DR/ ABD ALLAH NAZEER. MD.

Radiological imaging of caudal regression syndrome.

Caudal regression syndrome (CRS) is a spectrum of disorders of caudal vertebral agenesis or dysgenesis, often with spinal cord malformations that is associated with other congenital anomalies, especially of the genitourinary and gastrointestinal systems.The incidence of CRS is 1 to 5 cases in 100,000 births. The cause of CRS is largely unknown, but in 16% of the cases, the syndrome is associated with maternal diabetes. We present a rare case of Group 2 CRS in a 10-year-old girl with associated findings including anterior epidural lipoma, anterior lipomyelocystocele, an irregular trabeculated urinary bladder, bilateral hydronephrosis, and bilateral hydroureter.

Clinical presentationCaudal regression syndrome may present with a broad range of symptoms:neurogenic bladder and anorectal malformationssensorimotor paresis (motor deficits > sensory deficits)features of sacral agenesis: narrow hips, hypoplastic gluteal muscles, shallow intergluteal cleftmild foot deformities and gait abnormalities

PathologyCaudal regression syndrome results from an insult in early pregnancy (<4th week of gestation). Hyperglycemia, infection, toxic and ischemic insults have been implicated.Two possible etiologies are suspected:disturbance of the primary neurulation processderailment of the process of degeneration and differentiation of an initially normally developed primary and secondary neural tube.

Associationscongenital genitourinary abnormalities (renal agenesis or hydronephrosis, various forms of duplication of the Mullerian ducts)anorectal anomalies, particularly anal atresiaother spinal anomalies:

vertebral anomaliesdiastematomyeliaterminal hydromyeliamyelomeningocelelipomyelomeningoceleterminal myelocystoceleanterior sacral meningocelesacral agenesis (sometimes considered as part of the syndrome)spinal canal lipoma

Tethered cord (the cord may be tethered despite being high)orthopedic abnormalities (range from isolated deformities of the feet (e.g. clubfoot) to lower limb contracturescongenital cardiovascular anomaliespulmonary hypoplasiaIn an antenatal setting there is also associations with:maternal diabetes: type I or type II

present in ~20% of cases with CRS 4

~20% of cases of CRS are associated with either type I or type II diabetes mellitus in the motherCRS occurs in up to 1% of pregnancies of women with diabetes.

polyhydramnios

Radiographic featuresImaging appearances can significantly vary depending on the severity of regression. In general the following may be seen:lumbosacral vertebral body dysgenesis/hypogenesisthe level of atresia/dysgenesis is usually below L1 and often limited to sacrumtruncated blunt spinal cord terminating above the expected level (wedged- or cigar-shaped conus medullaris)severe canal narrowing rostral to last intact vertebraAssociated abnormalities may also be demonstrated (see above).Antenatal ultrasounda blunted sharp ending distal cord on a longitudinal sonogram is typical the conus often ends way above the expected level (sometimes even higher than L1) absent/hypoplastic sacrum hypoplastic extended lower extremities (limbs are separate c.f. sirenomelia)may show a "shield sign": opposed iliac bones in absence of sacral vertebrae: typically seen on a axial scanfetal 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

MRIshows similar features to those on ultrasound but in more detailuseful to assess canal stenosisa characteristic wedge-shaped cord terminus may be seenImaging allows differentiation of two broad groups of patients with CRS:group 1:

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 conusthese patients have major sacral deformities

group 2: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

Caudal regression syndrome

Caudal regression syndrome.

Caudal regression syndrome with lumbosacral agenesis.

Caudal regression syndrome.

Ten-year-old girl diagnosed with Group II Caudal regression syndrome. (a and b) Sagittal T1 weighted images show bilateral sacral agenesis (white arrow, S2 level) with anterior lipomyelocystocele (curved white arrow).

Ten-year-old girl diagnosed with Group II Caudal regression syndrome. Sagittal T2 weighted image shows low lying spinal cord (white arrow, L5 level) with syringohydromelia (pointed yellow arrow) of the caudal spinal cord.

Ten-year-old girl diagnosed with Group II Caudal regression syndrome. (a) Axial T2 weighted image shows anterior epidural lipoma (white arrow). (b) Axial T2 weighted image shows bilateral hydronephrosis (black arrowhead) and bilateral hydroureter (yellow arrowhead). (c) Coronal T2 weighted image reveals lumbosacral scoliosis (yellow arrow).

MRI Sagittal T2w images of lumbo sacral spine shows:Hypoplastic S1 and S2 with failure of formation of S3 and onwards. Cord ending at a higher level at D12-L1 with 'wedge' shaped termination.No cord tethering. No terminal cord cyst or syrinx. Imaging diagnosis : Caudal Regression, Group I.

Caudal regression syndrome

A) Lateral radiograph of lumbosacral spine reveals absence of distal sacrum (arrow). (B) Sagittal T1-weighted turbo spin echo MRI reveals abrupt termination of the conus medullaris with double bundle arrangement of nerve roots (arrow). (C) Sagittal T1-weighted turbo spin echo MRI reveals abrupt termination of the conus medullaris (arrow) and partial sacral agenesis.

Caudal Regression Syndrome

Hypoplasia of the sacrum and abnormal sacroiliac joints. Other findings include:tethered cord, diastomatomyelia (splitting) of the distal cord, hydromyelia of the distal cord which extends to the right hemicord, the right hemicord ends in small lipoma

Caudal regression (sacral agenesis). The conus medullaris of this 7-month-old infant is wedge- or hatchet-shaped and terminates at T11. There is hypoplasia of the S1 and S2 vertebral bodies, with no evidence of the more caudal portions of the sacrum or coccyx.

Spinal MRI of CRS types I and II. A: Type I: the terminal spinal cord is wedge-shaped and high-lying (white arrow).B: Type II: the spinal cord terminus is low-lying and tethered by a tight filum terminale and lipomatous tissue (white arrow).

Sagittal T1-weighted (A), T2-weighted (B) and coronal T2-weighted (C) MRI showing abrupt club-shaped termination of the conus medullaris (arrowheads) with double-bundle arrangement of nerve roots (curved arrows). There is a partial sacral agenesis.

MR spin-echo sagittal (A) T2- and (B) T1-weighted images showing malformed terminal segments of the sacrum, terminal spinal syrinx, and minimally prominent spinal canal at the lumbar levels. Axial spin-echo T1-weighted images (C, D, E) through the pelvis and sacrum showing the malformed S1 segment of the sacrum. A bony rib arises from it, and there is presence of a malformed joint between the rib and sacrum. The rib extends into the subcutaneous tissues overlying the left gluteal region.

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