Proton Magnetic Resonance Spectroscopy of Hydrocephalic Infants

Abstract

The authors present the first report evaluating neonates with chronic hydrocephalus using proton magnetic resonance spectroscopy (1H MRS). The goals of the study were (1) to determine absolute brain metabolite concentrations in premature infants and neonates with hydrocephalus and age-matched controls, (2) conduct an initial survey of potential biochemical abnormalities of the newborn hydrocephalic brain, and (3) determine whether 1H MRS can be used for outcome prediction in this population. Thirteen infants with chronic hydrocephalus were imaged with magnetic resonance imaging (MRI) and 1H MRS during an 18-month interval. Absolute metabolite concentrations were tabulated and compared with those of 26 age-matched controls. Metabolite abnormalities were evaluated for correlation with clinical outcome at last follow-up. Mean lactate (Lac), glutamine (Gln) and alanine (Ala) concentrations in hydrocephalic patients were significantly elevated. These metabolite elevations did not correlate significantly with outcome. There was no evidence of altered neuronal maturation in patients with congenital hydrocephalus. Two patients with dramatically reduced N-acetyl-aspartate and elevated Lac had poor neurologic outcome and were found to have neurologic disease that had not been identified with prior diagnostic tests. Premature infants and neonates with hydrocephalus have elevated Lac, Gln and Ala compared with age-matched controls. Further investigation and follow-up is required to assess the significance of these findings. In general, 1H MRS is of limited value in predicting outcome in infants with hydrocephalus. However, 1H MRS may be useful in identifying subsets of hydrocephalic neonates that, in fact, have severe neurologic disease and poor prognosis.