40.: Diagnosis in rapidly progressive dementia: Hopeless but not meaningless situation

This study aimed to illustrate the importance of making a diagnosis in a patient with rapidly progressive dementia. A 69-year-old man presented with ∼6 months history of visual and gait disturbances, involuntary jerks and tremor, mild cognitive impairment and grossly disturbed sleep resembling nocturnal seizures. Electroencephalogram revealed non-specific generalised slowing. MRI revealed age related changes only. Blood work was non-contributory. There was no evidence of malignancy or paraneoplastic limbic encephalitis based on antibody testing (including NMDA receptor antibodies and a positron emission tomography scan). Lumbar puncture revealed mildly elevated protein but was again non-contributory and 14-3-3 test was negative. The post mortem, performed with appropriate consent from family members, revealed macroscopic and microscopic changes consistent with fatal familial insomnia. As there was no family history, his case was considered to be sporadic, but confirmatory molecular testing is being performed at Australian Creutzfeldt-Jakob Disease Registry. Despite our current inability to intervene and alter the natural course of a rapidly dementing illness, it is important that these patients undergo rigorous work up pre-mortem and the need for a post mortem is discussed with the next of kin as in some cases, like this one, the diagnosis could have significant implications for other family members.