Coccygodynia (Tail bonepain): Causes

What is a dynia?

The "dynias" are a group of chronic, focal pain syndromes with a predilection for the orocervical and urogenital regions. They include glossodynia, carotidynia, vulvodynia, orchidynia, prostatodynia, coccygodynia, and proctodynia. In some cases, the dynias occur secondarily, but more often, despite an exhaustive evaluation, no etiology is found and in these remaining cases, the cause of the pain remains enigmatic. The controversy that surrounds this group of disorders, which ranges from questioning their existence to suggesting that they are purely psychosomatic, is counterbalanced by an extensive literature attesting to their organicity (1).

What is coccygodynia? & Causes of coccygodynia:

The three most common functional disorders causing anorectal and perineal pain are levator ani syndrome, coccygodynia and proctalgia fugax. However, Alcock's canal syndrome is also responsible for pain in these areas (3).
A review of Mayo clinic records Physical Medicine and Rehabilitation from 1970 through 1975 with pelvic floor myalgia (pyriformis syndrome, coccygodynia, levator ani spasm syndrome, proctalgia fugax, or rectal pain) is associated with poor posture, deconditioned abdominal muscles, and generalized muscle attachment tenderness. The most effective therapeutic regimen was a combination of rectal diathermy, Thiele's massage, and relaxation exercises (20).
Local pain in the area of coccyx (tail bone) is called coccygodynia. Chronic coccygodynia is a difficult problem diagnostically and therapeutically (2). According to Dr. Cyriax (Father of orthopedic medicine) there are 4 different causes of coccygodynia.
1. Trauma by direct blow to the coccyx
2. Sprain of sacro-coccygeal & Ilio-coccygeal ligament
3. Sprain of muscle fibers attached to the over lying sacro-coccygeal & Ilio-coccygeal ligaments

Coccyx disc disorder in common idiopathic coccygodynia: Coccygodynia are usually attributed to soft tissue injuries or psychologic disturbances. However Maigne et al (13) in 1994 has hypothesized that the source of coccygodynia as a lesion of the coccygeal disc. Basing on discography study Maigne et al (13) found Common coccygeal pain could come from the coccygeal disc in approximately 70% of cases.

True & pseudo coccygodynias: According to Traycoff et al (4) true coccygodynia consists of pain arising from the sacrococcygeal joint, whereas pseudococcygodynia consists of pain referred to but not arising from the coccyx. Coccygodnia can usually be distinguished from pseudococcygodynia by physical examination with the diagnosis being confirmed by injection of local anesthetic into the sacrococcygeal joint. The etiology of pain not relieved by intraarticular injection can be further defined by selective neuroblockade.

Differentiating traumatic and idiopathic coccygodynia:

Intercoccygeal angle: It is the angle between the first and last segment of the coccyx (11). According to Kim et al (11) intercoccygeal angle in the normal population is around 52.3 degrees. Intercoccygeal angle of the idiopathic (non-traumatic) coccygodynia is greater than that of the traumatic and normal population.Increased intercoccygeal angle can be considered a possible cause of idiopathic coccygodynia. The intercoccygeal angle was a useful radiological measurement to evaluate the forward angulation deformity of the coccyx.
According to Kim et al (11) the differences observed between traumatic & non-traumatic coccygodynia are
1. There is no difference between the traumatic and idiopathic coccygodynia groups in terms of age, male/female sex ratio, and the number of coccyx segments.
2. Significant differences between the traumatic and idiopathic coccygodynia groups are marked in terms of the pain score, the intercoccygeal angle, and the satisfactory outcome of conservative treatment.
a. If pain is compared in sitting then the pain in traumatic coccygodynia is more than non traumatic category.
b. If pain is compared on defecation then the pain in non traumatic coccygodynia is more than traumatic category.
c. Intercoccygeal angle is more in non traumatic coccygodynia than traumatic category.
d. Response to conservative treatment is better with non traumatic coccygodynia

Pregnancy & Coccygodynia: Coccygodynia appears to occur more in females. Coccydynia can result from a varying number of causes, parturition being one of them (6). Ryder et al (5) reviewed literature to find out coccydynia with specific reference to those cases of pregnancy and birth-related onset. They found there is little information about incidence, prevalence, pathophysiology, methods of differential diagnosis and efficacy of treatment for these women. No qualitative data from women with pregnancy or birth-related coccydynia were identified.
However according to a case report by Kaushal et al (6) strains and sprains of the ligaments attached to the coccyx is thought to be the usual cause for coccydynia occurring after childbirth, an intrapartum coccygeal fracture dislocation can result in the same. Similarly Jones et (12) reported a case of coccygodynia due to coccygeal fracture secondary to parturition.

Cyst in precoccygeal region as a cause of coccygodynia: Jaiswal et al in 2008 (7) reported for the first time a single case precoccygeal epidermal inclusion cyst presenting as a coccygodynia. This study suggests that patients with intractable coccygodynia should have a magnetic resonance imaging to rule out treatable causes of coccygodynia.
A few coccygodynia cases are attributed to so-called pericoccygeal glomus tumors. Pericoccygeal soft tissues normally contain numerous small glomus bodies and a larger one known as the glomus coccygeum, which can reach several millimeters in diameter. Most reported cases of alleged pericoccygeal glomus tumors represent normal, incidentally discovered coccygeal glomus bodies (14).
Intracoccygeal glomus tumor are also reported as a cause of coccygodynia. However, Pericoccygeal and intracoccygeal glomus bodies are normal findings in humans at all ages. They should not be mistaken for tumors, and their role in the pathogenesis of coccygodynia is questionable (14).
Ziegler et al (17) have reported a case of typical coccygodynia caused by a sacral nerve cyst. Relief of the pain by excision of the cyst occurred.
No case of arachnoid cyst causing coccygodynia has been found available in medical literature till Kepski A et al (18) reported a case of arachnoid cyst of cauda equina with severe chronic coccygodynia. Arachnoid cysts are often asymptomatic, by they may be responsible for coccygodynia and/or incomplete cauda equina syndrome (19).
Arachnoid cysts are called Tarlov’s cysts (perineurel meningeal cysts on the sacral nerve roots).It’s presence is suggested by the characteristics of the symptoms which are paroxysmal, exacerbated in standing position, relieved in dorsal position and revived by percussing the sacrum. Treatment is medical in most cases. The decision to operate depends on the persistence and intensity of pain and on whether signs of neurological defecit are present (19).
According to a single case study by Charpentier et al (21) ependymoma of the filum terminale caused the coccygodynia in that case. Similarly according to a single case study by Chateau et al (22) ependymoma of the filum terminale caused the coccygodynia in that case.

Association of depression with coccygodynia: Maroy B (15) investigated association of depression with coccygodynia in 1988. Out of 313 patients with signs of depression or spontaneous or evoked pain of coccygeal area were studied over six months. One hundred eighty (58 percent) had no spontaneous pain, 87 (28 percent) had moderate pain, and 46 (15 percent) a severe coccygodynia leading to consultation.

Association of jeans seam with coccygodynia: Stoshak ML (16) et al have tried to associate jeans seam with coccygodynia back in 1985.

Normal coccygeal movement during defecation don’t cause coccygodynia: Over view of coccygeal movement
An abnormal motion (laxity or hypermobility) of the coccyx that occurred in the sitting position and spontaneously was reducible when placed in the lateral decubitus position (13). According to a dynamic MRI study by Grassi R et al (2), coccyx is mobile during defecation and that it is possible to demonstrate coccygeal excursions by assessing the difference between its positions at maximum contraction and during straining-evacuation. This study also found there is no correlation between coccygeal movements and age, sex, parity, minor trauma and coccygodynia.
Dynamic radiography is a useful tool to differentiate posttraumatic from idiopathic coccygodynia (9).
Changes in post traumatic coccygodynia:
In an analysis of morphological changes associated with 23 different patients with post traumatic coccygodynia the following ware found by Brusko et al (8)
1. Coccyx cartilaginous tissue showed dystrophic changes of chondrocytes, destruction of the basic material with partial replacement of a fibrillar cartilaginous tissue with a hyaline cartilage were observed with a different degree of manifestation.
2. Vessels and sacrococcygeal nervous plexus were subjected to pathological changes.
3. Increased post-traumatic mobility, alterations in the process of ossification, deceleration of physiological joining of coccyx vertebras and sacrococcygeal joint alter biomechanical properties of coccyx at sitting.
Study by Brusko et also found that these above alterations lead to the long-lasting traumatization with degenerative - dystrophic changes, reinforcement of pain syndrome and manifestation of dysfunctions of organs of pelvis (8).

