Occult spinal dysraphism
Overview
A rare disorder characterized by progressive neurological deterioration due to compression of the spinal cord in the spine.
Symptoms
* Defective neural tube closing * Lower spine lesion * Lower spine hair patch * Lower spine dimple * Lower spine fatty tumor
Causes
Normally, about 20 days after conception, the embryo develops a neural groove in the dorsal ectoderm. This groove rapidly deepens, and the two edges fuse to form the neural tube. By about day 23, this tube is completely closed except for an opening at each end. Theoretically, if the posterior portion of this neural tube fails to close by the 4th week of gestation, or if it closes but then splits open from a cause such as an abnormal increase in CSF later in the first trimester, a spinal defect results. Viruses, radiation, and other environmental factors may be responsible for such defects. However, spinal cord defects occur more often in offspring of women who have previously had children with similar defects, so genetic factors may also be responsible.
Diagnosis
Meningocele and myelomeningocele are obvious on examination; transillumination of the protruding sac can sometimes distinguish between them. (In meningocele, it typically transilluminates; in myelomeningocele, it doesn’t.) In myelomeningocele, a pinprick examination of the legs and trunk shows the level of sensory and motor involvement; skull X-rays, cephalic measurements, and a computed tomography scan demonstrate associated hydrocephalus. Other appropriate laboratory tests in patients with myelomeningocele include urinalysis, urine cultures, and tests for renal function starting in the neonatal period and continuing at regular intervals. Although amniocentesis can detect only open defects, such as myelomeningocele and meningocele, this procedure is recommended for all pregnant women who have previously had children with spinal cord defects; these women are at an increased risk for having children with similar defects. If these defects are present, amniocentesis shows increased alpha-fetoprotein levels by 14 weeks’gestation. Ultrasonography can also detect or confirm the presence and extent of neural tube defects.
Treatment
Spina bifida occulta usually requires no treatment. Treatment of meningocele consists of surgical closure of the protruding sac and continual assessment of growth and development. Treatment of myelomeningocele requires repair of the sac and supportive measures to promote independence and prevent further complications. Surgery doesn’t reverse neurologic deficits. A shunt may be needed to relieve associated hydrocephalus. If the patient has a severe spinal defect, short- and long-term treatment will require a team approach, including a neurosurgeon, orthopedist, urologist, nurse, social worker, occupational and physical therapists, and parents.