Biomedical subjects

M Stura

Publications and source records attributed to M Stura.

22 records · Page 2Linked to original sources

PubMedDate not supplied

[The influence of click polarity and stimulation rate on the auditory evoked response in relation to age].

In order to study the changes which occur in phase of the click stimulus and its relation to the stimulus repetition rate on the auditory brainstem response (ABR) as a function of age, the Authors recorded the ABR from the scalp's surface of 10 newborns and 40 infants, 3 months, 6 months, 1 year and 3 years old as well as from 10 normal adults. The stimulus was a square wave of 0.1 msec duration and 90 dBHL level. The stimulus equipment was calibrated twice under visual inspection to ensure that the C and R clicks resulted in an initial membrane deflection toward and from the ear drum respectively. No significant differences could be found for the latencies and amplitude in the C-R comparison. However, the mean values of the complete group of test subjects showed most intraindividual stability for the conventional click stimulation. The latency of the ABR with excitation of the cochlea seemed to be mainly determined by the internal oscillation sequence in the cochlea and not by the stimulus polarity. The amplitudes and latencies of the ABR components tend to decrease when the stimulus rate increases and the age decreases. The importance of the stimulus characteristics is discussed and some suggestions for clinical use of ABR are made.

Acoustic Stimulation↗

PubMedDate not supplied

[Development of auditory evoked potentials of the brainstem in relation to age].

In order to study the various changes which occur in the waveform, latency and amplitude of the auditory brainstem evoked response (BSER) as a function of age, the authors recorded the BSER from the scalp's surface of 20 newborns and 50 infants, 3 months, 6 months, 1 year and 3 years old as well as from 20 normal adults. The data obtained show that the most reliable waves during the first month of life are waves I, III, V, which is often present even when other vertex-positive peaks are absent. The latencies of the various potential components decreased with maturation. Wave V, evoked by 90 dB sensation level clicks, changed in latency from 7, 12 msec at 1-4 weeks of age to 5,77 msec at 3 years of life. The auditory processes related to peripheral and central transmission were shown to mature at differential rates during the first period of life. By the 6th month, in fact, wave I latency had reached the adult value; in contrast, wave V latency did match that of the adult until approximately 1 year old. One obvious explanation for the age-related latency shift is progressive myelination of the auditory tract in infants, for this is know to occur. The authors conclude that the clinical application of this technique in paediatric patients couldn't provide reliable informations about auditory brain stem activity regardless of evaluation of the relationship between age and characteristics of BSER.

Adult↗

PubMedDate not supplied

[Evaluation of auditory function in homozygous beta-thalassemia].

We examined the auditory function of 29 subjects affected by homozygous beta-thalassemia, managed with an high transfusion scheme and regularly treated with 40-60 mg/kg/day of desferrioxamine. A group of 29 healthy subjects is studied as control. We found conductive hearing defect in 8 thalassemics (6 bilateral) and sensory-neural hearing loss at high frequencies in 4. Thalassemic patients showed more auditory impairment than controls, an higher incidence of tonsillar hypertrophy, adenotonsillitis and submandibular lymph-node enlargement.

Acoustic Impedance Tests↗

PubMedDate not supplied

[Ototoxicity following the administration of high doses of cisplatin in children with malignant neoplasms].

CDDP is an antitumor agent which has shown effectiveness in a variety of pediatric and adult solid tumors. Main toxic effects of CDDP involve kidney, bone marrow and ear functions. Recently, CDDP has been used at "high doses" (200 mg/sq m, compared with 90-100 mg/sq m used previously) on the basis of its dose dependent antitumor activity. Ear toxicity might be higher with the "high doses" schedule, and this could be of much importance for younger patients, due the irreversibility of the lesion induced by the drug on the ear structure. In this study, the Authors have prospectively evaluated the ear function in children undergoing treatment with "high doses" CDDP and have compared it with that determined by the drug administered at "traditional" doses. Between september 1984 and march 1985, ten children aged 3-10 years, affected by tumors either resistant to first line therapy or at relapse, were treated with CDDP, 200 mg/sq m divided in five daily doses (days 2-6) (Vincristine, 2 mg/sq m and Cyclophosphamide, 600 mg/sq m, were given on day 1). Six out of ten children had been previously treated with CDDP at "traditional" doses. Acoustic function has been evaluated with tonal audiometry performed before therapy, 2 and 15 days after each cycle of therapy. A deficit was scored mild for levels between 15 and 30 dB, medium for levels between 30 and 60 dB, severe for levels greater than 60 dB. The Audiometry performed in six children who had previously been treated with CDDP at "traditional doses" demonstrated a deficit limited at 8000 Hz in five of them.(ABSTRACT TRUNCATED AT 250 WORDS)

Audiometry↗