Quantitative proton magnetic resonance spectroscopy of the subcortical white matter in motor neuron disease

BACKGROUND: Using proton magnetic resonance spectroscopy, the authors have previously demonstrated a reduction in the N-acetyl aspartate/(creatine and phosphocreatine) (NAA/(Cr+PCr)) ratio in the motor region in bulbar-onset MND patients, attributed to neuronal loss or dysfunction leading to a reduction in NAA. We have expanded this analysis to evaluate absolute concentrations of NAA, (Cr+PCr) and choline-containing compounds (Cho) in the subcortical white matter in the motor region in 16 MND patients (8 with bulbar onset and 8 with limb onset) and 8 healthy, age-matched controls. METHODS: Single voxel 1 H-MRS was performed using a PRESS localization sequence. Metabolite concentrations were determined using the water signal as an internal standard. RESULTS: We found no differences in the concentrations of NAA ([NAA]), (Cr+PCr) ([Cr+PCr]) or Cho ([Cho]) in the motor region on comparing the total MND group and controls (P>0.3). No difference was found in [NAA] in the bulbar-onset group compared with the limb-onset group (P=0.70), but [Cr+PCr] was significantly higher in the bulbar-onset group (P=0.04). CONCLUSIONS: Our results suggest that [Cr+PCr] may be affected by the pathological process in MND, and this should be considered in the interpretation of metabolite peak area ratios. The elevated (Cr+PCr) may represent gliosis in the subcortical white matter in the motor cortex region. (ALS 2000; 1:123–129)