Anomaly Name: CAUDAL REGRESSION SYNDROM
Synonym - SIRENOMELIA - most severe form of CRS
Incidence: One in 20 000 - 100 000 births.
Diagnosis:
The caudal Aplasia - Dysplasia sequence ic caused by a partial or total absence of the distal part of the NEURAT TUBE. This results in anomalies of the lower limb and of the gastrointestinal & nrogenital tracts.
Mostly sporadic occurrence, genetically HETEROGENEOUSE.
Autosomal or X - chromosomal - dominant inheritance has RARELY been described.
Embryology:
The lower segment of the Spine Canal develop until 7 weeks after conception. Primary absence of this segment, rather than secondary regression of an alredy formed segment, is the most probable cause of the Caudal Regression Syndrom. It is not yet clear whether SIRENOMELIA represents the most severe form of Caudal Regression Syndrom or whether it is a distinct entity. An early insult to the developing lower Spinal Column results in Aplasia or Dyspepsia of the Sacrum.
Associated Anomalies:
Cardiac anomalies are common. In the case of SIRENOMELIA, Renal anomalies are further evident. HYDROCEPHALUS may also develop.
Prognosis:
This is similar to that w/ MYELOMENINGOCELE situated at a higher lumbar level. Impaired lower limb function & fecal and urinal incontinence is to be expected.
OB Management:
Further U/s scanning, including fetal ECHOCARDIOGRAPHY and KARYOTYPING. Maternal Diabetes should be excluded. If the pregnancy is continued, normal antenatal care should be provided. Breech presentation is common, and a Cesarean Section may be necessary if ther is severe fetal abdom -in cranial disproportion.
Procedure after birth: Multidisciplinary care at a perinatal center.
U.S.A.:
Absence of the Sacrum, Talipes,abnormal lumbar vertebrae, deformation of the pelvis, Hypoplasia of the Femur, Club Feet, contractures of the lower limbs, decreased movements of the lower limbs. In addition, the following anomalies may be detected: