CONCEPTS ON THE PATHOGENESIS OF MIDDLE EAR EFFUSIONS CHARLES
D.
QUINTER
BLUESTONE,
C.
BEERY,
M.D.
PH.D.
PITTSBURGH, PENNSYLVANIA
SUMMARY - Several concepts related to the pathogenesis of middle ear effusions are postulated. The mechanisms proposed are based on an understanding of fluid mechanics. A flask with a long, narrow neck is presented as a model of the Eustachian tube-middle earmastoid system. Fluid flow into and out of the flask is dependent upon the pressure gradient, compliance of the narrow neck and whether or not the bulbous portion is intact. It is suggested that locking of the tube may be dependent upon the speed of the application of the negative pressure and the compliance. Eustachian tube opening appears to be related not only to active muscle forces but may also be dependent upon the presence of a pressure gradient which passively assists tubal function. It is proposed that middle ear effusions result from reflux, aspiration or insufflation of nasopharyngeal secretions (acute otitis media), or from persistent functional or mechanical Eustachian tube obstruction (secretory otitis media) or both.
From previous studies of the ventila- small amount of liquid is instilled into tory, protective and drainage functions the mouth of the flask, liquid flow will of the Eustachian tube in children, sev- stop somewhere in the narrow neck, due eral concepts related to the pathogenesis to the relative positive air pressure that of middle ear disease have been postu- develops in the chamber of the flask. lated."?" The mechanisms proposed are This basic geometric design is considered largely based on an understanding of to be critical for the protective function fluid flow through a compliant tube re- of the Eustachian tube-middle ear syslated to the geometry of the system made tem. Reflux of the liquid into the vessel up of the nasopharynx, Eustachian tube, occurs if a hole is placed in the bulbous middle ear, and mastoid air cells. The portion of the flask (Fig. lb), the presfollowing will be a description of some sure in the bottom of the flask remaining of these concepts, but before attempting ambient. This condition is analogous to to understand the possible mechanisms a perforation of the tympanic membrane involved, a basic knowledge of fluid or the presence of a tympanostomy tube flow through a flask is necessary. where reflux of nasopharyngeal secre(Liquid flow through this type of ves- tions could occur since the middle earsel will be presented for purposes of mastoid air cushion is lost. Similarly, graphic description but the principles following a radical mastoidectomy the apply equally to the flow of air.) Pos- presence of a patent Eustachian tube sible clinical correlations will also be dis- could cause troublesome otorrhea. Figure Ic shows the effect of the application of cussed. a negative pressure to the bottom of the Fluid Flow Through a Flask. The Eu- flask. The liquid is aspirated into the stachian tube, middle ear, and mastoid vessel. In the clinical situation, the prescan be likened to a flask with a long, ence of high negative middle ear air narrow neck (Fig. I), the mouth of the pressure could aspirate nasopharyngeal flask representing the nasopharyngeal secretions into the middle ear. Figure ld end, the narrow neck the isthmus of the shows the effect of applied positive presEustachian tube, and the bulbous por- sure to the mouth of the flask. The liquid tion the middle ear and mastoid air is insufflated into the vessel. Nose blowchamber. Figure la shows that when a ing, crying or closed-nose swallowing From the Department of Otolaryngology, Children's Hospital of Pittsburgh, University of Pittsburgh School of Medicine, Pittsburgh, Pa.
182
183
PATHOGENESIS
L
-:
ASPIRATION
j'/ /
o
SLOW NEGATIVE PRESsuRE
Fig. 1. Fluid flow into a flask.
