The Preoperative Diagnosis Of Tympanosclerosis

BackgroundTympanosclerosis is the regeneration of middle ear connective tissue caused by a long-term chronic inflammation, which is one of the important causes of conductive deafness. Its main pathological change represents the appearance of hyaline degeneration and calcareous deposit in the submucosal of middle ear cavity and lamina propria in tympanic membrance. The concept of tympanosclerosis was described by Von Troltsch in detail for the first time in 1869. He also proposed the new term "sclerosis".In 1956, Zollner wrote a paper called "Tympanosclerosis" after a great deal of myringoplasty, so tympanosclerosis was officially named. The reported incidence of tympanosclerosis is inconsistent,20% to 43% abroad, while 3.1%to 1 1.7% in China.At present, the etiology and pathogenesis of tympanosclerosis is still unclear. However, with the development of tympanoplasty and wide use of the surgical microscope, the disease is drawing more and more attention. Research reports concerning the etiology and treatment effect of tympanosclerosis have increased gradually, while the research concerning of tympanosclerosis diagnosis are poor. Nowadays the actual diagnosis of tympanosclerosis often relies on surgical exploration and pathological changes.Now,it remains a problem that how to improve the preoperative diagnosis level of tympanosclerosis (namely the preoperative confirmation of lesion properties and range, making certain about the function of ossicular chain), in order to determine an appropriate operation scheme and communicate better with patients before operation.Objective1. To study the characteristics of image manifestation of temporal bone in tympanosclerosis using High Resolution Computed Tomography(HRCT), and discuss the diagnosis value of HRCT to tympanosclerosis and its lesion range and the evaluation of ossicular chain state.2. To study the audiology characteristic of pure tone threshold determination of tympanosclerosis, and discuss the preoperation diagnosis value of pure tone audiometry to the function evaluation of ossicular chain in tympanosclerosis.3. To study the diagnosis value of ear endoscope to the lesion properties and lesion range of tympanosclerosis with the symptom of tympanic membrane perforation and ossicular chain state.4. To discuss one kind of examination method which combines HRCT, pure tone audiometry and ear endoscope all together, comprehensively analyse and evaluate the results of the method, summarizing the diagnosis value of the method to the lesion properties and lesion range of tympanosclerosis and ossicular chain state and the guideline of the method to the making of operation program and the prediction after operation.Methods1. Research objectsInclusion criteria①Patients with the disease of tympanosclerosis who need tympanic exploration or mastoidectomy in the clinical diagnosis;②All the files including clinical and hearing information and image data(HRCT data) are available;③The initial operation is not the repeatedly modified operation;④The initial operation is carried out by the same treatment group.From August 2006 to August 2010, the number of ears satisfying the inclusion criteria was 56 which came from 52 tympanosclerosis resident surgical cases carried out by the same treatment group. Among them, the male cases was 35, the female cases was 17, which aged from 12 to 64 and the average age was 35.74. The medical history ranged from 1 year to 40 years,and the average was 16.48 years. The both ears cases was 4, and the single ear cases was 48, of which 8 ears owned unbroken tympanic membrane, the cases together with the symptom of tympanic membrane perforation was 48, of which 39 cases was Pars tensa perforation, and 9 cases was coalescent Pars tensa perforation. All the cases were diagnosed tympanosclerosis by operation and pathological diagnosis.2. Methods of examination and interpretation of resultsHRCT:Axial scan and coronal reconstruction were conducted by US GE64 Rows Lightspeed VCT scanistor. The base line of axial scan was the upper line of hearing orbit, the scan range was from arcuate eminence to the lower wall of external auditory canal. Targeted scan was conducted. The matrix was 512×512 for bone arithmetic reconstruction. The thickness and spacing of scanning layers were both 1mm, window width was 4000Hu, window location was 700Hu,FOV=32. The characteristic changes of tympanosclerosis refer to the emerge of high density calcification or ossification image in tympanic membrane, tympanic cavity and around auditory ossicle, and the noncharacteristic changes of tympanosclerosis refer to the thickening of tympanic membrane, mastoid soft tissue density image of tympanic cavity and the damage of auditory ossicle and tympanic cavity wall.Pure tone audiometry:The index of the variables in preoperation pure tone threshold determination:Taking the mean value of air conduction and bone conduction at 500,1000,2000Hz as average PTA (pure tone audiometry). ABG(air bone gap) is obtained by AC(air conduction) minus the corresponding period BC(bone conduction). Taking ABG≥30dB as the judgement standard of ossicular chain fixation or discontinuity.Ear endoscopy:Ear endoscopy was carried out in partial cases (48 ears) with the symptom of tympanic membrane perforation, and pathological change situation was recorded. Taking the emerge of calcification and ossification in tympanic cavity and around auditory ossicle as the diagnostic criteria of tympanosclerosis. 