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Biomedical subjects

B Magnuson

Publications and source records attributed to B Magnuson.

At least 19 recordsLinked to original sources
PubMed2001

Speech recognition in background noise: monaural versus binaural listening conditions in normal-hearing patients.

HYPOTHESIS: Patients with unilateral conductive hearing impairment often experience a great advantage in improved hearing thresholds after reconstructive ear surgery because the binaural hearing leads to increased speech recognition in competing noise. The aim of this study was to develop a clinical audiometric test to quantify the ability of speech recognition in background noise preoperatively and postoperatively. METHODS: A model consisting of phonetically balanced (PB) monosyllabic words and/or a just-follow-conversation test (JFC) was used in 16 normal-hearing listeners. In 8 of the participants, JFC at two levels of background noise (60 and 40 dB sound pressure level) was used as the only method. The tasks were performed in an anechoic chamber with varying spatial separations of speech and noise sources under free field conditions. The tests were made binaurally and monaurally; the latter condition was achieved by occluding one ear with a hearing protector. In PB word tests, the percent of correctly repeated words was scored. In the JFC task, the speech signal was adjusted by the listener to a level where he or she could just understand what was being said. This was expressed as a signal-to-noise (S/N) ratio. RESULTS: In both types of tests, the subjects achieved significantly better speech recognition scores in the binaural situations. In summary, compared with monaural conditions, the subjects achieved 17% to 18% better speech recognition in PB tests, and in JFC tests a 2-to 3-dB lower S/N ratio in binaural conditions. CONCLUSION: These free field tests can be developed further as a clinical tool preoperatively and postoperatively to evaluate the effect of binaural hearing after ear surgery.

Audiometry, Pure-Tone↗
PubMed2000

On the physics of the infant feeding bottle and middle ear sequela: ear disease in infants can be associated with bottle feeding.

BACKGROUND: When using conventional feeding bottles, negative pressure is generated in the oral cavity, as well as, in the bottle when fluid is removed by sucking. The negative pressure inside the bottle causes the infant to suck excessively and the intraoral negative pressure may subsequently be transmitted to the middle ear via the eustachian tube. METHODS: in seven infants, simultaneous pressure recordings were performed in the feeding vessel and the middle ear using three types of feeding bottles. RESULTS: with conventional non-ventilated and under-ventilated bottles a negative pressure formed while the infant sucked and negative intratympanic pressure was frequently generated. CONCLUSIONS: it is suggested that this sequence of events may lead to secretory otitis and it's accompanying consequences. In contrast, a fully ventilated bottle showed positive pressure throughout the feeding procedure, which is similar to normal breast-feeding, and negative pressure changes were not recorded in the middle ear.

Bottle Feeding↗
PubMed2000

Variability of Eustachian tube function in children with secretory otitis media. Evaluations at tube insertion and at follow-up.

OBJECTIVE: Despite the variable clinical course of diseases related to Eustachian tube function, the variability of tubal function has been less focused than outcomes of single tests. This study aimed to compare the passive and active tubal function and its variability in children with secretory otitis media (SOM) at tube insertion and at follow-up. METHOD: Thirty-eight ears in 19 children aged 4-10 years (mean 7.0 years) with long-standing SOM were examined 4-6 h after tube insertion, at 4 months and at 9 months. The pressure in the middle ear and the nasopharynx were recorded while performing (1) forced opening test, (2) equalization of +100 and -100 daPa, (3) Valsalva test, and (4) sniff test. The procedure was repeated after 30 min. Relationships were analyzed by uni- and multi-variate analysis of variance. RESULTS: From tube insertion to 4 months, the mean forced opening pressure increased from 282+/-128 to 355+/-153 daPa (P<0.01), and the mean closing pressure from 91+/-51 to 126+/-82 daPa (P<0.01). There was no further change at 9 months. Female gender, serous effusion (in contrast to mucoid), and more than three previous episodes of acute otitis media were related to higher opening and closing pressures. At tube insertion, 60% and 16% equalized +100 and -100 daPa, respectively, and 28% succeeded in performing Valsalva inflation. The sniff test was positive in 32%, indicating a closing failure. These rates did not change significantly over time. For individual ears, outcomes of all tests varied considerably when retested after 30 min; P(o) changed by +/-12% and P(c) by +/-26%, and 9-29% of the ears changed from a positive to negative response, or vice versa, in the equalization, Valsalva, and sniff tests. CONCLUSIONS: The unexpected finding of weaker closing forces at the day of tube insertion and increased tubal resistance at follow-up might be ascribed to changes in the muco-adhesive forces related to the disease and tube treatment. The pronounced intra-individual variability of test outcomes indicates that tubal function is dynamic and variable in ears prone to SOM, which emphasizes that results of single tubal function tests have very low prognostic value.

