Changes in putamen N-acetylaspartate and choline ratios in untreated and levodopa-treated Parkinson's disease: A proton magnetic resonance spectroscopy study

Abstract

We have carried out single-voxel proton magnetic resonance spectroscopy centered on the putamen both ipsilateral and contralateral to the worst affected side in nine subjects with drug naive idiopathic Parkinson's disease (IPD); seven chronically levodopa-treated dyskinetic IPD subjects; and 11 age-matched healthy controls. Measurements of N-acetylaspartate (NAA)/choline (Cho), NAA/(Creatine + Phosphocreatine) (Cr + PCr), and Cho/(Cr + PCr) were made. We found a significant reduction in NAA/Cho ratios from the putamen contralateral to the most affected side in the drugnaive group (p = 0.009), but not the levodopa-treated IPD groups compared with controls. There were no significant differences in NAA/(Cr + PCr) or Cho/(Cr + PCr) ratios. In untreated IPD, reduced putaminal NAA/Cho ratios may reflect loss of nigrostriatal dopamine terminals or alternatively indicate a functional abnormality of striatal putaminal neurons, such as membrane dysfunction due to striatal deafferentation. This study suggests that NAA/Cho ratios may be affected by L-dopa therapy and this may provide a reversible marker of neuronal dysfunction in the striatum.

Neuroimaging in Parkinson's Disease

“…Proton magnetic resonance spectroscopy of the striatum has provided variable results in PD itself, but this technique may be useful for differentiating between PD and atypical parkinsonian syndromes, such as multiple system atrophy or progressive supranuclear palsy [13][14][15][16], and there may also be changes in the posterior cingulate [17] and presupplementary motor area cortex [18]. Phosphorus spectroscopy may also reveal changes that appear to differ between PD and multiple system atrophy [19,20].…”

Applications of neural network analyses to in vivo 1H magnetic resonance spectroscopy of Parkinson disease patients

“…Furthermore, MRS in carefully selected, early idiopathic PD patients exhibited a consistent, reproducible, and significant reduction in NAA/Cho ratio (attributed most likely to NAA changes) (9). It was also discussed that NAA/Cho ratios might be affected by dopaminergic therapy and did not correlate with asymmetry or severity of disease (9). In a study of 15 patients, Choe, et al (25) concluded that significant differences existed between symptomatic and asymptomatic sides, on the basis of NAA/Cr ratios.…”

“…In a study by Ellis,et al (9), reduced NAA/Cho ratios were observed in drug-naïve idiopathic PD patients. Furthermore, MRS in carefully selected, early idiopathic PD patients exhibited a consistent, reproducible, and significant reduction in NAA/Cho ratio (attributed most likely to NAA changes) (9). It was also discussed that NAA/Cho ratios might be affected by dopaminergic therapy and did not correlate with asymmetry or severity of disease (9).…”

“…In vivo 1 H MRS has been used to investigate brain metabolism in PD by several groups (5)(6)(7)(8)(9). In vivo 1 H MRS data are most often analyzed by conventional statistical methods.…”

Magnetic resonance spectroscopy imaging of medulla oblongata and substantia nigra in idiopathic Parkinson's disease

“…This result was supported by earlier findings. 11 Additionally, Ellis and colleagues, 12 reported no metabolite differences between controls and PD patients receiving treatment but found a significant reduction in NAA/Cr ratio among the untreated PD patients. In contrast, some studies have reported no differences between PD and control subjects in either metabolite ratios or concentrations of NAA, Cr, and Cho.…”