Otosclerosis and Stapedectomy: Diagnosis, Management & Complications by Christopher De Souza and Michael E. Glasscock

605ae9a26889870-261x361.jpg Author Christopher De Souza and Michael E. Glasscock
Isbn 9781588901699
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Year 2003
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Otosclerosis and Stapedectomy Diagnosis, Management, and Complications Thieme Otosclerosis and Stapedectomy Diagnosis, Management, and Complications Christopher de Souza, M.D., F.A.C.S. Visiting Assistant Professor in Otolaryngology State University of New York Brooklyn, New York and Visiting Assistant Professor in Otolaryngology Louisiana State University Health Science Center Shreveport, Louisiana and Ear, Nose, and Throat and Skull Base Surgeon Tata Memorial Hospital Lilavati Hospital Holy Family Hospital Holy Spirit Hospital Mumbai, India Michael E. Glasscock, III, M.D., F.A.C.S. Clinical Professor Emeritus Department of Otolaryngology Vanderbilt University Medical Center Nashville, Tennessee Thieme New York • Stuttgart Thieme Medical Publishers, Inc. 333 Seventh Ave. New York, NY 10001 Assistant Editor: Owen Zurhellen Consulting Editor: Esther Gumpert Director, Production and Manufacturing: Anne Vinnicombe Production Editor: Becky Dille Marketing Director: Phyllis Gold Sales Manager: Ross Lumpkin Chief Financial Officer: Peter van Woerden President: Brian D. Scanlan Compositor: Compset, Inc. Printer: Sheridan Books, Inc. Library of Congress Cataloging-in-Publication Data De Souza, Chris Otosclerosis and stapedectomy: diagnosis, management, and complications / Christopher de Souza, Michael E. Glasscock III. p. ; cm. Includes bibliographical referencesand index. ISBN 1–58890–169–6 TMP : alk. paper—ISBN 1. Otosclerosis. 2. Stapedectomy. [DNLM: 1. Otosclerosis—surgery. 2. Otosclerosis—diagnosis. 3. Stapes Surgery. WV 265 D467o 2004] I. Glasscock, Michael E., 1933– II. Title. RF270 .D47 2004 617.8'82—dc22 Copyright © 2004 by Thieme Medical Publishers, Inc. This book, including all parts thereof, is legally protected by copyright. Any use, exploitation or commercialization outside the narrow limits set by copyright legislation, without the publisher’s consent, is illegal and liable to prosecution. This applies in particular to Photostat reproduction, copying, mimeographing or duplication of any kind, translating, preparation of microfilms, and electronic data processing and storage. Important note: Medical knowledge is ever-changing. As new research and clinical experience broaden our knowledge, changes in treatment and drug therapy may be required. The authors and editors of the material herein have consulted sources believed to be reliable in their efforts to provide information that is complete and in accord with the standards accepted at the time of publication. However, in the view of the possibility of human error by the authors, editors, or publisher, of the work herein, or changes in medical knowledge, neither the authors, editors, or publisher, nor any other party who has been involved in the preparation of this work, warrants that the information contained herein is in every respect accurate or complete, and they are not responsible for any errors or omissions or for the results obtained from use of such information. Readers are encouraged to confirm the information contained herein with other sources. For example, readers are advised to check the product information sheet included in the package of each drug they plan to administer to be certain that the information contained in this publication is accurate and that changes have not been made in the recommended dose or in the contraindications for administration. This recommendation is of particular importance in connection with new or infrequently used drugs. Some of the product names, patents, and registered designs referred to in this book are in fact registered trademarks or proprietary names even though specific reference to this fact is not always made in the text. Therefore, the appearance of a name without designation as proprietary is not to be construed as a representation by the publisher that it is in the public domain. Printed in the United States of America 54321 TMP ISBN 1–58890–169–6 GTV ISBN 3 13 136051 8 iv This book is dedicated to Evi Maria, Priyanka, Tara, and Rosemarie. v Contents 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. The Historical Background of Otosclerosis . . . . . . . The Pathology of Otosclerosis . . . . . . . . . . . . . . . . . Physical Examination and Clinical Evaluation of the Patient with Otosclerosis . . . . . . . . . . . . . . . . . . Audiological Evaluation of the Patient with Otosclerosis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Radiological Imaging of Otosclerosis . . . . . . . . . . . . Cochlear