Objective

To develop a technique for performing the mandibular nerve block in Nile crocodiles.

Study design

Experimental cadaveric study.

Animals

A total of 16 juvenile Nile crocodile heads.

Methods

To study the course of the mandibular nerve, one head was dissected. Computed tomography (CT) examination was performed in two heads to identify useful landmarks. Thereafter, a hypodermic needle was inserted through the external mandibular fenestra of 17 hemimandibles (13 heads), and a mixture of methylene blue and iohexol was injected. Injection volumes were 0.5 (n = 7) and 1.0 mL (n = 10) for hemimandibles < 15 and ≥ 15 cm long, respectively. Iohexol spread and nerve staining with methylene blue were assessed with CT and anatomical dissection, respectively. Data were analysed with one-sample t test or Mann–Whitney U test. Significance was set at p < 0.05.

Results

Both anatomical dissection and imaging confirmed the external mandibular fenestra as a useful anatomical landmark for needle insertion. The CT images acquired after needle positioning confirmed that its tip was located on the medial bony mandibular surface formed by the fusion of the angular and coronoid bones in 100% cases. In all the hemimandibles, the rostrocaudal spread of contrast was > 23 mm. The length of the stained mandibular nerve in the temporal region and of the stained medial branch of the mandibular nerve, as well as the dorsoventral and mediolateral spread of iohexol, was greater in group 1.0 than in group 0.5 (p < 0.001). The caudal spread of iohexol was greater in group 1.0 than in group 0.5 (p = 0.01).

Conclusions and clinical relevance

The technique developed in this study is feasible. Both injection volumes resulted in staining of the mandibular nerve. The spread of contrast in the anatomical region of interest may result in successful sensory block.

中文翻译：

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少年尼罗鳄的下颌神经阻滞：尸体研究

目的

开发一种在尼罗河鳄鱼中进行下颌神经阻滞的技术。

学习规划

实验尸体研究。

动物

共有16个尼罗河鳄鱼幼鱼头。

方法

为了研究下颌神经的进程，解剖了一个头。计算机断层扫描（CT）检查在两个脑袋中进行，以识别有用的标志。此后，将皮下注射针头插入17个可弯曲性（13个头）的下颌外窗，并注射亚甲蓝和碘海醇的混合物。 长度小于15厘米和≥15厘米的半定量样品的进样量分别为0.5（n  = 7）和1.0 mL（n = 10）。分别通过CT和解剖解剖评估碘海醇的扩散和亚甲蓝的神经染色。数据采用一样本t检验或Mann-Whitney U检验进行分析。显着性设定为p＜0.05。

结果

解剖解剖学和影像学检查均证实下颌外窗是针插入的有用解剖学标志。针头定位后获得的CT图像证实，在100％的病例中，其尖端位于由角和冠状骨融合形成的内侧下颌骨下表面。在所有的半可燃物体中，反面尾骨的对比度扩展> 23 mm。1.0组的碘伏醇在颞区和下颌神经的染色斑的长度以及下颌内侧的染色分支的长度以及背腹和中外侧的扩散均大于0.5组（p <0.001）。1.0组碘海醇的尾部扩散大于0.5组（p  = 0.01）。

结论与临床意义

在这项研究中开发的技术是可行的。两种注射量均导致下颌神经染色。对比在感兴趣的解剖区域中的扩散可能会导致成功的感觉阻滞。