Reduction of neuromelanin-positive nigral volume in patients with MSA, PSP and CBD

Diseases presenting extrapyramidal symptoms are accompanied by nigral cell loss. In the previous study, we demonstrated the reduction of the neuromelanin-positive volume of substantia nigra (SN) pars compacta (SNc) in patients with Parkinson's disease (PD) using 3-Tesla MRI. In the present study we investigated the neuromelanin-positive SNc volume in patients with the other parkinsonian disorders including multiple system atrophy (MSA), progressive supranuclear palsy (PSP) and corticobasal degeneration (CBD) and compared the results with those with PD, spinocerebellar ataxia (SCA) and controls.

Axial T1-weighted (T1W) images were obtained with a 3-Tesla MRI scanner. The border of the neuromelanin-positive region of the SNc was traced manually on these images with a pentablet pointing device and the SNc volume was calculated. The SNc volumes of 28 patients with MSA, 11 patients with PSP and 10 patients with CBD were compared with those of 80 patients with PD, 9 patients with SCA and 54 patients who had suffered mild acute ischemic stroke as controls. The mean volumes for the left and right SN were used for statistical analyses.

The volumes of the neuromelanin-positive SNc region in patients with MSA, PSP and CBD, but not SCA were reduced to the same extent as PD patients compared with controls.

Reduced volume of the neuromelanin-positive SNc region of patients with MSA, PSP and CBD was detected by neuromelanin MR imaging. Volumetric evaluation of neuromelanin MR imaging may provide a biomarker of nigral degeneration in patients with MSA, PSP and CBD as in patients with PD.