Patients with idiopathic REM sleep behavior disorder follow-up - phenoconversion into parkinsonian syndrome and dementia
Abstract
Background and aim: Idiopathic REM sleep behavior disorder (iRBD) is regarded as the initial stage of neurodegenerative diseases, especially synucleinopathies. The aim of this study was to evaluate the phenoconversion into parkinsonian syndrome and dementia in patients diagnosed with iRBD.
Methods: This is a retrospective study comprising of patients diagnosed with iRBD prior to 2015 at the Centre for Sleep and Wake Disorders, Department of Neurology, First Faculty of Medicine, Charles University and General University Hospital in Prague. