Caudal regression syndrome (CRS) represents a spectrum of structural defects of the caudal region. Malformations vary from isolated partial agenesis of the coccyx to lumbosacral agenesis.
Caudal regression syndrome is rare, with an estimated incidence of 1:7500-100,000 7,10.
The vast majority of cases are sporadic, however familial cases occasionally occur. An association with VACTERL and Currarino triad syndromic complexes has been reported. Severe cases are usually identified in-utero or at birth. Mild cases may not be identified until adulthood. There is no gender predilection.
Caudal regression syndrome results from an insult in early pregnancy (< 4th week of gestation). Hyperglycaemia, infection, toxic and ischemic insults have been implicated.
Two possible aetiologies are suspected 3
- disturbance of the primary neurulation process
- derailment of the process of degeneration and differentiation of an initially normally developed primary and secondary neural tube
Caudal regression syndrome may present with a broad range of symptoms:
- neurogenic bladder and anorectal malformations
- sensorimotor paresis (motor deficits > sensory deficits)
- features of sacral agenesis - narrow hips, hypoplastic gluteal muscles, shallow intergluteal cleft
- mild foot deformities and gait abnormalities
- congenital genitourinary abnormalities (renal agenesis or hydronephrosis, various forms of duplication of the Mullerian ducts)
- anorectal anomalies, particularly anal atresia
- other spinal anomalies
- tethered cord (the cord may be tethered despite being high
- orthopaedic abnormalities (range from isolated deformities of the feet (e.g. clubfoot) to lower limb contractures
- congenital cardiovascular anomalies
- pulmonary hypoplasia
In an antenatal setting there is also associations with
- maternal diabetes - type I or type II
- present in ~ 1/5th of cases with CRS 4
- up to 22% of cases of CRS are associated with either type I or type II diabetes mellitus in the mother.
- CRS occurs in up to 1% of pregnancies of women with diabetes2.
- polyhydramnios 9
Imaging appearances can significantly vary depending on the severity of regression. In general the following may be seen:
- lumbosacral vertebral body dysgenesis/hypogenesis
- truncated blunt spinal cord terminating above the expected level (wedged- or cigar-shaped conus medullaris)
- severe canal narrowing rostral to last intact vertebra
Associated abnormalities may also be demonstrated (see above).
- a blunted sharp ending distal cord on a longitudinal sonogram is typical 1
- the conus often ends way above the expected level (sometimes even higher than L1) 7
- absent/hypoplastic sacrum
- hypoplastic extended lower extremities (limbs are seperate c.f. sirenomelia)
- may show a "shield sign" : opposed iliac bones in absence of sacral vertebrae : typically seen on a axial scan
- fetal extremities may be seen in a "crossed legged tailor" position or a "buddha" position
- in an early scan (1st trimester), the crown rump length may be less than expected for gestational age as an indirect feature
- shows similar features to those on ultrasound but in more detail
- useful to assess canal stenosis
- a characteristic wedge-shaped cord terminus may be seen 8
Imaging allows differentiation of two broad groups of patients with CRS7:
- the conus medullaris is blunt and terminates above the normal level. there is sometimes an associated dilated central canal or a cerebrospinal fluid–filled cyst at the lower end of the conus.
- these patients have major sacral deformities.
- the conus medullaris is elongated and tethered by a thickened filum terminale or intraspinal lipoma and ends below the normal level. neurologic disturbances are more severe in this group.
Treatment and prognosis
Both treatment and prognosis depend on the extent of regression. Morbidity is mainly from genitourinary and neuromuscular complications and management options are often centered around these with both urological and orthopaedic input.
General imaging differential considerations include
On antenatal ultrasound also consider
- 1. Lowe LH, Johanek AJ, Moore CW. Sonography of the neonatal spine: part 2, Spinal disorders. AJR Am J Roentgenol. 2007;188 (3): 739-44. doi:10.2214/AJR.05.2160 - Pubmed citation
- 2. Stroustrup Smith A, Grable I, Levine D. Case 66: caudal regression syndrome in the fetus of a diabetic mother. Radiology. 2004;230 (1): 229-33. doi:10.1148/radiol.2301020942 - Pubmed citation
- 3. Nievelstein RA, Valk J, Smit LM et-al. MR of the caudal regression syndrome: embryologic implications. AJNR Am J Neuroradiol. 1994;15 (6): 1021-9. AJNR Am J Neuroradiol (abstract) - Pubmed citation
- 4. Rufener SL, Ibrahim M, Raybaud CA et-al. Congenital spine and spinal cord malformations--pictorial review. AJR Am J Roentgenol. 2010;194 (3): S26-37. doi:10.2214/AJR.07.7141 - Pubmed citation
- 5. Singh SK, Singh RD, Sharma A. Caudal regression syndrome--case report and review of literature. Pediatr. Surg. Int. 2005;21 (7): 578-81. doi:10.1007/s00383-005-1451-4 - Pubmed citation
- 6. Hentschel J, Stierkorb E, Schneider G et-al. Caudal regression sequence: vascular origin? J Perinatol. 2006;26 (7): 445-7. doi:10.1038/sj.jp.7211534 - Pubmed citation
- 7. Unsinn KM, Geley T, Freund MC et-al. US of the spinal cord in newborns: spectrum of normal findings, variants, congenital anomalies, and acquired diseases. Radiographics. 20 (4): 923-38. Radiographics (full text) - Pubmed citation
- 8. Barkovich AJ, Raghavan N, Chuang S et-al. The wedge-shaped cord terminus: a radiographic sign of caudal regression. AJNR Am J Neuroradiol. 10 (6): 1223-31. AJNR Am J Neuroradiol (abstract) - Pubmed citation
- 9. Stroustrup smith A, Grable I, Levine D. Case 66: caudal regression syndrome in the fetus of a diabetic mother. Radiology. 2004;230 (1): 229-33. doi:10.1148/radiol.2301020942 - Pubmed citation
- 10. Entezami M, Albig M, Knoll U et-al. Ultrasound Diagnosis of Fetal Anomalies. Thieme. (2003) ISBN:1588902129. Read it at Google Books - Find it at Amazon
- 11. Diel J, Ortiz O, Losada RA et-al. The sacrum: pathologic spectrum, multimodality imaging, and subspecialty approach. Radiographics. 21 (1): 83-104. Radiographics (citation) - Pubmed citation
Synonyms & Alternative Spellings
|Synonyms or Alternative Spelling||Include in Listings?|
|Caudal regression syndrome (CRS)||✗|
|Caudal dysplasia sequence||✓|