Coccyx Pain

The coccyx is the terminal end of the spine, just inferior to the sacrum. The human coccyx is often considered a vestigial remnant or corollary of a tail; thus, the coccyx is colloquially referred to as the tailbone. The word coccyx comes from the Greek word for cuckoo, the name apparently having been derived from the tailbone’s shape, which resembles that of a cuckoo’s beak.[2]

The human coccyx is composed of 3-5 individual segments (coccygeal vertebrae), with variations occurring with regard to the number of segments, the overall angulation (curve) of the coccyx, and the degree of articulation versus fusion between the individual segments. In 80% of patients, the coccyx is made up of 4 coccygeal vertebrae. Typically, the coccyx is concave anteriorly and convex posteriorly.

The base of the coccyx articulates with the sacral apex via the sacrococcygeal junction. The sacrococcygeal articulation and intracoccygeal articulations contain fibrocartilaginous discs, somewhat comparable to the intervertebral discs present at other spinal levels. The apex (distal tip) of the coccyx is typically rounded, but may be bifid. (See the image below.)

Lateral view of the pelvis and coccyx. The bracket shows the area of focus for radiographs that would provide a coned-down view of mainly the coccyx and distal sacrum. A more common lateral view would often also include larger bony structures, such as the lumbar spine and femur, all of which would make it difficult to optimize visualization of the small bones of the coccyx. In patients with coccyx pain, these coned-down, lateral views of the coccyx can provide important diagnostic information. Coned-down images obtained in the weight-bearing (seated) position can be compared with those obtained in a non–weight-bearing position (eg, side lying), thus allowing assessment for dynamic instability (eg, dislocations that occur only while seated).

Muscles and ligaments

In humans, the coccyx serves important functions, including as an attachment site for various muscles, tendons, and ligaments. Physicians and patients should remember the importance of these attachments when considering surgical removal of the coccyx.

Muscles inserting on the anterior coccyx include the levator ani, which is sometimes considered as several separate muscle parts, including the coccygeus, iliococcygeus, and pubococcygeus muscles. This important muscle group supports the pelvic floor (preventing inferior sagging of the intrapelvic contents) and plays a role in maintaining fecal continence. A midline component is the anococcygeal raphe, by which the coccyx supports the position of the anus.[2] Muscles originating on the posterior coccyx include the gluteus maximus, which is the largest of the gluteal (buttock) muscles and which functions to extend the thigh during ambulation.

Multiple important ligaments attach to the coccyx.[2] The anterior and posterior sacrococcygeal ligaments attach the sacrum to the coccyx (similar to the functions of the anterior and posterior longitudinal ligaments spanning cervical, thoracic, and lumbosacral spinal segments). Laterally, the transverse process of the coccyx serves as an attachment site for the lateral sacrococcygeal ligaments (arising from the inferolateral sacrum), as well as for fibers from the sacrospinous ligament (arising laterally from the spine of the ischium) and the sacrotuberous ligament (connecting the sacrum with the ischial tuberosity, but with fibers attaching to the coccyx as well).

Function

The coccyx serves somewhat as a weight-bearing structure when a person is seated, thus completing the tripod of weight bearing composed of the coccyx and the bilateral ischium. The ischial weight-bearing surfaces are, more specifically, at the ischial tuberosities and inferior rami of the ischium.

The coccyx bears more weight when the seated person is leaning backward; therefore, many patients with coccydynia sit leaning forward (flexing at the lumbosacral and hip regions), which shifts more of the weight to the bilateral ischium rather than the coccyx (see the images below). Alternatively, patients with coccydynia may sit leaning toward one side so that the body weight is exerted mainly on one ischial tuberosity or the other, with less pressure on the coccyx. Such side leaning may lead to concomitant ischial bursitis in addition to the antecedent coccydynia.

Coccyx pain (coccydynia, or tailbone pain) is typically worse when the patient is sitting. Often, the pain is even worse when sitting leaning slightly backward, since this increases the weight bearing on the coccyx, as shown in this image. Dynamic radiographs of the coccyx involve obtaining coned-down (focused) views of the coccyx while the patient is seated (eg, in his or her most painful position). Often, this involves having the patient lean backward 0-40°, depending on the symptoms. Radiographs obtained in this position are compared with those obtained in a non–weight-bearing position (eg, side lying) to assess for instability or dislocations in the seated position.

Patients with a painful coccyx often find it more comfortable to sit leaning slightly forward, as shown in this image. This forward-leaning position minimizes any weight bearing on the coccyx itself and thus minimizes the exacerbation of coccyx pain. As shown, when a patient sits leaning forward, most of the weight bearing occurs bilaterally through the inferior ischial regions of the pelvis and the posterior thigh (femur) regions.

Causes of coccyx pain include trauma, fractures, dislocations, and primary or metastatic malignancies.[14, 15, 16] (A retrospective study by Dang et al of primary spinal tumors [438 patients] indicated that those of the sacrum or coccyx are more likely to be malignant.[17] ) Sources of acute, abrupt trauma include internal trauma (eg, giving birth) and external trauma (eg, falling onto the coccyx). Nonabrupt trauma may include prolonged sitting. Tailbone pain may begin after certain medical procedures, such as colonoscopy.[18] Some cases of coccydynia are idiopathic, without any identified etiology.

