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Biomedical subjects

R Albera

Publications and source records attributed to R Albera.

49 records · Page 3Linked to original sources
PubMedDate not supplied

[The measurement of cochlear flow by laser Doppler in man: the preliminary results].

Laser-Doppler flowmetry is presently one of the methods of choice in measuring cochlear blood flow. The techniques is non-invasive and is based on the frequency shift of the laser beam induced by the red blood cell movement. Previous studies of cochlear blood flow carried out on animals and humans demonstrated the reliability of laser-Doppler flowmetry and its usefulness in understanding inner ear microcirculation physiology. In this paper we present preliminary data obtained from three patients examined under general anesthesia while undergoing tympanoplasty. Results showed that tracings, whose baseline is proportional with the blood flow, are characterized by waves correlated to pulse beat and automatic ventilation. Moreover, intrinsic contractions of inner ear vessels (waves of vasomotion) as exist in cerebral microcirculation, were observed. Pharmacological hypotension hypocapnia and the application of epinephryne determine a significant reduction of cochlear blood flow. These results suggest that while cochlear blood flow is related to systemic pressure, it has an intrinsic control system. As well since we did not obtain any modification in bone conduction threshold after surgery, we conclude that laser-Doppler flowmetry is a safe technique.

Adolescent↗
PubMedDate not supplied

[Identification of the waveform of cortical auditory evoked potentials].

Slow vertex response (SVR) audiometry is presently one of the methods of choice in objective auditory threshold assessment. The aim of this study, carried out on twenty subjects with various degrees and types of hearing loss, was to evaluate the difficulties found in N1P2 complex identification. Tracings, presented as single averages and super-imposed averages, were examined separately by two Authors who had not been received any information concerning the audiometric thresholds of the subjects under investigation. Results showed that erroneous identification of SVR waveforms occurred frequently, especially near threshold level. The rate of false negatives (i.e. a waveform present but not identified) was higher than the rate of false positives (i.e. erroneous identification of a non-existing N1P2 complex). High intra- and interindividual discrepancies were also found. Our results appear to indicate that the SVR waveform is not easily identifiable and thus that SVR audiometry cannot, therefore, be considered a truly objective audiometric test since analysis of the tracings may be influenced by the high degree of variability in individual interpretation.

Adolescent↗
PubMedDate not supplied

[Relations between pure-tone audiometry and cortical evoked auditory potentials].

Slow vertex response (SVR) audiometry is presently one of the methods of choice in objective auditory threshold assessment. The aim of this study was to evaluate, as objectively possible, the relationship existing between the thresholds of SVR and or pure tone audiometry (PTA). The study was carried out on twenty subjects with hearing losses of various degrees and types. While mean differences between SVR and PTA thresholds ranged between 6 to 13 dB, in some cases values over 30 dB were found. No statistically significant intra- and interindividual discrepancies were found, even though in some cases the thresholds were given different in evaluations by different examiners. No statistically significant difference in SVR versus PTA thresholds was found in patients with sensory-neural and conductive hearing loss, while in subjects with normal hearing the difference between the thresholds was greater. Our results suggest that SVR is a reliable technique in objective threshold evaluation but that in single cases its threshold cannot be directly compared to that of pure tone audiometry.

Audiometry, Pure-Tone↗
PubMedDate not supplied

[Transcranial magnetic stimulation of the facial nerve: evaluation of a new method in neurophysiological study of Bell's palsy].

Transcranial magnetic stimulation is a new technique used to stimulate brain areas as well as peripheral nerves in healthy, waking persons. To date this technique has appeared safe. The aim of the present study was to assess the clinical application of this method in patients with Bell's palsy. Electromyographic responses were elicited by electrical and magnetic transcranial stimulation of the facial nerve in 26 patients affected by Bell's palsy. Electrical stimulation: stimuli of 0.1 ms duration, and up to 15 V, were delivered through surface electrodes set 2.5 cm apart over the facial nerve at the stylomastoid foramen. Magnetic stimulation: the coil was placed tangent to the parieto-occipital surface of the scalp. The stimulus intensity was then increased stepwise until a supramaximal response was obtained. Recording: the focal recording electrode was placed ipsilateral to the side stimulated over the superior orbicularis oculi; the reference electrode was placed over the nasal bone. The patients were tested with two neurophysiological determinations: the first 15-30 days from the onset of the palsy; the second 30-60 days after the first. A clinical follow-up was performed six months after the second determination. The results indicate that, contrary to traditional electroneurography, transcranial magnetic stimulation is not able to supply useful neurophysiological indications in patients with Bell's palsy. Although the absence of compound muscle action potential upon stimulation of the side with the lesion did demonstrate some impediment to conduction, it did not have any prognostic value since it was also present in patients who were clinically well at the time of the second check-up.

Adult↗
PubMedDate not supplied

[Modified Semont's maneuver in the treatment of benign paroxysmal positional vertigo].