Otosclerosis . . . . . . . . . . . . . . . . . . . . . . . . Medical Treatment of Otosclerosis . . . . . . . . . . . . . . Hearing Aids and Otosclerosis . . . . . . . . . . . . . . . . . Lasers in Otosclerosis . . . . . . . . . . . . . . . . . . . . . . . . Stapedectomy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Obliterative Otosclerosis . . . . . . . . . . . . . . . . . . . . . Poststapedectomy Perilymph Fistulae . . . . . . . . . . . Sudden Sensorineural Hearing Loss Immediately Following Stapedectomy . . . . . . . . . . . . . . . . . . . . . Stapedectomy versus Stapedotomy . . . . . . . . . . . . . Bilateral Otosclerosis . . . . . . . . . . . . . . . . . . . . . . . . Special Conditions and Complications in Otosclerosis Surgery . . . . . . . . . . . . . . . . . . . . . . . . . Otodystrophies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . The Biomechanics of Stapes Replacement . . . . . . . . Appendix: Quiz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 3 23 31 41 51 59 69 73 89 119 129 137 141 149 157 169 183 189 199 vii Foreword The ankylosis of the stapes was first described by Valsalva1 in 1735 when he performed an autopsy on a deaf patient. In 1841, Toynbee2 reported 1659 cases of stapes fixation at autopsy. Politzer was the first to associate stapes ankylosis with a primary disease of the labyrinthine capsule in 1893.3 There are many theories on the etiology of otosclerosis that are not in the scope of an introduction. There are numerous sources for this information.4 Attempts to improve hearing by attacking stapes fixation in the oval window date back to 1878 when Kessel5 exposed the middle ear and attempted to mobilize the stapes. Miot6 reported 200 cases of stapes mobilization with results similar to those reported by Rosen7 in 1952. It was Lempert8 who proved that it was possible to operate on the inner ear without producing a sensorineural hearing loss. His one stage fenestration opened the door for the successful stapes surgery that followed. Shea9 revised the stapedectomy of Blake10 and Jack,11 and had the advantage of modern antibiotics and the operating microscope. Shea’s great improvement over the earlier surgeons work was his realization that to be successful, the ossicular chain must be reconstructed, after the stapes has been removed. He accomplished this by placing a tissue seal over the open oval window and using a prosthesis from the long process of the incus to the tissue seal. Over the years, there have been a number of variations on the theme of stapes surgery. Many different prosthesis have been suggested by a variety of otologic surgeons as the best one to use. In recent years, the stapedotomy procedure has produced a great deal of interest.10 Lasers, both CO2 and argon, have been employed successfully in stapedectomies as well as stapedotomies.12 Stapes surgery of either variety is successful in a high percentage of cases regardless of the technique used. Most surgeons report closure of the airbone gap to within 10dB in over ninety percent of the cases. Dead ears occur somewhere between .5 and 3 percent.13–15 What is as important as the surgical skill of the otologist, is the fact that other than the fixation of the stapes, these ears are generally normal in all other aspects. In other words, they have normal Eustachian tube function, middle ear mucosa, and tympanic membranes. The future always holds surprises. Perhaps in the next few years surgery will be obsolete. With all that is occurring in the field of genetics, gene manipulation may someday be the treatment of choice. Just think what Valsalva would think if he could walk into a modern operating room and observe a laser-assisted stapedotomy through an observation tube or better still, on a three-dimensional color television screen. Michael E. Glasscock III ix INTRODUCTION REFERENCES 1. Valsalva AM. Opera, hoc est, tractatus de aure humana. Venice; Pitteri: 1735. 2. Toynbee, J. Pathological and surgical observations on the diseases of the ear. Medico-Chir Tr. 1841;24:190. 3. Politzer A. Ueber primare Erkrankung der knochernen Labyrinthkapsel. Ztschr Ohrenh. 1893;25:309. 4. Shea JJ, Shea PF, McKenna MJ. Surgery of the Ear, vol. 5. 2002;519–520. 5. Kessel J. Uber ds Mobilisieren des Stiegbugels durch Ausschneiden des Trommelfelles, Hammers und Amboss bei undurchgangigkeit der Tuba. Arch Ohrenh. 1878;13:69. 6. Miot C. De la mobilization de I’etrier. Rev. Laryng. 1890;10:49, 83, 145, 200. 7. Rosen S. Palpation of stapes for fixation: preliminary procedure to determine fenestration suitability for otosclerosis. Arch Otol. 1952;56:610. 8. Lempert J. Improvement of hearing in cases of otosclerosis: new one-stage surgical technic. Arch Otolarnygol. 28:42, 1938 9. Shea JJ Jr. Fenestration of the oval window. Ann Otol Rhin Laryng. 