One risk factor for coccyx pain is aging; degenerative changes of the sacrococcygeal junction and the intracoccygeal junctions, as well as fusion at these sites, seem to increase with age.

A gender-specific risk factor in females is trauma related to giving birth; substantial pressure may be placed on the coccyx as the baby descends through the mother's pelvis.

Coccydynia is considered to be relatively uncommon, but data are lacking on the exact incidence and prevalence of the condition.

Coccydynia is seen in males and females; however, women seem to be affected more frequently than men.[3] As previously mentioned, one gender-specific risk factor in females is trauma related to giving birth; the coccyx may endure substantial pressure as the baby descends through the mother's pelvis.

Coccydynia can occur in children and adults. Degenerative changes of the sacrococcygeal junction and the intracoccygeal junctions, as well as fusion at these sites, seem to increase with age.

While some patients with coccydynia have complete relief via natural recovery over time, others develop a persistent, chronic pain syndrome at the coccyx region.

One proposed reason why coccyx pain seems to be more chronic than other injury sites is the inability to immobilize or brace the site (eg, as compared with bracing and casting that is available for injuries at the wrist, ankle, or others, but is not available for similar immobilization at the coccyx). This may contribute to delayed or prolonged recovery as well as the development of chronic, persistent, intractable pain syndromes.

Once the coccyx pain has become chronic (persisting for more than 3-6 mo), it may be less likely to resolve by natural recovery alone, more likely to continue indefinitely, more likely to be resistant to treatment, and more likely to require a multimodal treatment approach (eg, oral medications combined with local injections).

Early interventions (eg, oral medications, injections, physical therapy) are presumed to decrease the chance that acute coccydynia will develop into chronic coccydynia. This may be considered a reason for aggressive nonsurgical treatment early on, to potentially decrease the chances of lifelong pain and disability.

Although coccydynia is generally not associated with increased mortality, it is often associated with substantial morbidity. Patients with coccydynia often report severe and persistent pain that compromises functional activities requiring sitting and diminishes their quality of life.

A study by Kodumuri et al indicated that body mass index (BMI) and traumatic etiology independently predict coccydynia treatment outcomes. Individuals in whom coccydynia resulted from trauma seemed to respond better to treatment than did the other patients, with a higher mean outcome satisfaction score (80%) than that of the rest of the group (61%), at 6 weeks postintervention. Treatment responses also tended to be more favorable in patients with a BMI of below 30.[19]

One case series indicated that a positive coccygeal discogram is correlated with better outcome from surgery, but these results were based on small numbers, including just 2 surgical patients who had positive preoperative discograms and 2 surgical patients who had negative preoperative discograms.[20] Further, the usefulness of a positive discogram at predicting surgical outcome intuitively seems to be contraindicated by a separate, histologic study showing that disc degeneration at the sacrococcygeal joint in 5 patients was associated with poor surgical outcome in all 5 cases.[21]

The author of this Medscape Reference article (Dr. Foye) has provided further information on the topic of tailbone pain at the following websites:

• Coccyx Pain Relief - A blog about coccyx pain

• Dr. Foye's website on tailbone pain, at www.TailboneDoctor.com

• Treatment of tailbone pain (coccyx pain, coccydynia) by injection of local anesthetic to the ganglion Impar

• Radio interviews with Dr. Patrick M Foye, specifically discussing tailbone pain - The interviews can be heard for free online.

The history obtained from a patient with coccydynia involves details regarding the coccydynia itself and other underlying conditions that may refer pain to the coccyx region. Questions relate to the following:

• Localization of pain - The patient should be asked to indicate or point to the painful site or sites

• Severity of coccyx pain - The patient should be asked to rate the level of coccygeal pain (0-10 scale) when it is at its best and at its worst and to indicate overall pain severity

• Duration and onset date of coccydynia - The patient should be asked whether any identifiable traumatic incident, recent or remote, occurred

• Exacerbating factors - The patient should be asked whether there is pain associated with, for example, prolonged sitting or sitting on hard versus soft surfaces, as well as with sexual intercourse, standing up after sitting, or bowel movements

• Sitting tolerance - The patient should be asked to quantify how many minutes of sitting can be tolerated before the pain mandates changing position

Other elements of the patient's history that should be obtained include the following:

• Cushions tried - Such as donut cushions, which have a circular hole in the middle, or wedge cushions, which have a triangular wedge cut out posteriorly

• Oral medications tried and response to these

• Interventional pain management procedures and response to these - Such as caudal or other epidurals, local anesthetic blocks, and steroid injections, as well as whether these were administered blindly or guided fluoroscopically

• Gastrointestinal (GI) symptoms – Constipation, diarrhea, bright red blood per rectum, melena (black, tarry stool), and fecal incontinence (GI workup, such as GI consult, colonoscopy, or rectal exam)

