We present a 61-year-old male patient with progressive dementia. A brain SPECT 
with Tc-99m-bicisate was performed for confirmation of clinically suspected 
Alzheimer-dementia. At the time of the SPECT-investigation marked apraxia and 
aphasia besides severe dementia were present. Electrophysiological as well as 
anatomical neuroimaging findings showed non-diagnostic alterations. SPECT 
revealed distinct perfusion defects, which made Alzheimer Dementia unlikely. The 
further course of the patient was determined by rapidly progressive 
deterioration with development of akinetic mutism. Thereafter, increased levels 
of neuron-specific enolase as well as 14-3-3 proteins were found in the 
cerebro-spinal fluid (CSF). The patient finally died with signs of cerebral 
decortication. Due to the clinical course and the CSF-findings the patient's 
final diagnosis was Creutzfeldt-Jakob-disease, nevertheless no autopsy was 
performed. The presented case report underscores the clinical utility of 
perfusion brain SPECT in the differential diagnosis of dementias.