
==== Front
Interv Pain Med
Interv Pain Med
Interventional Pain Medicine
2772-5944
Elsevier

S2772-5944(22)00071-1
10.1016/j.inpm.2022.100080
100080
Imaging Studies
Imaging optimization for fluoroscopically guided caudal epidural coaxial view
Silva-Ortiz Victor M. drvictorsilva@gmail.com
∗
Pain Management Department, Centro Medico Zambrano Hellion, Tecnologico de Monterrey, Escuela de Medicina y Ciencias de La Salud, Monterrey, Nuevo Leon, Mexico
∗ Pain Management Department, Centro Medico Zambrano Hellion, Batallon de San Patricio 112, Real San Agustín, Nuevo Leon, 66278, Mexico. drvictorsilva@gmail.com
10 3 2022
6 2022
10 3 2022
1 2 10008010 11 2021
25 2 2022
25 2 2022
© 2022 The Author(s)
2022
https://creativecommons.org/licenses/by-nc-nd/4.0/ This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
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pmcThe sacral hiatus (SH) is the result of a lack of fusion of the spinous process and the inferior portion of the sacrum lamina. Caudal epidural injection (CEI) was first described in 1901 [1], since then, it is one of the most frequently performed regional anesthetic techniques in children and its use for gynecological, urological, and perineal surgeries in adults has also been described [2].

In chronic pain, CEI is indicated to treat radicular symptoms with or without lumbar axial pain. It is useful in patients who have previous lumbar surgery and in cases in which the foraminal approach is difficult. It can be used as an access for epiduroscopy and to perform epidural neuroplasty.

An advantage of the CEI technique is the low risk of inadvertent thecal sac puncture or intrathecal injection and its ability to reach the ventrolateral epidural space with a catheter.

Fluoroscopic guidance is currently the gold standard for CEI, its success depends on the correct placement of the needle through the SH [3].

The sacrum is the area of the spine that has the most anatomical variations, particularly in the sacral hiatus, which may be closed, asymmetrically open or wide open, this approach can become difficult in some cases.

Palpating the bilateral sacral cornua is recommended to locate the SH prior to performing puncture, but sometimes this anatomical reference is not available since an agenesis or very small sacral cornua is considered absent for palpation purposes.

Nakahashi et al., in a retrospective study involving 76 patients found poor palpability in 23 patients and reported that the mean distance from the skin to the sacral cornua and body mass index were found to be associated with the palpability of the SH [4].

Sekiguchi et al. showed that CEI failure might occur in 3–11% of patients due to anatomic abnormalities. Defining a height of at least 3 mm as palpable, they reported that sacral cornua was bilaterally palpable in only 19%, unilaterally palpable in 25%, and bilaterally impalpable in 54% of isolated adult sacral bone.

This is one of the reasons why it is important to look for an adequate and safe radiological vision. According to what we have described above, we recommend multiplanar views for almost all procedures, not only this technique.

The proposal of this manuscript is to use a coaxial view of the SH as a first step in the CEI technique [5].

The technique used was according to the following description. After the skin was prepared with chlorhexidine, the patient was placed in prone position, with a pillow under the pelvis to elevate the sacrum angle, the fluoroscope was set with caudad tilt between 45 and 55° up to align the anterior and dorsal aspect of the sacrum which would give us a coaxial view of the sacral hiatus (Fig. 1). We marked the entry point and injected local anesthesia using 2 ml of lidocaine 1% with a 25 gauge needle, after that, we inserted a 18 gauge Tuohy needle into the SH with a coaxial or trajectory view technique (Fig. 2), it was corroborated in lateral projection and finally in an anteroposterior projection to control the depth and cephalic advancement of the needle preventing not passing the level of s2 where there's a risk of puncturing the thecal sac [6] (see Fig. 3).Image 1 Patient in a prone position with fluoroscope in caudad tilt. With the permission of the patient.

Image 1

Image 2 Figure A and B: Needle trajectory in coaxial view in the sacral hiatus. White dots indicating the boundaries of the sacral hiatus, black dot indicating the needle position. With the permission of the patient.

Image 2

Fig. 3 Needle positioning in lateral projection with contrast. With the permission of the patient.

Fig. 3

Fig. 4 Needle positioning in lateral projection without contrast. With the permission of the patient.

Fig. 4

Fig. 5 Needle positioning in anteroposterior view with contrast. With the permission of the patient.

Fig. 5

This described technique can be adopted as a safety protocol to perform fluoroscopically guided CEI, also increasing the accuracy of the procedure, especially in patients in whom the sacral cornua are not palpable or have anatomical variants that make access difficult. We propose it as an optimal vision when combined with traditional projections, not as a single projection. (see Fig. 4, Fig. 5)

The possible limitations of this technique could be large image intensifier, large body habitus or large buttocks that could worsen the fluoroscope image.

Declaration of competing interest

The authors whose names are listed immediately below certify that they have NO affiliations with or involvement in any organization or entity with any financial interest (such as honoraria; educational grants; participation in speakers’ bureaus; membership, employment, consultancies, stock ownership, or other equity interest; and expert testimony or patent-licensing arrangements), or non-financial interest (such as personal or professional relationships, affiliations, knowledge or beliefs) in the subject matter or materials discussed in this manuscript.
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References

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