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Biomedical subjects

C B Pedersen

Publications and source records attributed to C B Pedersen.

At least 55 records · Page 3Linked to original sources
PubMed1999

The low-power laser in the treatment of tinnitus.

The purpose of this study was to evaluate the low-power laser on the treatment of tinnitus. In a randomized, prospective, double-blind, placebo-controlled trial, either active or placebo low-power laser irradiation was given through the external acoustic meatus of the affected ear towards the cochlea. The active laser applied 50 mW (cw, 830 nm) over a period of 10 min per session. Forty-nine patients with severe, chronic uni- or bilateral tinnitus were studied. The main outcome was measured using psychoacoustical match of tinnitus loudness and pitch, Visual Analogue Scale (VAS) ratings of subjective loudness, annoyance and attention involved, scores on the Tinnitus Handicap Inventory (THI), the Tinnitus Coping Style Questionnaire (TCSQ), and a number of psychosocial questionnaires. The results showed only moderate (18%) subjective improvement with no statistically significant differences between the effects of the active laser and placebo treatments. Also, there were no statistically significant differences in prepost measurements of tinnitus loudness, VAS scores, THI scores, or TCSQ scores for patients treated with active laser compared with those treated with placebo. We conclude that low-power laser treatment is not indicated in the treatment of tinnitus. Reports of significant benefits of this treatment in previous, mostly uncontrolled or single-blinded studies may be explained by the placebo effect.

Adaptation, Psychological↗
PubMed1999

Stimulus-dependent central processing of auditory stimuli: a PET study.

Positron emission tomography (PET) was used to investigate the neural systems involved in the central processing of different auditory stimuli. Noise, pure tone and pure-tone pulses, music and speech were presented monaurally. O-15-water PET scans were obtained in relation to these stimulations presented to five normal hearing and healthy subjects. All stimuli were related to a basic scan in silence. Processing of simple auditory stimuli, such as pure tones and noise, predominantly activate the left transverse temporal gyrus (Brodmann area [BA] 41), whereas sounds with discontinued acoustic patterns, such as pure-tone pulse trains, activated parts of the auditory association area in the superior temporal gyri (BA 42) in both hemispheres. Moreover, sounds with complex spectral, intensity, and temporal structures (words, speech, music) activated spatially even more extensive associative auditory areas in both hemispheres (BA 21, 22). PET has revealed a remarkable potential to investigate early central auditory processing, and has provided evidence of the coexistence of functionally linked, but individually active parallel and serial auditory networks.

Acoustic Impedance Tests↗
PubMed1998

[Vestibular schwannoma. Incidence of the disease and the consequences].

During the period 1977-1996 142 vestibular schwannomas in 138 patients in a well-defined population in the County of Aarhus, Denmark were registered. The incidence of vestibular schwannomas changed from approximately six tumours pr. million inhabitants in the years 1977-1981 to 18 tumours pr. million in the period 1992-1996. Most tumours were operated, a smaller group of vestibular schwannomas were observed by repetitive tomographic imaging, due to small tumour size, advanced age, poor health conditions or the patient's refusal of operation. Whether the strategy for the treatment of vestibular schwannomas is an immediate operation or observation of selected patients, the future management of the increasing number of vestibular schwannomas will require an extension of the present surgical and MR-imaging capacity.

Adolescent↗
PubMed1998

Acute mastoidectomy in a Danish county from 1977 to 1996 with focus on the bacteriology.

To evaluate if the nature of acute mastoiditis (AM) treated surgically has changed during the last 20 years (1977-1996), the data from patients undergoing acute mastoidectomy were examined retrospectively. Cases with cholesteatomas and intracranial complications were excluded, while 79 patients (48% male) with a median age of 16 months were included. There was a history of infectious middle ear disease in 37% and the mean duration from onset of symptoms to admission was 9 days. The well-being was affected in 46 and 82% had fever. Purulent middle ear effusion was recognized in 92%. A subperiosteal abscess in 66% of the ears peroperatively. Specimens yielded growth of pathogens in 58%, predominantly gram positive bacteria, fully or partially sensitive to penicillin. Antimicrobial treatment before admittance masked or reduced more symptoms significantly. The patients from the last 10-year-period had less frequently acute otitis media in their history, shorter duration of hospitalization, and more frequently haemolytic Streptococcus group A. Conclusively, AM affects especially infants without previous middle ear disease. The clinical picture has become more subtle in time, probably due to antibiotics, and concomitantly the bacteriological pattern has changed.

Acute Disease↗
PubMed1997

The size of acoustic neuromas: CT and MRI.

