林凱南臺灣大學：臨床醫學研究所江秉穎Chiang, Rayleigh Ping-YingRayleigh Ping-YingChiang2007-11-272018-07-062007-11-272018-07-062004http://ntur.lib.ntu.edu.tw//handle/246246/55542背景 內耳的疾病，包括耳蝸或前庭的病變，若症狀突然發生，常被認為與內耳的血液循環障礙有關。突發性耳聾(sudden deafness)為原發性(idiopathic)突然發生之感音神經性聽力喪失(sensorineural hearing loss)。這是一種常見的急性聽力喪失，亦可能會合併有眩暈的症狀。其致病原因目前有釵h不同的學說，較為普遍接受者有二：1. 發炎學說：病毒感染或自體免疫系統的作用造成內耳迷路發炎。2. 血液循環學說：內耳血液循環不良導致內耳的缺血狀態。目前突發性耳聾的治療方式以全身性投予高劑量類固醇及合併血管擴張劑或血液循環促進劑為主。但是，投予高劑量類固醇常會伴隨不必要的副作用。因此，直接由耳內(intratympanic)投予類固醇至內耳為一值得考量的方式。此種方式除了可以避免經靜脈，肌肉注射或口服投予所造成的全身性副作用之外，並能以較低的劑量達到更高的局部藥物濃度。 類固醇藥物的抗發炎作用已廣為接受，然而其對血液循環的作用，雖有研究者提出，但卻結果不一。尤其類固醇對耳蝸血液循環的影響仍未確立。本研究的主要目的乃經由動物實驗來探討耳內局部投予dexamethasone對耳蝸血液微循環(microcirculation)的影響。 在研究中，我們另外選擇兩種臨床上對血液循環有迅速且顯著作用的藥物，一為血管擴張劑 － 硝化甘油(nitroglycerin, NTG)，另一為血管收縮劑 － 腎上腺素(epinephrine, EPI)。回顧目前文獻，類固醇藥物若對血液循環產生影響，不論其結論是促進或抑制，釵h學者的研究認為是透過一氧化氮合成酶(nitric oxide synthase)調控一氧化氮(nitric oxide, NO)的生成來作用。因此我們經由相同的路徑投予一氧化氮的提供者(NO donor) － NTG，觀察耳蝸血流是否受到影響。另外，在中耳手術時，我們會施打局部麻醉藥物於外耳。這種含有epinephrine的局部麻醉藥物多少會流入中耳腔。除此之外，中耳手術時也常使用沾上epinephrine的棉花來止血。因此，我們利用相同的動物模式，研究耳內投予epinephrine是否會影響耳蝸血流。 方法 我們採用具良好Preyer’s反射的白色Hartley種天竺鼠。在全身麻醉之下，先施行氣管切開術(tracheostomy)，並接上呼吸器。藉由股動脈插管及肛溫計全程監測血壓及體溫。在手術顯微鏡下深入顳骨骨胞(bulla)，露出耳蝸，並找到圓窗膜(round window membrane)。接著用雷射都卜勒血流測定儀(laser Doppler flowmeter)測量耳蝸的血液流量。首先，測量20分鐘，視為基礎血流量。之後，於圓窗膜上分別投予dexamethasone，epinephrine，NTG，生理食鹽水，並測量耳蝸血流量0.5到2小時。 結果 共有61隻天竺鼠進入實驗，有效樣本數為45隻。Dexamethasone組有23隻天竺鼠，其中18隻(78.26%)顯示耳蝸血流量無顯著變化，1隻(4.35%)顯示耳蝸血流量顯著增加，另外4隻(17.39%)的血流量顯著減少。在NTG組的8隻動物中，5隻(62.5%)動物耳蝸血流量顯著增加，另3隻(37.5%)無明顯變化。在epinephrine組，9隻動物中有7隻(77.78%)的耳蝸血流量顯著減少，另2隻(22.22%)的血流量無顯著變化。在對照組中，所有動物(n=5)的耳蝸血流均無明顯變化。 結論 耳內投予dexamethasone對耳蝸血流量並不一致，而且耳蝸中，類固醇接受器(receptors)的確存在。這意味著，在生理狀態之下，dexamethasone對耳蝸的作用可能不是改變血流量。再者，耳蝸血流量會因耳內投予一氧化氮的提供者 － NTG而增加，表示一氧化氮-環鳥糞核糖單磷酸路徑(NO-cGMP pathway)在耳蝸血液循環的調控，應該和其他組織一樣，佔有重要的地位。另外，耳內投予epinephrine會減少耳蝸血流量。因此，在中耳手術時，應避免含有血管收縮劑epinephrine的局部麻醉藥物流至中耳腔之圓窗附近，以免導致耳蝸血流量的減少。Background Many kinds of inner ear diseases with suddenly occurred synptoms, either originating from cochlea or vestibule, were considered to be related to the impairment of the blood circulation. Sudden deafness is defined as idiopathic, sudden-onset sensorineural hearing loss. Traditional treatment for sudden deafness is by systemic administrated high dose steroid. There is, however, a new way to deliver the steroids through the “intratympanic” route to avoid possible side effects with traditional treatment and to achieve higher inner ear concentration of medicine. The anti-inflammatory effects of steroids have been well accepted. However, the influence of steroids on blood circulation, more specifically, the cochlear microcirculation, is controversial. The main goal of this study is to determine if intratympanic delivered dexamethasone (DEX) affect the cochlear blood flow. In addition, we use two drugs with clinically prompt and prominent vascular effects, i.e. nitroglycerin (NTG) and epinephrine (EPI). Reviewing the literatures, many authors considered the blood circulation effects of steroids, either promoting or reducing, are through modulating nitric oxide synthase(NOS) and the production of nitric oxide(NO). So we intratympanically administrate the NO