3. Operation examination and lesion classificationGeneral anesthesia, regular examination of tympanic cavity or/and mastoidectomy. According to lesion range and the situation of ossicular chain, the cases could be classified as 4 types:Type I, ossification nidus only influenced tympanic membrane; TypeⅡ, ossification nidus influenced the upper tympanic cavity so that malleus and incus were fixed, or merged with the scute. Stapes could move well and had a complete structure; Type III, ossification nidus in the upper and middle tympanic cavity influenced ossicular chain so that stapes was fixed, while the Chui Zhan bone could move well; Type IV, tympanic cavity and tympanic antrum was filled up with ossification tissue so that ossicular chain was wrapped up and fixed, partial ossicular was broken and absorbed.4. Comparative study and statistic analysis①Comparing temporal bone HRCT imaging manifestation with the results of operation examination, get the diagnosis agreement rate of all types.②Statistic analysis of pure tone audiometry results and intraoperative lesion classification and ossicular chain situation.③Comparative study of ear endoscopy and intraoperative examination results.④Analyse the pure tone audiometry characteristic of the misdiagnosis cases of temporal bone HRCT imaging diagnosis and the ear endoscopy examination results, and make a comprehensive analysis of the cases.Results1. Temporal bone HRCT imaging manifestation and operation examination resultsPreoperation CT imaging manifestation①tympanic membrane:20 ears thickened,29 ears calcified,44 ears were pierced;②tympanic antrum and tympanic cavity:calcification oven or high density ossification were found in 23 ears, both calcification nidus (or high density ossification)and soft tissue density image were found in 9 ears, the only soft tissue density image found in 7 ears.③ mastoid cavity:soft tissue density image were found in 6 ears④ossicular chain: 21 ears calcified and were wrapped up. Wormerode-like change or sclerotin damaged but continuous were found in 15 ears, sclerotin damaged and discontinuous were found in 6 ears.⑤no apparent abnormality were found in tympanic cavity and ossicular chain in 14 ears.Intraoperative examination results:①tympanic membrane:24 ears thickened,33 ears calcified,48 ears were pierced;②tympanic antrum and tympanic cavity:calcification oven or ossification plaque were found in 20 ears. Calcification nidus and ossification plaque with the symptom of granulation were found in 19 ears, with cholesteatoma found in 4 ears, with secretory tympanitis found in 2 ears, no abnormality found in tympanic antrum and tympanic cavity in 11 ears;③granulation tissue was found in mastoid cavity in 6 ears.④ossicular chain:ossicular was fixed owing to calcification oven, of which malleus and incus were fixed in 21 ears, stapes were fixed in 14 ears, the whole ossicular chain was wrapped up in 10 ears. Ossicular chain was only wrapped up in 14 ears,ossicular damaged but continuous were found in 22 ears, ossicular damaged and discontinuous were found in 9 ears, no abnonnality was found in ossicular chain in 11 ears.No calcification was found in 18 (11+7) ears by high-resolution CT, of which no apparent abnonnality were found in imaging manifestation except for tympanic membrane perforation in 11 ears. Out of the 11 ears, tympanic membrane calcification were found in 4 ears by operation examination, calcification were found in tympanic antrum and the upper tympanic cavity in 9 ears, calcification was found on the surface of promontoryoftympanum in 5 ears, ossicular chain was calcified and wrapped up in 7 ears,5 ears belonged to malleus and incus fixed type, 2 ears belonged to stapes fixed type. Only soft tissue density image was found in the other 7 ears, of which tympanic membrane calcification was found in 1 ear by operation examination, calcification oven was found in tympanic antrum and the upper tympanic cavity in 2 ears, calcification was found on the surface of promontoryoftympanum in 3 ears, ossicular chain was calcified and wrapped up in 1 ear. Intraoperative lesion classification and the diagnosis agreement rate of CT protocoling classification:11 ears for TypeⅠ, agreement rate 9//11=81.82%; 21 ears for Type II, agreement rate 14/21=66.67%,14 ears for Type IIII, agreement rate 6/14=42.86%,10 ears for Type IV, agreement rate 3/10=30%, of which, for 32 ears, classification diagnosis results of image protocoling diagnosis accorded with that of operation examination, the diagnosis rate was high for Type I, but not high for others, the overall classification diagnosis agreement rate was 57.14%。