1719 THE CO2 RESPONSE TEST (CO2RT) IN CHILDREN WITH MENINGOMYELOCELE

Abstract

Meningomyelocele is accompanied by the Chiari II malformation of the brainstem which can cause life-threatening symptoms. Since hypercapneic respiratory drive is a medullary function which can be measured, we performed 35CO2RT (δ minute ventilation/kg. % δ PACO2) on 31 patients (ages 1 day to 19 years) with meningomyelocele. Results were classified using published norms. 19 of 31 patients had an abnormal test. The mean age of those with an abnormal test (3.8 years), was less than that of those with a normal test (8.8 years), p <.01. Of the 19 patients with an abnormal CO2RT, 9 had or developed serious signs of brainstem dysfunction (7 had stridor, diminished gag or dysphagia; 2 had apnea with stridor; 1 had apnea alone; 1 had breath holding spells with anoxic seizures). Of the 12 patients with a normal CO2RT, 1 child had mild dysphagia (p <.05). Increased tone and decreased strength of the arms were equally frequent in both groups.4 patients had 2 CO2RTs each, 2 improved clinically and had an increase in the CO2RT; 2 worsened and had a decrease in the CO2RT. 6 patients had CO2RTs prior to posterior fossa decompression and laminectomy. The 3 requiring the operation for brainstem dysfunction had an abnormal CO2RT; the 3 with progressive arm weakness alone had a normal test.The CO2RT results correlate with clinical evidence of brainstem function in children with meningomyelocele and the Chiari II malformation.