RESUMEN
Nine different definitions of asymmetric sensorineural hearing loss (SNHL) have been reported in literature. The objectives of this study are to: (1) compare all these definitions of asymmetric SNHL; (2) measure the agreement between these definitions in detecting vestibular schwannoma (VS); and (3) determine the strongest association between an asymmetric SNHL definition and positive VS on magnetic resonance imaging (MRI). The study is a retrospective chart review in a tertiary care center. Cases were included if they were evaluated by an audiometric assessment and a posterior fossa MRI. Definitions of asymmetric SNHL reported in literature were applied to request for a further MRI investigation. The likelihood ratio (LR) for a positive test result (LR+) was the highest for the Rule 3,000 (2.91). On comparing all the other definitions with Rule 3,000, seven of the eight existing definitions have a kappa under the clinical usefulness threshold (Kappa < 0.6). When specification tests were applied, the Chi-square test identified Rule 3,000 with a highly significant P value (P < 0.0001). Rule 3,000, defined as asymmetric SNHL of 15 dB or more at the frequency 3,000 Hz, could serve as a universal referral guide for further MRI investigation. Results show that Rule 3,000 is more reliable to detect VS on MRI, a very simple rule that covers all the eight definitions of asymmetric SNHL reported in literature. This would help to reduce the number of negative MRI and to save time and money. If asymmetric SNHL is less than 15 dB, a biannual audiometry testing follow-up could be done.
Asunto(s)
Audiometría , Pérdida Auditiva Sensorineural/diagnóstico , Imagen por Resonancia Magnética , Neuroma Acústico/diagnóstico , Adulto , Femenino , Pérdida Auditiva Sensorineural/etiología , Humanos , Masculino , Persona de Mediana Edad , Neuroma Acústico/complicaciones , Valor Predictivo de las Pruebas , Sensibilidad y EspecificidadRESUMEN
In an effort to obtain the most accurate climate change impact assessment, greenhouse gas (GHG) accounting is evolving to include life-cycle thinking. This study (1) identifies similarities and key differences between GHG accounting and life-cycle assessment (LCA), (2) compares them on a consistent basis through a case study on a waste management business unit. First, GHG accounting is performed. According to the GHG Protocol, annual emissions are categorized into three scopes: direct GHG emissions (scope 1), indirect emissions related to electricity, heat and steam production (scope 2) and other indirect emissions (scope 3). The LCA is then structured into a comparable framework: each LCA process is disaggregated into these three scopes, the annual operating activities are assessed, and the environmental impacts are determined using the IMPACT2002+ method. By comparing these two approaches it is concluded that both LCA and GHG accounting provide similar climate change impact results as the same major GHG contributors are determined for scope 1 emissions. The emissions from scope 2 appear negligible whereas emissions from scope 3 cannot be neglected since they contribute to around 10% of the climate change impact of the waste management business unit. This statement is strengthened by the fact that scope 3 generates 75% of the resource use damage and 30% of the ecosystem quality damage categories. The study also shows that LCA can help in setting up the framework for a annual GHG accounting by determining the major climate change contributors.
Asunto(s)
Contaminación del Aire/análisis , Dióxido de Carbono/análisis , Monitoreo del Ambiente/métodos , Efecto Invernadero , Administración de Residuos/métodos , Contaminación del Aire/prevención & control , Comercio/organización & administración , Comercio/estadística & datos numéricos , Eficiencia Organizacional , Calentamiento Global , Modelos Químicos , Residuos/análisis , Residuos/clasificaciónRESUMEN
OBJECTIVE: To assess the diagnostic yield of audiograms associated to electronystagmography (ENG) for screening vestibular schwannomas (VSs), to determine what definition of asymmetric sensorineural hearing loss (ASNHL) fits best for the diagnosis of VS, and to determine if cochleovestibular symptoms and atherosclerotic potential risk factors play a role in the VS screening. STUDY DESIGN: Retrospective chart review in a tertiary care center. METHODS: One hundred twenty-two patients were included in the study and divided into 2 groups: 1) patients presenting a VS (n = 74) and 2) patients without VS (n = 48). They had received an audiometry assessment, an ENG, and a posterior fossa magnetic resonance imaging (MRI). In addition, a variety of risk factors and clinical data were collected. Mean hearing threshold by frequency, mean asymmetries by frequency, speech discrimination score (SDS), ENG results, and presence or absence of vertigo are studied. Cochleovestibular symptoms and atherosclerotic potential risk factors were collected. Characteristics were studied with analysis of variance, chi2 test, or a paired t test. A receiver operating characteristic curve was obtained. A logistic regression with a step-wise selection based on the likelihood ratio was used to identify the best subgroup of predictors of the VS. RESULTS: The most revealing data were the mean ASNHL at 3,000 Hz (p < 0.001), the interaural SDS asymmetry (p < 0.001), the vestibular deficit (p < 0.049), and the absence of vertigo (p < 0.001). The ASNHL at 3,000 Hz was the most representative value of all the frequencies and for the SDS asymmetry. Interaural difference of 15 dB or more at 3,000 Hz is sufficient to consider hearing loss as asymmetric. When the cutoff for a positive test was placed at 50% probability, the receiver operating characteristic curve shows a sensitivity of 73%. The grade of the tumor was also related with the degree of ASNHL at 3,000 Hz. Caloric test does not predict the localization or the grade of the VS. Tinnitus and atherosclerotic potential risk factors were not considered significantly linked with VS. CONCLUSION: To reduce the number of negative MRI performed in the investigation of an ASNHL, we propose the "rule 3,000," ASNHL of 15 dB or more at the 3,000-Hz frequency. In this case, an investigation with MRI is crucial. If this ASNHL is less than 15 dB, we recommend a biannual audiometric follow-up.