could create a high positive nasopharyngeal pressure and result in a similar condition in the human system. However, one of the major differences between a flask with a rigid neck and a biological tube such as the Eustachian tube is that the isthmus (neck) is compliant. Application of positive pressure at the mouth of a flask with a compliant neck would distend the neck, enhancing fluid flow into the vessel. The effect of applied negative pressure in a flask with a compliant neck is shown in Figure 2. Liquid flow through the neck would not occur (Fig. 2a) until a negative pressure is slowly applied to the bottom of the flask (Fig. 2b). Fluid flow would occur even if the neck was collapsed. However, if the negative pressure is suddenly applied, temporary locking of the compliant neck prevents the flow of the liquid (Fig. 2c). Therefore, the speed of the application of the negative pressure as well as the compliance in such a system would appear critical. Clinically, aspiration of gas into the middle ear would be possible since negative middle ear pressure would develop slowly as gas is absorbed by the middle ear mucous membrane. However, sudden application of negative middle ear pressure such as would occur with rapid alterations in atmospheric pressure, e.g., airplane flying, diving, or when attempting to test the ventilatory function of the Eustachian tube, could lock the tube preventing the flow of air. Likewise, sudden application of negative pressure at the nasopharyngeal portion of a highly compliant tube could also result in locking. Negative pressure in the middle
Further understanding of the anatomy and physiology of the nasopharynx, Eustachian tube and middle ear system will be necessary to uncover the pathogenic mechanisms involved in the middle ear effusion problem.
REFERENCES 1. Lupovich P, Bluestone CD, Paradise JL, et al: Middle ear effusions, preliminary viscometric, histologic and biochemical studies. Ann Otol Rhinol Laryngol 80:342-346, 1971 2. Bluestone CD: Eustachian tube obstruction in the infant with cleft palate. Ann Otol Rhinol Laryngol 80 (Suppl 2:1-30), 1971
3. Bluestone CD, Wittel RA, Paradise JL: Roentgenographic evaluation of Eustachian tube function in infants with cleft and normal palates. Cleft Palate J 9:93-100, 1972 4. Bluestone CD, Wittel RA, Paradise JL, et al: Eustachian tube function as related to adenoidectomy for otitis media. Trans Am Acad Ophthalmol Otolaryngol 76: 1325-1339, 1972 5. Bluestone CD, Paradise JL, Beery QC, et al: Certain effects of cleft palate repair on Eustachian tube function. Cleft Palate J 9: 183-193, 1972 6. Bluestone CD, Paradise JL, Beery QC: Physiology of the Eustachian tube in the pathogenesis and management of middle ear effusions. Laryngoscope 82: 1654-1670, 1972 7. Bluestone CD, Beery QC, Andrus S: Mechanics of the Eustachian tube as it influences susceptibility to and persistence of middIe ear effusions in children. Ann Otol Rhinol Laryngol83 (Suppl 11:27-34), 1974 8. Bluestone CD, Cantekin EI, Beery QC:
Certain effects of adenoidectomy on Eustachian tube ventilatory function. Laryngoscope 85: 113-127, 1975 9. Bluestone CD, Cantekin EI, Beery QC, et al: Eustachian tube ventilatory function in relation to cleft palate. Ann Otol Rhinol Laryngol 84:333-338, 1975 10. Cantekin EI, Bluestone CD, Parkin LP: Eustachian tube ventilatory function in children, Presented at the International Symposiurn on Recent Advances in Middle Ear Effusions, May 30, 1975, Columbus, Ohio. Ann Otol Rhinol Laryngol 85 (Suppl 25:171-177) 1976 11. Rich AR: Physiological study of Eustachian tube and its related muscle. Bulletin of Johns Hopkins Hospital 31 :206-214, 1920 12. Beery QC, Bluestone CD, Cantekin EI: Otologic history, audiometry and tympanometry as a case finding procedure for school screening. Laryngoscope 85:1976-1985, 1975 13. Bluestone CD, Cantekin EI, Moran PT, et al: Unpublished data 14. Paparella MM, Hiraida F, Juhn SK, et al: Cellular events involved in middle ear fluid production. Ann Otol Rhinol Laryngol 79:766-779, 1970 15. Odoi H, Proud GO, Toledo PS: Effects of pterygoid hamulotomy upon Eustachian tube function. Laryngoscope 81:1242-1244, 1971
Charles D. Bluestone, M.D., Dept. of Otolaryngology, Children's Hospital of Pittsburgh, University of Pittsburgh School of Medicine, Pittsburgh, PA. 15213.