Analysis of Variance↗
PubMed2000

Eustachian tube function varies over time in children with secretory otitis media.

Impaired opening and closing functions of the Eustachian tube are considered to be pathogenic factors in secretory otitis media (SOM). As the clinical course of SOM is variable, the variability of tubal function is of interest. We aimed to explore the short- and long-term variability of tubal opening and closing functions in SOM. The study comprised 42 ears in 21 children (13 males and 8 females) with tympanostomy tubes due to SOM. The middle ear pressure was recorded during repeated passive forced openings, equalization of + 100 daPa and - 100 daPa by swallowing, Valsalva inflation and forceful sniffing. Test sessions were performed twice (separated by 30 min) on each of 2 days, with a mean interval of 3.7 months in between. In the forced opening test there was a considerable intra-individual variability over time. Expressed as SD of the mean, the variability of the forced opening and closing pressures in individual ears was on average 15% and 23%, respectively, between sessions and 20% and 30% respectively, between test days. In the equalization, Valsalva and sniff tests the rates of responses that changed from positive to negative between sessions and test days ranged from 12% to 33%. Female gender and retraction pockets were related to poorer opening function in the forced opening test. Ears with serous effusion (in contrast to mucoid) showed a similar trend and also a lower occurrence of positive equalization, Valsalva and sniff tests. It was concluded that Eustachian tube opening and closing functions are highly variable in ears with SOM. Consequently, single tubal function tests have low value when used as a prognostic tool in individual ears.

Analysis of Variance↗
PubMed2000

Variability of Eustachian tube function: comparison of ears with retraction disease and normal middle ears.

OBJECTIVE: To explore the short-term and longterm variability of tubal opening and closing in ears with advanced retractions and in healthy ears. STUDY DESIGN/METHODS: Twenty ears with retraction type middle ear disease (R-MED) and 20 normal ears underwent direct recording of the middle ear pressure during repeated forced openings, equalization of +100 daPa and -100 daPa by swallowing, Valsalva inflation, and forceful sniffing. Tests were performed twice (separated by 30 min) on each of 2 days separated by 3 to 4 months. RESULTS: There was considerable intraindividual variability of the forced opening pressure and the closing pressure in both groups, within as well as between sessions and test days. Although the variability was 1.5 to 2 times higher in ears with retraction than in the normal group, mean Po and Pc did not differ between the groups. Compared with normal ears, ears with retraction changed more frequently from a positive to negative test response, or vice versa, when re-tested after 30 minutes. Rates of positive response in the equalization and Valsalva tests were significantly lower in diseased ears compared with normal ears. CONCLUSIONS: Eustachian tube opening and closing functions vary more in ears with retraction disease than in normal ears, which is consistent with the variable clinical course of R-MED and implies that single tubal function tests have little prognostic value on the individual level.

Adolescent↗
PubMed2000

MRI screening of the cerebellopontine angle and inner ear with fast spin-echo T2 technique.

In patients with unilateral hearing loss and dizziness it is important to rule out a cerebellopontine angle process. This is often done by audiological and otoneurological investigations. However, in many cases we must rely on the imaging of the temporal bone and the cerebello-brainstem area. The paper has presented the three dimensional (3D) Fast Spin-Echo (FSE) T2 weighted, 0.7 mm thick MR images, which in addition to being quick, does not require the use of expensive contrast material. Between September 1996 and November 1997, 152 patients with unilateral hearing loss and/or balance disorders were investigated. In normal cases the 7th and 8th nerves could be followed accurately from the brainstem to the internal auditory meatus. The found tumors were hypointense compared to the cerebrospinal fluid and could be outlined with reasonable accuracy even without gadolinium contrast. The inner ear had high signal, like cerebrospinal fluid. The patency of the cochlea could be estimated accurately. Thus, 3D FSE T2 weighted images can reliably differentiate between patients with and without pathologies of the cerebellopontine angle. The use of gadolinium contrast could be avoided in most of the cases, but contrast is necessary for differential diagnostic purposes in patients with alterations in the cerebellopontine angle or in doubtful cases.

