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Biomedical subjects

G Salomon

Publications and source records attributed to G Salomon.

64 records · Page 4Linked to original sources
PubMedDate not supplied

Cerebrospinal fluid loss and threshold changes. 1. Hearing loss in the contralateral ear after operation for acoustic neuroma: an analysis of the incidence, time course, frequency range, size and pathophysiological considerations.

In a prospective study, 60 patients who underwent surgery for unilateral acoustic neuromas had the hearing on the contralateral ear tested before and several times after surgery. In 40 patients, a threshold increase was found during the following 9 days. The changes were greatest in the low frequencies immediately after surgery, but after 1 week the treble also became involved. After 3 months, the hearing was normalized. The elder patients more than 50 years of age were more often affected, whereas sex, tumor size, surgical approach or duration of surgery had no influence. The pathophysiological mechanisms are discussed and an intracochlear fluid dysfunction caused by the loss of cerebrospinal fluid is suggested.

Adult↗
PubMedDate not supplied

Otospongiosis and sodium fluoride. A blind experimental and clinical evaluation of the effect of sodium fluoride treatment in patients with otospongiosis.

The effect of sodium fluoride treatment in patients with otospongiosis has been evaluated blindly in a morphological and microchemical element analysis of otospongiotic specimens together with a prospective clinical double-blind, placebo-controlled study. The results show that using the calcium/phosphorus ratio as an indication for bone maturity, the sodium fluoride treatment can stabilize otospongiotic lesions in retaining calcium relative to phosphorus. The clinical double-blind, placebo-controlled study of 95 patients showed a statistically significant worse deterioration of the hearing loss in the placebo group than in the active treated (40 mg sodium fluoride daily) group, supporting the view that sodium fluoride can change otospongiotic, active lesions to more dense, inactive otosclerotic lesions. We have postulated in the past that the actual mechanism of the cochlear loss is toxic enzymes produced by histiocytes at the periphery of the microfoci, and it may be that sodium fluoride has some effect on these enzymes.

Adolescent↗
PubMedDate not supplied

A new concept of vertex ERA and EEG analysis applying inverse filtering.

Evidence for a common anatomical and physiological substrate for the generation of the background EEG and the vertex-evoked response led to the hypothesis that the EEG can be interpreted as the output from a time varying filter driven by (a) a noise generator responsible for the background activity, and (b) a pulse generator creating the evoked response. The characteristics of the filter can be estimated by autoregression. The application of such a model results in considerable theoretical and practical improvements in the detection of evoked responses. Selected averaging on EEGs classified according to the filter characteristics shows improved S/N ratios and considerable diversity between classes. Investigations of an estimate of the input signal to the filter, derived by deconvolution, reveal a sound-evoked potential which is less variable than the response in the EEG. The study concludes that the proposed model and methods have a sufficient applicability and physiological relevance to support further developments.

Audiometry↗
PubMedDate not supplied

Temporal integration of acoustic energy.

Perception of sound shows an increase in loudness related to the duration of the acoustic stimulus. This phenomenon has been studied at threshold (temporal integration) in normal and impaired ears. Normal ears showed an improved threshold with impulse durations up to 200 msec. In cochlear hearing loss, regardless of pathology, the threshold improvement was reduced. A method to evaluate these changes has been designed (Brief Tone Audiometry). When using this method, a quantitative comparison showed the same reduction in temporal integration in ears with hearing loss, regardless of pathology. By using a loudness balance test, the increase in loudness related to prolongation of the stimulus was investigated (Loudness Summation). Loudness growth was measured at various intensities and the results from normal and hearing-impaired ears were compared. At a given sound intensity both normal and hearing-impaired ears showed the same Loudness Summation, which in turn showed a simple relationship to Brief Tone Audiometry in impaired ears. Physiological and diagnostic aspects of these findings are discussed.

Acoustic Stimulation↗
PubMedDate not supplied

Conductive hearing loss evaluated by brief tone audiometry.

Bone-conduction measurements are inaccurate and often troubled by masking problems. Determination of the temporal integration of acoustic energy by Brief Tone Audiometry permits an estimate of the cochlear threshold. In 71 patients with middle ear pathology, the conductive impairment was measured using both conventional audiometry and Brief Tone Audiometry. In 85% of the patients, the estimates coincided within 15 dB. Results from pre- and post-operative measurements are given, and it is demonstrated that Brief Tone Audiometry can be used as an alternative to bone-conduction audiometry to determine the degree of conductive loss with the same accuracy, but without the latter's limitations.

Audiometry↗
PubMedDate not supplied

The effect of neonatal universal hearing screening in a health surveillance perspective--a controlled study of two health authority districts.

The contribution describes the effect of a neonatal hearing screening program in terms of estimated prevalence rate of congenital hearing impairment and age at identification in two five-year cohorts born between 1990 and 1994 as a function of health authority districts (HADs). In addition, identically defined five-year birth cohorts from 1970 to 1974 and 1980 to 1984 living in the same HADs evaluated previously are used in the analysis, offering longitudinal data. In 1990 a non-targetted neonatal hearing screening program based on EOAE was introduced in the County-HAD, whereas the City-HAD continued its child hearing health surveillance program unchanged. Assuming an unchanged prevalence estimate of 1.5 per 1000 of congenital or early acquired (i.e. neonatal period) hearing disability, i.e. > or = 25 dB HL for the better ear at 0.5-4 kHz in both HADs, an underestimate of 68 per cent in the City and of 20 per cent in the County, respectively, was found at the time of data collection (January 1995). Significant longitudinal improvements in the early identification from the 1970-1974 cohort compared to the 1980-1984 cohort has been demonstrated, but the improvement in the proportion of children identified as a function of both 6 and 12 months of age in the 1990-1994 cohort is significantly greater, showing a median age at identification of 11 months in the County-HAD. The cross-sectional and longitudinal comparisons between the HADs imply that a neonatal universal hearing screening program with a 20 per cent coverage may add significantly to the early identification of children with early-onset hearing impairment.

Cohort Studies↗