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D.
QUINTER
BLUESTONE,
C.
BEERY,
M.D.
PH.D.
PITTSBURGH, PENNSYLVANIA
SUMMARY - Several concepts related to the pathogenesis of middle ear effusions are postulated. The mechanisms proposed are based on an understanding of fluid mechanics. A flask with a long, narrow neck is presented as a model of the Eustachian tube-middle earmastoid system. Fluid flow into and out of the flask is dependent upon the pressure gradient, compliance of the narrow neck and whether or not the bulbous portion is intact. It is suggested that locking of the tube may be dependent upon the speed of the application of the negative pressure and the compliance. Eustachian tube opening appears to be related not only to active muscle forces but may also be dependent upon the presence of a pressure gradient which passively assists tubal function. It is proposed that middle ear effusions result from reflux, aspiration or insufflation of nasopharyngeal secretions (acute otitis media), or from persistent functional or mechanical Eustachian tube obstruction (secretory otitis media) or both.
From previous studies of the ventila- small amount of liquid is instilled into tory, protective and drainage functions the mouth of the flask, liquid flow will of the Eustachian tube in children, sev- stop somewhere in the narrow neck, due eral concepts related to the pathogenesis to the relative positive air pressure that of middle ear disease have been postu- develops in the chamber of the flask. lated."?" The mechanisms proposed are This basic geometric design is considered largely based on an understanding of to be critical for the protective function fluid flow through a compliant tube re- of the Eustachian tube-middle ear syslated to the geometry of the system made tem. Reflux of the liquid into the vessel up of the nasopharynx, Eustachian tube, occurs if a hole is placed in the bulbous middle ear, and mastoid air cells. The portion of the flask (Fig. lb), the presfollowing will be a description of some sure in the bottom of the flask remaining of these concepts, but before attempting ambient. This condition is analogous to to understand the possible mechanisms a perforation of the tympanic membrane involved, a basic knowledge of fluid or the presence of a tympanostomy tube flow through a flask is necessary. where reflux of nasopharyngeal secre(Liquid flow through this type of ves- tions could occur since the middle earsel will be presented for purposes of mastoid air cushion is lost. Similarly, graphic description but the principles following a radical mastoidectomy the apply equally to the flow of air.) Pos- presence of a patent Eustachian tube sible clinical correlations will also be dis- could cause troublesome otorrhea. Figure Ic shows the effect of the application of cussed. a negative pressure to the bottom of the Fluid Flow Through a Flask. The Eu- flask. The liquid is aspirated into the stachian tube, middle ear, and mastoid vessel. In the clinical situation, the prescan be likened to a flask with a long, ence of high negative middle ear air narrow neck (Fig. I), the mouth of the pressure could aspirate nasopharyngeal flask representing the nasopharyngeal secretions into the middle ear. Figure ld end, the narrow neck the isthmus of the shows the effect of applied positive presEustachian tube, and the bulbous por- sure to the mouth of the flask. The liquid tion the middle ear and mastoid air is insufflated into the vessel. Nose blowchamber. Figure la shows that when a ing, crying or closed-nose swallowing From the Department of Otolaryngology, Children's Hospital of Pittsburgh, University of Pittsburgh School of Medicine, Pittsburgh, Pa.
182
183
PATHOGENESIS
L
-:
ASPIRATION
j'/ /
o
SLOW NEGATIVE PRESsuRE
Fig. 1. Fluid flow into a flask.
