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Magnetic resonance imaging in progressive supranuclear palsy and other parkinsonian disorders
M Savoiardo1, F Girotti, L Strada
1Department of Neuroradiology, Istituto Nazionale Neurologico C. Besta, Milano, Italy.
Abstract:
High field intensity MRI may demonstrate signal abnormalities consistent with deposits of iron or other paramagnetic substances in several extrapyramidal disorders. Hallervorden-Spatz disease was the only disorder widely known to have iron deposits in the pallidum, that are now easily demonstrated in vivo by MRI. However, lower field intensity MRI may also demonstrate characteristic findings. In progressive supranuclear palsy, definite atrophy of the midbrain and of the region around the third ventricle is seen in slightly more than half of the cases. Minimal signal abnormalities are sometimes seen in the periaqueductal region, but MRI studies remain of little help in establishing the diagnosis of the disease. Asymmetric atrophy in the parietal regions is seen in corticobasal degeneration, as expected from pathological studies. Minimal alterations may be seen in the substantia nigra in Parkinson's disease. The most interesting MRI findings are observed in multiple system atrophies. Variable abnormal signal intensities, depending on the field intensity, are visible in the putamen in striatonigral degeneration and in Shy-Drager syndrome; in this latter condition the abnormalities are due to its striatonigral degeneration component. Atrophy of the pons, middle cerebellar peduncles, and cerebellum, and signal abnormalities in a characteristic distribution are visible in olivopontocerebellar atrophy. A combination of these posterior fossa abnormalities and putaminal alterations may confirm the involvement of the cerebellar and extrapyramidal systems in multiple system atrophies.
Insights
Magnetic Resonance Imaging (MRI) reveals signal abnormalities in extrapyramidal disorders, aiding in the diagnosis of conditions like Hallervorden-Spatz disease and multiple system atrophies.
Area of Science:
- Neurology
- Radiology
- Neuroimaging
Background:
- Extrapyramidal disorders often involve the basal ganglia and related structures.
- Iron deposition and atrophy are common pathological findings in these conditions.
- Magnetic Resonance Imaging (MRI) is a key tool for in vivo visualization of brain structures.
Purpose of the Study:
- To review the utility of MRI in diagnosing various extrapyramidal disorders.
- To correlate MRI findings with pathological hallmarks such as iron deposition and atrophy.
- To highlight specific MRI patterns associated with different neurodegenerative conditions.
Main Methods:
- Review of MRI findings in patients with Hallervorden-Spatz disease, progressive supranuclear palsy, corticobasal degeneration, Parkinson's disease, and multiple system atrophies.
- Correlation of imaging findings with known pathological features.
- Analysis of signal abnormalities and structural changes at different MRI field intensities.
Main Results:
- High-field MRI detects iron deposits in Hallervorden-Spatz disease pallidum.
- Progressive supranuclear palsy shows midbrain and third ventricle atrophy; MRI is less diagnostic.
- Corticobasal degeneration exhibits parietal atrophy; Parkinson's disease shows minimal substantia nigra changes.
- Multiple system atrophies demonstrate variable putaminal signal abnormalities and posterior fossa changes (pons, cerebellum).
Conclusions:
- MRI, particularly high-field intensity, is valuable for detecting iron in Hallervorden-Spatz disease.
- Specific MRI patterns aid in diagnosing multiple system atrophies by identifying putaminal and posterior fossa abnormalities.
- While MRI shows changes in other disorders, its diagnostic utility varies, with some conditions like progressive supranuclear palsy being less clearly defined by imaging alone.