Neural tube defect

Mrs. Abhilasha SahaAssociate professor- Paediatric NursingNational medical college, Birgunj, Nepal

Spina bifida is a birth defect that involves the incomplete development of the spinal cord or its coverings characterized by defective closure of the bony encasement of the spinal cord through which the spinal cord and meninges may or may not protrude.

The term spina bifida comes from Latin and literally means "split" or "open" spine.

Spine bifida also called spinal dysraphia, refers to a malformation of the spine in which the posterior portion of the laminae of the vertebrae fails to close.

It occurs in 1 per 1,000 live births.

Most common developmental defect of the CNS.

Types of Spina Bifida

The two forms of spina bifida are Spina bifida occulta and Spina bifida manifesta.

Spina bifida occulta is the mildest form of spina bifida (occulta means hidden). Most children with this type of defect never have any health problems, and the spinal cord is often unaffected.

Spina bifida manifesta includes two types of spina bifida:

Meningocele, Myelomeningocele/ meningomyelocele.

Meningocele involves the meninges, the membranes responsible for covering and protecting the brain and spinal cord. If the meninges push through the hole in the vertebrae (the small, ring-like bones that make up the spinal column), the sac is called a meningocele.

Myelomeningocele is the most severe form of spina bifida. It occurs when the meninges push through the hole in the back, and the spinal cord also pushes though. Most babies who are born with this type of spina bifida also have hydrocephalus, an accumulation of fluid in and around the brain.

Occurs four to five times more frequently than meningocele

Causes Unknown etiology

Genetic predisposition triggered by environmental factors- drugs ( valproic acid ) during pregnency

Women and having one child affected

Causes Arrest in the orderly formation of the vertebral

arches and spinal cord between 4 _ 6th wk) of pregnancy when the two sides of the embryo's spine fail to join together, leaving an open area.

Incomplete closure of neural tube during 4th wk of embryonic life.

The neural tube forms adequately, then rupture

Maternal folic acid deficiency has been linked to spina bifida, and researchers believe that many cases can be prevented if women of childbearing age consume 0.4 milligrams (400 micrograms) of folic acid every day, and continue to take it throughout the first trimester.

Symptoms of Spina Bifida Babies who are born with spina bifida occulta

often have no outward signs or symptoms. The spinal cord does not protrude through the skin, although a patch of hair, a birthmark, or a dimple may be present on the skin over the lower spine.

Meningocele Fluid-filled sac visible on the back. The sac is

often covered by a thin layer of skin and can be as small as a grape or as large as a grapefruit.

Seldom evidence of weakness of the legs or lack of sphincter control

Myelomeningocele A sac-like mass that bulges from the back,

but a layer of skin may not always cover it. In some cases, the nerves of the spinal cord may be exposed. A baby who also has hydrocephalus will have an enlarged head, the result of excess fluid and pressure inside the skull.

Bladder dysfunction Fecal incontinence and constipation Developmental disabilities- average

intellectual

Diagnostic evaluation Prenatal detection- The alpha-fetoprotein

(AFP) test, performed between the 16th and 18th weeks of pregnancy, measures how much AFP, which the fetus produces, has passed in the mother's bloodstream. If the amount is high, the test is repeated because in many cases, high AFP readings are false. If the second result is high, other tests will be done to double-check and confirm the diagnosis.

CT scan and MRI Ultrasound Amniocentesis- A needle is inserted through

the mother's belly and into the uterus to collect fluid that is tested for AFP.

Clinical manifestations

Treatment Children with spina bifida occulta seldom

need treatment.

In cases of spina bifida manifesta, treatment depends on the type of spina bifida and its severity.

Babies with meningocele usually have an operation during infancy in which doctors push the meninges back and close the hole in the vertebrae. Many will have no other health problems later unless there is nerve tissue involved with the sac.

Babies with myelomeningocele need more immediate attention and often have surgery within the first 1 to 2 days after birth. During this first surgery, doctors push the spine back into the vertebrae and close the hole to prevent infection and protect the spine.

Procedure – laminectomy and closure of the open lesion or removal of sac

A baby who also has hydrocephalus will need an operation to place a shunt in the brain. The shunt is a thin tube that helps to relieve pressure on the brain by draining and diverting extra fluid.

Nursing management Risk for impaired skin integrity r/t impaired

motor and sensory function Risk for infection r/t contamination of the

myelomeningocele site Altered urinary elimination r/t neurological

deficits Altered cerebral tissue perfusion r/t

hydrocephalus Fear r/t neurological disorder and surgery

Ineffective thermoregulation following surgery Bowel incontinence/ constipation r/t the

abnormal development of and damage to the spinal cord

Body image disturbance r/t child’s appearance, difficulty in locomotion, lack of control over excretory functions