The overall diagnosis rate of CT diagnosis was 67.86%, misdiagnosis rate was 18/56=32.14%。2. The characteristic of pure tone audiometry and intraoperative lesion classificationPreoperative audiometry results:①the average of air conduction threshold was 35-65dBHL②for 51 cars, the spacing between bone conduction and air conduction≥30dBHL, for 5 ears,≤30dBHL, for all the other cases except Type I,≥30dBHL③for 34 ears, Carchart-like incisura change was found in audiogram.Intraoperative examination of ossicular chain function:11 ears could move well, malleus and incus were fixed in 14 ears, stapes fixed in 21 ears, the whole ossicular chain fixed in 10 ears. Ossicular chain was calcified and wrapped up in 22 ears, sclerotin damaged but continuous were found in 16 ears, sclerotin damaged and discontinuous were found in 7 ears, no abnormality was found in ossicular chain in 11 ears.Intraoperative lesion classification and the ABG mean value of audiometry for all types:11 ears for Type I, ABG=2.60+6.33dBHL; 21 ears for Type II, ABG=35.70++8.43dBHL; 14 ears for TypeⅢ, ABG=41.33+9.87dBHL; 10 ears for Type IV, ABG=39.23+8.75dBHL。3. Ear endoscope examinationThe preoperative ear endoscope examination for 48 ears with the symptom of tympanic membrane perforation:①the tympanic membrane of 24 ears thickened, 32 ears calcified,48 ears were pierced;②coralreef-like or onionskin-like calcification oven was found on the surface of promontoryoftympanum in 14 ears, 10 ears with the symptom of granulation,4 ears with cholesteatoma.③the surroundings of ossicular chain was wrapped up by calcification oven in 17 ears, sclerotin damaged but continuous in 7 ears, sclerotin damaged and discontinuous in 4 ears, no abnormality was found in ossicular chain in 11 ears.Findings from the same group of patients:①the tympanic membrane of 24 ears thickened,32 ears calcified,48 ears were pierced;②calcification oven or calcification plaque were found in tympanic antrum and the upper and middle tympanic cavity in 17 ears,10 ears with the symptom of granulation,4 ears with cholesteatoma.4 ears with mastoid cavity granulation tissue.③malleus and incus were fixed owing to calcification oven around ossicular chain in 16 ears, stapes were fixed in 11 ears, the whole ossicular chain was wrapped up in 10 ears. Ossicular damaged but continuous were found in 12 ears, ossicular damaged and discontinuous were found in 7 ears, no abnormality was found in ossicular chain in 11 ears.4. Comprehensive diagnosisIn the 56 cases by temporal bone HRCT imaging diagnosis,18 ears were misdiagnosed, the diagnosis rate was 38/56=67.86%.In the pure tone audiometry results of the 18 misdiagnosed ears, all the visible ABG≥30dBHL.The ear endoscope examination results for 12 ears of the 18 misdiagnosed ears, tympanic membrane calcification was found in 4 ears, no tympanic membrane calcification in 8 ears. Coralreef-like calcification oven was found on the surface of promontoryoftympanum in 9 ears. Ossicular was wrapped up by calcification in 4 ears.4 ears with the symptom of cholesteatoma,1 ear with granulation.As for the 5 ears with the simptom of granulation and cholesteatoma, no ossification diagnosis was drawn by endoscope examination owing to the impact of complication, the diagnosis of tympanosclerosis was drawn by operation examination. As for other 6 misdiagnose ears with complete tympanic membrane, the operation examination showed that 4 ears belonged to malleus and incus fixed type,2 ears belonged to stapes fixed type. Conclusion1. The pathognomonic HRCT manifestation of tympanosclerosis was that ossification speckle or calcification plaque were found in tympanic membrane or middle ear cavity, ossicular chain and its surrounding structures were in disorder and calcified and wrapped up. HRCT had a higher diagnosis value to the prediction of tympanosclerosis and its preoperative lesion range and the damage of ossicular chain. However, misdiagnosis still existed.2. The audiology characteristic of pure tone threshold determination of tympanosclerosis influencing ossicular chain was that ABG≥30dBHL, and carchart-like incisura change emerged. Pure tone audiometry could well evaluate the functional situation of ossicular chain.3. For the patients of tympanosclerosis with the symptom of tympanic membrane perforation, the results of preoperative ear endoscope examination were that white ossification plaque was found in tympanic cavity, and could wrap the ossicular up. ear endoscope examination was very helpful to the diagnosis of tympanosclerosis and leaning about the situation of ossicular, but had little help in the preoperational evaluation of lesion range.4. By the comprehensive diagnosis of HRCT, pure tone audiometry and ear endoscope, the preoperatioal diagnosis rate of tympanosclerosis could increase, and the functional situation of ossicular chain could be better known. Thus, it could provide basis for the determination of operational program and the prediction and evaluation of hearing function.