上鼓室内陷袋的高分辨CT表现

The Expression of Attic Retraction Pocket with High Resolution Computed Tomography Scans

目的探讨上鼓室内陷袋颞骨高分辨CT的表现及其中耳、乳突通气情况。方法对43例(54耳)上鼓室内陷袋患者(内陷袋组)行颞骨高分辨CT检查,重建其乳突气房,对蒲氏间隙、鼓峡、盾板到锤骨柄的距离、上鼓室等进行观察。正常44耳作为对照组。结果①内陷袋组乳突气化良好率和气化不良率分别为9.3%、90.7%,其乳突气房平均容积为0.350cm3;正常组乳突气化良好率和不良率分别为75%、25%,乳突气房平均容积为4.854cm3,二者间差异有统计学意义(P<0.05);②内陷袋组盾板最低点到锤骨间距离平均值为0.20±0.05cm,对照组平均值为0.23±0.06cm,二者间差异有统计学意义(P<0.05);③Ⅲ、Ⅳ级内陷袋盾板破坏,外上鼓室增宽,Ⅳ级内陷袋多伴听骨链破坏;④内陷袋组蒲氏间隙堵塞占66.7%,鼓峡堵塞占63%,上鼓室、鼓窦、乳突、中鼓室及咽鼓管口软组织影出现率分别为59.2%、66.7%、30%、16.8%、13%。结论①乳突气房发育是内陷袋形成的原因之一,其气化程度和内陷袋的程度无关;②内陷袋的形成和蒲氏间隙的狭窄、堵塞及鼓峡堵塞导致通气不良有关,炎性病变多以听骨链区域为主。

Objective To explore and evaluate the features of attic retraction pocket in the temporal bone high resolution computed tomograhhy scans（HRCT）. Methods 43 cases （55 ears）, gathered between February 2006 and February 2007,were examined with the HRCT. Using a three dimensional multiplanar volume rendering technique, the mastoid air cell systems were measured. The Prussak＇s space, the distance from scutum to manubrium of malleus （SM value） ,tympanic isthmus and others were analyzed. The normal 44 ears were used as control group. Results （1）The rates of better mastoid pneumatlzation ;and hypocellularity were 9.3 % and 90.7 % in retraction pocket group, and the mean volume of mastoid air cell was 0. 350 cm^3. For the control group , the rates were 75% and 25% while the mean volume of the mastoid air cel was 4. 854cm^3. There was statistical difference inn the rate of the mastoid pneumatization between the two groups, but no statistical difference between the different grade retraction pocket. （2）The mean SM value was 0. 20±0. 05 cm in 1 grade, 1 grade retraction pocket group ,while 0.23±0.06 cm in control group. There were statistical differences between them. （3）The seumb plate was eroded in grade Ⅲ. The ossicular chain was eroded in grade Ⅳ. （4）It was found that 36 ears （66.7%） were obstructed by soft tissue in Prussak＇s space ,34 ears （63%） in the tympanic isthmus . The rates of soft tissue in attic were 59.2% ,66.7% in tympanic antrum, 30 % in mastoid cavity, 16.8 % in the mesotympanum, 13 % in the tympanic opening of Eustachian tube. Conclusion Hypocellularity is one factors of the attic retraction pocket, but there is no relationship with the grade of retraction. The narrow Prussak＇s space and the obstruction in Prussak＇s space and tympanic isthmus contribute to the pars flaccida retracted. The pathological tissue is around the ossieular chain and surgeons should pay more attention to the potential problem.