donor, NTG, to see if the cochlear blood flow affected. During middle ear surgery, epinephrine would come around round window membrane, either with epinephrine-containing anesthetics incidentally or with epinephrine-soaked cotton pledgets for hemostasis. We use the same animal model to see the effects of intratympanic epinephrine on the cochlear blood flow. Methods White Hartly guinea pigs with good Preyer’s reflex were used. After anesthesia, tracheostomy was done. Then systemic BP and body temperature were monitored. Under surgical microscope, mastoidectomy was performed to expose the cochlea. We applied dexamethasone, epinephrine, nitroglycerin or normal saline (as control) separately on to and around the round window membrane in this experiment. Laser Doppler flowmeter was used for CoBF measurement. The first 20 minutes was as the baseline, followed by 0.5 to 2 hours’ recording after medications. Results Valid data were from 45 guinea pigs. In dexamethasone group, CoBF increased significantly in 1 of 23 animals(42.9%), decreased in 4(17.39%) and showed no significant change in 18(78.26%). In NTG group, CoBF increased significantly in 5(62.5%) animals. In epinephrine group, CoBF decreased significantly in 7(77.78%) animals. In control group, CoBF didn’t change significantly in all 5 animals. Conclusions In this study, the effects of dexamethasone on CoBF were variable and not significant. There were, however, evidences to show that the glucocorticosteroid receptors do exist in the cochlea, which means that physiologically dexamethasone could excert some effect in the cochlea but not through the change of blood flow. The vaso-dilatational effect of the NO donor, NTG, on CoBF make us to infer that the NO-cGMP pathway play an important role in the regulation of blood circulation of cochlea as in other organs. Epinephrine yielded more consistent vaso-constrictional effect in this study. We suggest that ear surgeons avoid epinephrine incidentally placed around the round window membrane to avoid some undesirable outcome.目 錄 縮寫表 1 壹、 中文摘要 2 貳、 緒論 4 一、 背景及文獻回顧 4 I. 突發性耳聾 4 II. 耳內注射療法 (intratympanic injection therapy) 4 III. Dexamethasone耳內注射療法之作用機轉 5 IV. 圓窗膜(round window membrane)的組織結構 6 V. 內耳中的糖皮質類固醇接受器(glucocorticoid receptors) 6 VI. 類固醇對血液循環的影響 6 VII. 耳蝸內的腎上腺素接受器(adrenergic receptors) 7 二、 欲研究的問題及其重要性 8 參、 研究材料與方法 9 一、 研究材料 9 二、 實驗進行步驟 9 I. 麻醉 9 II. 術前準備及體溫測量 10 III. 氣管切開術 (tracheostomy) 10 IV. 血壓測量步驟 10 V. 耳蝸血流的測量 11 VI. 實驗完畢後天竺鼠的處置 11 肆、 結果 13 一、 實驗動物基本資料 13 二、 耳蝸血流量的變化 13 三、 資料間的相關性 15 伍、 討論 16 一、 關於實驗設計 16 I. 使用天竺鼠的原因 16 II. 使用雄性天竺鼠的原因 16 III. 手術時動物採側仰臥姿式 16 IV. 投藥方式 16 V. 投藥劑量 16 VI. 術中與投藥時避免碰觸聽小骨 17 VII. 選擇經由股動脈插管測量血壓的原因 18 VIII. 避免氣流的干擾 18 IX. 避免耳蝸表面微血管的干擾 18 二、 研究中的干擾因子 18 I. 外界的震動或噪音 18 II. 麻醉深度 18 III. 體溫、血壓 18 IV. 室溫 19 V. 外界的光線 19 三、 結果判讀 19 四、 結論 20 陸、 展望 23 一、 臨床上的應用 23 二、 本研究在基礎與臨床上的貢獻 23 三、 未來的發展 24 柒、 論文英文簡述(Summary) 26 捌、 參考文獻 28 玖、 圖表 33 壹拾、 附錄 58 動物實驗審查申請表 581010187 bytesapplication/pdfen-US腎上腺素dexamethasone耳蝸血流量硝化甘油耳內投予突發性耳聾雷射都卜勒血流測定儀epinephrinenitroglycerinsudden deafnesslaser Doppler flowmetercochlear blood flowintratympanic administrationtexthttp://ntur.lib.ntu.edu.tw/bitstream/246246/55542/1/ntu-93-P91421031-1.pdf