The growth rate of acoustic neuromas is very variable: some tumours grow rapidly, some do not grow and some even get smaller. When making treatment decisions, it may be important to have an idea of the growth rate of the individual tumour, and this is only possible when there are comparable examinations. We performed both CT and MRI on 15 patients. Two radiologists estimated the size of their acoustic neuromas. There was a significant difference between the two examiners' calculations of tumour volumes on CT and between the first examiner's CT and MRI volume calculations. No difference was found between the two MRI volume estimations or the second examiner's estimation of volumes on CT and MRI. Measurements of the maximal tumour diameter along the pyramid showed good concordance. We conclude that measurement the size of acoustic neuromas is reproducible with MRI and the measurement of the maximal tumour diameter is in practice a better parameter for comparison than calculation of real volume.

Adult↗
PubMed1997

Preconditioning the tympanic membrane: identification of cholesteatoma prone ears?

Preconditioning refers to changes in the mechanical properties of tissues due to repeated stress-strain experiments. Generally, after a number of cyclic deformation, a steady state is reached, where the experiment becomes repeatable, and the specimen is preconditioned. Tympanometric measurements of middle ear compliance also show increasing values for repeated trials until after 5 or 6 measurements, where steady state is reached. However, in some normal cases with high compliance it has previously been found that the tympanic membrane is not always able to reach a steady state, but displays larger and larger compliance over trials. This property may be characterized as a decreased resistance against pressure loads, which may lead to retractions, atelectasis, and cholesteatomas. Preconditioning was investigated in a group of 21 patients with cholesteatomas. Due to perforations and discharge the contralateral ear was measured. Nine tympanometries were recorded in one sequence. The increase in compliance between trials showed a complete overlap with a group of 25 normal subjects. For both groups good repeatability between trials with insignificant effect of preconditioning can be obtained after 4 trials.

Acoustic Impedance Tests↗
PubMed1996

Drugs in blood samples from unconscious drug addicts after the intake of an overdose.

This investigation includes whole blood samples from 53 drug addicts found unconscious in the Copenhagen area with evidence of a heroin overdose. Heroin/morphine was detected in 85% of the patients and other opioids in 11%. One or more benzodiazepines, most often diazepam, were detected in 75% of the patients. A blood alcohol concentration higher than 1.00 mg/g was detected in 57% of the patients. Methadone was detected in seven patients, ketobemidone in four, amphetamine in five and cocaine in one. This investigation showed widespread multi-drug abuse and heroin/morphine alone was detected in only one patient. As indicators of heroin intake, 6-mono-acetylmorphine (MAM) and morphine were detected in this investigation.

Adult↗
PubMed1996

Revision surgery in otosclerosis--an investigation of the factors which influence the hearing result.

The hearing improvement obtained by revision surgery for otosclerosis has been assessed in 163 patients with a conductive hearing loss. Several different surgical techniques had been used at the primary operation. On average at revision a hearing improvement of 11 dB was obtained. The hearing improvement was related to the surgical technique of the primary operation, the middle ear abnormalities and the surgical technique used at revision. Patients in whom a small-fenestra-technique had been used for the primary as well as the revision procedure, had a better result than patients who had total removal of the footplate. Patients with adhesions and an eccentric prosthesis only showed a small hearing improvement. Patients with necrosis of the long process of the incus were also difficult to manage. Since the complication rate was low it does not seem to be more dangerous to perform a revision than to perform a primary operation. The results obtained by revision are poorer than can be obtained by the primary procedure. This indicates that in stapes surgery the greatest chance for hearing improvement is the first operation, therefore centralization of this type of operation should be considered.

Ear, Middle↗
PubMed1995

[Size of acoustic neurinomas assessed by CT and magnetic resonance scanning].

Some acoustic neuromas do not grow or grow very slowly. It is therefore of value to compare the results of measuring the size of acoustic neuromas by either CT or Magnetic Resonance Imaging (MRI) scanning with a view to being able to observe the growth rate of these tumours. Fifteen patients with acoustic neuromas had both CT- and MRI-scans performed. Two trained radiologists evaluated the size of the tumours in a blinded fashion. There was a significant difference between one observer's calculations from the CT- and the MRI-scans, and also a significant difference between the two observers' calculations from the CT-scans. No difference in calculating tumour size was found between the two observers' calculations from the MRI-scans. It is concluded that the size of acoustic neuromas i evaluated more equally by two observers using MRI-scans than when using CT-scans. By the use of repeated MRI-scanning it is possible to keep patients with acoustic nouromas under observation and avoid operation in those patients where the tumour does not grow.

