Glutamate in cerebral tissue of asphyxiated neonates during the first weekof life demonstrated in vivo using proton magnetic resonance spectroscopy

We tested the hypothesis that glutamate (Glx) levels as demonstrated by pro ton magnetic resonance spectroscopy (H-1-MRS) are elevated in brain tissue of neonates with severe hypoxic-ischemic encephalopathy (HIE). Studies were performed in 26 neonates (median gestational age 40.5 weeks, range 36.7-42 .4 weeks; median birth weight 3,360 g, range 2,180-4,200 g). The median pos tnatal age at the time of testing was 2.5 days (range 1-7 days). HIE was sc ored according to Sarnat as grade I (n = 4), grade II (n = 15) or grade III (n = 7). Results for neonates with mild to moderate HIE (group I)were comp ared to those with severe HIE (group 2). After magnetic resonance imaging,H -1-MRS was performed in a single volume of interest including the basal gan glia. An echo time of 31 ms was used. After curve-fitting procedures, peak area ratios of different brain metabolites were calculated. The median tota l Girl N-acetylaspartate ratio was 1.21 (range 0.64-3.25) in group 1 versus 1.55 (range 1.10-2.75) in group 2 (p = 0.035). The median total Girl choli ne ratio was 1.33 (range 0.71-2.52) in group 1 versus 2.14 (range 1.21-3.55 ) in group 2 (p = 0.019). We concluded that during the first days of life, Glx was elevated in the basal ganglia of neonates with severe HIE. Copyrigh t (C) 2001 S. Karser AG. Basel.