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Biomedical subjects

O Densert

Publications and source records attributed to O Densert.

At least 19 recordsLinked to original sources
PubMed2001

Tonsillotomy in children with tonsillar hypertrophy.

Tonsillectomy is one of the most frequent surgical procedures carried out on children. Obstructive sleep apnea syndrome, caused by tonsillar hypertrophy, has been attracting increasing interest and tonsillectomy is often performed as a result of this indication. Regardless of the indication, the main aim of tonsillectomy has always been to remove the tonsils completely. The present study was undertaken in order to investigate the effect of two different surgical techniques, tonsillectomy and tonsillotomy, on clinical symptoms in children with symptoms of obstructive sleep apnea syndrome due to tonsillar hypertophy. The study was conducted as a prospective, randomized trial comparing the clinical effects of standard tonsillectomy and tonsillotomy using a CO2 laser. Forty-three children aged 2-9 years were included. Both groups of patients experienced comparable relief from symptoms of snoring and apneas at follow-up after 3 months and 2 years. There was no significant statistical difference between the two groups of patients in terms of both short- and long-term effects on clinical symptoms. Tonsillotomy caused no measurable bleeding during surgery. Postoperative pain and distress were less pronounced in the tonsillotomy group according to visual analog scale evaluations made by patients, parents and nursing staff. In conclusion tonsillotomy appears to be the less traumatic surgical method in cases of upper airway obstruction in children caused by tonsillar hypertrophy.

Child↗
PubMed1997

Immediate effects of middle ear pressure changes on the electrocochleographic recordings in patients with Menière's disease: a clinical placebo-controlled study.

OBJECTIVE: The aim of the study was to evaluate effects of middle ear pressure changes on the electrocochleographic responses in patients with well-defined Menière's disease. STUDY DESIGN AND INTERVENTIONS: The investigation was conducted as a placebo-controlled, randomized clinical study. Electrocochleographic measurements were performed before and after the insertion of a transtympanic ventilation tube and immediately after the exposure to active or placebo treatment. SETTING: The study was carried out in one secondary referral center and one tertiary referral center on an ambulatory basis. PATIENTS: Thirty-nine patients with well-defined Menière's disease were included in the study. MAIN OUTCOME MEASURES: The summating potential/action potential ratio of the electrocochleographic response complex was chosen as the main variable for statistical evaluation of results. Other parameters of the recordings such as responses to low-frequency burst stimulation also were evaluated. Subjective symptoms (e.g., vertigo, tinnitus, and aural pressure) were assessed before and after insertion of the ventilation tube and before and after exposure to treatment. RESULTS: A statistical difference was shown in the electrocochleographic response in the active group before and after exposure to middle ear pressure changes. In the placebo group, no change was found. Changes in electrocochleographic parameters in the active group indicated an improvement in inner ear electrophysiology. No significant changes were found in subjective symptoms in the active or the placebo group. Evaluation before and after insertion of the ventilation tube showed no significant improvement in any variable. CONCLUSIONS: This is the first study in which electrophysiologic parameters were evaluated in a placebo-controlled clinical trial of overpressure treatment in Menière's disease. The results show that electrophysiologic parameters can be improved by the application of positive pressure pulses of low amplitude in the middle ear.

Adult↗
PubMed1992

Pressure transfer between the perilymph and the cerebrospinal fluid compartments in cats.

This is a review of our studies of the labyrinthine fluid pressure in cats subjected to pressure changes in the middle ear (implosive routes) and the cerebrospinal fluid compartment (explosive routes) as well as to changes in vascular and ambient pressures. The perilymph, cerebrospinal fluid (CSF), middle ear, venous and arterial pressures were measured with the cochlear aqueduct (CA) patent as well as surgically blocked. Experiments on explosive pressure changes revealed that the perilymph pressure was regulated by the CSF in case of CA patency. The CSF influence was dominant enough to obscure any direct effect on the labyrinth from other sources. With the CA obstructed the CSF influence on the labyrinth was apparently mainly via the endolymphatic sac and duct although limited and much delayed. Systemic arterial pressure changes had a pronounced influence on the perilymph pressure, but this effect was revealed only when the CSF influence was reduced by CA obstruction. Experiments on implosive and ambient pressure changes suggested that there was no fundamental difference in the perilymph response to equivalent levels of implosive versus hypobaric pressure. Three factors determined the effect of implosive and hypobaric pressure: the patency of the CA, the rate of the pressure change, and the eustachian tube function.