• Urinary symptoms - For instance, urinary incontinence or dysuria (urinary diagnostic workup, such as urology consult or urinalysis)

• Female intrapelvic history - Such as uterine fibroids or ovarian cysts

• Female obstetric history - Childbirth, vaginal or cesarean delivery, and any associated difficulties at the time

• Female menopausal status - Premenopausal, perimenopausal, or postmenopausal

• Lower limb neurologic symptoms - Such as radicular pain or lower limb numbness or weakness

• Concomitant ischial bursitis - Such as unilateral or bilateral ischial buttock pain due to leaning to either side to avoid sitting with pressure on the midline/coccyx region

• Body weight - Such as any significant increase or decrease in body weight preceding the onset of the symptoms

• History of cancer - Especially colon, prostate, ovarian, cervical, testicular, or other intrapelvic malignancies.

• Risk factors for cancer - Blood per rectum, abnormal vaginal bleeding, unexplained weight loss, fevers, or chills

Palpation

Sacrococcygeal palpation involves identifying and exerting pressure onto the sacrococcygeal junction and the coccyx and noting whether the presenting symptoms localize well to that site (ie, exquisite tenderness at the coccyx and/or sacrococcygeal junction, with only mild or absent tenderness at adjacent structures).

Some clinicians palpate the coccyx via an internal/external approach; using a gloved hand, they place 1 or 2 fingers inside the rectum (anterior to the coccyx) and, with another 1 or 2 fingers, palpate externally (posterior to the coccyx). In this way, some clinicians also attempt to assess for increased or decreased sacrococcygeal mobility. Patients with severe coccydynia may have difficulty tolerating this examination.

Palpation of other (noncoccygeal) lumbosacral structures is an important aid in ruling out pain generators from the ischial bursae, sacroiliac joints, lumbosacral facet joints, and lumbosacral or gluteal muscles.

In one study, 25 out of 30 (83%) patients with a bone spicule at the distal coccyx had a "pit" noted in the overlying skin.[22]

Additional assessments

Other aspects of the physical examination include the following:

• Skin inspection – Direct visual inspection of the skin over the coccygeal region is important. An underlying pilonidal cyst may produce visible discharge, local rash, or a visible skin opening (fistula). In addition, inspecting for a local dimple/divot may be relevant, because in one study, as noted above, 25 (83%) of 30 patients with a bone spicule at the distal coccyx had a "pit" noted in the overlying skin.[22]

• Neurologic examination - Strength, sensation, and muscle-stretch reflexes can be assessed throughout the bilateral lower limbs to evaluate for any lumbosacral radiculopathy

• Lumbosacral range of motion - This can be assessed in multiple planes, including documentation of pain with these motions, particularly if the presenting symptoms are reproduced

• GI and gynecologic physical examination - Depending on the patient's history and the clinician's expertise, abdominal and gynecologic physical examinations may be performed; manual digital rectal examination can assess for hemorrhoids or other intrarectal masses

Some physicians may have an unintentional bias against patients with coccydynia, inappropriately attributing the pain to underlying psychological conditions, such as anxiety, neurosis, or even hysteria.[3] Patients with coccydynia often report frustration with physicians who minimize their symptoms or tell them that the pain is "all in their head."[5] However, behavioral assessments of patients with coccydynia have shown a psychological profile similar to that of any other group of patients (ie, without any increased evidence of overt psychopathology).[3]

Patients with coccydynia deserve appropriate workup, treatment, and compassion, the elements of care provided to patients with other neurologic or musculoskeletal chronic pain syndromes.

Electrodiagnostics

Electromyography (EMG) and nerve conduction studies (NCSs) are usually unnecessary in cases of isolated coccydynia. However, electrodiagnostics are potentially helpful in cases in which concomitant lumbosacral radiculopathy is suspected.

Anesthesia response

The patient's response to injection of local anesthetic agents, with or without corticosteroids, can provide helpful information regarding whether the patient's pain generator has been accurately identified. However, the injection response may not be considered truly diagnostic of whether the pain generator is a specific anatomic structure unless the injection is performed with the guidance of fluoroscopy or other imaging aids. Similarly, if large volumes of fluid are injected, extravasation from the targeted site decreases the diagnostic specificity.

Complications from focal injections seem to be uncommon if the injections are performed using a sterile technique and fluoroscopy or other image guidance to assist in accurate placement. Some patients may experience exacerbation during the first few days after the injection procedure, but this is generally only temporary and self-limited.

Histologic findings

A single case series of 8 patients who had undergone coccygectomy (surgical removal of the coccyx) revealed that in 5 patients, the main histologic change was disc degeneration at the sacrococcygeal joint; the surgical outcome was poor in all 5 patients. Two other cases had degenerative articular cartilage changes at the sacrococcygeal joint, and the postsurgical outcome was excellent in 1 of these patients and good in the second one.[21]

Lab work

No specific blood work is recommended for coccydynia.

Plain radiographs are typically the initial imaging study of choice for patients with coccydynia, especially in cases of focal sacrococcygeal trauma.

