Coccyx pain (coccydynia) apparently occurs far less commonly than lumbosacral pain. Coccydynia can be a severe and persistent pain, causing significant suffering, frustration, and functional limitations (199). These patients often have a history of coccyx trauma (e.g., from a fall or childbirth) resulting in contusions, fractures, dislocations, or other injuries. However, other cases are idiopathic. Typical symptoms include focal tailbone pain, particularly worse with sitting and sometimes immediately worse upon going from sit-to-stand (199). Careful screening should seek to exclude malignancies of the spine (e.g., chordoma) and intrapelvic structures (e.g., rectum) (199,200). Useful diagnostic studies may include x-rays, MRI, CT scans, and colonoscopy (199). Dynamic radiographs comparing coccygeal alignment and angulation while sitting (weight bearing on the coccyx) versus standing may reveal dynamic instability (dislocations) not visualized via non—weight-bearing studies (201,202).
Injections for coccyx pain may include focal corticosteroids placed at the posterior coccyx or into a sacrococcygeal or coccygeal joint, ideally performed under fluoroscopic guidance to maximize injection accuracy and minimize the risk for inadvertent puncture of the rectum or other nearby structures. Diagnostic nerve blocks can include local anesthetic blockade of the somatic posterior coccygeal nerve fibers as well as the sympathetic nerve fibers (ganglion Impar) anterior to the coccyx (203–207). For both diagnostic and therapeutic injections, it is frequently helpful to simultaneously block both the anterior (sympathetic) and posterior (somatic) nerves. This combination can more completely shut off all afferent inputs from the coccyx, with resultant relief implying that the coccyx is the source of pain. Also, effective local anesthetic blockade can provide therapeutic benefit, sometimes including complete and permanent relief (208). The mechanism is perhaps via disrupting hyperactive and/or hypersensitive afferent reflex arcs or sympathetically maintained pain. The various technical approaches to the ganglion Impar include injecting a spinal needle from inferior to the coccyx (above the anus), or passing the needle through the sacrococcygeal joint or through the intracoccygeal joints (203–207). Fluoroscopic guidance is crucial for safe and effective performance of sympathetic nerve blocks at the ganglion Impar, especially given the close proximity to the bacteria-laden rectum. Nerve ablation in the coccyx region may be beneficial for selected patients with coccydynia (207). Most patients with tailbone pain will obtain adequate relief via nonsurgical treatments such as injections, thus often avoiding the need for surgery and its potential complications (209).