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E Arslan

Publications and source records attributed to E Arslan.

At least 55 records · Page 3Linked to original sources
PubMed1981

Habituation and rate effect in the auditory cortical potentials evoked by trains of stimuli.

The effects of the stimulus repetition rate over the habituated auditory cortical evoked responses were studied. The stimulation pattern consisted of trains of pure tone bursts with interstimulus interval (ISI) of 1 s, and intertrain interval (ITI) of 5 s, delivered with constant time and intensity parameters during 93 min. The analysis of the responses was based upon across averaging of the trains, each single response being evaluated in the latency and amplitude parameters. Two time-dependent factors affected the responses in a distinct way: the habituation throughout the whole stimulation and the rate effect within the train. The linear regressions of the time/amplitude functions of the responses were calculated in relation to the duration of ISI and ITI. By introducing a correction factor depending on the repetition rate it was possible to evaluate the relationships between habituation and repetition rate. Changes in the repetition rate do not have any effect on the habituation process. The two phenomena are completely distinct, and they probably have neurophysiologic substances corresponding to different levels in the central nervous system (CNS).

Acoustic Stimulation↗
PubMed1981

The auditory brainstem response to binaural delayed stimuli in man.

The brainstem responses (BER) evoked by binaural clicks (0.1 ms) with interaural time differences (delta t) from 0 to 3.5 ms were studied in 6 normal subjects. The responses analysis was carried out via computer in two different ways: (a) Comparison between binaural BER and templates obtained with the addition of two monaural BERs. (b) Extraction from the binaural BER of the second delayed pattern. The results suggest that an algebraic addition of the responses from the two stimulated sides is the main mechanism of the binaural BER generation. In comparison with the templates, the binaural response shows some differences which are evident at delta t = 0--1.5 ms and are limited in the region of VI and VII waves. Such differences are caused essentially to an amplitude decrease of the second pattern--that is response to the delayed stimulus--mainly at delta t 1.5 ms. However these results do not allow us to say if the phenomenon recorded at the surface is due to central adaptation or to specific mechanism of binaural interaction.

Acoustic Stimulation↗
PubMed1981

Phonometric approach to the analysis of cardiac acoustic phenomena.

The use of phonocardiography is limited by the lack of standardization of acoustical signal pick-up and of the filters. Moreover, quantitative evaluations are not possible. This limits the analysis of acoustic phenomena and makes confrontation between different laboratories impossible. To avoid these drawbacks we have developed a method based on phonometric principles. Heart sounds of twenty for normal subjects were recorded by an air-coupled microphone with the standard 6 ml cavity. The response curve of the microphone is flat from .2 to 8000 Hz. The signal was measured and stored on an analogic tape recorder together with the ECG. For each subject the 3 weighting networks (A, B and C, according to the American National Standard Institute) and the linear recording (SPL) were used and the peak value of every record was written down in dB-peak. The amplitude spectra were obtained through the FFT algorithm. Normal heart sounds reached a high frequency limit of 170 Hz. with a maximum amplitude of 67 dB SPL, 24 dB A, 42 dB B and 59 dB C. Each spectral pattern can provide a useful reference to compare with pathological acoustical findings.

Adolescent↗
PubMed1980

[Spectral analysis of a "sea gull cry" murmur (author's transl)].

"Precordial honk" is a loud, high pitched, musical and usually intermittent systolic noise. The concept of extracardiac origin and "inocence" of this finding is superseded and today its valvular origin during mitral prolapse, mitral or tricuspidal insufficiency - due to rheumatic or ischaemic disease - or during cardiomiopathy is demonstrated. The acoustic characterization of this finding was based on phonocardiographic registration. All the authors describe the "precordial honk" as a high frequency murmur without specifying the acoustic characteristics of the phenomenon. A spectral analysis technique applied to the acoustic cardiac signal (Fourier analysis) has been employed in order to study the "precordial honk" of a 15-year-old boy with mitral valve prolapse. This made possible to show that this sound had only one fundamental frequency at 300 Hz. without harmonics; a "sea gull cry" murmur (as the cry of many birds is) justifying the name given by clinicians. The spectral analysis of phonocardiography signal allow to study, more precisely, the cardiac acoustic phenomenon.