Plain radiographs may reveal fractures, abnormal sacrococcygeal curvature, osteophytes, or dislocations of the sacrococcygeal junction or intracoccygeal segments.[6, 7]

However, be aware that there is substantial baseline, preinjury coccygeal variability with regard to the angulation of the coccygeal vertebrae and the sacrococcygeal joint, the degree of fusion between the coccygeal vertebrae and the sacrococcygeal joint, and the total number of coccygeal vertebrae. This preinjury variability creates challenges when interpreting sacrococcygeal imaging studies. It may become difficult to know whether apparent abnormalities truly signal acute or ongoing pathology or just represent normal baseline anatomic variability.

Lateral view

In the lateral view, the easiest way to identify the sacrococcygeal junction typically is to look just anteroinferior to the sacral cornua and anterior to the coccygeal cornua. The cornua are horn-shaped, bony projections; 2 sacral cornua (the right and left cornua) extend inferiorly from the sacrum, and 2 coccygeal cornua extend superiorly from the coccyx. On the lateral radiographic view, the 2 sacral cornua seem to overlap and appear as one, with a similar overlapping noted for the coccygeal cornua.

Some French clinicians advocate radiographically assessing sacrococcygeal mobility through the comparison of lateral radiographs performed while the patient is seated versus standing.[6, 7] Within most radiology departments, however, such dynamic radiography is not widely performed or readily available.

Anteroposterior view

In the anteroposterior (AP) view, the first (most superior) coccygeal vertebra can be distinguished from the other coccygeal vertebrae by the presence of the bilateral coccygeal cornu posteriorly and the bilateral transverse processes laterally. (The transverse processes of the first coccygeal segment are much wider and much more prominent than are the transverse processes of the inferior coccygeal vertebrae.)

The apex of the coccyx is usually rounded, but a bifid appearance can sometimes be appreciated in the AP radiographic view. The apex is typically midline but may deviate laterally.

Coned-down view

In addition to obtaining the standard AP and lateral lumbosacral radiographs, explicitly requesting coned-down (focused) views of the coccyx itself is often important to ensure adequate visualization and an appropriate degree of radiographic exposure (see the image below). Standard sacrococcygeal radiographs include the entire sacrum and coccyx, the lower lumbar region, and, frequently, the bilateral ilia and hip joints. Thus, images that are not coned-down to focus on the coccyx often result in suboptimal radiographic exposure at the coccyx, making the coccygeal segments difficult to clearly visualize.

Lateral view of the pelvis and coccyx. The bracket shows the area of focus for radiographs that would provide a coned-down view of mainly the coccyx and distal sacrum. A more common lateral view would often also include larger bony structures, such as the lumbar spine and femur, all of which would make it difficult to optimize visualization of the small bones of the coccyx. In patients with coccyx pain, these coned-down, lateral views of the coccyx can provide important diagnostic information. Coned-down images obtained in the weight-bearing (seated) position can be compared with those obtained in a non–weight-bearing position (eg, side lying), thus allowing assessment for dynamic instability (eg, dislocations that occur only while seated).

Lumbosacral magnetic resonance imaging (MRI) studies usually fail to include the coccyx unless a specific request is made for coccygeal visualization. Thus, patients whose imaging studies have been limited to a standard lumbosacral MRI scan (without plain radiographs first and without additional MRI of the coccyx) have often received no radiologic imaging of the coccyx.

Lumbosacral MRI would be most helpful in cases in which the coccygeal pain is suspected to be referred from anatomic structures located more superiorly within the spine (ie, at the lumbar or sacral regions).

Lumbosacral MRI can help to diagnose lumbosacral disc pathology, degenerative joint disease of the lumbosacral facet joints (zygapophyseal joints), and pathology of the sacroiliac joints. However, the notable caveat is that many degenerative changes of these structures are considered to be a normal, often nonsymptomatic, part of the aging process. Thus, any such abnormalities must be put into the context of the patient’s overall history and physical so that the physician can make an educated determination as to whether the lumbosacral MRI findings represent pain generators or incidental findings.

In most cases of coccydynia, bone and computed tomography (CT) scanning are not necessary. In cases of suspected fracture with negative or inconclusive plain radiographic findings, however, these studies can be performed to better delineate the bony anatomy. This is notable because normal coccygeal variability and technical difficulties with radiographic exposure sometimes limit the ability of plain radiographs to aid in the diagnosis of a coccygeal fracture.

Bone and CT scanning studies may particularly be considered in medicolegal cases in which objective evidence is needed regarding the presence or absence of a coccygeal fracture or in cases in which bony cancer or metastases are being considered.

Note that bone scans that only include AP and/or PA views generally fail to show the coccyx, since coccygeal visualization is obstructed by the nuclear medicine materials pooling in the bladder prior to urination. Using oblique and lateral views, rather than just the AP or PA views, can help avoid this problem.