1958;67:932. 10. Blake CJ. Middle ear operations. Tr Am Otol Soc. 1892;5:2, 306. 11. Jack FL. Further observations on removal of the stapes. Tr Am Otol Soc. 1893;5:3, 474. 12. Perkins RC. Laser stapedectomy for otosclerosis. Laryngoscope. 1980;90:880. 13. Sheehy JL, House HP. Causes of failure in stapes surgery. Laryngoscope. 1962; 73:10–31. 14. Hough JVD. Recent advances in otosclerosis. Arch Otolaryngol. 1966;83:379–390. 15. Schuknecht HF. Sensorineural; hearing loss following stapedectomy. Arch Otolaryngol. 1962;54:336–347. x Preface Stapedectomy still remains one of the most demanding and technical surgeries. There is virtually little room for error and the first surgical effort should be the best effort. In addition the experience garnered by earlier surgeons remains a distant dream for otological surgeons of today. For instance Jean Bernard Causse, a pioneer in this field had performed 25,000 stapedectomies in his lifetime. For today’s surgeon this would be next to impossible to accomplish in a single lifetime. I have been very fortunate to have first trained with Dr. Michael Paparella and then with Dr. Michael Glasscock. Through Dr. Paparella I received a clear insight as to how the otosclerotic process acted on temporal bones. The temporal bone laboratory at the University of Minnesota remains one of the finest in the world and it was there that I received several opportunities to look at the many temporal bones of patients who had suffered from otosclerosis. The microphotographs that appear in this book have been generously supplied by Dr. Paparella from the temporal bone lab at the University of Minnesota. I also had the unique opportunity to see Dr. Paparella operate on patients suffering from otosclerosis. This served to provide me the unique chance to translate histopathologial findings into clinical applications. Mike Paparella has provided many students all over the world a superb understanding not only of otosclerosis but also of many other otological problems. I am among many others who are indebted to him for this unique learning experience. Dr. Marcos Goycoolea, who studied otosclerosis extensively, also influenced me deeply with his observations on otosclerosis. Dr. Goycoolea wrote one of the finest chapters on otosclerosis in the book edited by Dr. Paparella. Later, I worked with Dr. Michael Glascock in Nashville at Baptist Hospital. This was the turning point in my life. It was there that I saw first hand the vastness of Dr. Glasscock’s experience with otosclerosis. I saw virgin stapedectomies, revision stapedectomies, re-revision stapedectomies, and so on. I also saw many patients who were referred by other physicians to Dr. Glasscock for surgery. Many of these had developed complications and were sent to him for treatment. It was here that the complexity of the approach to managing the patient suffering from otosclerosis really became apparent, especially if the patient had undergone unsuccessful surgery elsewhere. Decision making, timing of surgery, which ear to operate on and all the debates that one reads about in textbooks were brought to life in Dr. Glasscock’s practice. It was a very edifying experience to have trained with Dr. Glasscock and I will always remain deeply indebted to him for his willingness to share his thoughts, expertise, and experience with all those who were unafraid to approach him. He gave me not only his professional experience but also his warm, deep, and gracious personal friendship. To all his many students Dr. Glasscock will always be a legend. I have a great sense of pride and honor to assist Mike as a coauthor on this book. xi PREFACE I’d also like to thank Dr. C. Gary Jackson who was Mike’s partner in Nashville. Gary has a tremendous sense of humor and keen observation. Gary’s work was also extensive and we shared many a lively debate. I deeply appreciated everything I learned from Gary’s wide experience. I am deeply appreciative of the team at Thieme. J. Owen Zurhellen, Esther Gumpert, and Becky Dille, who were amazingly efficient, meticulous, and professional. They were also very, very kind. I’d like to thank Mr. Herman Rodrigues for all his help, time, and expertise that he generously gave to me. Finally in conclusion it has been my observation that all authors in their books end up thanking their families. I agree and I agree with a lot of certainity. This is so because time spent working on a book means time away from the family. So Mommy has been instrumental in a big way because she has been Mommy and Daddy to the children while Daddy works at being an author. Chris de Souza, M.D., F.A.C.S. July 10, 2003 xii Chapter 1 The Historical Background of Otosclerosis Otosclerosis is a disorder that affects the otic capsule exclusively. The term otosclerosis is itself actually a