A clinical role for [I-123] MIBG myocardial scintigraphy in the distinction between dementia of the Alzheimer's-type and dementia with Lewy bodies

Objective-Scintigraphy with [I-123]metaiodobenzyl guanidine ([I-123]MIBG) e nables the quantification of postganglionic sympathetic cardiac innervation . Recently, myocardial [I-123]MIBG scintigraphy has been found to be useful in distinguishing Parkinson's disease, a Lewy body disease, from other aki netic rigid syndromes. Some patients initially diagnosed with dementia of t he Alzheimer's type (DAT) are discovered to have an alternative disease suc h as dementia with Lewy bodies (DLB), despite the application of stringent diagnostic criteria. In the present study, examinations were performed to c larify the usefulness of myocardial [I-123]MIBG scintigraphy in improving t he differential diagnosis between patients with DLB and DAT. Methods-Fourteen patients with DLB and 14 patients with DAT underwent scint igraphy with [I-123]MIBG, combined with orthostatic tests and cardiac exami nations. Results-In all patients with DLB, the heart to mediastinum (H/M) ratio of M IBG uptake was pathologically impaired in both early and delayed images, in dependently of the duration of disease and autonomic failure. All patients with DAT had successful MIBG uptake in the heart regardless of duration of disease and autonomic failure. Orthostatic hypotension was seen in four pat ients with DAT and 13 patients with DLB. Conclusions-[I-123]MIBG myocardial scintigraphy might detect early disturba nces of the sympathetic nervous system in DLB and might provide useful diag nostic information to discriminate DLB from DAT. The distinction between DL B and DAT may be improved by greater emphasis on cardiac sympathetic distur bances.