Coccyx instability following post traumatic coccygodynia:
Coccyx instability is a fairly common phenomenon after trauma to this area. Mouhsine et al reported 15 posttraumatic coccygodynia with instability which was diagnosed with dynamic lateral radiography and magnetic resonance imaging (MRI) (9). Doursounian et al between 1993 and 2000 surgically treated 61 patients with instability-related coccygodynia using a single technique. Twenty-seven patients had hypermobility of the coccyx and 33 subluxation. In all cases, the unstable portion was removed through a limited incision directly over the coccyx.

Complications of coccygodynia:
Complications of coccygodynia are not many however coccygodynia out of Coccygeal fracture dislocation may result in introital dyspareunia and tension myalgia of the pelvic floor. Pain from this lesion may become recurrently symptomatic (6).

References:
1. Wesselmann U et al; Semin Neurol. 1996 Mar; 16(1):63-74. (The dynias)
2. Grassi R et al; Eur J Radiol. 2007 Mar;61(3):473-9. Epub 2007 Jan 16. Coccygeal movement: assessment with dynamic MRI.
3. Mazza L et al; Tech Coloproctol. 2004 Aug;8(2):77-83. (Anorectal and perineal pain: new pathophysiological hypothesis.)
4. Traycoff RB et al; Orthopedics. 1989 Oct;12(10):1373-7. (Sacrococcygeal pain syndromes: diagnosis and treatment.)
5. Ryder I et al; Midwifery. 2000 Jun;16(2):155-60. (Coccydynia: a woman's tail.)
6. Kaushal R et al; J Surg Orthop Adv. 2005 Fall;14(3):136-7. (Intrapartum coccygeal fracture, a cause for postpartum coccydynia: a case report.)
7. Jaiswal A et al; Singapore Med J. 2008 Aug;49(8):e212-4. (Precoccygeal epidermal inclusion cyst presenting as coccygodynia.)
8. Brusko AT, Fiziol Zh. 2004;50(6):114-7.( Morphofunctional changes of coccyx area in posttraumatic coccygodynia)
9. Mouhsine E et al; Spine J. 2006 Sep-Oct;6(5):544-9. Epub 2006 Jul 26. (Posttraumatic coccygeal instability.)
10. Doursounian L et al; Int Orthop. 2004 Jun;28(3):176-9. Epub 2004 Mar 13. (Coccygectomy for instability of the coccyx.)
11. Kim NH et al; Yonsei Med J. 1999 Jun;40(3):215-20. (Clinical and radiological differences between traumatic and idiopathic coccygodynia.)
12. Jones ME et al; Injury. 1997 Oct;28(8):549-50. (A case of coccygodynia due to coccygeal fracture secondary to parturition.)
13. Maigne JY et al; Spine (Phila Pa 1976). 1994 Apr 15;19(8):930-4. (Idiopathic coccygodynia. Lateral roentgenograms in the sitting position and coccygeal discography.)
14. Albrecht S et al; Surgery. 1994 Jan;115(1):1-6. (Intracoccygeal and pericoccygeal glomus bodies and their relationship to coccygodynia.)
15. Maroy B; Dis Colon Rectum. 1988 Mar;31(3):210-5. (Spontaneous and evoked coccygeal pain in depression.)
16. Stoshak ML et al; Pediatrics. 1985 Jul;76(1):138. (Jean seam coccygodynia.)
17. Ziegler DK et al; eurology. 1984 Jun;34(6):829-30. (Coccygodynia caused by perineural cyst.)
18. Kepski A et al; Neurol Neurochir Pol. 1978 Jan-Feb;12(1):109-12. (Arachnoid cyst of the cauda equina: a contribution to the etiology of coccygodynia)
19. Dehaine V et al; Rev Med Interne. 1990 Jul-Aug;11(4):280-4. (Coccygodynia disclosing Tarlov's cysts)
20. Sinaki M et al; Mayo Clin Proc. 1977 Nov;52(11):717-22. (Tension myalgia of the pelvic floor.)
21. Charpentier J et al; Rev Neurol (Paris). 1968 Feb;118(2):160-2. (Coccygodynia revealing an ependymoma of the filum terminale. Complete removal without sequelae)
22. Chateau R et al; Med Lyon. 1967 Apr 5;48(118):573-8. (Coccygodynia revealing a giant tumor of the cauda equine)

Interesting note by the author: The above picture of an MRI is taken in my center shows a coccyx fracture dislocation with no coccygodynia. The patient is a 32 year old lady.