CT scanning and/or MRI of the pelvis can be helpful in cases in which intrapelvic pathology (ovarian, cervical, colon, testicular, or prostate cancer or their associated metastases) is suspected.[8] CT scanning may be particularly helpful with bony lesions and is less expensive than MRI.

MRI is superior to CT scanning at visualization of soft-tissue structures, including with regard to showing pathology of the ovaries, uterus, prostate, urinary bladder, and bowels. Also, unlike MRI, CT scanning carries notable risks of radiation exposure.

Screening questions for possible malignancy should be completed prior to commencing focal treatment for coccydynia.

Physical therapy

Relatively few physical therapists have expertise in pelvic pain syndromes, pelvic floor muscle dysfunction, and/or pelvic floor rehabilitation. A small, but growing, number of therapists are receiving specialized training in this area. Thus, inquiring as to the degree of experience of a given therapist is important.

Physical therapy for coccydynia may involve manually working on tight, painful muscular structures such as the levator ani, coccygeus, or piriformis muscles. Myofascial release techniques may be used. Local modalities also may be helpful.

Generally, all nonsurgical care of coccydynia can be performed on an outpatient basis, including follow-up visits and local injections.

A retrospective study by Scott et al indicated that pelvic floor physical therapy is an effective treatment for those who have chronic coccydynia even after coccygectomy. Among the 79 patients who finished therapy (a mean of nine physical therapy sessions), using numeric rating scales, the mean average pain rating and the mean highest pain rating fell from 5.08 to 1.91 and from 8.81 to 4.75, respectively. A secondary measure, the mean percent global improvement, was 71.9%. (Although physical therapy was the primary treatment in the study, baclofen, ganglion impar blocks, and coccygeus trigger point injections were also used.)[23]

With regard to surgical treatment, a number of small to modest-sized case series have seemed to indicate that a significant quantity of properly selected patients may receive relief via coccygectomy but that postoperative complications (especially infection) are common.

Avoidance

Patients with coccydynia usually know which activities to avoid in order to minimize exacerbation of their tailbone pain. Examples include prolonged sitting (eg, long car or airplane rides), bike riding, horseback riding, and canoeing.

Consultations

Physicians who are unfamiliar with treating coccydynia or are inexperienced at administering the injections that are commonly used as treatment may wish to consult a pain management physician (eg, a physical medicine and rehabilitation physician or an anesthesiologist) with expertise in this area.

Surgical treatment for coccydynia includes coccygectomy, in the form of partial or complete surgical removal of the coccyx.[9, 10]

Care must be taken during the surgery to avoid injury to the rectum, which is located just anterior to the coccyx. The ganglion impar also is located just anterior to the coccyx, so a potential risk of injury to the sympathetic nervous system exists during coccygectomy.

The multiple muscular and ligamentous attachments to the coccyx present additional anatomic concerns for patients undergoing coccygectomy. For example, the levator ani and other pelvic floor muscles attach directly to the coccyx; thus, some degree of sagging of the pelvic floor is possible after coccygectomy. Another important attachment to the coccyx is the sphincter ani externus, which is responsible for bowel continence (thus raising the possibility of surgical complications, such as fecal incontinence).

Coccygectomy has been associated with relatively high rates of postoperative infection. A case series of 20 patients treated with total coccygectomy reported that 90% of the patients eventually felt improvement, but overall postoperative complications included 7 wound problems (thus more than one third of the patients)—4 patients with superficial infections and 3 patients with persistent drainage.[24]

In a retrospective study of 32 patients with coccydynia who were treated by an orthopedic spine surgeon, the investigators concluded that patients with coccydynia should be managed conservatively when possible, including with nonsteroidal anti-inflammatory drugs (NSAIDs) and repeat injections. In the study, 11 patients (34%) underwent surgical treatment via coccygectomy. Marked improvement was reported in 9 (82%) of the surgical patients, but 3 (27%) of the 11 developed wound infections and 1 (9%) developed wound dehiscence.[25] The authors felt that coccygectomy can offer reasonable results when conservative treatment fails but that patients should be warned of the high rate of infection.

In another small case series, which reported on coccygectomy in 16 patients with chronic coccydynia (8 patients with posttraumatic coccydynia and 8 patients with nontraumatic coccydynia), superior surgical results were reported in patients whose coccydynia had been preceded by trauma.[26]

A study by Hanley et al stated that coccygectomy can produce significant patient-reported improvement in chronic, conservative-treatment–resistant coccyx pain at 2-year follow-up, with risk factors for the procedure’s failure including psychiatric illness, higher preoperative pain levels, the presence of more than three comorbidities, and preoperative opiate use. The study involved 94 patients.[27]

A retrospective study by Doursounian et al suggested that coccygeal spicules can be successfully treated with coccygectomy. The study involved 33 patients with spicules, all of whom had obtained insufficient relief from conservative treatment; they were followed up postsurgically for periods of 30-42 months (13 patients), 48-66 months (10 patients), and over 72 months (10 patients). Surgical outcomes were considered very satisfactory in 26 patients (79%) but were reported as unsatisfactory in seven patients (21%).[28]

Although a number of small studies have reported significant rates of symptomatic relief via coccygectomy, the authors of these reports have generally indicated that surgery was performed in only a small percentage of the patients presenting with coccydynia. For example, one study reported that of all patients with coccydynia referred for orthopedic surgical consultation, only 15% underwent surgical treatment.[29]

Further, most of the authors of the surgical studies have recommended a thorough course of nonsurgical treatment (eg, oral medications, series of injections) prior to considering surgery.

The ganglion impar (ganglion of Walther) is the terminal ganglion of the paravertebral sympathetic nervous system; it is the only nonpaired sympathetic ganglion. The ganglion impar is usually located anterior to the sacrococcygeal junction, the first intracoccygeal junction, or the first coccygeal vertebra.[30, 31, 32, 33, 34, 35, 36]

One possible mechanism for persistent coccydynia is excessive activity or sensitivity of the ganglion impar, thus creating sympathetically maintained coccyx pain.[11]

Local injection of an anesthetic can effectively block the ganglion impar and thereby relieve coccyx pain. In a published report by Foye and colleagues, nerve blocks using local anesthetics with a fast onset (eg, lidocaine) were shown to provide substantial relief even by the time a patient sat up on the procedure table.[11]

After the local anesthetic block wears off, some of the coccyx pain may start to return, but generally it returns at a much lower severity than existed prior to the injection. Physical medicine and rehabilitation coccydynia physicians and researchers at New Jersey Medical School refer to this new plateau of severity as "resetting the thermostat."

Published reports document that some patients with coccydynia receive complete and permanent relief via a single ganglion impar block.[11]

In patients with less than 100% permanent relief, repeat ganglion impar blocks have been shown to provide additional benefit, further lowering the plateau level of pain. Thus, in patients without complete resolution, repeat injections are often medically necessary and clinically helpful.

Techniques

Older techniques for performing the ganglion impar block involved approaching the anterior sacrococcygeal region by using a curved needle inserted below the distal coccygeal tip. The older technique required a larger-diameter and longer-length needle (in particular, the longer length of that needle being inserted into the patient) compared with the current (transsacrococcygeal) approach, which uses a short, thin needle.

In the past, many coccygeal procedures were performed without image guidance (blind injection, such as without fluoroscopy), an omission with the potential to compromise the accuracy and safety of the injection.

The more recent transsacrococcygeal approach to the ganglion impar involves inserting a thin needle into the sacrococcygeal junction, from posterior to anterior.[37, 38] The transsacrococcygeal approach for ganglion impar sympathetic blockade uses a lateral fluoroscopic view to visualize the sacrococcygeal junction. A small, 25-gauge spinal needle is then inserted through the junction until the needle tip is just anterior to that articulation. Radiographic contrast can be used to confirm that the needle placement is not intravascular, not too far anterior (within the rectum), and not too superficial (within the sacrococcygeal disc).[11]

The procedure is only minimally invasive. It requires a sterile technique (particularly given the proximity to the anus and rectum) and fluoroscopic guidance to ensure safe and accurate needle placement.

A report by Sencan et al indicated that the transsacrococcygeal approach to ganglion impar block administration is safe and effective in treating chronic coccydynia, with significant pain relief obtained in 42.9% of study patients with a normal coccyx and 61.9% of those with an immobile coccyx. All patients received a single treatment with the block.[39]

The ganglion impar block (which is anterior to the coccyx) can be preceded by a separate local anesthetic block of the coccygeal nerve (a somatic, nonsympathetic nerve posterior to the coccyx) to anesthetize the posterior region prior to the impar injection and to provide more complete relief of the coccydynia. Often, it makes sense to combine these injections on the same injection date, so that both anterior and posterior relief is obtained.

A case series reported good results from the administration of 20 ganglion impar blocks by physical medicine and rehabilitation physicians at New Jersey Medical School to patients who were suffering from persistent coccydynia despite treatment with oral medications, cushions, and other conservative therapies. The results showed that each of the 20 injections provided significant relief in these patients. The percentage of relief obtained per injection varied from 20-75%, with most patients reporting 50-75% relief obtained per injection and with the relief generally lasting weeks to months or longer. For cases in which patients had incomplete relief after a given injection, additional analgesic benefit was obtained from subsequent injections. Thus, repeat injections were often helpful.

Foye and colleagues at New Jersey Medical School also published a new, slightly more direct approach to ganglion impar injections.[11] Specifically, they reported the option of passing the needle through the first intracoccygeal joint (the space between the first and second coccygeal segments) instead of through the sacrococcygeal joint.

