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Biomedical subjects

M Stecker

Publications and source records attributed to M Stecker.

12 recordsLinked to original sources
PubMed1996

Functional magnetic resonance imaging of regional brain activity in patients with intracerebral gliomas: findings and implications for clinical management.

Functional magnetic resonance imaging (fMRI) was performed in seven patients harboring intracerebral gliomas proven by histological analysis using a noninvasive blood oxygen level-dependent technique based on the documented discrepancy between regional increases in blood flow and oxygen use in response to regional brain activation. We combined fMRI with conventional magnetic resonance imaging (MRI) during motor or language task activation experiments to investigate the potential usefulness of mapping regional brain activity as part of treatment planning in patients with intracerebral gliomas, in whom preservation of areas of functioning brain tissue is critical. Statistical fMRI maps were generated and directly mapped onto conventional MRI scans obtained at the same session. Of the five patients cooperative enough to remain motionless for the study and perform the task, the location of activation in the primary sensorimotor cortex on the side of the tumor was clearly displaced compared with that in the normal contralateral hemisphere in four patients. Four of the five tumors in these patients showed fMRI activation within the periphery of (or immediately adjacent to) areas of presumed tumor based on spin-echo MRI. In some patients with neurological deficit, the extent of activation was reduced on the side of the tumor as compared with the normal hemisphere. The supplemental motor area and the ipsilateral primary motor cortex were also reproducibly activated during motor tasks. We conclude that blood oxygen level-dependent fMRI can localize areas of cortical function in patients undergoing treatment planning for gliomas so that therapy can be directed away from regions of residual function. Our preliminary data suggest that functioning cortex within or adjacent to tumor margins can be demonstrated, which may correspond to partial preservation of clinical function. Our preliminary data also suggest that there may be a quantifiable difference on fMRI between activation in tumor-bearing cortex and activation in corresponding normal cortex in the contralateral hemisphere. We postulate that the magnitude of this difference may relate to the severity of patient deficit.

Adolescent↗
PubMed1996

Use of positron emission tomography and evoked potentials in the detection of cortical afferents from the gastrointestinal tract.

OBJECTIVE: Positron emission tomography permits precision identification of the cerebral regions involved in physiologic functions. As the cerebral localization for visceral sensation has not been identified, our aim was to examine the cerebral viscerotopic representation for rectal sensation. METHODS: Cerebral-evoked potentials were measured in five healthy volunteers who underwent rectal balloon distension. Simultaneously, cerebral blood flow was measured using positron emission tomography with 15H2O. RESULTS: A cerebral-evoked potential occurred with rectal balloon distension. An increase in cerebral blood flow was noted in the pre- and postcentral gyrus and the thalamus. CONCLUSION: The techniques for measuring cerebral-evoked potentials and cortical blood flow are useful in the delineation of the cerebral regions subserving visceral sensation.

Brain↗
PubMed1995

[Screening program for selection of hearing loss in newborn infants instituted by the European Community].

Early identification of hearing impairment in children poses a major problem for clinical research and development. In the last two years we determined the hearing sensitivity of 1202 newborns, small infants and children. 52.4% of the children exhibited risk factors for hearing impairment in their medical history. The majority of children was referred to our department by pediatricians (52%), who first suspected hearing impairment, 40% by parents, 3.5% by otolaryngologists, 3% by educators, and 1.5% by general practitioners. The following examinations were performed: transiently evoked otoacoustic emissions (TEOAE), impedance audiometry, auropalpebralreflex, behavioral observation audiometry, and, if necessary, auditory brain stem response (ABR) with air and bone-conducted clicks as well as frequency-following responses at 500 Hz tone burst. In 378 children TEOAE were recorded on both sides, in 151 at least on one side. These results were confirmed by the other techniques. Only three children presented false negative results of TEOAE on one side. Two of these children had a middle ear effusion and a threshold of 35 dB, one had retrocochlear hearing loss. The absence of TEOAE in both ears in 155 children as well as in one ear in 16 children was detected by ABR. Seventy-seven patients showed no response on both sides, 25 on one side, although a hearing impairment more than 25 dB could not be verified by ABR. This high number of false positive results is explained in 77 cases (76%) by a middle ear dysfunction during the recording of TEOAE, when ABR was performed following adenotomy and paracentesis.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1994

Sexual dysfunction in partial epilepsy: a deficit in physiologic sexual arousal.

Men and women with epilepsy frequently complain of sexual dysfunction. We studied the sexual response in men and women with partial epilepsy of temporal lobe origin (TLE) by measuring genital blood flow (GBF) during sexual arousal. Nine women and eight men with TLE and 12 women and seven men as controls completed inventories for symptoms of depression, sexual experience, and sexual attitude and underwent measurement of digital pulse and GBF during alternating segments of sexually neutral and erotic videotape. Subjective ratings of arousal to the videotape were obtained. We calculated digital pulse and GBF response as the percentage increase in pulse amplitude during the erotic compared with the preceding sexually neutral film. No subject group reported symptoms of significant depression on the inventory. However, men and women with epilepsy had fewer sexual experiences than subjects without epilepsy, and women with epilepsy imagined specific sexual activities to be more anxiety-producing and less arousing than did women without epilepsy. Men and women with TLE had a diminished GBF response. The mean increase in GBF in men with TLE was 184% versus 660% for controls (p = 0.01). Women with TLE had a mean increase of 117% versus 161% for controls (p < 0.01). Digital pulse did not vary across stimulus conditions. Subjective ratings for all groups indicated moderate sexual arousal. We conclude that there is a diminution in one aspect of physiologic sexual arousal in some men and women with TLE.

Adolescent↗
PubMed1990

[In situ measurements for determining the effect of additional boring of the earmold].

To investigate the effect of earmould venting on the insertion gain of hearing aids in patients' ear canal, the authors sealed 35 earmould ventings with soft silicone after measurement under normal conditions and repeated the measurement. The size of the ventings varied from 0.8 mm to 3.5 mm in diameter. The results show the expected SPL-reducing effect of the ventings between 500 Hz and 1,000 Hz. Below 500 Hz the effect found was only slight, because of the low amplification in this frequency range. Above 1 kHz an increasing sound pressure level was measured as a result of resonance effects. This study illustrates the effect of earmould venting on insertion gain. To improve the hearing aid fitting the earmould venting should be used, deliberately and specifically, far more often than at present. The resulting effects of earmould modifications of real ear gain can only be determined by in situ measurements on the patient's eardrum. This method also enables resonance to be compensationed for in a controlled manner.

Audiometry, Pure-Tone↗
PubMed1988

[Evoked response audiometry in pediatric audiology].

Since we know that maturation of the hearing system occurs within the first few weeks after birth, audiologic testing should be performed as soon as possible whenever there is the slightest suspicion of a hearing disorder. The only reliable test method in this early period of life is the electric response audiometry. To use the advantages of this objective test method, several criteria must be observed. The most important of these are: 1. good sedation, 2. sufficient test routine comprising not only clicks but also 500 Hz pulses and bone-conducted stimuli, and 3. sufficient experience in the interpretation of the various recorded response patterns. Comparing subjective and objective results in 533 children, the ERA proves to be the more reliable and effective method giving extensive information on the hearing threshold and the dynamic response of audition and allowing an exact control and correction of the hearing aid adjustment.

Audiometry, Evoked Response↗
PubMed1986

[Preliminary studies of deaf patients assessed for cochlear implantation].

Two techniques were employed to assess the suitability of deaf patients for cochlear implantation: electrical stimulation by means of ear canal electrode and promontorium electrode. The results of the ear canal tests indicate that the patients may be divided into three groups: I. non-usable dynamics, II. usable dynamics in low-frequency range, and III. usable dynamics over a wider frequency range. Comparable results were obtained via the promontory tests. Since the promontory tests showed a more accurate description of the subjective sensations, it is recommended that this test be performed with those patients who have been preselected on the basis of ear canal stimulation.

Auditory Pathways↗
PubMed1983

[Problems of electric response audiometry in practice].

In recent years Electric Response Audiometry (ERA) has become a valuable method in the clinical audiology. However, there are two specific problems that make Electric Response Audiometry more complicated than other hearing tests. First, the evaluation of the averaged signals is subjective, and in some cases the distinction between response signals and remaining electrical background noise or artifacts may be rather difficult. The second problem concerns the interpretation of response signals. As there is no simple but only an ambiguous relation between response parameters and the different types of hearing disorders, again, it depends on clinical experience and knowledge to avoid misinterpretations and to arrive at a reliable diagnosis.

Audiometry↗
PubMed1982

[Objective hearing aid fitting].

In many cases speech and pure tone audiometry are not practicable. Therefore, the hearing aid fitting is based on objective techniques, like the measurement of the stapedius-reflex threshold or acoustically evoked neural responses. In particular, brain stem responses are very helpful for an objective hearing-aid fitting. They represent the full scale of hearing dynamics and supply direct information for selection and adjustment of the hearing aid. Control of the fitting can also be effected directly by measuring brain stem responses.

Acoustic Stimulation↗