Successful Injection for Coccyx Pain

An obese 70-yr-old woman presented with severe focal coccyx pain (coccydynia) after sitting on the relatively narrow seat of a stationary bike. Her pain was exacerbated by any sitting whatsoever, particularly on the bike. Her symptoms persisted for many weeks, despite oral analgesics, use of additional cushions while sitting, and cessation of cycling.

Physical examination revealed exquisite focal tenderness during palpation of the coccyx and sacrococcygeal junction, reproducing her presenting symptoms. Conversely, her symptoms were not reproduced via palpation of the ischial tuberosities, sacroiliac joints, lumbosacral zygapophysial (facet) joints, lumbosacral paraspinal muscles, gluteal muscles, or greater trochanters. Neurologic examination was normal.

Because her coccydynia was significantly persistent and problematic, despite other treatments, she received interventional treatment via nerve block of the ganglion impar, which carries sympathetic pain afferent input from the coccyx region.

After the fluoroscopically guided ganglion impar block with lidocaine, she reported immediate 100% relief of her coccyx pain, with the ability to sit up on the procedure table without any discomfort at all. Throughout her follow-up visits for unrelated conditions, she has continued to report 100% relief of her coccyx symptoms, without any coccydynia recurrence even 1 yr later.

Coccyx pain (coccydynia, coccygodynia) is caused by various pathogeneses, including fracture, sprain of the sacrococcygeal junction or intercoccygeal segments, infection, tumor, and degenerative changes.¹ The mechanism of injury, if identified, may include trauma (e.g., falls, childbirth, horseback riding).¹ The above patient’s symptoms began via repetitively sitting on the relatively narrow seat of a stationary bike.

The primary symptom of coccydynia is focal coccyx or sacrococcygeal pain exacerbated by sitting.¹ The primary physical examination finding is focal tenderness of the coccyx or sacrococcygeal junction.¹ Imaging studies may be helpful, particularly with blunt trauma or suspected deformity or malignancy.¹ Treatment may include oral analgesics, donut cushions or wedge cushions (to minimize coccygeal pressure during sitting), injections, manipulation, and even coccygectomy (surgical removal of the coccyx).¹

Injections used for coccydynia include corticosteroid injections into the caudal epidural space or into the sacrococcygeal junction.¹ Alternatively, local anesthetic injections can block the ganglion impar (ganglion of Walther).^2,3 The most direct technique to reach the ganglion impar is by the posterior approach, via inserting a thin (25 gauge) spinal needle through the sacrococcygeal junction/disk or through the first intracoccygeal junction, so that the tip of the needle reaches just anterior to the junction (as shown fluoroscopically in Fig. 1). Next, injecting contrast further confirms appropriate placement (Fig. 2) because the contrast pattern remains just anterior to the coccyx and sacrum, where the ganglion impar is located, and seems neither intravascular nor too far anterior into the rectum. Next, local anesthetic is injected, thus blocking the ganglion impar. The procedure often takes less than 5 mins. This technique often produces 50–75% relief of coccyx pain.³ The patient above obtained 100% pain relief, without any subsequent recurrence.

FIGURE 1: Lateral view, fluoroscopic image, showing needle placement through the sacrococcygeal junction/disk, with the needle tip near the ganglion impar.

FIGURE 2: Contrast confirms appropriate needle placement because the contrast remains just anterior to the sacrum and coccyx, covering the location of the ganglion impar.

In conclusion, ganglion impar blocks are minimally invasive treatments that can provide dramatic improvement for coccydynia, a condition that is otherwise often difficult to treat.