Abnormal control of ventilation in adolescents with myelodysplasia.

Infants with myelomeningocele have abnormalities in ventilatory control. To determine whether these persist into later life, we studied 14 patients with myelomeningocele and Arnold-Chiari malformation (age 18.0 +/- 0.8 (SE) years), and compared them with 14 control subjects (age 24.0 +/- 0.9 years). Pulmonary function and ventilatory muscle strength did not differ between patients with myelomeningocele and control subjects. Hypercapnic ventilatory responses were significantly lower in the group with myelomeningocele (1.98 L/min/mm Hg) compared with control values (3.33 L/min/mm Hg; p less than 0.01). Hypoxic ventilatory responses (-1.4 L/min/%oxygen saturation of hemoglobin in arterial blood) were not significantly different from control values (-2.14 L/min/%oxygen saturation). In control subjects the hypercapnic and hypoxic ventilatory responses were highly correlated with each other within subjects (r = 0.84; p less than 0.002) but not in those with myelomeningocele (r = 0.34; not significant). We concluded that adolescents and young adults with myelomeningocele have abnormalities in control of ventilation during sleep and wakefulness. We speculate that the Arnold-Chiari malformation interferes with central chemosensitivity (hypercapnic ventilatory response) and central integration of chemoreceptor output.