Adult↗
PubMed1995

Regional cerebral activation during auditory stimulation in patients with cochlear implants.

OBJECTIVE: To evaluate a possible change in the regional cerebral blood flow (rCBF) in the language-related cortical areas of the brain during stimulation of a cochlear implant. METHODS: The rCBF was measured by single-photon emission tomography and inhalation of Xenon Xe 133, providing information on the regional functional level of the brain. A supplementary single-photon emission tomographic scan was also performed, using technetium Tc 99m hexamethylpropyleneamineoxime as a flow marker. The rCBF was measured during rest (baseline) and during auditory stimulation by presenting white noise and running speech to the ear with the implant. PATIENTS: Five deaf patients who had undergone intracochlear or extracochlear implantation surgery. RESULTS: As in subjects with normal hearing, notable activation was not found in the relevant primary auditory cortex on stimulation with white noise. Two of the patients with implants had an increase in the rCBF in the relevant contralateral hemisphere on stimulation with running speech, but in the other three patients, a notable increase was not detected. This lack of increase in the rCBF on speech stimulation was consistent with the lack of speech recognition experienced by the subjects when using the implant. In one subject, the implant had a beneficial effect on speech understanding that was associated with a significant increase in the cerebral blood flow in the Broca's speech area and Wernicke's second speech area. CONCLUSIONS: Although the results are preliminary, the single-photon emission tomographic technique may be useful when evaluating the function of a cochlear implant. The method may also help select patients and/or ears for cochlear implantation. Four of five patients had functional defects of auditory relevant cortical areas, suggesting that their deafness might be associated with central impairment in addition to their cochlear defects.

Acoustic Stimulation↗
PubMed1995

Appearance of isochromosome 18q can be associated with in vitro immortalization of human T lymphocytes.

T lymphocytes cultured from a skin biopsy specimen of a patient with atopic dermatitis developed isochromosome 18q concomitant to escape from replicative senescence. Furthermore, two T-cell lines established from patients with cutaneous T-cell lymphoma also developed isochromosome 18q during continuous growth. The results indicate that a pathway leading to immortalization of human T lymphocytes could involve genes located at chromosome 18.

Cell Division↗
PubMed1995

Common clonal chromosome aberrations in cytokine-dependent continuous human T-lymphocyte cell lines.

Antigen-mediated T-cell proliferation is a transient phenomenon. Like other somatic cells, T lymphocytes generally show replicative senescence in vitro. However, we here show that cytokine-dependent continuous (immortal) T-cell lines can be established from skin biopsy specimens of inflammatory skin diseases. Continuous growth can be obtained by culturing T cells in medium supplemented with interleukin-2 and interleukin-4, but without antigen or antigen-presenting cells added. Loss of the T-cell antigen receptor complex is observed in some of the continuous T-cell lines. Most T-cell lines develop clonal chromosome aberrations during continuous growth. Aberrations for chromosomes 1, 2, 8, 16, and 18 are most commonly observed.

Cell Division↗
PubMed1994

[Exostosis of the external auditory meatus or ear canal nodes. A study of etiology and therapeutic results].

In this study we evaluated the relation between exposure of the ear canal to cold water and development of exostosis. Furthermore we wanted to evaluate the clinical outcome of surgical removal of the exostosis. The material consisted of a group of 15 winter bathers who had been exposed to cold water over a period varying from three to 45 years. All but one subject who had exposed the ear canal to cold water had developed exostoses of the ear canals. Follow-up examinations of nine patients after surgical removal of the exostosis revealed normal, well calibrated ear canals. Three winter bathers who continued the exposure to cold water developed a new exostosis.

Adult↗
PubMed1994

In vitro genetically aberrant T-cell clones with continuous growth are associated with atopic dermatitis.

Atopic dermatitis is a disease with a genetic predisposition affecting the immune system, with T lymphocytes participating in the immune dysregulation. Most in vitro T lymphocyte studies of atopic dermatitis have focused on antigen-specific T-cell clones. However, antigen-non-specific regulatory T lymphocytes may also take part in the pathway leading to antigen-specific clonal T-lymphocyte proliferation. T lymphocytes from skin biopsy specimens from three patients with severe atopic dermatitis were cultured in the presence of IL-2 and IL-4, but without antigen added. Initially, proliferation was oligo- or polyclonal, but in all cases overgrowth by T cells with clonal chromosomal aberrations was subsequently observed. These abnormal T-cell clones demonstrated continuous growth and complete or partial phenotypic loss of the T-cell antigen receptor complex. In summary, these findings suggest that a subset of aberrant skin-homing T lymphocytes is associated with atopic dermatitis.

Adult↗