Adolescent↗
PubMed1979

The fast Fourier transform in the analysis of the normal phonocardiogram.

The present study is focused on spectrum analysis as a useful method of processing the PCG in order to obtain the frequency spectral distribution of normal heart sounds. Thirty normal subjects aged from 17 to 34 were studied. PCG was recorded on the fourth intercostal space at the left sternal border using a sound level meter coupled with a standard 6 ml cavity. The microphone had a linear response from 0.2 to 8,000 Hz. The signal was filtered with the standard B network according to the ANSI specifications and was registered on a four track FM tape recorder. A four channel analyzer with a microprocessor for off-line elaborations was used with 10 KHz sampling frequency. The PCG signal was triggered by a QRS detector on the R wave of the simultaneously recorded ECG. Fast Fourier transform was performed employing either a four channel analyzer with a microprocessor, or an A/D converter with a computer. Finally the results of the analysis were statistically elaborated. The described procedures permit to obtain a direct and exact tracing of the acoustic features of the heart, thus representing an attempt to come closer to the standardization and automatic analysis of the phonocardiographic technique.

Adolescent↗
PubMed1979

[Technical and methodological aspects concerning the application of Fourier's analysis to phonocardiography (author's transl)].

The frequency spectrum analysis (Fourier's analysis) has recently been applied to phonocardiography. Using this mathematical approach instead of the current empirical analysis, it is possible to obtain -- on a less subjective basis -- more precise pathophysiological and diagnostic information from the acoustic cardiac phenomena. On the other hand, this refinement of the method of analysis stresses the need for better technical and methodological solutions, in order to reach the standardization of both the transduction and the recording of the acoustic signal at higher level of sensibility, fidelity and reproducibility. With this in mind, and on the basis of their experience, the Authors suggest the adoption of devices with specific technical characteristics, and propose a suitable method of application of Fourier's analysis to the phonocardiogram.

Fourier Analysis↗
PubMed1977

[External recording of His bundle electrical activity (author's transl)].

A noninvasive method to record His' potentials in man is described. In several patients who needed intracardiac recording, a bipolar lead was placed across the chest, directed as conveniently as possible for the recording of His bundle electrical activity. A signal filtered (70-300 Hz) and amplified (X 100.000), was processed by a multichannel analyzer for averaging. The temporal regime of the averager was determined by a trigger which established a fiducial point on the ECG. For this purpose a QRS detector fed to a normal peripheral bipolar lead was used. The temporal stability of the system was continually checked in order to reject the recordings over the limits of +/- 1 msec. The computer program was chosen in order to select a window (usually 200 msec) which occurred up to 150 msec prior and 50 msec after the trigger signal. The sampling rate was 5 KHz for 1024 samples and the sweep counts were fixed from 128 to 512. At the same time, the D1, D2 and D3 were recorded in the other three channels of the analyzer for a more accurate measurement of the HV interval. Then an example comparing the external and interval recording was presented. Finally several external recordings were measured and the exact reproducibility of the G wave was confirmed. In conclusion we can say that the G wave is significant and suggests the electrical activity of the bundle of His.

Bundle of His↗
PubMedDate not supplied

Electrocochleography potentials evoked by condensation and rarefaction clicks independently derived by a new numerical filtering approach.

The cochlear microphonic potential (CM) and the compound action potential (CAP) cannot be measured separately but only in combination. In the literature their individual estimates are conventionally recovered by the so-called CM cancellation technique. This method averages the potential obtained in response to rarefaction and condensation clicks under the assumption that changing the polarity of the clicks only affects the CM sign and does not alter the CAP in any way. However, both theory and evidence suggest that these hypotheses can be critical. In addition, recent contributions in the electrocochleography (ECochG) literature suggested that assessing the influence of stimulus polarity on the evoked CAP may constitute an indicator of clinical usefulness which the CM cancellation method cannot supply. In this work we propose a new algorithm to estimate the cochlear potentials evoked from positive clicks, CAP+ and CM+, and those evoked from negative clicks, CAP- and CM-, by processing the same kind and amount of data employed in the CM cancellation method. The application to real data taken from 3 subjects exhibiting quantitatively and qualitatively different ECochG responses at various levels of stimulation intensity is presented. In addition, simulated problems where the true CAP and CM are known are studied to permit a fair assessment of the proposed technique. Results suggest that the new algorithm is potentially able to point out small differences between CAP+ and CAP-. This encourages its further employment on a larger scale.

