Spina Bifida (Spinal Dysraphism)
Spina bifida is a birth defect that occurs when the spine and spinal cord don't form properly. It's a type of neural tube defect. Normally, the neural tube forms early in pregnancy and it closes by the 28th day after conception. In babies with spina bifida, a portion of the neural tube doesn't close or develop properly, causing defects in the spinal cord and in the bones of the spine.Spina bifida can range from mild to severe, depending on the type of defect, size, location and complications. When necessary, early treatment for spina bifida involves surgery.
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Types
Spina bifida occulta
It's the mildest and most common type. Spina bifida occulta results in a small separation or gap in one or more of the bones of the spine (vertebrae).
Myelomeningocele
Also known as open spina bifida, myelomeningocele is the most severe type. The spinal canal is open along several vertebrae in the lower or middle back. The membranes and spinal nerves push through this opening at birth, forming a sac on the baby's back, typically exposing tissues and nerves. This makes the baby prone to life-threatening infections and may also cause paralysis and bladder and bowel dysfunction. Myelomeningocele is also associated with Arnold–Chiari malformation, necessitating a VP shunt placement.
Lipomyelomeningocele
This is one of the forms of closed spinal dysraphism. This usually present as a subcutaneous fatty mass just above the intergluteal cleft. However, some lipomyelomeningoceles may occur at other locations along the spinal canal.Lipomyelomeningocele may be clinically detectable as a subcutaneous fatty mass above the intergluteal crease.
Split cord malformations (SCM)
These are a form of spinal dysraphism in which the spinal cord itself is split into two hemicords. In type 1 SCM, the two hemicords are contained within two separate dural sleeves, often separated by a bony or cartilaginous septum. In type 2 SCM, both hemicords are contained within the same dural sleeve. The signs and symptoms of diastematomyelia may appear at any time of life, although the diagnosis is usually made in childhood. Cutaneous lesion, such as a hairy patch, dimple, Hemangioma, subcutaneous mass, Lipoma or Teratoma over the affected area of the spine is found in more than half of cases. The symptoms are weakness in the legs; low back pain; scoliosis; and incontinence. The surgical procedure required for the effective treatment of diastematomyelia includes decompression (surgery) of neural elements and removal of bony spur.
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Signs and symptoms of spina bifida vary by type and severity, and also between individuals.
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Spina bifida occulta. Typically there aren't any signs or symptoms because the spinal nerves aren't involved. Sometimes there may be skinchanges above the spinal defect, including an abnormal tuft of hair, or a small dimple or birthmark.
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In this severe type of spinabifida:The spinal canal remains open along several vertebrae in the lower or middle back. There is a swelling over back which contains nervous tissue. The baby can have weakness in lower limbs, bowel and bladder weakness,enlarged head due to hydrocephalus.
Causes and risk factors
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Folate deficiency. .
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Family history of neural tube defects
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Some medicationssuch as valproic acid
Diagnosis
Open spina bifida can usually be detected during pregnancy by fetal ultrasound. Increased levels of maternal serum alpha-fetoprotein (MSAFP) and amniocentesis of the mother's amniotic fluid (to test for alpha-fetoprotein and acetylcholinesterase). MRI brain and Spine is done to see site , structures involved ,severity and the associated brain anomalies.
Treatment
Standard treatment is surgery after delivery. This surgery aims to prevent further damage of the nervous tissue and to prevent infection and improve cosmosis. Pediatric neurosurgeons operate to close the opening on the back. In addition, a shunt may be put in brain to provide a continuous drain for the excess cerebrospinal fluid produced in the brain.
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