MYELOMENINGOCELE

Myelomeningocele

Myelomeningocele

The care and treatment of an 8 month old male with myelomeningocele (MMC) continues to challenge health care providers and parents because of the multifaceted problems including hydrocephalus, the need for shunting, motor and cognitive impairments, urologic and bowel disorders, and social and emotional challenges. Hydrocephalus, shunting, and shunt malfunction are a primary focus of clinical follow-up. Infants will have an 80% to 85% risk of having hydrocephalus develop that necessitates placement of a cerebral spinal fluid shunt. (Soare 1977)Hydrocephalus may not be apparent at birth but shunting is usually required within the first week of life after lesion closure. Rintoul et al showed that lesion level significantly affected the incidence of shunting from a single center retrospective review of 297 patients with MMC with an overall shunt rate of 81% (100% thoracic, 88% lumbar, and 68% of sacral lesions). Preliminary data from 2 centers suggested fetal MMC closure might favorably influence the outcome of this disease. In each study, the incidence of shunting was reported to be lower after in utero surgical closure, due in part to reversal of cerebellar herniation that is a component of the Arnold-Chiari II malformation. (Mirzai 1998)

Children with MMC are at increased risk for cognitive impairments including nonverbal skills, arithmetic achievement, and visual-motor integration that become more evident with increasing age. Both shunt status and anatomic lesion level has been shown to affect cognitive functioning. The relationship between the degree of cognitive impairment and uncomplicated shunted hydrocephalus have been variable suggesting that the presence of hydrocephalus has a profound effect on cognitive function, whereas others found similar cognitive performance between unshunted and shunted patients when neither had a history of ventriculitis. (Iborra 2004) The relationship between shunt complications and cognitive outcome remain undefined, with studies suggesting an inverse relationship between number of shunt complications and intellectual deficits, whereas others found no such correlation.

Midgestation in utero closure of fetal MMC is presently under investigation in a prospective, randomized National Institute of Health (NIH)-sponsored clinical trial. However, such surgery has potentially serious maternal and fetal risks and exposes the fetus to combination anesthetic agents, alterations in amniotic fluid volume that may alter intraoperative placental blood flow, chronic exposure to tocolytic agents, and necessitates preterm delivery. (Jensen 1987) There are no data reported on neurodevelopmental and cognitive outcomes in children who have undergone in utero MMC closure. We therefore followed a select population of fetuses that underwent midgestation in utero MMC closure before the NIH-sponsored clinical trial and examined neurodevelopmental outcome.

Material and methods

From 1998 to 2002, 51 fetuses with prenatally diagnosed MMC underwent in utero fetal neurosurgical closure and have subsequently delivered. Fetal surgery selection criteria (Table I) and pregnancy outcome data have been previously described. This research was approved by The Children's Hospital of Philadelphia Institutional Review Board(Mapstone 1984).

Table I: Selection criteria for fetal MMC closure

• Less than 26 wks' gestational age.

• Confirmed normal karyotype.

• Absence of associated congenital anomalies.

• Maximum lateral ventricular diameter of <17 mm.

• Grade III (severe) Chiari II malformation.

• Normal leg movement and absence of talipes ...