The composition of gases and the gas tension in middle ear effusion in patients with serous otitis media have been investigated. By using a specially designed micro-method, very small amounts of middle ear fluid could be analyzed. The effusion was obtained by puncturing the air cells of the mastoid process. The average value of P-O2 was 41 mm Hg; Pco2 was 58 mm Hg, pH 7.24. The possible mechanism for the impaired perfusion of the mucous membranes is discussed as well as some clinical consequences.

Atmospheric Pressure↗

PubMedDate not supplied

Physiology of the Eustachian tube.

A method for studying the middle ear mechanics is described. The method permits continuous recording of the volume deviation of the drum in relation to the neutral position, both on change in the ambient pressure and in the pressure in the middle ear. One hundred and two volunteers with normal hearing, i.e., a normal audiogram and normal ear findings, were tested repeatedly. This is the most detailed and extensive investigation hitherto performed on healthy volunteers with the aid of a sophisticated, reliable scientific method not suitable for clinical use.

Atmospheric Pressure↗

PubMedDate not supplied

Vertigo due to relative overpressure in the middle ear. An experimental study in man.

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Adult↗

PubMedDate not supplied

Immediate restoration of basal sensorineural hearing (Mb Meniere) using a pressure chamber.

A new technique for the restoration of basal sensorineural hearing loss in Mb Meniere was described. Three cases with unilateral basal sensorineural hearing loss, fullness of the ear, and tinnitus were reported. In the acute stage of their disease the patients were treated in a pressure chamber where it was possible to increase or decrease the air pressure within the range +/- 110 cm H2O. The equilibration of middle ear pressures to surrounding air pressures was checked. Exposure to underpressure resulted in a rise of the hearing thresholds at low frequencies and relief of subjective symptoms. When the air pressure was increased the hearing thresholds were lowered and the sensation of tinnitus and fullness of the ear was accentuated. Changes in air pressure did not affect the healthy ears or the high frequencies in the diseased ear. Hearing improvement attained at exposure to underpressure seemed to remain at atmospheric pressure level. The investigation was performed on the hypothesis that a distended membranous labyrinth might cause a venous congestion of the vestibular aqueduct, resulting in impaired endolymph absorption in the endolymphatic sac. Possible effects of changes in environmental air pressure on the inner ear were discussed.

Adult↗

PubMedDate not supplied

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↗

PubMedDate not supplied

Immediate relief of symptoms during acute attacks of Meniere's disease, using a pressure chamber.

Five patients with Meniere's disease were exposed to underpressure in a pressure chamber while suffering from acute attacks with vertigo, nausea, tinnitus and fullness of the ear. Spontaneous nystagmus was the objective criterion for the selection of suitable cases. Subjective as well as objective symptoms subsided much faster than they do with other kinds of treatment. Four patients were free from symptoms within 40 minutes, while the fifth case still complained of vertigo, tinnitus and fullness of the ear after the treatment. However, the symptoms were less severe. A mechanism is discussed by means of which an ambient pressure decrease might cause a reduction of the endolymphatic volume, thus relieving acute symptoms of Meniere's disease.

Acute Disease↗

PubMedDate not supplied

Volume displacement of the tympanic membrane in the sitting position as a function of middle ear muscle activity. A quantitative microflow method.

An open microflow meter system has been worked out for quantitative recording of the volume displacement of the tympanic membrane and its movement direction at stapedius reflex. An acoustically elicited M. stapedius contraction can be recognized by the characteristic response and latency time. The stapedius reflex contraction causes an outward or inward movement of the tympanic membrane. The magnitude of the volume displacement of the tympanic membrane is influenced by the middle ear pressure and in some ears the movement direction of the tympanic membrane changes.

Adult↗

PubMedDate not supplied

Volume displacement of the tympanic membrane at stapedius reflex activity in different postures. Studies on variations in perilymphatic pressure.

With the microflow method the volume displacement of the tympanic membrane and its direction of movement can be recorded at stapedius reflex contraction. There is an outward or inward movement of the tympanic membrane, which is affected by changes in posture. The results indicate that the perilymphatic pressure in man varies with the posture and that these variations can be measured indirectly outside the tympanic membrane. This can only be done, however, on condition that there are no pressure variations across the tympanic membrane. This method opens up new ways of studying possible pressure changes in the inner ear in acute diseases.

Auditory Threshold↗