Presentation
Cognitive decline with visual hallucinations.
Patient Data
MRI demonstrates only mild to moderate generalized cerebral volume loss. Mild chronic small vessel ischemic change. The right anteroinferior part of the caudate head has a region of focal gliosis and volume loss with dystrophic calcification. The brainstem and cerebellum are unremarkable.
Conclusion:
Features are non-specific with no features particularly suggestive of a neurodegenerative condition. The appearances are, however, compatible with the clinical impression of dementia with Lewy bodies.
Significant reduction in metabolism affecting the posterior parietal lobes and occipital cortices bilaterally is noted. Mild reduction of metabolism is also seen affecting the right precuneus but not the posterior cingulate. Metabolism in the basal ganglia is preserved.
Conclusion:
Findings are consistent with Lewy body dementia.
SPECT studies of the brain were performed following 99mTc ECD infusion with mental stimulation. Neurostat data analysis was applied.
These studies are of poor quality technically but do show reduced perfusion predominantly to the posterior aspect of both cerebral hemispheres cortices sparing the posterior cingulate and precuneus regions. There is only mild reduction of perfusion to the mid and anterior cerebral cortices.
Perfusion to the basal ganglia and brainstem and cerebellum appear normal.
Conclusion:
The findings are highly consistent with the diagnosis of Lewy's dementia showing posterior cerebral cortical hypoperfusion with retained posterior cingulate/precuneus perfusion.
Case Discussion
The diagnosis of dementia with Lewy Bodies is difficult if not impossible on the basis of MRI alone. Nuclear medicine studies (both FDG-PET and SPECT) are far more helpful in demonstrating characteristic occipitoparietal hypometabolism with sparing of the posterior cingulate - known as the cingulate island sign.
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