Presentation
Long standing dementia - nursing home. Now fall.
Patient Data
Marked volume loss is seen involving both hippocampi and parahippocampal gyri, especially anteriorly, with relative sparing of the rest of the temporal lobe.
No intracranial hemorrhage. Periventricular and deep white matter hypodensity in keeping with moderate small vessel ischemia. No evidence of acute infarction. Ventricles are enlarged but are unchanged in size compared to the previous CT with a maximum biventricular distance of 4.6cm. No calvarial fracture or suspicious bony abnormality seen. Imaged paranasal sinuses and mastoid air cells are clear.
Features are consistent with the clinical impression of Alzheimer disease.
Case Discussion
The degree of atrophy in advanced dementia can be striking. The preferential involvement of the hippocampi and parahippocampal gyri, with relative sparing of the rest of the temporal lobe is fairly typical of Alzheimer disease or limbic-predominant age-related TDP-43 encephalopathy (LATE).
Unfortunately, these two entities can not only mimic each other clinically and radiologically but can also co-exist. An amyloid PET can be useful but currently, a definite antemortem diagnosis cannot be reached.