiação , Planejamento da Radioterapia Assistida por Computador , Radioterapia de Intensidade Modulada/métodos , Humanos , Neoplasias Pancreáticas/cirurgia , Estudos Retrospectivos
13.
Int J Radiat Oncol Biol Phys ; 82(3): e477-84, 2012 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-22177626

RESUMO

PURPOSE: To perform a dosimetric comparison of intensity-modulated radiotherapy (IMRT), passive scattering proton therapy (PSPT), and intensity-modulated proton therapy (IMPT) to the para-aortic (PA) nodal region in women with locally advanced gynecologic malignancies. METHODS AND MATERIALS: The CT treatment planning scans of 10 consecutive patients treated with IMRT to the pelvis and PA nodes were identified. The clinical target volume was defined by the primary tumor for patients with cervical cancer and by the vagina and paravaginal tissues for patients with endometrial cancer, in addition to the regional lymph nodes. The IMRT, PSPT, and IMPT plans were generated using the Eclipse Treatment Planning System and were analyzed for various dosimetric endpoints. Two groups of treatment plans including proton radiotherapy were created: IMRT to pelvic nodes with PSPT to PA nodes (PSPT/IMRT), and IMRT to pelvic nodes with IMPT to PA nodes (IMPT/IMRT). The IMRT and proton RT plans were optimized to deliver 50.4 Gy or Gy (relative biologic effectiveness [RBE)), respectively. Dose-volume histograms were analyzed for all of the organs at risk. The paired t test was used for all statistical comparison. RESULTS: The small-bowel V(20), V(30), V(35), andV(40) were reduced in PSPT/IMRT by 11%, 18%, 27%, and 43%, respectively (p < 0.01). Treatment with IMPT/IMRT demonstrated a 32% decrease in the small-bowel V(20). Treatment with PSPT/IMRT showed statistically significant reductions in the body V(5-20); IMPT/IMRT showed reductions in the body V(5-15). The dose received by half of both kidneys was reduced by PSPT/IMRT and by IMPT/IMRT. All plans maintained excellent coverage of the planning target volume. CONCLUSIONS: Compared with IMRT alone, PSPT/IMRT and IMPT/IMRT had a statistically significant decrease in dose to the small and large bowel and kidneys, while maintaining excellent planning target volume coverage. Further studies should be done to correlate the clinical significance of these findings.


Assuntos
Neoplasias do Endométrio/radioterapia , Irradiação Linfática/métodos , Terapia com Prótons , Radioterapia de Intensidade Modulada/métodos , Neoplasias do Colo do Útero/radioterapia , Aorta Abdominal , Neoplasias do Endométrio/patologia , Feminino , Humanos , Rim/efeitos da radiação , Órgãos em Risco , Pelve , Lesões por Radiação/prevenção & controle , Dosagem Radioterapêutica , Reto/efeitos da radiação , Eficiência Biológica Relativa , Espalhamento de Radiação , Medula Espinal/efeitos da radiação , Carga Tumoral , Bexiga Urinária/efeitos da radiação , Neoplasias do Colo do Útero/patologia
14.
AJR Am J Roentgenol ; 197(4): W687-95, 2011 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-21940541

RESUMO

OBJECTIVE: There is a wide spectrum of established and emerging genetic mutations associated with intraadrenal and extraadrenal paragangliomas. In this review, we present the typical radiologic patterns of disease associated with six well-characterized genetic mutations and discuss other inherited and nonfamilial syndromes currently under characterization. CONCLUSION: Contrary to previous understanding, recent genotype advances suggest that the majority of paragangliomas may be genetically predisposed.


Assuntos
Diagnóstico por Imagem , Paraganglioma/diagnóstico , Paraganglioma/genética , Meios de Contraste , Predisposição Genética para Doença , Humanos , Mutação , Paraganglioma Extrassuprarrenal/diagnóstico , Paraganglioma Extrassuprarrenal/genética , Síndrome
15.
J Minim Access Surg ; 7(2): 158-60, 2011 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-21523243

RESUMO

The patient is a 39-year-old male with a five-month history of progressive dysphagia and a 70 lb weight loss. On upper gastrointestinal (GI) endoscopy he was found to have a near-obstructing mass in the lower oesophagus that was proven by biopsy to be oesophageal adenocarcinoma. Stricture caused by the adenocarcinoma mass was stented with a Cook Evolution 12.5 cm / 24 Fr stent, which dislodged subsequently. We report the first case of a dislodged Cook Evolution 12.5 cm / 24 Fr oesophageal stent that was retrieved using combined laparoscopic and transabdominal endoscopy.

16.
Insights Imaging ; 2(4): 431-438, 2011 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-22347965

RESUMO

BACKGROUND: Paragangliomas are rare tumours derived from the autonomic nervous system that have increasingly been recognised to have a genetic predisposition. Mutations of the enzyme succinyl dehydrogenase (SDH) have proven to result in paraganglioma formation. There are four subunits (A through D) that form the enzyme complex and are associated with different genophenotypic expressions of disease. SDHB and SDHD mutations are more common, whereas SDHA and SDHC mutations are rare. Patients with SDHB mutations are prone to extra-adrenal pheochromocytomas, malignant disease and extra-paraganglial neoplasia, whereas SDHD mutations have a greater propensity for multiple, benign head and neck paragangliomas. METHODS: Diagnosis of a sporadic paraganglioma or pheochromocytoma should lead to a full genetic workup of the patient and family if SDH mutations are found. RESULTS: Further annual screening will be required depending on the mutation, which can have a significant impact on radiologists and the resources of the radiology department. CONCLUSION: We present our imaging experience with a series of patients with proven SDH mutations resulting in paragangliomas with a review of the literature.

