Pharyngeal airway wall mechanics using tagged magnetic resonance imaging during medial hypogiossal nerve stimulation in rats
Pharyngeal airway wall mechanics using tagged magnetic resonance imaging during medial hypogiossal nerve stimulation in rats
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DOI：
10.1113/jphysiol.2004.073502
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发表时间：
2004-12-01
影响因子：
5.5
通讯作者：
Kuna, ST
中科院分区：
文献类型：
--
作者：
Brennick, MJ;Pickup, S;Kuna, ST
为了更好地了解咽喉气道力学，因为它与阻塞性睡眠呼吸暂停的发病机制和治疗有关，我们开发了一种新的应用磁共振成像（MRI）与无创组织标记来测量气道主动扩张期间咽壁组织的运动。11只麻醉后的Sprague-Dawley大鼠在手术前用铂电极刺激双侧舌下神经内侧分支，该分支为舌突肌和舌内肌提供运动输出。在4.7 T磁体上使用门控多层、破坏梯度回忆（SPGR）成像方案获得刺激前和刺激期间咽气道的图像。在刺激之前使用标签脉冲，产生了一个磁性嵌入的黑线网格模式，显示了在刺激期间获得的图像中的组织运动。当对吻侧、中咽和尾咽进行平均时，刺激显著增加口咽和腭咽气道的横截面积、前后和外侧尺寸（P < 0.001）。用于组织运动跟踪和有限元分析的定制软件显示，气道大小的变化与鼻侧、中端和尾端咽部腹侧壁组织的腹侧位移（P < 0.0032）和中端和尾端侧壁的腹侧位移（P < 0.0001）有关。此外，中、尾侧咽部腹外侧方向的最大主张力显著增加（P < 0.023），各区域的最大主压缩（垂直于拉伸）显著增加（P < 0.0001）。刺激不会引起任何水平咽侧壁的侧向移位。结果表明，刺激舌下神经内侧支引起的咽气道大小的增加主要是由于咽壁的腹侧移位。
To better understand pharyngeal airway mechanics as it relates to the pathogenesis and treatment of obstructive sleep apnoea, we have developed a novel application of magnetic resonance imaging (MRI) with non-invasive tissue tagging to measure pharyngeal wall tissue motion during active dilatation of the airway. Eleven anaesthetized Sprague-Dawley rats were surgically prepared with platinum electrodes for bilateral stimulation of the medial branch of the hypoglossus nerve that supplies motor output to the protrudor and intrinsic tongue muscles. Images of the pharyngeal airway were acquired before and during stimulation using a gated multislice, spoiled gradient recalled (SPGR) imaging protocol in a 4.7 T magnet. The tag pulses, applied before stimulation, created a grid pattern of magnetically imbedded dark lines that revealed tissue motion in images acquired during stimulation. Stimulation significantly increased cross-sectional area, and anteroposterior and lateral dimensions in the oropharyngeal and velopharyngeal airways when results were averaged across the rostral, mid- and caudal pharynx (P < 0.001). Customized software for tissue motion-tracking and finite element-analysis showed that changes in airway size were associated with ventral displacement of tissues in the ventral pharyngeal wall in the rostral, mid- and caudal pharyngeal regions (P < 0.0032) and ventral displacement of the lateral walls in the mid- and caudal regions (P < 0.0001). In addition, principal maximum stretch was significantly increased in the lateral walls (P < 0.023) in a ventral-lateral direction in the mid- and caudal pharyngeal regions and principal maximum compression (perpendicular to stretch) was significantly increased in the ventral walls in all regions (P < 0.0001). Stimulation did not cause lateral displacement of the lateral pharyngeal walls at any level. The results reveal that the increase in pharyngeal airway size resulting from stimulation of the medial branch of the hypoglossal nerve is predominantly due to ventral displacement of the ventral and lateral pharyngeal walls.