could create a high positive nasopharyngeal pressure and result in a similar condition in the human system. However, one of the major differences between a flask with a rigid neck and a biological tube such as the Eustachian tube is that the isthmus (neck) is compliant. Application of positive pressure at the mouth of a flask with a compliant neck would distend the neck, enhancing fluid flow into the vessel. The effect of applied negative pressure in a flask with a compliant neck is shown in Figure 2. Liquid flow through the neck would not occur (Fig. 2a) until a negative pressure is slowly applied to the bottom of the flask (Fig. 2b). Fluid flow would occur even if the neck was collapsed. However, if the negative pressure is suddenly applied, temporary locking of the compliant neck prevents the flow of the liquid (Fig. 2c). Therefore, the speed of the application of the negative pressure as well as the compliance in such a system would appear critical. Clinically, aspiration of gas into the middle ear would be possible since negative middle ear pressure would develop slowly as gas is absorbed by the middle ear mucous membrane. However, sudden application of negative middle ear pressure such as would occur with rapid alterations in atmospheric pressure, e.g., airplane flying, diving, or when attempting to test the ventilatory function of the Eustachian tube, could lock the tube preventing the flow of air. Likewise, sudden application of negative pressure at the nasopharyngeal portion of a highly compliant tube could also result in locking. Negative pressure in the middle
Further understanding of the anatomy and physiology of the nasopharynx, Eustachian tube and middle ear system will be necessary to uncover the pathogenic mechanisms involved in the middle ear effusion problem.
REFERENCES 1. Lupovich P, Bluestone CD, Paradise JL, et al: Middle ear effusions, preliminary viscometric, histologic and biochemical studies. Ann Otol Rhinol Laryngol 80:342-346, 1971 2. Bluestone CD: Eustachian tube obstruction in the infant with cleft palate. Ann Otol Rhinol Laryngol 80 (Suppl 2:1-30), 1971
3. Bluestone CD, Wittel RA, Paradise JL: Roentgenographic evaluation of Eustachian tube function in infants with cleft and normal palates. Cleft Palate J 9:93-100, 1972 4. Bluestone CD, Wittel RA, Paradise JL, et al: Eustachian tube function as related to adenoidectomy for otitis media. Trans Am Acad Ophthalmol Otolaryngol 76: 1325-1339, 1972 5. Bluestone CD, Paradise JL, Beery QC, et al: Certain effects of cleft palate repair on Eustachian tube function. Cleft Palate J 9: 183-193, 1972 6. Bluestone CD, Paradise JL, Beery QC: Physiology of the Eustachian tube in the pathogenesis and management of middle ear effusions. Laryngoscope 82: 1654-1670, 1972 7. Bluestone CD, Beery QC, Andrus S: Mechanics of the Eustachian tube as it influences susceptibility to and persistence of middIe ear effusions in children. Ann Otol Rhinol Laryngol83 (Suppl 11:27-34), 1974 8. Bluestone CD, Cantekin EI, Beery QC:
Certain effects of adenoidectomy on Eustachian tube ventilatory function. Laryngoscope 85: 113-127, 1975 9. Bluestone CD, Cantekin EI, Beery QC, et al: Eustachian tube ventilatory function in relation to cleft palate. Ann Otol Rhinol Laryngol 84:333-338, 1975 10. Cantekin EI, Bluestone CD, Parkin LP: Eustachian tube ventilatory function in children, Presented at the International Symposiurn on Recent Advances in Middle Ear Effusions, May 30, 1975, Columbus, Ohio. Ann Otol Rhinol Laryngol 85 (Suppl 25:171-177) 1976 11. Rich AR: Physiological study of Eustachian tube and its related muscle. Bulletin of Johns Hopkins Hospital 31 :206-214, 1920 12. Beery QC, Bluestone CD, Cantekin EI: Otologic history, audiometry and tympanometry as a case finding procedure for school screening. Laryngoscope 85:1976-1985, 1975 13. Bluestone CD, Cantekin EI, Moran PT, et al: Unpublished data 14. Paparella MM, Hiraida F, Juhn SK, et al: Cellular events involved in middle ear fluid production. Ann Otol Rhinol Laryngol 79:766-779, 1970 15. Odoi H, Proud GO, Toledo PS: Effects of pterygoid hamulotomy upon Eustachian tube function. Laryngoscope 81:1242-1244, 1971
Charles D. Bluestone, M.D., Dept. of Otolaryngology, Children's Hospital of Pittsburgh, University of Pittsburgh School of Medicine, Pittsburgh, PA. 15213.
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