Open spina bifida
What is it?
Open Spina bifida is a congenital defect occurring in less than 1/1000 fetuses. It is caused by incomplete closure of one or more vertebrae with failure of neural canal to close with exposition of the spinal cord and meninges. The defect can involve few centimeters or a large portion of the spine. This pathology involves motor and functional disabilities such as loss of mobility of the lower limbs, difficulty in controlling the sphincters and other neurological complications. Diabetes mellitus and antiepilectic drugs are common risk factors. Risk of chomosomal abnormalities (mainly trisomy 18) and single gene disorders is rather rare in isolated forms.
Which are the symptoms?
Pregnant patients with fetal anomalies generally do not refer specific symptomps. The clinical picture is detected at prenatal ultrasound. Fetal and neonatal symptomps include central nervous system abnormalisies such as ventriculomegaly or hydrocephalus, macrocephaly and loss of motor function in the lower limbs.
- caudal displacement of the brain stem and obliteration of cisterna magna (Arnold Chiari II malformation)
- frontal bone scallopping (lemon sign)
- posterior fossa abnormalities
- curvature of the cerebellar haemispheres (banana sign)
How is it diagnosed?
Diagnosis of all fetal malformations is based upon fetal ultrasound assessment. Diagnosis of open spina bifida can be challenging in the first trimester in which period it can be suspected by abnormal measurements of posterior fossa spaces (diameter of the brain stem is increased, the distance between the brain stem and the occipital bone is decreased and the ratio of the brain stem to BSOB is >1.0). In the second trimester the diagnosis can be carried out in most cases accurately due to frontal bone scalloping (lemon sign), and obliteration of the cisterna magna with either an undetectable cerebellum or abnormal anterior curvature of the cerebellar hemispheres (banana sign). A variable degree of ventricular enlargement is present in virtually all cases of open spina bifida at birth, and in about 70% of cases at the mid-trimester. The diagnostic path includes detailed ultrasound scan with neurosonography, fetal cardiac scanning to exclude associated cardiac defects, amniocentesis to exclude associated chomosomal or genetic conditions and fetale magnatic resonance imaging to describe all subtle details of the neuroanatomy.
How is it treated?
It is debated whether prenatally diagnosed open fetal spina bifida requires or not delivery with cesarean section in order to prevent infection of the defect with subsequent infection of the central nervous system (meningitis or encephalitis). The classic treatment is carried out at birth with repair of the neural defect in order to restore the neuroanatomy (closure of the layers of the defect: neural tissue, myofacial tissue and skin). In utero closure of spina bifida (fetal surgery), reduces the need for postnatal shunt placement to treat hydrocephalus, it improves motor function and may improve urologic function as compared to neonatal surgical treatment.
Where do we treat it?
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