Cerebral metabolism within 18 hours of birth asphyxia: A proton magnetic resonance spectroscopy study

Proton magnetic resonance spectroscopy (H-1 MRS) was performed within 18 h of birth (median 13, range 4-18 h) on 16 term infants with clinical features of birth asphyxia. Ten infants with no evidence of birth asphyxia were studied as controls at 5-18 (median 8) h after birth. To detect delayed impairments in cerebral energy metabolism, 15 infants suspected of asphyxia underwent P-31 MRS at 33-106 (median 62) h of age. Choline, creatine, and N-acetylaspartate (NAA) were detected in spectra located to the basal ganglia in all infants. Lactate was detected in 15 of the 16 infants suspected of asphyxia, but in only 4 of the 10 controls (p < 0.05, chi(2)). Glutamine and glutamate (Glx) was detected in 11 infants suspected of asphyxia and in three controls, but this difference was not significant at the 5% level. The spectra revealed no other significant differences between asphyxiated infants and controls. In the asphyxiated infants, there was a negative correlation between the ratio of lactate to creatine in the first 18 h of life and phosphocreatine/inorganic phosphate (PCr/P-i) at 33-106 h (p < 0.001). Five severely asphyxiated infants had PCr/P-i < 0.75 (median 0.53, range 0.14-0.65), indicating a poor neurodevelopmental prognosis, and a further infant died before PCr/P-i could be measured. Ten infants had PCr/P-i > 0.75 (1.03, 0.76-1.49). Median lactate/creatine was 1.47 (range 0.67-3.81) in the six severely affected subjects, 0.38 (0-1.51) in the latter group, and 0 (0-0.6) in controls (p < 0.0005), Kruskall-Wallis). These results suggest that, after birth asphyxia, cerebral energy metabolism is abnormal during the period when P-31 MRS characteristically gives normal results. 1H MRS might be of value in predicting which infants are likely to suffer a decline in cerebral high energy phosphate concentrations and subsequent neurodevelopment impairment.