Sven Ingelstedt

The Normal Function of the Eustachian Tube: A Study of 102 Cases

A method permitting quantitative tubal function tests across an intact tympanic membrane has been worked out. The method permits a continuous recording of the volume deviation of the drum in relation to the neutral position both at changes of the ambient pressure and changes of the pressure in the middle ear. Repeated testings have been performed on 102 cases with normal ears which all had normal hearing, i.e. a normal audiogram, and normal ear findings. 64 % could equilibrate under dynamic pressure conditions, i.e. simulated descent, 84 % could propagate a square wave pressure from the rhinopharynx to the ear and 79 % had a positive Toynbees test. 12 % could equilibrate negative ear pressures completely while the rest have a reduced capacity to equilibrate or none at all, though the ears were regarded as normal. The findings are discussed.

On Middle Ear Pressure

A new method for producing pressure variations in the pneumatic system of the human ear under control is described, i.e. the mastoid puncture technique. Several investigations are made; the volume displacement capacity of the normal ear drum, the role of the drum as a middle ear pressure regulator, vacuum effects on hearing and transudation, all these changes arc produced by intra-aural pressure variations under control. The accuracy of the previous methods for indirect determination of the middle tar pressure is analysed.

Mechanisms of the Gas Exchange in the Normal Human Middle Ear

The spontaneous rate of the middle ear ventilation through the Eustachian tube in the aural flow direction was determined on 3 normal subjects for some hour by a pressure-flow technique. This rate of ventilation was considered to reflect the normal rate of gas volume absorption from the middle ear space to the blood. Assuming that the rate of ventilation determined is valid for 24 hours, the daily ventilation through the Eustachian tube into the middle ear for obtaining normal ear pressure conditions only reaches 1—2 ml.Finally two accessory mechanisms are discussed which may facilitate the ventilation of the middle ear.

Controlled “Ear Aspiration” of Air: A “physiological” test of the tubal function

A new method is described, making possible a study of the tubal function following direct application of negative (or positive) pressure into the ear space. Tubal passages of air are recorded as steplike pressure variations towards equilibration when air is sucked into the closed ear-manometer system during deglutition.

Gas Tension and pH in Middle Ear Effusion

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 Po2 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.

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.

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

It was possible to elicit vertigo in 5 out of 79 otologically healthy subjects by exposure to simulated ascents and passive clearing of the ears. The experimental situation closely resembled the real situation during flying and diving since most pilots and divers usually do not clear their ears actively at ascents, but wait for the ears to be cleared passively when the relative overpressure in the middle ears is great enough to force the Eustachian tubes open. The subjects who reported vertigo were found to have a high forcing pressure on one side when compared with the mean value of 79 normal subjects. Nystagmus was seen synchronous with every period of vertigo, and it was found that the vestibular stimulation was not induced at the moment of pressure regulation as an effect of sudden movements of the stapes, but during the period of asymmetric middle ear pressure and not until the relative overpressure in the “not-cleared” ear had reached a certain level.Bei 5 von 79 otologisch gesunden Versuchspersonen...

A Method for Studies of the Middle Ear Mechanics

A method for studying the middle ear mechanics is described. It is a further development of a method described by Ingelstedt et al. (1967). The basic principle is the recording of the volume deviation of the tympanic membrane during and after changes of the ambient as well as the intratympanic pressure. The method permits quantitative studies of the elastic properties of the tympanic membrane system during both static and dynamic pressure conditions. The volume of the closed airfilled middle ear can be determined, as can the tubal function during both static and dynamic conditions. A new way to determine the middle ear pressure is presented.

Immediate Relief of Symptoms During Acute Attacks of Meniere's Disease, Using a Pressure Chamber

Five patients with Menieres 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 Menieres disease.

The Valve and “Locking” Mechanisms of the Eustachian Tube

In controlled “ear aspiration” experiments on normals it is shown that the air volumes passing through the tube during deglutition gradually decrease with lowering of the negative middle ear pressure. If tympanic inflations are performed simultaneously i.e. “aspiration” + inflation with a very slight overpressure, the air volumes passing the tube at identical middle ear pressures are far greater as compared with “aspiration” only.At “common cold” the tube can be “locked” by very small negative middle ear pressure. Now, if during the “locking” period attempts are made to open the tube by swallowing, further negative pressure spikes are simultaneously produced in the closed ear space thanks to the action of the muscular opening forces on the tube. In this way these forces oppose themselves. These phenomena are further illustrated by an ear-Eustachian tube model.