Ö. Tjernström

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.

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...

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.

Changes in Eustachian Tube Function with Age in Children with Normal Ears: A Longiudinal 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.

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.

PRESSURE OPENING AND CLOSING FUNCTIONS OF THE EUSTACHIAN TUBE BY INFLATION AND DEFLATION IN CHILDREN AND ADULTS WITH NORMAL EARS

Different inflationary (e.g. Valsalvas) 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.

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 Menieres disease, relief of symptoms was achieved by means of ambient pressure changes of the same magnitude.

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.

Middle Ear Mechanics and Alternobaric Vertigo

The effects of overpressure induced locally in the middle ear through free air communication between the middle ear and the external ear canal were compared with the effects of a relative overpressure of the same magnitude, induced indirectly by lowering the ambient pressure. The same vestibular response was seen and the main condition for inner ear stimulation was the fact that the overpressure should reach a certain level. However, a certain pressure difference between the ears is also involved. The overpressure seemed to affect the inner ear without involvement of the eardrum, and merely a movement of the eardrum could not be shown to affect the inner ear. The possibility of caloric stimulation due to temperature changes of the middle ear gas volume was also considered and excluded.

Further Studies on Alternobaric Vertigo: Posture and Passive Equilibration of Middle Ear Pressure

The passive equilibration of the middle ear pressure during simulated ascents was affected by different postures, and the level of the relative overpressure in the middle ear (Ptm) required to force the Eustachian tubes open was higher in the recumbent than in the sitting position. Subjects with a high forcing pressure (FPL) in one ear, and with experience of Alternobaric Vertigo, were exposed to simulated ascents in different postures and the Ptm, recorded at the moment of onset of nystagmus (nystagmus pressure level, NPL), was also higher in the recumbent position. However, an initially high FPL was not increased as regularly as an initially low FPL, and the absence of vestibular stimulation in some subjects when examined in the recumbent position was explained by the fact that the FPL did not reach the NPL. A relation between the middle and the inner ear pressure being the prerequisite for vestibular stimulation is discussed.ZUSAMMENFASSUNGDer passive Druckausgleich im Mittelohr wahrend simulierter Ste...