Audiometry, Evoked Response↗
PubMedDate not supplied

Bilateral complete avulsion of ocular globes in a Le Fort III maxillofacial fracture: a case report and review of the literature.

PURPOSE: The purpose of this paper is to demonstrate a case of bilateral complete avulsion of the globes following maxillofacial trauma. METHODS: A 23-year-old man with bilateral complete globe avulsion following a maxillofacial trauma. Both globes were luxated out of the orbit and suspended on the skin of the upper lid below the brows. No direct or indirect light reflexes or any eye movements could be noted. Computerized tomography showed complete lacerations of both optic nerves at a level just anterior to the optic canal. There were also multiple fractures corresponding to Le Fort III fracture with Le Fort II components. The brain parenchyma was normal with an exception of brain edema. As the globes were unsuitable for repositioning, both were enucleated. The maxillofacial fractures were immobilized with plates and screws. Although the patient gained consciousness with normal vital signs in the early postoperative period, he died on the ninth day due to Pseudomonas aeruginosa infection, despite invasive antibiotic treatment. DISCUSSION: The optic nerve and the globes are very resistant to mild and moderate trauma. The avulsion of the nerve at the canalicular or more posterior level may demonstrate central nervous system complications resulting in life-threatening conditions. The most critical issue in complete globe avulsions with a transected optic nerve is to rescue the vision. In total transected optic nerves the final eyes could only have had cosmetic benefits. In spite of promising experimental research on optic nerve regeneration, there are unknowns, such as the methods to eliminate the risk of anterior segment ischemia and phthisis bulbi. CONCLUSIONS: Globe avulsions with a complete optic nerve cut remain a challenging problem. More research is required to better understand the pathophysiology of optic nerve repair.

Accidents, Traffic↗
PubMedDate not supplied

The behaviour of wave V latency in cochlear hearing loss.

The audiological approach to the early diagnosis of cerebellopontine angle tumours (APC) is based mainly on ABR. In present work, wave V latency has been studied in two groups of patients: 308 cochlear cases and 74 retrocochlear cases (APC surgically confirmed tumours), in order to increase the sensitivity and specificity of the diagnostic indexes I-V, IT5 and Delta V. Wave V latencies have been evaluated in relation to hearing loss at 2-4 kHz and audiometric profile. Both these factors show a highly significant positive correlation with the latency, which consequently increases proportionally to hearing loss and high-frequency audiometric loss. A multiple regression analysis was therefore used to analyse the effects from the two variables, and a correction factor was calculated to compensate the latency values for hearing loss and threshold configuration. The effects of such a correction on the clinical results consist mainly of a reduction in the rate of cochlear false-negative results, which corresponds to improving the ABR specificity.

Audiometry, Evoked Response↗
PubMedDate not supplied

[Quantitative abnormalities in nystagmus induced by caloric stimulation in multiple sclerosis].

Vestibular nystagmus induced by caloric stimulation (20 degrees and 44 degrees C) was evaluated in terms of duration, frequency and slow phase velocity in 80 patients suffering from clinically defined multiple sclerosis. Criteria of abnormality were established with reference to 3 confidence levels from normative data of a 15-subject control group. Abnormal data representative of vestibular hypo- and hyperreflexia were found ranging between 27 and 53% depending on different parameters and diagnostic criteria. Significant differences in occurrence of nystagmus abnormalities became evident by analyzing 6 different windows of the vestibular response. Different distributions of hypo- and hyperreflexia were observed in relation to the time-course of the normal cumulative response curve, as well as to different stimulus temperatures. For each subject the abnormal data of the 2 stimulated ears X 2 caloric stimulations X 6 analysis windows were cumulated, yielding an overall outcome of pathological results in 66% to 90% of the patients, depending on the different diagnostic criteria.

Adolescent↗