An important benefit to this approach over the transsacrococcygeal one is that the first intracoccygeal joint is often easier to visualize, since it is not obstructed by the sacral or coccygeal cornua. This site is slightly closer to the location of the ganglion impar, according to cadaver dissection studies.[33]

A study by Gopal and McCrory indicated that treatment of the ganglion impar with pulsed radiofrequency can improve pain in some patients with chronic coccydynia. In the retrospective review, 20 patients whose coccydynia did not respond to medical management underwent pulsed radiofrequency treatment, with follow-up at 6 and 12 months. In 15 patients, the mean pretreatment visual analogue scale score fell significantly, from 6.53 to 0.93. Treatment in the remaining patients was unsuccessful, with no change in the visual analogue scale score at follow-up.[40]

Sacrococcygeal joint injections

When the primary pain generator is thought to be at the sacrococcygeal joint, local injection can be administered to this site. Image guidance (eg, fluoroscopy) can be helpful to ensure accurate placement, particularly because the joint space is typically narrow and individual anatomic coccygeal variability may make surface palpation alone unreliable.

Injection with local anesthetic (eg, lidocaine) alone (ie, without any corticosteroids) may serve as a diagnostic injection if fluoroscopy and contrast have first confirmed accurate placement within the joint.

Injection with corticosteroids may be helpful in cases of focal inflammation at the sacrococcygeal joint (eg, after local trauma and perhaps with degenerative changes at this site).

If injected too superficially (posterior to the sacrococcygeal junction), corticosteroids may theoretically cause subcutaneous fat atrophy at this site.

A study by Finsen et al found that in patients with chronic coccydynia who received one injection of either betamethasone (6 mg) or triamcinolone (20 mg), effective long-term pain relief (mean 36 mo) was achieved in 15% of the group, with the overall rate reaching 29% after 62 of the 241 patients received a second injection. The investigators also determined that triamcinolone was the more successful pain reliever and that patients who had been suffering from symptoms for less than 12 months were more likely to experience long-term relief.[41]

Epidural steroid injections

Although many pain management centers perform caudal epidural steroid injections for coccydynia, a relative paucity of published research supports epidural steroid use for coccyx pain.

Ischial bursa injections

The authors of this article have found that in cases in which ischial bursitis is suspected as a substantial component of the patient's buttock pain, local injection of the bursa can be performed either with local anesthetic alone (diagnostic injection) or with corticosteroids (therapeutic injection).

Ablation injections may provide more long-lasting relief in appropriately selected patients. Ablation is the intentional destruction of human tissue for treatment purposes. For instance, ablation can be used to intentionally destroy nerve fibers at the coccyx, so that those nerves can no longer send pain signals to the brain. Thermocoagulation of the ganglion impar using radiofrequency ablation (RFA) has been reported.[12, 13] Ablation can also be accomplished chemically (eg, by carefully injecting neurotoxic agents such as phenol and/or ethyl alcohol directly onto the targeted nerve tissues). These coccygeal ablation injections have been in clinical use for multiple decades and thus are no longer considered experimental.[2]

Ablation is typically reserved for patients whose pain has failed to be adequately relieved via oral analgesic medications, cushions, coccyx steroid injections, and coccygeal sympathetic nerve blocks (ganglion impar). The ideal specific site for ablation may depend on the individual patient’s specific site of coccygeal pathology. Prior to ablation, a diagnostic injection (test injection, with local anesthetic) is generally performed to ascertain whether a specific target site is likely to provide relief if ablated. Patients who obtain substantial transient (anesthetic) relief via the diagnostic injection would be good candidates for subsequent nerve ablation at the same site where the diagnostic injection was done.

If ablation fails to provide as much relief as the anesthetic/test injection provided, the ablation may soon be repeated, to provide more complete destruction of those nerve fibers.

Even after successful relief via ablation, some patients may have eventual return of the some of their coccyx pain many months or years later, if the remaining coccygeal nerve fibers regrow collateral reinnervation to the sites denervated by the ablation. In those cases, repeat ablation may be performed.

Since ablation injections are intended to cause destructive (albeit therapeutic) changes, they should only be performed by physicians skilled and experienced in these procedures. In addition, they should be performed under image-guidance (eg, fluoroscopy, to add to the specificity of the targeted injection site) and using the smallest amount (eg, milliliters) of ablation necessary to provide the desired therapeutic relief.

Ablation injections may help some coccydynia patients avoid more invasive treatments, eg, helping them avoid surgical removal of the coccyx (coccygectomy).

A retrospective study by Adas et al indicated that radiofrequency therapy of the ganglion impar via a transsacrococcygeal approach can effectively treat chronic coccydynia. The investigators found that compared with pretreatment visual analogue scale scores, there was significant improvement in early, 1-month, and 6-month postprocedure scores, with successful outcomes reported for 90.2% of patients at 6 months.[42]

Osteopathic, chiropractic, or other "manual medicine" techniques to mobilize the coccyx are sometimes performed by clinicians who feel that the sacrococcygeal segments of a given patient have decreased mobility.

Manipulation with fingers placed inside the rectum may theoretically have a role in helping to relocate a dislocated coccygeal vertebra.[2] Adequate anesthesia may be necessary for the patient to tolerate the relocation.

Since effectively bracing/immobilizing a dislocated coccyx in the relocated position is not possible, it is unclear whether relocation via manipulation provides sustained improvement in position.

A randomized study in patients with chronic coccydynia found that 51 patients treated with intrarectal manipulation had good results almost twice as frequently as did the control group, as determined at 1 month (36% vs 20%, P = .075) and at 6 months (22% vs 12%, P = .18). The main predictors of a good outcome were a stable coccyx, shorter symptom duration, traumatic etiology, and a lower score in the affective (emotional) parts of the McGill and Dallas questionnaires. The authors concluded that intrarectal manipulation had "mild effectiveness" for chronic coccydynia.[43]

As previously stated, early interventions (eg, oral medications, injections, physical therapy) are presumed to decrease the chance that acute coccydynia will become chronic.

Once the coccyx pain has become chronic (persisting for more than 3-6 mo), it may be less likely to resolve by natural recovery alone, more likely to continue indefinitely, more likely to be resistant to treatment, and more likely to require a multimodal treatment approach (eg, oral medications combined with local injections).

Nonsteroidal anti-inflammatory drugs, analgesics, and anticonvulsants can all be used to manage pain in patients with coccydynia.

Class Summary

NSAIDs have analgesic, anti-inflammatory, and antipyretic activities. The mechanism of action may be inhibition of cyclo-oxygenase (COX) activity and prostaglandin synthesis. Other mechanisms may include inhibition of leukotriene synthesis, lysosomal enzyme release, lipoxygenase activity, neutrophil aggregation, and various cell membrane functions.

Ibuprofen (Advil, Motrin, Caldolor, Neoprofen, Ibu)

This is a classic anti-inflammatory used for patients with mild to moderate pain. It inhibits inflammatory reactions and pain by decreasing prostaglandin synthesis.

Class Summary

Pain control is essential to quality patient care. Analgesics ensure patient comfort and have sedating properties that may be beneficial for patients who experience pain.

Acetaminophen (Aspirin Free Anacin, FeverAll, Tylenol, Mapap)

Acetaminophen is a first-line medication for treating pain in patients with documented hypersensitivity to aspirin or NSAIDs, with upper GI disease, or who are taking oral anticoagulants.

It is effective in relieving mild to moderate acute pain; however, acetaminophen has no peripheral anti-inflammatory effects. It may be preferred in elderly patients because of fewer GI and renal side effects.

Tramadol (Ultram, Ryzolt, Rybix ODT)

Tramadol inhibits ascending pain pathways, altering the patient's perception of and response to pain. It inhibits the reuptake of norepinephrine and serotonin.

Pregabalin (Lyrica)

Pregabalin is a structural derivative of gamma-aminobutyric acid (GABA); its mechanism of action is unknown. Pregabalin binds with high affinity to the alpha2-delta site (a calcium channel subunit). It reduces the calcium-dependent release of several neurotransmitters in vitro, possibly by modulating calcium channel function. Pregabalin has been approved by the US Food and Drug Administration (FDA) for the treatment of neuropathic pain associated with diabetic peripheral neuropathy or postherpetic neuralgia.

Fentanyl citrate (Duragesic, Abstral, Actiq, Fentora, Onsolis)

Fentanyl citrate is a synthetic opioid that has 75-200 times more potency and a much shorter half-life than morphine sulfate. It has fewer hypotensive effects than morphine and is safer in patients with hyperactive airway disease because of minimal or no associated histamine release. By itself, fentanyl citrate causes little cardiovascular compromise, although the addition of benzodiazepines or other sedatives may result in decreased cardiac output and blood pressure.

Fentanyl citrate is highly lipophilic and protein-bound. Prolonged exposure to it leads to accumulation of the drug in fat and delays the weaning process. Consider continuous infusion because of the medication's short half-life.

The parenteral form is the drug of choice for conscious-sedation analgesia. Fentanyl citrate is ideal for analgesic action of short duration during anesthesia and the immediate postoperative period. It is an excellent choice for pain management and sedation with short duration (30-60 min) and is easy to titrate. The drug's effects are easily and quickly reversed by naloxone.

After the initial parenteral dose of fentanyl citrate, subsequent parenteral doses should not be titrated more frequently than every 3 or 6 hours thereafter.

The transdermal form is used only for chronic pain conditions in opioid-tolerant patients. When using the transdermal dosage form, most patients are controlled with 72-hour dosing intervals; however, some patients require dosing intervals of 48 hours.

Oxycodone (OxyContin, Roxicodone)

Oxycodone is indicated for the relief of moderate to severe pain.

Oxycodone and acetaminophen (Percocet, Roxicet, Endocet, Primlev, Tylox)

This drug combination is indicated for the relief of moderate to severe pain.

Class Summary

These are used as adjuvants for neuropathic pain.

Gabapentin (Neurontin)

Gabapentin is a membrane stabilizer. A structural analogue of the inhibitory neurotransmitter GABA, gabapentin paradoxically is thought not to exert an effect on GABA receptors. It appears to exert its action via the alpha2-delta1 and alpha2-delta2 auxiliary subunits of voltage-gated calcium channels.

Gabapentin is used to manage pain and provide sedation in neuropathic pain. Titration to effect can take place over several days (300mg on day 1, 300mg twice on day 2, and 300 mg 3 times on day 3).