Abnormalities in control of ventilation in newborn infants with myelomeningocele.
OBJECTIVE
The objective of this study was to assess respiratory responses of newborn infants with myelomeningocele through pneumograms and carbon dioxide challenge, and to evaluate the possibility of predicting which patients with myelomeningocele acquired respiratory symptoms related to the Arnold-Chiari deformity and brain-stem dysfunction.


METHODS
All surviving infants with spina bifida who were born at the University of Iowa Hospitals and Clinics (UIHC) or were transferred there on the first day of life between January 1987 and January 1991 were assessed with a pneumogram and CO2 challenge once they were medically stable, and were followed for a mean of 30 months (10 to 53 months).


RESULTS
Thirty patients met the inclusion criteria for this study; four died before being studied. Of the 26 remaining patients, 12 were born at the UIHC and 14 were transferred to the UIHC on the first day of life. Of the 26 infants studied, 12 (46%) had abnormalities on the pneumogram, including 2 with significant periodic breathing and 10 with episodes of desaturation below 87%. Of the 26 infants studied, 4 had no detectable response to an increasing fraction of CO2 in inspired air on the CO2 challenge and 12 had an increase in exhaled minute ventilation per increase in the alveolar fraction of CO2 in exhaled air more than 2 SD below the mean. Only 10 patients (38.5%) had normal ventilatory responses to the increasing fraction of CO2 in inspired air. On follow-up, only one study patient had symptoms related to Arnold-Chiari deformity and brain-stem dysfunction (bilateral vocal cord paralysis). His neonatal CO2 challenge results and his pneumogram were normal.


CONCLUSIONS
We conclude that these two tests are not useful in predicting which patients will have symptoms related to Arnold-Chiari deformity. Specificity for the pneumogram and the CO2 challenge was 0.52 and 0.36, respectively. Sensitivity was zero for both tests, although this result is limited by the low incidence of symptomatic Arnold-Chiari deformity in this sample. As previous investigators have found, a significant number of patients with meningomyelocele had abnormal ventilatory patterns. These ventilatory abnormalities indicate that even in the absence of severe symptoms, the control of the ventilatory response is somewhat impaired in many patients with meningomyelocele. This alteration in ventilatory control is probably related to abnormalities in the development of the brain stem.
Petersen
M C
MC
Department of Pediatrics, University of Iowa, Iowa City, USA.
Wolraich
M
M
Sherbondy
A
A
Wagener
J
J
D001139:Arnold-Chiari Malformation / Q000209:etiology*; D002245:Carbon Dioxide; D002675:Child, Preschool; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008591:Meningomyelocele / Q000150:complications / Q000503:physiopathology*; D012119:Respiration; D016135:Spinal Dysraphism / Q000150:complications / Q000503:physiopathology
D002245:Carbon Dioxide