Air Pressure↗
PubMed1987

Life-threatening laryngeal polyp in a child (a case report).

A laryngeal polyp caused a life-threatening airway obstruction in a 3-year-old child. This condition required an emergency tracheotomy, which was performed without previous intubation. The histological picture indicated the diagnosis of a teleangiectatic granuloma. No other case of solitary laryngeal polyp causing upper airway obstruction in a child has been previously reported.

Airway Obstruction↗
PubMed1987

Air-bone gap in Menière's disease after exposure to overpressure.

Equal loss in sensitivity for air and bone conduction and poor speech discrimination are considered characteristic of the hearing impairment in Menière's disease. Periodic pressure changes applied to the middle ear produced an air-bone gap in 16 out of 19 patients with advanced Menière's disease. The air-bone gap was associated with an improvement in speech discrimination scores. Subsequently, the air-conduction hearing loss decreased. The shapes of psychoacoustic tuning curves of patients with the air-bone gaps showed an improvement in frequency resolution. The curves remained elevated in threshold, however, which indicates an attenuation of the sound stimuli. The relative change in bone conduction sensitivity was interpreted as an early sign of improvement in the inner ear mechanics, caused by exposure to pressure changes.

Air Pressure↗
PubMed1986

Quantifying psychoacoustic tuning curves for clinical use.

Psychoacoustic tuning curves (PTCs) were obtained in a number of normal-hearing and hearing-impaired subjects using a simultaneous tone-on-tone masking technique. PTCs at three different centre frequencies (500, 1,000 and 2,000 Hz) were studied. In order to estimate the degree of frequency selectivity of the inner ear, an algorithm for quantification of PTCs was constructed. The method of linear regression was used to calculate the slopes of the linearized curves. Three different parameters of the curve, the low and high frequency slope and the height of the curve, were calculated using computer programs which allowed automatic evaluation of the data. The values of these parameters concerning normal and hearing-impaired subjects are presented in terms of scores and percentages of normal values. The algorithm for quantification of PTCs presented in this paper may in clinical work serve as a method of evaluating auditory frequency selectivity, particularly for very abnormal PTCs.

Audiometry, Pure-Tone↗
PubMed1983

Tetracycline induced esophageal ulcers. a clinical and experimental study.

Medication with oral drugs has not been considered as a cause of esophageal lesions in the general literature of esophageal disease. This study demonstrates 40 patients with complaints of sudden onset of intense retrosternal pains and odynophagia during treatment with oral tetracyclines. All patients had distinct circumferential ulcers in the esophagus. Medical history, barium swallows, esophagoscopy, biopsies and esophageal manometry revealed no other apparent etiology but a local corrosive effect of the tetracyclines. Experimental tests on the esophagus of the cat verified a severe local corrosive effect of the tetracyclines. Another tetracycline, lymecycline, not reported previously to induce esophageal lesions in man, was significantly less ulcerogenic than doxycycline and oxytetracycline. Drug induced esophageal ulcerations are likely to be more numerous than previously suspected. The experimental model used appears to be sound for investigating ulcerogenic potentials of orally administered drugs.

Adolescent↗
PubMed1982

Overpressure in treatment of Meniere's disease.

Influence of ambient pressure changes on the hearing levels in Meniere's disease was previously demonstrated, using a pressure chamber. The present report concerns a new method for management of Meniere's disease by local application of overpressure. The experimental background and methodologic considerations in therapy are summarized. Five illustrative cases of verified Meniere's disease are presented. The patients had advanced, nonfluctuating hearing loss and incapacitating vestibular symptoms. Long periods of remission were obtained in all cases. Improvement of hearing was a major clinical consideration in the treatment. Use of local overpressure seems to offer possibilities of improving hearing even in advanced stages of Meniere's disease. Despite the disabling pretreatment hearing loss, hearing in these 5 patients was restored to normal or serviceable levels. The follow-up period was about 2 years from start of treatment.