Artifacts↗
PubMed1999

The character and consequences of disturbing sound sensations in retraction type middle ear disease.

OBJECTIVE: Transient sound disturbances are common but neglected symptoms in retraction type middle ear disease (R-MED). The aim of this study was to explore and describe their character, their individual consequences, and their role in the development of tympanic membrane retractions. METHODS: Fifty-three subjects with manifest retractions and experiences of disturbing sound and ear sensations were interviewed. A qualitative method was used for analysis of the transcribed interviews. RESULTS: Two different patterns emerged from the interviews. 1. Too weak sound was the least common and most tolerable disturbance. It occurred in 45% and was eliminated by Valsalva's inflation. 2. Sudden and transient sensations of too loud and piercing sound, and intermittent autophony frequently caused intense and intolerable discomfort, which might in turn cause loss of control of speech and conversation. These types occurred in 74% and 60%, respectively, and were eliminated by evacuating the middle ear, for example by sniffing. Subjects who described too loud sound or intermittent autophony commonly preferred a retracted tympanic membrane position. This may explain why pressure equalization by swallowing, and inflation by Valsalva's manoeuvre often elicited discomfort. CONCLUSIONS: Transient experiences of too loud sound or intermittent autophony may indicate a shift of sound preference towards the sound experienced at negative middle ear pressure, and an unreliable tubal function in the sense that it fails to stay closed to protect the ear from sounds and pressure variations in the nasopharynx. Such experiences of altered sound may trigger evacuation of the middle ear, which eliminates the sound disturbance. It is crucial to identify, interpret, and explain the disturbances correctly in the therapy and prevention of retractions, since habitual evacuation exposes the tympanic membrane to strong negative pressure loads and a subsequent risk of developing retraction.

Adult↗
PubMed1998

Nasal gas composition in humans and its implication on middle ear pressure.

The amount and composition of gas that enters the middle ear by the Eustachian tube is of interest in the study of middle ear pressure regulation. We have studied the gas composition in the nasal cavity through the respiratory cycle in humans by mass spectrometry. The findings were correlated to earlier findings regarding synchronization of swallowing and breathing. The composition of the gas that may pass the Eustachian tube at openings during swallowing seems to be very close to expiratory values: nitrogen 79.19%, oxygen 14.69%, argon 1.00% and carbon dioxide 5.10%.

Adult↗
PubMed1998

Three-Dimensional Fast Spin-Echo T2-Weighted Magnetic Resonance Images of the Cerebellopontine Angle.

In patients experiencing dizziness and hearing disorders, it is essential to rule out the possibility of an intracranial affection, typically a cerebellopontine angle (CPA) process. Clinically, this often is accomplished using audiology and otoneurology and by interpreting the time course of the symptoms. However, in many cases, we must resort to imaging of the skull base and the CPA. The use of thin-section, fast spin-echo, heavily T2-weighted images can eliminate the need for gadolinium contrast administration, offering a cheaper and quicker investigation as compared with the customary T1-weighted images using gadolinium. With three-dimensional volume sampling, slice thickness can be reduced to 0.7 mm. Data reconstruction in every desired direction is possible. Ninety-two patients with hearing and balance disorders were examined using this method. In subjects free of tumor in the CPA, the seventh and eighth nerves could be followed accurately from the internal auditory meatus to the brainstem. The tumors could be outlined with reasonable accuracy even without gadolinium contrast. Three-dimensional, fast spin-echo, T2-weighted images are useful in evaluating the CPA in cases of suspected tumor. Most often the use of gadolinium can be avoided. This seems to be a cheap alternative for magnetic resonance screening of patients experiencing dizziness and hearing disorders.