18.
Radiographics ; 28(6): 1631-43, 2008 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-18936026

RESUMO

Urethral injury is a common complication of pelvic trauma that, if undiagnosed, may lead to significant long-term morbidity. Segments of the urethra that are near the pubic rami and the puboprostatic ligaments are particularly vulnerable. Although computed tomography is commonly used for the initial imaging evaluation of patients with polytrauma, urethral injury is better assessed and classified by using urethrography. Complete urethral imaging is especially important at presentation because the insertion of a transurethral bladder catheter may exacerbate an existing injury (eg, cause a partial urethral tear to become a complete transection). However, even for radiologists who are familiar with standard technique, urethrography after pelvic trauma may be particularly challenging because the patient is immobile or a surgical fixation device or indwelling urethral catheter is present. Various methods may used to overcome these difficulties and ensure that optimal images are obtained so that a correct diagnosis can be made without additional imaging evaluations.


Assuntos
Fraturas Ósseas/complicações , Fraturas Ósseas/diagnóstico por imagem , Ossos Pélvicos/diagnóstico por imagem , Ossos Pélvicos/lesões , Uretra/diagnóstico por imagem , Uretra/lesões , Humanos , Radiografia
19.
Biomed Eng Online ; 4: 53, 2005 Sep 07.
Artigo em Inglês | MEDLINE | ID: mdl-16146569

RESUMO

BACKGROUND: Classifying the types of extracellular potentials recorded when neural structures are activated is an important component in understanding nerve pathophysiology. Varying definitions and approaches to understanding the factors that influence the potentials recorded during neural activity have made this issue complex. METHODS: In this article, many of the factors which influence the distribution of electric potential produced by a traveling action potential are discussed from a theoretical standpoint with illustrative simulations. RESULTS: For an axon of arbitrary shape, it is shown that a quadrupolar potential is generated by action potentials traveling along a straight axon. However, a dipole moment is generated at any point where an axon bends or its diameter changes. Next, it is shown how asymmetric disturbances in the conductivity of the medium surrounding an axon produce dipolar potentials, even during propagation along a straight axon. Next, by studying the electric fields generated by a dipole source in an insulating cylinder, it is shown that in finite volume conductors, the extracellular potentials can be very different from those in infinite volume conductors. Finally, the effects of impulses propagating along axons with inhomogeneous cable properties are analyzed. CONCLUSION: Because of the well-defined factors affecting extracellular potentials, the vague terms far-field and near-field potentials should be abandoned in favor of more accurate descriptions of the potentials.


Assuntos
Potenciais de Ação/fisiologia , Axônios/fisiologia , Mapeamento Potencial de Superfície Corporal/métodos , Mapeamento Encefálico/métodos , Líquido Extracelular/fisiologia , Potenciais da Membrana/fisiologia , Modelos Neurológicos , Animais , Simulação por Computador , Campos Eletromagnéticos , Humanos , Condução Nervosa/fisiologia
20.
Surg Clin North Am ; 84(4): 1035-59, vi, 2004 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-15261752

RESUMO

Endoscopic ultrasound (EUS) was introduced in the early 1980s in an attempt to improve sonographic imaging of the pancreas. Its uses have been expanded to include examination of the upper and lower gastrointestinal tracts, hepatobiliary and portal systems,and the anal sphincter; diagnosis and staging of esophageal, gastric,and pancreaticobiliary tumors; and evaluation of mediastinal nodes in lung cancer. Although EUS has its limitations and is greatly dependent on operator skill, it has wide-ranging interventional and therapeutic applications that can be expected to increase in the future with technologic advances and greater educational opportunities for physicians.


Assuntos
Neoplasias do Sistema Digestório/diagnóstico por imagem , Endossonografia , Ultrassonografia de Intervenção , Adenoma/diagnóstico por imagem , Neoplasias dos Ductos Biliares/diagnóstico por imagem , Neoplasias dos Ductos Biliares/cirurgia , Ductos Biliares Intra-Hepáticos/diagnóstico por imagem , Doenças Biliares/diagnóstico por imagem , Ablação por Cateter , Colangiocarcinoma/diagnóstico por imagem , Colangiocarcinoma/cirurgia , Neoplasias do Sistema Digestório/cirurgia , Procedimentos Cirúrgicos do Sistema Digestório/métodos , Duodeno/diagnóstico por imagem , Varizes Esofágicas e Gástricas/diagnóstico por imagem , Humanos , Estadiamento de Neoplasias/métodos , Neoplasias Pancreáticas/diagnóstico por imagem , Pseudocisto Pancreático/diagnóstico por imagem , Neoplasias Retais/diagnóstico por imagem , Reto/diagnóstico por imagem , Estômago/diagnóstico por imagem , Tomografia Computadorizada por Raios X
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