[The diagnosis of neurodegenerative disorders based on clinical and pathological findings using an MRI approach]

Diffusion tensor imaging and voxel based morphometry are efficient in the diagnosis of neurodegenerative disorders, however, these technologies are available at a limited number of facilities. Thus, conventional MRI remains important in the diagnosis of neurodegenerative disorders. Dorsolateral putaminal hyperintensity (DPH) and hot cross bun sign discriminate Parkinson's disease from multiple system atrophy (MSA). However, differences in magnetic field strength and sequence affect the sensitivity of DPH, and mild DPH may be observed in normal elderly subjects. Patients with progressive supranuclear palsy (PSP) presenting Richardson's syndrome show midbrain tegmentum atrophy, but Parkinsonian PSP (PSP-P) and pure akinesia with gait freezing, which are other phenotypes of PSP, may not show especially during early course of illness. In patients with corticobasal degeneration (CBD), asymmetrical cerebral atrophy corresponding with corticobasal syndrome (CBS) may be a characteristic finding. However, at autopsy, CBS patients presenting asymmetrical cerebral atrophy have CBD as the underlying pathology in approximately 50% of PSP patients. The sensitivity and specificity of MRI for the diagnosis of MSA, PSP, and CBD is based generally on clinical diagnostic criteria. Diagnosis based on MRI has limitations, and, therefore, we should reconsider our diagnoses, particularly during the early course of illness.