Ultrasound Imaging and Ultrasound-Guided Injection of the Coccygeal Nerve for Coccydynia
Journal
American Journal of Physical Medicine and Rehabilitation
Journal Volume
101
Journal Issue
7
Pages
E108-E109
Date Issued
2022
Author(s)
Abstract
This feature is a unique combination of text (voice) and video that more clearly presents and explains procedures in musculoskeletal medicine. These videos will be available on the journal’s Website. We hope that this feature will change and enhance the learning experience. Walter R. Frontera, MD, PhD Editor-in-Chief A 54-yr-old woman presented with coccydynia after a fall onto her buttocks 1 wk prior. She reported pain while sitting and lying supine. On physical examination, there were ecchymosis and severe tenderness over the coccygeal region. A coccyx fracture was confirmed on both radiography (Fig. 1A) and ultrasonography (Fig. 1B). Because the pain did not improve with oral nonsteroidal anti-inflammatory drugs (naproxen tablet 250 mg twice per day for 1 wk), she was referred for ultrasonography-guided intervention. An 18-MHz transducer (HI VISION Ascendus; Hitachi Medical Systems, Japan) was first placed on the medial sacral crest in line with the fourth sacral foramina and then shifted caudally to the levels of the sacral cornu (SC; Figs. 1C, D) and coccygeal cornu (CC; Figs. 1C, E). The coccygeal nerve in the short axis was superomedial to the CC in the subcutaneous tissue layer. Ultrasonography-guided hydrodissection was administered using 5 ml of 5% dextrose and 0.5 ml of 1% lidocaine via an in-plane approach, targeting the short axes of the bilateral coccygeal nerves (Fig. 1F, video; https://links.lww.com/PHM/B581). For postprocedure care, she used a doughnut-shaped pillow over the buttock if sitting for more than 10 mins. She received no physical therapy for her buttock pain. After the first injection, the Visual Analog Scale score for pain decreased from 8 to 5. Therefore, she received a second injection 2 wks later, with the Visual Analog Scale decreasing to less than 3 thereafter.FIGURE 1: The lateral radiograph (A) and ultrasound image (B) show the coccyx fracture. The illustration depicts the course of the coccygeal nerve (C). Ultrasound images at the level of the sacral (D) and coccygeal (E) cornu show the coccygeal nerve. The in-plane lateral-to-medial approach during guided injection (F). Black arrowhead, fracture of the coccyx; white arrowhead, coccygeal nerve; white arrow, needle; blue-shaded region, intercornual ligament. CC, coccygeal cornu; H, hiatus; SCL, sacrococcygeal ligament; SC, sacral cornu.The coccygeal nerve, emerging from the conus medullaris and initially coursing inside the sacral hiatus, pierces the posterior sacrococcygeal ligament as it travels distally toward the subcutaneous layer.1,2 It descends along the medial aspect of the SC and CC and laterally to the transverse processes of the first coccygeal vertebra, supplying the skin overlying the coccyx.2 On the other hand, the S5 ventral ramus exits the sacral hiatus through the gap between the SC and CC underneath the intercornual ligament (Fig. 1C).2 The two nerves fuse to become the anococcygeal nerve supplying the skin surrounding the anus.1,2 Gruber et al.3 demonstrated that the coccygeal nerve could be observed through a high-frequency transducer on top of the SC. However, at the previously mentioned level, the coccygeal nerve may sometimes course underneath the sacrococcygeal ligament next to the medial wall of the SC, which makes it difficult to visualize. Therefore, Domingo-Rufes et al.4 suggested that the needle could be inserted into the sacral canal along the medial edge of the SC using the out-of-plane approach (black syringe in Fig. 1C). Herein, we modified the scanning method proposed by Gruber et al.3 by placing the transducer on top of the CC, where the coccygeal nerve mostly emerges from the underlying ligament and where the injection could be performed in the in-plane approach (white syringe in Fig. 1C). With our technique, the coccygeal nerve could be precisely identified with the needle outside the sacral hiatus, which might be clinically better than the method proposed by Domingo-Rufes et al.4 A previous network meta-analysis5 revealed that 5% dextrose was most effective for symptom relief in carpal tunnel syndrome, the most common nerve entrapment disorder, and was thus chosen as the injectate in our case. In patients with recurrent coccydynia after blocks or hydrodissection, radiofrequency ablation can be considered for long-term relief. This case highlights the usefulness of ultrasonography in locating the coccygeal nerve and guiding subsequent injections for coccydynia.
SDGs
Publisher
Lippincott Williams and Wilkins
Type
journal article