misnomer. It is localized otoporosis, not sclerosis of the otic capsule in its active stage. Many authors prefer the term otospongiosis because they feel this word more accurately describes the disease in its active phase. For the purposes of convenience, the disease is described as otosclerosis for the rest of this book. It was Italian anatomist Valsalva who,on a postmortem examination of a deaf patient, described ankylosis of the stapes to the margins of the oval window. English otogist Toynbee noted osseous ankylosis in his dissection of over a thousand temporal bones. It was Politzer who first applied the term otosclerosis. He based this on his findings on temporal bones of patients whom he had diagnosed to be suffering from “deafness that had previously been attributed to chronic interstitial middle ear catarrh with secondary stapes ankylosis.” Politzer’s discovery was confirmed by Bezold and by Siebenmann. In 1912, Siebenmann proposed a change in nomenclature from otosclerosis to otospongiosis. This change received support from the French otologist Sourdille. In 1950, Raymond Thomas Carhart, an audiologist, originated the term air-bone gap. He reported the notching in bone conduction in the condition of stapedial otosclerosis, notching that has been subsequently known as Carhart’s notch. Carhart in 1964, and again in 1966, described audiometric findings that were typical of stapedial and cochlear otosclerosis. EVOLUTION OF STAPES SURGERY In 1878, Kessel described the first successful stapes surgery. The patient, a young man who had been diagnosed as suffering from otosclerosis, had fallen off a wagon and struck his head on the ground. After a brief spell of unconsciousness, the young man found that his sense of hearing had greatly improved. The patient later died of his injuries, and Kessel was able to study his temporal bones. He concluded that the stapes had been mobilized and tried to duplicate this in his surgeries. Many others attempted to emulate Kessel’s work. Boucheron in France reported using techniques similar to that of Kessel. In 1890, Miot reported a series of 200 stapes mobilizations without a single death or labyrinthine 1 OTOSCLEROSIS AND STAPEDECTOMY complication. All this was done using gaslight and a reflector and local anesthesia. Blake from Boston in 1892 and Jack in 1893 also reported good results from stapes mobilizations. It was in 1900 at the International Congress of Otolaryngologists in Europe that Politzer and Siebenmann condemned stapes surgery because of its potential to cause meningitis. The result of this public condemnation caused a complete halt to stapes surgery for the next quarter century. FENESTRATION OF THE LABYRINTH In 1916, Holmgren began a long series of operations for stapes ankylosis. He demonstrated that by using careful sterile techniques, the labyrinth could be safely opened. Holmgren’s assistant, Nylen, first employed the microscope for ear surgery. Holmgren was not successful, however, in maintaining an open fenestra. In 1924, Sourdille devised a procedure that he termed tympanolabyrithopexy. This two-stage procedure began to give lasting results. Sourdille’s success lay in covering the fistula in the horizontal semicircular canal with a very thin skin of the external auditory canal. Lempert, in 1941, found that extraction of the incus did not cause a reduction in hearing; rather, it provided him with more space to create a wider fenestra over the ampullated end of the lateral semicircular canal. Lempert’s was a one-stage technique. In 1953, Rosen accidentally mobilized the stapes of a patient under local anesthesia. The patient reported that his hearing had suddenly improved. In 1956, Shea reported the first stapedectomy using the operating microscope. Shea sealed the oval window and placed a homograft bone implant between the oval window and the incus; there was an immediate hearing gain. Over time, a conductive hearing loss reappeared because of adhesions. Shea soon replaced that with a Teflon replica of the stapes. In 1960, Shea inserted a Teflon piston into a small fenestra; thus, stapes surgery was born. Also in that year, Schuknecht used a stainless steel wire prosthesis placed against Gelfoam to seal the oval window. REFERENCES Howard HP. The evolution of otosclerosis surgery. Otolaryngol Clin North Am. 1993;26:323–333. Shambaugh GE. Definition and historical background. In: Wiet RJ, Causse JB, Shambayh GE, Causse JR, eds. Otosclerosis (Otospongiosis). American Academy of Otolaryngology—Head and Neck Surgery Foundation; Alexandria, Va; 1991;9–23. 