Benign paroxysmal positional vertigo (BPPV) is one of the most frequent causes of vertigo. It is characterized by a peripheral balance impairment which occurs during specific movements or positions of the head. The etiology of BPPV is not clear although recent studies by Harada have given more weight to the otolithic theory. The present author has found frequent otoconia attached to the dark cell area around the crista of the semicircular canals. The treatment of BPPV is based on functional re-education of the patient (Semont maneuvers, the Brandt Daroff technique, Norre's V.H.T). The present study involves 62 patients affected by BPPV. The Hallpike maneuver was employed to define the affected side and then the modified Semont maneuver was performed. Recovery was obtained in all patients. The cure rate proved to be 82% after the first examination. The modified Semont maneuver is easier to perform than the traditional maneuver and has given excellent therapeutic results.

Adolescent↗
PubMedDate not supplied

[Smooth pursuit eye movements evoked by head-phone acoustic stimulation].

Smooth pursuit eye movement evoked by binaural acoustic stimulation is examined in the present work. The effect of lateralization was achieved by modulating the interaural difference in intensity, within the headphone, following a pendular pattern. The test was performed on 10 healthy subjects; oscillation frequencies of the acoustic target being 0.15, 0.5 and 0.83 Hz, stimulus intensity 65 and 92 dB SPL. The acoustic signal consisted of white noise. Each trial was performed with eyes closed and then with eyes open. The results demonstrate that sinusoidal eye movement can only be obtained in a few subjects when the acoustic target has the lowest velocity and especially at the higher intensity. In all other cases eye movement was characterized by multiple saccades. The variability in eye movement amplitude is reduced and the value of this parameter decreases significantly under open-eye conditions. The data obtained are in agreement with other reports obtained with free field acoustic stimulation and demonstrate that smooth pursuit eye movement is principally an ocular reflex. In conclusion, acoustic smooth pursuit eye movement appears normally to be characterized by multiple saccades whose pattern can be modulated by intensity and oscillation frequency of the acoustic target as well as by the presence of visual inputs and attentional factors.

Acoustic Stimulation↗
PubMedDate not supplied

[Behavior of 8000 Hz audiometric threshold in chronic acoustic trauma].

The paper analyzes the 8 KHz threshold in subjects with noise-induced hearing loss. The study group consisted of 315 subjects occupationally exposed to noise and suffering from acoustic trauma, which was considered as a mean threshold of more than 25 dB at 2, 3 and 4 KHz. The mean shape of audiograms was characterized by a neurosensory deficit which was more elevated at 4 and 6 KHz whereas the threshold at 8 KHz was better. However, this pattern was found in 60% of the cases whereas in the remaining 40% the threshold at 8 KHz was worse. Subjects with the most impaired audiometric threshold at 8 KHz were mainly older, although cases were found in a low percentage of younger subjects. The results demonstrate that in individual cases it is impossible, on the basis of the shape of the audiogram, to establish whether a hearing loss is due to noise or age.

Adolescent↗
PubMedDate not supplied

[Relationship between auditory disability and auditory threshold in acute acoustic trauma: pilot study].

The aim of this study was to determine the relationship existing between auditory disability, according to WHO 1980, and pure tone audiometry threshold in noise induced hearing loss. Disability was evaluated on the basis of a questionnaire submitted to 286 subjects with acoustic trauma. Answers obtained were considered reliable on the basis of statistical analysis. Results showed that subjects with disability have an higher pure tone threshold than subjects without auditory disability. However it appears difficult to determine a precise threshold level ever which auditory disability may be considered present. The Authors suggest that this limit could be determined on the basis of pure tone threshold at the 10th centile of the group of subjects with disability or at the 90th centile of subjects without disability.

Adult↗
PubMedDate not supplied

[Determination of the onset of occupational hearing loss].

The paper examines the different aspects of the diagnosis of noise induced hearing disability and handicap. In the author's opinion a diagnosis of this kind can be made only if both an occupational acoustic trauma and a hearing disability or handicap are present. An occupational acoustic trauma can be considered to be present if the subject works in a noisy environment, if there are no auditory diseases other than of occupational origin, and if the audiometric threshold is neurosensorial, bilateral, more elevated at the higher frequencies and higher than the threshold of subjects on the same age but not exposed to industrial noise. On the other hand, the authors deem that there is a loss of hearing function when hearing disability and handicap are present according to the WHO definition. An experimental model is proposed that will establish the presence of hearing disability and handicap.

Audiometry↗
PubMedDate not supplied

[Course of the audiometric threshold in relation to the age in chronic acoustic trauma].

Until now the relationship between auditory threshold and age has been evaluated in normal subjects only. In this study the Author reports results obtained in a cross-sectional study on 416 subjects suffering from noise-induced hearing loss who were exposed to noise for 10 years at least. The results show that hearing loss over time was more correlated to age than to noise exposure. Moreover, the evolution of hearing loss over time had a linear shape while in noise-induced hearing loss evolution has a logarithmic shape and in presbyacusis it has an exponential shape. The differential threshold between 30 and 60 years obtained by applying the linear regression model was, at higher frequencies, significantly reduced compared to normal subjects. These results suggest that threshold values related to age obtained in normal subjects can not be applied in subjects affected by noise-induced hearing loss.

Adult↗