Journal Article↗
PubMed1997

Enteral feeding in the home environment.

Nutritional status has a major influence on wound healing, immunity, and quality of life for home care patients. This article presents the rationale, guidelines, and troubleshooting strategies home care nurses can use in caring for patients receiving enteral nutrition.

Community Health Nursing↗
PubMed1997

Middle ear gas composition in pathologic conditions: mass spectrometry in otitis media with effusion and atelectasis.

It is generally assumed that the gas enclosed in the middle ear and mastoid air cell system is subject to continuous absorption, and that partial pressures for oxygen and carbon dioxide equal those of "mixed venous blood." We previously determined the concentrations in 10 adults with healthy ears by means of mass spectrometry. The results showed that the value for oxygen was in the expected range, but that the value for carbon dioxide was higher than in "mixed venous blood." The aim of the present investigation was to measure the gas concentrations with the same technique in diseased ears, to see if there are any differences in middle ear gases between healthy and diseased ears. In terms of group means, the present measurements in 13 ears of children with otitis media with effusion or atelectasis did not differ from the values previously obtained for healthy ears of adults for any of the gases.

Adolescent↗
PubMed1997

Hearing results in otosclerosis surgery after partial stapedectomy, total stapedectomy and stapedotomy.

Hearing results in a consecutive series of 407 patients with otosclerosis undergoing primary stapes surgery were analysed (437 operated ears). Partial stapedectomy was performed in 70 ears (16%), total stapedectomy in 205 ears (47%), in both groups using the House steel wire prosthesis on fascia in the oval window. The remaining 162 ears (37%) underwent stapedotomy using the Fisch 0.4 mm teflon-platinum piston. No case of cochlear loss (> 15 dB) occurred in the total series. The comparison between the three groups one year postoperatively showed that the air-bone gap was smaller for partial and total stapedectomy for all frequencies except 4 kHz. The air-bone gap was calculated as the difference between the preoperative bone conduction and the postoperative air conduction thresholds. Partial and total stapedectomy also showed larger improvements of bone conduction thresholds compared with stapedotomy for all frequencies but 4 kHz. At the 3-year follow-up, the hearing gain for all frequencies (250-8000 Hz) was larger for partial and total stapedectomy. Yet, when comparing the decline of hearing from 1 to 3 year postoperatively, the hearing gain achieved with partial and total stapedectomy seemed to deteriorate at a higher rate, which was considered to be caused by impaired sensorineural function. Our results show that in the short-term perspective partial or total stapedectomy can still compete for better hearing results even at higher frequencies, but stapedotomy seems to yield more stable hearing results over time and should therefore be considered as the method of choice.

Adolescent↗
PubMed1995

Structural changes in the rat tympanic membrane following repeated pressure loads.

Healthy adult laboratory rats were exposed to alternating negative pressure and atmospheric pressure to replicate the clinical situation found in patients with chronic sniffing habits and chronic middle ear disease. The rats were placed in a box in which the pressure changed at intervals of 30 s between atmospheric pressure and a negative pressure of -3 kPa. This was repeated continuously for periods of 3 and 7 days. At completion of the experimental period, all rats had a normal otomicroscopic status. However, histological studies demonstrated that the pars flaccida was wrinkled and the loose connective tissue contained large fibroblasts with their long axes lying in a disorganized manner. The cells of the keratinizing epithelium were thicker than normal and mitoses were seen. Epithelial crypts filled with keratin were numerous along the epithelium. In the pars tensa, all layers were thicker than normal. These findings demonstrate that repeated pressure loading can create structural changes in the tympanic membrane.

Animals↗
PubMed1994

Pentobarbital coma in neurosurgical patients: nutrition considerations.

Neurosurgical patients in pentobarbital coma are a complex nutrition support population. Physiologic changes associated with the primary injury to the brain, combined with the pharmacodynamic influences of barbiturate therapy, contribute to the difficulties of initiating aggressive nutrition support. Early nutritional repletion is important to the overall outcome of traumatically injured patients. Consequently, factors that influence nutrition support decisions must be understood to assure appropriate intervention. The metabolic changes associated with traumatic head injury, pentobarbital therapy, and nutrition support strategies are reviewed.

Coma↗