Myelodysplasia in Childhood and Adolescence
Robert Wm. Blum MD, MPH, PhD1
Kathleen Pfaffinger PNP, PhD2
1 Professor and Director, Division of General Pediatrics and Adolescent Health
2 Psychologist, Group Health of Minnesota. This paper was written when Dr Pfaffinger was Psychology Fellow, Adolescent Health Program, University of Minnesota, Minneapolis, MN.
The Nature of the Condition
Myelomeningocele—also commonly referred to as meningomyelocele—is a defect of neural tube formation that is akin embryologically to anencephalus. The larger category, spina bifida, includes the benign condition of spina bifida occulta; myelodysplasia is inclusive of all neural tube anomalies. Myelomeningocele is the most common major congenital anomaly in the United States, having an incidence, until recently, of 4 per 1000 births (see Epidemiology).
Approximately 80% of all children born having myelomeningocele have associated hydrocephalus. Likewise, nearly all of these children are born having Arnold-Chiari (or Chiari II) malformation of the midbrain and upper spinal cord, which is associated with displacement of the inferior cerebellar vermis, caudal fourth ventricle, and medulla oblongata into the spinal canal. The Arnold-Chiari malformation may cause its own symptom complex, including lower cranial nerve dysfunction, sensory loss, and spasticity.
The extent of neurologic, urologic, and orthopedic involvement depends primarily on the level of the lesion (Table 1). Additionally, the work of Luthy et al strongly suggests that if the condition is diagnosed prenatally, infants delivered via cesarean section have significantly less paralysis at 2 years of age than do those who have comparable lesions and who are delivered vaginally.
Additional complicating factors and associated findings of myelomeningocele may include:
