Clinical correlation of striatal 1H MRS changes in Huntington's disease

To study the clinical significance of metabolic alterations as measured in vivo with proton MRS in the striatum of patients with Huntington's disease (HD).

Localized, single-voxel MRS was performed on the basal ganglia of 10 HD patients (4 presymptomatic gene carriers and 6 akinetic patients) and 5 age-matched healthy individuals. Metabolite quantification was performed by referring the areas of the respective spectral peaks to that of water in the analyzed voxel. The spectroscopic findings were correlated with motor and cognitive performance in several specific tests and with the length of the CAG repeat expansion normalized for age.

N-acetylaspartate (NAA) and creatine were reduced markedly in both groups of patients, particularly in the advanced group (approximately 60%), but the decrease was also significant in presymptomatic patients (approximately 30%) whose motor and cognitive performances were within the normal range. Both metabolites correlated highly with the motor score of the Unified Huntington's Disease Rating Scale and with computed measurements of saccadic and tapping speed. Creatine reduction was also well correlated with performance in cognitive timed tasks and with the length of CAG expansion (r = -0.81).

The creatine signal appears to be an interesting marker for progression in HD and could be useful in assessing therapeutic outcome, particularly during the initial stages when most clinical indices are still within the normal range.