myelomeningocele

myelomeningocele /my·elo·me·nin·go·cele/ (-mĕ-ning´go-sēl) hernial protrusion of the spinal cord and its meninges through a defect in the vertebral arch.

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my·e·lo·me·nin·go·cele (m-l-m-nngg-sl)

n.

Protrusion of the spinal membranes and spinal cord through a defect in the vertebral column. Also called meningomyelocele.

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myelomeningocele

[mī′əlō′məning′gōsēl]

Etymology: Gk, myelos + menix, membrane, kele, hernia

a developmental defect of the central nervous system in which a hernial sac containing a portion of the spinal cord, its meninges, and cerebrospinal fluid protrudes through a congenital cleft in the vertebral column. The condition is caused primarily by failure of the neural tube to close during embryonic development, although in some instances it may result from the reopening of the tube as a result of an abnormal increase in cerebrospinal fluid pressure. Also called meningomyelocele, myelocele, myelocystocele, myelocystomeningocele. Compare meningocele. See also neural tube defect, spina bifida cystica.

observations The defect, which occurs in approximately 2 in every 1000 live births, is readily apparent and easily diagnosed at birth. Although the opening may be located at any point along the spinal column, the anomaly characteristically occurs in the lumbar, low thoracic, or sacral region and extends for three to six vertebral segments. The saclike structure may be covered with a thin layer of skin or with a fine membrane that can be easily ruptured, increasing the risk of meningeal infection. The severity of neurologic dysfunction is directly related to the amount of neural tissue involved, which can be roughly estimated by the degree of the transillumination of the mass. Usually the condition is accompanied by varying degrees of paralysis of the lower extremities; by musculoskeletal defects such as clubfoot, flexion and joint deformities, or hip dysplasia; and by anal and bladder sphincter dysfunction, which can lead to serious genitourinary disorders. Hydrocephalus, frequently related to the Arnold-Chiari malformation, is the most common anomaly associated with myelomeningocele and occurs in approximately 90% of the cases in which the spinal lesion is located in the lumbosacral region. In most cases, hydrocephalus is apparent at birth, although it may appear shortly afterward. Supplementary diagnostic procedures include x-ray examination of the spine, skull, and chest to determine the extent of the vertebral defect and the presence of other malformations in other organ systems; a computed tomographic scan of the brain to establish the ventricular size and the presence of any structural congenital anomalies; and laboratory examinations, especially urine analysis, culture, blood urea nitrogen evaluation, and creatinine clearance determination. Amniocentesis is recommended for all pregnant women who have had a child with a neural tube defect.

interventions Immediate surgical repair is essential if the defect is leaking cerebrospinal fluid. However, surgical intervention may not be appropriate if neurologic involvement is extreme, if the lesion is infected, or if associated problems, such as hydrocephalus, are severe. When surgical repair of the spinal defect is recommended, associated problems are managed by appropriate measures, including shunt procedures for correction of hydrocephalus; antibiotic therapy to reduce the incidence of meningitis, urinary tract infections, and pneumonia; casting, bracing, traction, and surgical techniques for correction of hip, knee, and foot deformities; and prevention and treatment of renal complications. Prognosis is determined by the severity of neurologic involvement and the number of associated anomalies. With proper care and long-term maintenance most children can survive and do well. Early death is usually caused by central nervous system infection or by hydrocephalus, whereas mortality in later childhood is caused by urinary tract infection, renal failure, complications from shunt therapy, or pulmonary disease.

nursing considerations Immediate care centers on the prevention of local infection and trauma by carefully handling and positioning the infant, applying sterile moist dressings to the membranous sac, avoiding fecal contamination and breakdown of sensitive skin areas, and maintaining warmth, proper nutrition, and adequate hydration and electrolyte balance. Gentle range-of-motion exercises are carried out to prevent or minimize hip and lower extremity deformity. An important function of the nurse is to involve the parents in the care of the infant as soon as possible and to teach them the essential procedures for adequate home care, including how to observe for signs of complications. The nurse also helps the parents in long-term management by planning activities appropriate to the developmental age and physical limitations of the child and by providing information for teaching all family members about the condition.

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myeloma (mī´lō´m),

n a neoplasm characterized by cells normally found in the bone marrow.

myeloma, multiple,

n a primary malignant neoplasm of bone marrow characterized by proliferation of cells resembling plasma cells. Circumscribed radiolucencies are seen within the bones, and Bence Jones protein is usually found in the urine.

Multiple myeloma.

myeloma, plasma cell,

n a malignant neoplasm characterized by plasma cells. Solitary lesions may appear as radiolucencies in the bone and are sometimes considered benign, although most authorities believe that even these lesions become multiple and terminate fatally.

myeloma, solitary plasma cell,

n an incompletely understood monostotic neoplasm of bone that is histologically identical with multiple myeloma. Laboratory findings, positive in multiple myeloma, are usually negative in solitary plasma cell myeloma. Although usually benign, solitary plasma cell myelomas may be malignant.

myelomeningocele

(mī´lōmning´gōsēl),
n a condition in which part of the spinal cord protrudes from between the bones of the vertebrae. The condition can result in paralysis.

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myelomeningocele

hernial protrusion of the spinal cord and its meninges through a defect in the vertebral column.

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myelomeningocele

Neonatology A common birth defect characterized by nonclosure of the vertebral and spinal canal, resulting in protrusion of spinal cord and covering meninges from the dorsal surface; spina bifida is a more generic term which includes any defect characterized by incomplete spinal closure; myelomeningocele accounts for ±75% of all spina bifida, affecting ±1/800 infants; most of the rest are spina bifida occulta–the vertebral arches don't close, the spinal cord and meninges are simply covered by skin, and meningoceles–in which the meninges protrude through the vertebral defect while the spinal cord remains in place Etiology Unknown; folic acid deficiency may play a part in neural tube defects; it has a familial tendency, possibly triggered by a viral infection or environmental factors–eg, radiation; protrusion of cord and meninges damages the spinal cord and nerve roots, compromising function at or below the defect; most defects are lower lumbar or sacral, as these regions are the last to close in the early embryo Clinical Partial or complete paralysis, loss of sensation, bladder or bowel control; the exposed cord is at risk for infection. See Hydrocephalus, Hip dislocation, Spina bifida, Syringomyelia.