Fooken Jensen Pernille Vita, Gaihede Michael
Department of Otolaryngology, Head and Neck Surgery, Copenhagen University Hospital, Rigshospitalet, DK-2100 Copenhagen O, Denmark.
Department of Otolaryngology, Head and Neck Surgery, Aalborg University Hospital, DK-9000 Aalborg, Denmark; Department of Clinical Medicine, Aalborg University, DK-9220 Aalborg, Denmark.
Hear Res. 2016 Oct;340:121-126. doi: 10.1016/j.heares.2016.02.008. Epub 2016 Mar 3.
Micro-CT scanning of temporal bones has revealed numerous retroauricular microchannels, which connect the outer bone surface directly to the underlying mastoid air cells. Their structure and dimensions have suggested a separate vascular supply to the mastoid mucosa, which may play a role in middle ear (ME) pressure regulation. This role may be accomplished by changes in the mucosa congestion resulting in volumetric changes, which ultimately affect the pressure of the enclosed ME gas pocket (Boyle's law). Further, such mucosa congestion may be susceptible to α-adrenergic stimulation similar to the mucosa of the nose. The purpose of our study was to investigate these hypotheses by recording the ME pressure in response to adrenergic stimulation administered by retroauricular injections at the surface of the microchannels. In a group of 20 healthy adults we measured the ME pressure by tympanometry initially in the sitting position, and then in the supine position over a 5 min period with 30 s intervals. In each subject, the study included 1) a control reference experiment with no intervention, 2) a control experiment with subcutaneously retroauricular injection of 1 ml isotonic NaCl solution, and 3) a test experiment with subcutaneously retroauricular injection of 1 ml NaCl-adrenaline solution. In both control experiments the ME pressure displayed an immediate increase in response to changing body position; this pressure increase remained stable for the entire period up to five minutes. In the test experiments the ME pressure also showed an initial pressure increase, but it was followed by a distinct significant pressure decrease with a maximum after 90 s. The test group was injected with both a 5 and 10% adrenaline solution, but the responses appeared similar for the two concentrations. Subcutaneous retroauricular injection of adrenaline caused a significant pressure decrease in ME pressure compared with control ears. This may be explained by the microchannels conveying the adrenaline to the underlying mastoid mucosa, where it may result in a vascular constriction and decongestion, ultimately resulting in a ME pressure decrease. These findings suggest that the microchannels contain vascular connections to the mastoid mucosa, and that the mastoid mucosa is susceptible to vasoactive mediators, which may play a role in ME pressure regulation. Further anatomical and physiological experiments should be carried out to confirm these suggestions including pharmacological interactions with the mastoid mucosa.
颞骨的显微CT扫描显示，耳后有许多微通道，这些微通道将骨外表面直接与下方的乳突气房相连。它们的结构和尺寸表明，乳突黏膜有独立的血管供应，这可能在中耳（ME）压力调节中发挥作用。这一作用可能是通过黏膜充血的变化导致体积改变来实现的，最终影响封闭的中耳气腔的压力（波义耳定律）。此外，这种黏膜充血可能与鼻黏膜一样，对α-肾上腺素能刺激敏感。我们研究的目的是通过记录中耳压力对耳后微通道表面注射肾上腺素能刺激的反应来验证这些假设。在一组20名健康成年人中，我们首先在坐位通过鼓室图测量中耳压力，然后在仰卧位5分钟内每隔30秒测量一次。在每个受试者中，研究包括1）无干预的对照参考实验，2）耳后皮下注射1毫升等渗氯化钠溶液的对照实验，以及3）耳后皮下注射1毫升氯化钠-肾上腺素溶液的测试实验。在两个对照实验中，中耳压力对体位变化均立即升高；这种压力升高在整个5分钟内保持稳定。在测试实验中，中耳压力也出现了初始压力升高，但随后明显显著下降，90秒后达到最大降幅。测试组注射了5%和10%的肾上腺素溶液，但两种浓度的反应相似。与对照耳相比，耳后皮下注射肾上腺素导致中耳压力显著下降。这可能是因为微通道将肾上腺素输送到下方的乳突黏膜，在那里可能导致血管收缩和充血减轻，最终导致中耳压力下降。这些发现表明，微通道包含与乳突黏膜的血管连接，并且乳突黏膜对血管活性介质敏感，这可能在中耳压力调节中发挥作用。应进行进一步的解剖学和生理学实验以证实这些观点，包括与乳突黏膜的药理学相互作用。
