Holcombe S J, Derksen F J, Stick J A, Robinson N E
Department of Large Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, East Lansing 48824, USA.
Am J Vet Res. 1997 Sep;58(9):1022-6.
To determine the effect of bilateral hypoglossal and and glossopharyngeal nerve block on epiglottic and soft palate position and tracheal and pharyngeal pressures in exercising horses.
5 Standardbreds.
Tracheal and pharyngeal pressures were measured in 5 Standardbreds exercising at the speed at which the horses achieved 50, 75, and 100% of maximal heart rate after bilateral hypoglossal and glossopharyngeal nerve block and without nerve block. Nerve block was achieved by injection of 1 to 2 ml of 2% mepivicaine hydrochloride between the glossopharyngeal and hypoglossal nerves, as they coursed through the medial compartment of the diverticulum of the auditory tube (guttural pouch), using videoendoscopic guidance and an injection apparatus.
Compared with control values, peak inspiratory tracheal pressure was significantly (P = 0.02) more negative, and peak pharyngeal inspiratory pressure was less negative (P = 0.004) after bilateral hypoglossal and glossopharyngeal nerve block. Respiratory frequency was significantly (P = 0.024) lower after nerve block, compared with control values. The epiglottis was unstable and retroflexed through the rima glottis during inspiration after bilateral hypoglossal and glossopharyngeal nerve block. Despite loss of contact between the epiglottis and the caudal free margin of the soft palate, dorsal displacement of the soft palate did not occur.
Loss of contact of the epiglottis with the soft palate did not affect soft palate position, suggesting that when the soft palate is normal, the epiglottis does not function as a support, holding the soft palate in a ventral position. Therefore, epiglottic dysfunction is not solely responsible for intermittent dorsal displacement of the soft palate in horses, and neuromuscular dysfunction involving the hyoepiglotticus muscle, geniohyoideus muscle, or the hypoglossal nerve may cause epiglottic retroflexion in horses.
确定双侧舌下神经和舌咽神经阻滞对运动马匹会厌和软腭位置以及气管和咽部压力的影响。
5匹标准赛马。
对5匹标准赛马在双侧舌下神经和舌咽神经阻滞前后，以达到最大心率50%、75%和100%的速度运动时测量气管和咽部压力。通过在舌咽神经和舌下神经穿过咽鼓管憩室（喉囊）内侧腔隙时，在视频内镜引导下使用注射装置注射1至2毫升2%盐酸甲哌卡因来实现神经阻滞。
与对照值相比，双侧舌下神经和舌咽神经阻滞后，吸气末气管峰值压力显著更负（P = 0.02），咽部吸气峰值压力负性更小（P = 0.004）。与对照值相比，神经阻滞后呼吸频率显著更低（P = 0.024）。双侧舌下神经和舌咽神经阻滞后，吸气时会厌不稳定并通过声门裂向后弯曲。尽管会厌与软腭尾侧游离缘失去接触，但软腭并未发生背侧移位。
会厌与软腭失去接触并不影响软腭位置，这表明当软腭正常时，会厌并不起到将软腭维持在腹侧位置的支撑作用。因此，会厌功能障碍并非马匹软腭间歇性背侧移位的唯一原因，涉及舌会厌肌、颏舌骨肌或舌下神经的神经肌肉功能障碍可能导致马匹会厌向后弯曲。
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