Eye movements as a function of active headturnings.
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Adult↗
Biomedical subjects
O Tjernström
Publications and source records attributed to O Tjernström.
Vertigo due to relative overpressure in the middle ear. An experimental study in man.
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Adult↗
Further studies on alternobaric vertigo. Posture and passive equilibration of middle ear pressure.
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Adult↗
Pressure-dependent variation in volume of mucosal lining of the middle ear.
A method is described for studying pressure-dependent variation in the volume of the mucosa of the middle ear. Studies were performed at different pressures in the middle ear as well as at different ambient pressures. It was found that the pressure-dependent volumetric changes of the mucosa were the same whether the pressure in the middle ear was changed directly by altering the intratympanic or indirectly by altering the ambient pressure. With the method described it is also possible to determine the middle ear volume without artefacts due to the middle ear mucosa. The volume-pressure relationship of the middle ear mucosa varied from 0.6 to 1.7 mul/cm H2O and linearly with the volume of the middle ear. Comparisons between determinations of the middle ear volume with and without consideration of the mucosal compliance showed differences, especially in small middle ears. The effect on the volume of the mucosa caused by variation of posture was also studied. The physiological middle ear pressure depends on the functional state of the Eustachian tube, the middle ear volume, the tympanic membrane and the middle ear mucosa. Thus, knowledge of the mucosa compliance is important for calculating middle ear pressure as well as for determining the volume of the air-filled middle ear space. The method might also prove a useful tool in the elucidation of the vascular bed both in health and in disease as well as the reaction of the mucosal vessels to drugs.
Atmospheric Pressure↗
Effects of middle ear pressure on the inner ear.
It was demonstrated in experiments on normal subjects that moderate ambient pressure changes, creating overpressure in the middle ear, may induce a vestibular reaction. In other experiments on subjects suffering from acute attacks of Meniere's disease, relief of symptoms was achieved by means of ambient pressure changes of the same magnitude.
Ear, Inner↗
The elastic properties of the tympanic membrane system in divers and non-divers.
The volume/pressure relationship of the tympanic membrane system was studied in 24 scuba divers. The results were compared with the results obtained from 98 non-diving subjects. Among persons with a good function of the Eustachian tube, divers had an increased mobility of the tympanic membrane system as compared to non-diving subjects. Divers with a reduced function of the Eustachian tube did not differ from the non-diving subjects with a reduced tubal function. Factors that might influence the volume/pressure relationship of the tympanic membrane system are discussed.
Adult↗
Eustachian tube function in normal children and adults.
Eustachian tubal function was studied in 85 otologically healthy children, 3-12 years of age. Middle ear pressure and muscular opening function was measured by tympanometry performed in a pressure chamber, and the results were compared with those obtained from 92 normal adults. Children were found to have a less good muscular opening function and more negative middle ear pressures within wider ranges, compared with adults. Improvement was also seen in children with increasing age. The results seemed to indicate a relation between muscular opening function and middle ear pressure. Even if it were possible to grade the muscular opening function by means of the test procedure, it would still not be possible to define what should be regarded as normal or abnormal tubal function. This report is the first in a series of tubal function studies in normal children.
Acoustic Impedance Tests↗
Ototoxicity of netilmicin.
Ototoxicity and efficacy of netilmicin was evaluated in 76 consecutive patients with moderate to severe infections with Gram-negative rods and Staphylococcus aureus. Netilmicin alone was efficacious in 47 patients and in another 23 patients cure or improvement was seen with netilmicin combined with another antibiotic, usually penicillin. Therapeutic failure was seen in 4 cases, 2 of which were regarded as netilmicin failures. Vestibular function and hearing acuity was thoroughly examined by electronystagmography and audiometry. In spite of the extensive examination of the audiovestibular function it was possible to detect only one probable case of ototoxicity related to netilmicin, a reversible vestibular dysfunction. The importance of pre-therapeutic audiovestibular examination is stressed.
Adolescent↗
Pressure opening and closing functions of the eustachian tube in children and adults with normal ears.
Eustachian tube function was studied with the impedance technique and a pressure chamber in 58 children, aged 3-12 years, and 61 adults, aged 17-73 years, all otologically healthy. The pressure opening and closing functions were measured, i.e. the relative overpressure in the middle ear required to force open the tube, and the residual overpressure in the middle ear after pressure opening, respectively. These "passive" functions of the tube, assumed to reflect the closing factors, did not differ significantly between normal children and adults. The muscular opening function, i.e. "active" pressure equilibration capacity, on the other hand, was significantly poorer in children than in adults and poorer in younger children than in older ones. The results can be used as a reference material in investigations of the Eustachian tube in children with middle ear disease.
Adolescent↗
Changes in Eustachian tube function with age in children with normal ears. A longitudinal study.
A longitudinal study of the Eustachian tube function by different pressure equilibration tests was performed during 11/2-3 years in 44 otologically healthy children, 3-12 years of age. The muscular opening function improved significantly with increasing age. The improvement was most frequent during pre-school ages (3-7 years). Also the tympanometrically measured middle ear pressure, related to the muscular opening function, tended to normalize during the follow-up study. The pressure opening and closing functions, reflecting the tubal closing forces, did not, however, change during the observation time. All the children with poorest muscular opening function at the initial test improved; none developed persistent middle ear disease during the follow-up. Using this standardized exhalation/inhalation test of the pressure equilibrating function of the tube it seems possible to grade the muscular opening function in a valid way. It is argued that the main cause of poor muscular opening function in children is not only due to anatomical differences of the skull base, the tube and peritubal structures but also to the immaturity of the neuromuscular system during childhood.
Aging↗
Pressure opening and closing functions of the Eustachian tube by inflation and deflation in children and adults with normal ears.
Different inflationary (e.g. Valsalva's) and deflationary (e.g. sniffing) manoeuvres were studied in 58 children and 61 adults, all otologically healthy, in order to evaluate qualitatively and quantitatively the pressure opening and closing functions of the Eustachian tube. Only 71% of the normal children could voluntarily increase the middle ear pressure compared with 100% of the adults. The corresponding figures for evacuating the middle ear by deflation were 24% and 34%, respectively. The rhinopharyngeal pressure levels during the manoeuvres were age-dependent and decided the response rate in children. Tubal factors also determined the response rate since low pressure opening and closing levels were related to successful deflation. Negative middle ear pressures found in the normal children were due to poor muscular opening function of the tube rather than successful deflation. The pressure closing level seems to be a reliable tool in grading tubal closing ability.
Adolescent↗
The effect of pressure change rate on the eustachian tube function in pressure chamber tests.
The capacity of the Eustachian tube to equilibrate pressure differences across the eardrum was tested repeatedly at different rates of pressure change with the aid of a quantitative impedance method in a pressure chamber. Three recordings of the active and passive pressure equilibration functions were made during chamber pressure changes of 0.3, 0.7 and 1.5 kPa-1s in 53 ears in 28 otologically healthy subjects. The middle ear pressures at which the active and passive equilibrations were achieved increased with increasing rates. The test-retest reliability was not rate dependent as regards the passive pressure equilibration functions, but tended to deteriorate with increasing rates for the active equilibration functions. Advantages and disadvantages of the different rates in such tests are discussed.
Adult↗