2 Chapter 2 The Pathology of Otosclerosis Otosclerosis is a primary and exclusive disease affecting only the otic capsule and the ossicles. It is a localized disorder of bone metabolism of the otic capsule avascular endochondral bone that is characterized by disordered resorption and deposition of bone. Otosclerosis occurs only in the temporal bone (Wang et al 1999). ETIOLOGY The exact etiology of otosclerosis is not known at this time, although many theories have been postulated. None of these theories have been proven to be a definite cause of otosclerosis. Postulated etiologies are hereditary factors, endocrine and metabolic factors, and vascular factors. Alterations in vascularity (either an increase or a decrease in blood supply) have been postulated by Witmaack (1930), Wolff (1950), and Mendoza and Ruis (1966) to play a role in the etiology of otosclerosis. Intrinsic and extrinsic mechanical stresses as the result of an erect posture were once considered (Mayer 1917) as a cause of otosclerosis, because the petrous pyramid is located at the base of the skull. Because it was located at the base of the skull, it was subjected to mechanical strains exceeding the physiological limits of tolerance, which resulted in defects in the endochondral layer of the bony labyrinth. It was further theorized that the stress factors appeared during the phylogenic and otogenic development due to rotation of the petrous bones at the base of the skull. It was thought that the cochlea moved forward and upward and the vertical semicircular canals backward and downward. Thus, the petrous pyramid has an almost horizontal position in humans versus a vertical position in quadrupeds. This theory was abandoned because otosclerotic changes first appeared in the footplate of the stapes. Fowler (1949) suggested that otosclerosis might be an expression of a general mesenchymal hypoplasia. This was further supported by Ogilvie and Hall (1962), who postulated that otosclerosis was a local manifestation of osteogenesis imperfecta. In recent times viral infections and autoimmune factors have also been postulated to trigger the otosclerotic processes. Ruedi (1963) demonstrated shunts between the vascular system of the otosclerotic bone and the inner ear, and suggested that venous stasis from these shunts might be responsible for sensorineural hearing loss. 3 OTOSCLEROSIS AND STAPEDECTOMY CLINICAL PRESENTATION Age of Onset It is difficult to assess the true onset of otosclerosis because the development of histopathologic changes is gradual. Clinical otosclerosis is commonly seen between the ages of 30 and 40 (Nager 1969), with the average age of presentation being 33. DeJuan (1960), comparing the age of onset among various age groups, noted that 28% of cases occurred between ages 18 and 21, 40% presented between ages 21 and 30, and 22% presented between ages 31 and 40. The clinical presentation of otosclerosis is usually that of a conductive hearing loss, which may be unilateral or bilateral. Occasionally it may present as a sensorineural hearing loss. The onset of hearing loss is usually between the fourth and fifth decades, with a higher prevalence in women than men (in the ratio of 2:1). Hearing impairment reaches its maximum in the third decade and then usually remains stable (Glorig and Gallo 1962). Prevalence The prevalence of otosclerosis has been reported as 0.1 to 1.0%, with an average of 0.3% (Gordon, 1989). Autopsy studies (Konigsmark and Gorlin 1976) have found histologic otosclerosis in 5 to 18% of the general population. Jahn and Vernick (1986) stated that 10% of Caucasians develop histologic otosclerosis, and 1% go on to develop clinical otosclerosis. Shambaugh (1961) found that histological otosclerosis was 10 times more common than clinical otosclerosis. Friedmann (1974) and Morrison (1967), however, found the incidence to be approximately 2%. It can therefore be seen that the exact incidence of clinical otosclerosis is not clear and next to impossible to determine. Many authors have noted that in recent years the incidence of patients presenting with otosclerosis has fallen dramatically. The prevalence varies in racial populations, being rare, for example, in African blacks and Asians. Race There is a definite racial predisposition. Otosclerosis is more commonly found in Caucasians. Clinical otosclerosis has been reported to be present in 1% of the population of the United Kingdom, occurring mostly among white females (Hinchcliffe 1961). Guild (1944) reported histologic evidence of otosclerosis in 18.5% of middle-aged white women, 9.7% of adult white men, and only 1% of adult blacks. Cawthorne (1952) found that otosclerosis was more prevalent in fair-haired men than in dark-haired men. The prevalence of otosclerosis is low among Asians (Altmann et al 1967; Nakamura 1968). The prevalence of otosclerosis is low among Japanese (Goto and Omori 1957; Horiguchi 1953; Takahara et al 1959), Chinese, and Indonesians (Nizar 1960). In a comparative study conducted in Hawaii, Joseph and Frazer (1964) found the incidence of otosclerosis to be more prevalent in Caucasians than in Japanese. Rosen and coworkers (1962) did not find clinical cases of otosclerosis in Sudan. Among the Todas in India, however, the prevalence of otosclerosis was estimated at 17%. Kapur and Patt (1966) emphasized the presence of consanguineous marriages, a custom among the 4 CHAPTER 2 ● THE PATHOLOGY OF OTOSCLEROSIS Todas. Consanguinity would then appear to influence the data retrieved. The prevalence of otosclerosis in Native Americans is extremely low across the North American continent (Cambon et al, 1965). Wiet (1979) evaluated a large number of Native Americans and found that only 10 had undergone stapedectomy, of which only three had confirmed otosclerosis, a number representing a minute fraction of the entire population examined. Tato and Tato (1967, 1969) evaluated 5000 Native Americans and found no cases of otosclerosis at all. When there is a racial mixture, however, otosclerosis begins to manifest itself (Goycoolea 1991). Gender Otosclerosis is thought to be more prevalent in women. Schmidt (1933) quoted a female preponderance of 72.5% incidence, whereas Shambaugh (1952) found an incidence of 68% and Cawthorne (1955) an incidence of 67% of women who developed otosclerosis. Because otosclerosis is not a genetically sex-linked characteristic, a ratio of 1:1 would have been expected. However, this has not been found to be true. Endocrinologic factors have been suspected in women. Hueb et al (1991) found a higher incidence of bilateral otosclerosis in women than in men, thus prompting them to believe that women would be more likely to seek medical advice than men. This might possibly account for the apparent gender predisposition. OTOSCLEROSIS AND PREGNANCY Otosclerosis becomes evident during the childbearing years. Most authors report otosclerosis becoming aggravated during pregnancy. Shambaugh (1967) analyzed 475 female patients and reported that 50% did not find any hearing impairment following pregnancies, whereas 8% noticed hearing impairment immediately following pregnancy. In the remaining 42% of patients, hearing loss was associated with pregnancy. Thus, in Shambaugh’s series there is a 50% chance of an association of hearing loss following pregnancy. Repeated pregnancies in the same woman, however, did not further worsen hearing. Walsh (1954) found no evidence of a relationship between hearing loss, pregnancy, and otosclerosis. Shambaugh (1967) estimated that the risk of hearing loss to a woman following pregnancy is approximately 1 in 24. Elbrond and Jensen (1979) and Gristwood and Venables (1983) also noted the association of hearing loss following pregnancy. Elbrond and Jensen (1979) studied the hearing threshold of 144 women before and after stapedectomy. The women were between 16 and 40 years old, and all had undergone stapedectomy for otosclerosis. The observation period for the women who became pregnant following stapedectomy was between 4 years and 9 months and 5 years and 8 months. The authors observed that (1) hearing loss became greater in those who became pregnant than in those who did not and (2) the hearing loss became significantly greater in the nonoperated ear of those patients who became pregnant following surgery. It would thus seem that stapedectomy confers some protection from further hearing loss following pregnancy. Although these authors note a correlation between pregnancy and the onset of hearing loss following pregnancy, they are not clear on how this occurs. Morrison (1979) attributed this to increased estrogen levels, which cause fragility of the lysosomal membranes, with the 5 OTOSCLEROSIS AND STAPEDECTOMY consequent release of enzymes that in turn activate the otosclerotic process. Causse and Causse (1991) postulated that the otosclerotic process is stimulated by the release of increased quantities of estrogen. The increase in estrogen levels causes the lysosomal membranes to become fragile, which in turn leads to the rupture of the membranes with the consequent diffusion of their enzymes, resulting in the destruction of the cochlea and its structures. DOES OTOSCLEROSIS PRESENT ONLY AS A CONDUCTIVE HEARING LOSS? A progressive conductive hearing loss in adults is typical of the way otosclerosis presents (Chole and McKenna 2001). This is due to the fixation of the stapedial footplate along its anterior anulus. On rare occasions, otosclerosis can be associated with sensorineural hearing loss (Schuknecht and Kirchner 1974). This is due to cochlear otosclerosis. It is thought that some individuals may present with cochlear otosclerosis in the absence of a conductive hearing loss. Temporal bone studies have shown that involvement of the endosteal portion of the cochlea is associated with sensorineural hearing loss and