Biomedical subjects
Publications and source records attributed to A Quaranta.
The effect of diazepam (10 mg i.m. X 7 days) on crossed and uncrossed acoustic stapedius reflex parameters (threshold, amplitude and duration) has been studied in 7 normal hearing subjects. The results showed that diazepam has a not clinically significant damping effect on the threshold, the amplitude and, very often, the duration of both ipsilateral and contralateral acoustic stapedius reflexes.
Vibrotactile evoked responses (VER) to 250 and 500 Hz presented respectively at 50 and 70 dB HL by BC vibrator placed on right thumb, were recorded in 20 children (10 with pathological EEG) with severe sensorineural hearing loss, or deaf since birth, both to control accuracy of cortical responses to high intensity auditory stimuli and to diagnose central non auditory pathways lesions. The results have shown that: VER are present in subjects with severe sensorineural hearing loss or deaf; in children with auditory lesions VER have parameters different from auditory evoked response (AER); VER recording is not related both to the presence of auditory lesions and to neurological pathology.
Remote masking (RM) consists of a rise of the threshold for low-pitched tones when the ear is exposed to a high-frequency noise band delivered with high intensity. This phenomenon has been attributed to mechanical non-linear distortion of the cochlear partition, as an effect of the envelope of a non-uniform signal. The authors studied RM in patients suffering from unilateral Menière's disorder, acoustic neuromata, other sensorineural lesions and presbyacusis. The behaviour of RM in the different experimental groups shows that the RM value is normal in acoustic neuromata; it is variable and not related to the severity of the hearing loss in sensorineural losses, and it is reduced in the affected ear in patients suffering from Menière's disorder. Finally, RM is reduced as a function of ageing, progressively and symmetrically in both ears in presbyacusic subjects. The results of the research seem to confirm the hypothesis that RM may be due to mechanical effects in the inner ear and suggest the possibility of using RM as a test of cochlear partition rigidity.
The authors have studied the relations between crossed and uncrossed acoustic stapedius reflex thresholds in presbyacusic subjects in order to verify whether ageing produces brain stem auditory lesions. The results showed in 55% of the presbyacusics a brain stem disorder characterized by the absence of one, several or all the acoustic reflexes; very often there was only an abnormal difference between crossed and uncrossed acoustic reflex thresholds.
Remote Masking (RM) (a rise in threshold for low-frequency tones when the ear is exposed to a high intensity noise band of high frequency) has been attributed to mechanical nonlinear distortion of the cochlear partition, as an effect of the envelope of a nonuniform signal. Clinical studies using RM have revealed RM is normal only when both the endolabyrinthine pressure and the cochlear hydrodynamics are normal. Increasing the stiffness of the cochlear partition affects adversely the mechanism of motion of the cochlear duct and reduces RM values. We studied RM in normal young Ss and in patients with presbycusis in order to determine whether aging of the inner ear also induces stiffness of the cochlear partition. In presbycusic Ss the RM values were indeed reduced symmetrically in both ears and progressively as a result of aging. Thus RM demonstrates the existence of cochlear conductive presbycusis and can be considered a useful test of stiffness of the cochlear partition.
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The relationship between the tonal masking level difference performance and the behavior of the "sensitized speech tests" according to Bocca and Calearo, were studied in subjects with normal hearing who were suffering from CNS diseases. The results have shown that pathological masking level difference values are present in all cases with pathological sensitized speech tests, and are related principally to the following two conditions: (1) the bulbo-pontine lesions and (2) the central hearing functional asymmetry. In subjects with normal hearing who have CNS diseases, pathological tonal masking level differences indicate the existence of central hearing pathways lesions.
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