SPORADIC FATAL INSOMNIA IN A YOUNG MAN

OpenAlex İngilizce

Fatal insomnia (FI) is an extremely rare form of prion disease, which is usually due to a mutation in the prion protein gene (PRNP), but it may be seen even in rarer sporadic form (sFI). Due to its rarity it presents difficult diagnostic pitfalls for the clinician especially for sFI, for which the diagnosis of the reported handful of cases had usually been possible post-mortem. Here we report a very young case with sFI, whose diagnosis was possible belatedly with the help of distinctive sleep study and specific positron emission tomography (FDG-PET) findings. This 28-year-old man was first admitted in July 2015 with 3-month history of unsteady gait, slurred speech, daytime sleepiness, panic attack-like episodes. After an extensive diagnostic work-up, which focused especially on a possible autoimmune encephalitis, he was discharged with a diagnosis of psychogenic movement disorder, having found no objective clinical or laboratory finding. The patient returned and readmitted in December. This time he had a well-established pyramido-cerebellar syndrome, absent smooth-pursuit eye movements and pronounced daytime drowsiness. An FDG-PET revealed bilateral thalamic hypometabolism. A 24-hour long polysomnography disclosed findings compatible with agrypnia excitata. His CSF total tau level was moderately elevated (382pg/ml). PRNP genetic analysis was pending at the date of submission of this abstract. To our knowledge, excluding one adolescent boy whose disease onset was at 13 years of age, this case is the youngest so far reported. Although extremely rare, this diagnosis must not be overlooked in a patient with chronic insomnia and subacute progressive cerebellar syndrome, when more likely and most often treatable causes like autoimmune encephalitides, such as Morvan's syndrome or NMDAR encephalitis are excluded after a meticulous work-up.