diminished bone conduction hearing thresholds (Ghorayeb and Linthicum, 1978; Hueb et al, 1991). Hyalinization of the spiral ligament adjacent to the otosclerotic foci has been shown to be associated with sensorineural hearing loss (Antoli-Candela et al 1977; Gussen 1975; Hinojosa and Marion 1987). HISTOLOGIC OTOSCLEROSIS Although less than 1% of the population develops clinical otosclerosis, the finding of an otosclerotic focus upon autopsy is much more common. Histologic otosclerosis (Guild 1944) is a disease process without clinical symptoms or manifestations and can only be discovered by routine sectioning of temporal bones (Fig. 2–1) at autopsy. Histologic otosclerosis may be seen as an incidental postmortem finding without causing clinical symptoms. Clinical otosclerosis is otosclerosis at a site where it causes a hearing loss, which may be conductive, sensorineural, or mixed. Histologic otosclerosis has been reported as 8.3% and 11% in large random autopsy series. Otosclerotic foci can sometimes be seen on high-resolution computed tomography (CT) scans of the temporal bone as areas of hypodensity of the otic capsule or in the vicinity of the oval window (Valvassori 1993). CT scanning, however, is not reliable in detecting otosclerosis, especially when the lesions are sclerotic (Thiers et al 1999). It is possible that future advances in CT imaging and densitometry may be more sensitive in the detection of these lesions. Otosclerotic lesions may also show contrast enhancement on magnetic resonance imaging (Ziyeh et al 1997). SIMILAR DISORDERS Otosclerosis, or otosclerotic-like lesions of the footplate and otic capsule, has been observed in other inherited bone disorders. Otosclerosis is also seen in some patients with osteogenesis imperfecta who commonly develop conductive hearing loss. The lesions in the temporal bone appear similar to 6 CHAPTER 2 ● THE PATHOLOGY OF OTOSCLEROSIS A B Figure 2–1 (A) Photomicrograph of a human temporal bone with histologic otosclerosis (O). This focus lies anterior to the oval window and has not resulted in any symptoms. This is an incidental finding on autopsy, discovered accidentally, and is termed histologic otosclerosis. (B) Magnified view of the same human temporal bone section demonstrating histologic otosclerosis. those of otosclerosis (Nager 1988), although some patients have lesions consisting of diminished calcification and microfractures. The bony lesions of Paget’s disease in the otic capsule may appear similar to otosclerosis, although their distribution within the temporal bone is distinct (Fig. 2–2). Large multinucleate osteoclasts are much more prominent in Paget’s disease than in otosclerosis. It must be stated that the conductive hearing losses sometimes associated with Paget’s disease are not due to ossicular lesions, but may be due to the loss of mineral density in the otic capsule (Khetarpal and Schuknecht 1990). Paget’s disease of the bone, like otosclerosis, is a disorder of localized bone remodeling, with osteoclastic resorption followed by compensatory increases in bone formation. Paget’s disease affects localized regions of the skeleton while sparing others; however, unlike otosclerosis, it is not restricted to the temporal bone. Thirty percent of those suffering from Paget’s have a family history of the disease, causing speculation about a genetic basis of this disease. There is recent evidence from linkage studies 7

Author Christopher De Souza and Michael E. Glasscock Isbn 9781588901699 File size 2.7MB Year 2003 Pages 212 Language English File format PDF Category Medicine Book Description: FacebookTwitterGoogle+TumblrDiggMySpaceShare Co-authored by leading specialists, this comprehensive and current book provides a detailed and practical discussion of otosclerosis patient diagnosis, treatment, and management. The book presents a step-by-step account of stapedectomy surgery, and also covers: the pros and cons of all lasers including the latest erbium lasers and their current applications; the analysis of recent otosclerosis studies using CT scanning and audiometry as parameters; stapedectomy versus stapedotomy; frequent complications encountered in otosclerosis surgery; and much more! Key features: Walks beginners through the fundamental steps necessary to fully understand otosclerosis and stapedectomy Solutions to difficult problems encountered daily by experienced otologists Special chapters on revision and laser stapedectomy surgeries Practical quiz that helps reinforce all the salient features of the book Appealing to the novice as well as the experienced professional, this book is a key resource for any practitioner in the field – general ENT specialists, ENT surgeons, as well as medical students and otology fellows. Use this book to keep up-to-date on this important topic.