Adult↗
PubMed1980

Nonlinear aspects of infrasonic pressure transfer into the perilymph.

The perilymphatic pressure was studied in response to various low frequency pressure changes in the ear canal. The pressure transfer was analysed and found to be nonlinear in many aspects. The pressure response was found to contain two time constants representing the inner ear pressure regulating mechanisms. The time constants showed an asymmetry in response to positive and negative going inputs--the effects to some extent proportional to input levels. Further nonlinearities were found when infrasonic sine waves were applied to the ear. Harmonic distortion and modulation appeared. When short bursts of infrasound were introduced a clear d.c. shift was observed as a consequence of an asymmetry in the response to positive and negative going pressure inputs. A temporary change in mean perilymphatic pressure was thus achieved and continued throughout the duration of the signal. At very low frequencies a distinct phase shift was detected in the sine waves. This appeared as a phase lead, breaking the continuity of the output sine wave.

Acoustic Stimulation↗
PubMed1980

Esophageal lesions caused by orally administered drugs. An experimental study in the cat.

This article presents an experimental method using cats for investigation of the local ulcerogenic properties of oral drugs in the esophagus. 15 drugs in current clinical use were tested. The drugs were placed in esophagus and the animals were sacrificed after 5--8 h, 4--7 or 21 days. The esophagus was cut open, photographed macroscopically and sectioned for light microscopy. Several drugs, e.g. doxycycline, alprenolol, propranolol, ferrosuccinate, ferrosulfate, and emepronium bromide showed marked ulcerogenic properties, whereas indomethacin and betamethasone did not cause any lesions in the cat esophagus. The results seem to be in accordance with the local effect these same drugs exert on the human esophageal mucosa. In order to predict and prevent drug-induced esophageal lesions in man we suggest that oral drugs should be tested concerning their local ulcerogenic properties in the esophagus.

Administration, Oral↗
PubMed1979

Pressure-regulating mechanisms in the inner ear.

The perilymphatic pressure was studied in relation to pressure step variations in the external ear canal and in the middle ear. The transfer of pressure via the ossicular chain reached its limiting value at quite low pressures. When pressure steps were applied directly to the middle ear, there was almost a direct transfer of pressure for positive changes. Nonlinearities were shown between positive and negative pressure steps. The pressure-regulating ability of the inner ear was illustrated by means of calculating the time constants of the pressure transfer curves.

Animals↗
PubMedDate not supplied

Innervation of the feline eustachian tube.

The distribution of adrenergic, cholinergic and peptidergic nerves in the feline eustachian tube was studied using histochemical techniques. Adrenergic, acetylcholinesterase-positive and vasoactive intestinal polypeptide immunoreactive nerves were numerous in the tubal wall. All three types of nerve fibers occurred in the subepithelial layer, around small blood vessels and around the acini of seromucous glands. No nerves displaying substance P or enkephalin immunoreactivity were observed.

Acetylcholinesterase↗
PubMedDate not supplied

Functional patency of the cochlear aqueduct.

The perilymphatic (PP) and cerebrospinal fluid (PCSF) pressures were investigated in relation to pressure variations in the ear canal, middle ear and intracranial compartment before and after occlusion of the cochlear aqueduct (CA). Experiments using intracranial infusion showed that the CA was responsible for a perfect hydrodynamic balance between the CSF and the perilymph. There are indications of additional pressure release factors but their capacities were not sufficient to prevent the appearance of a longstanding and substantial pressure gradient following occlusion of the CA. A gradual PP build-up, from zero to its original level after the CA was opened and occluded, indicated perilymph production within the labyrinth. Investigation of pressure transfer from the ear canal and middle ear to the perilymph showed that the CA was the major pressure release route from the cochlea. Occlusion of the CA reduced the compliance of the inner ear and severely reduced the pressure release capacity. In such a situation the inner ear is almost incapable of equilibrating ambient pressure changes.

Animals↗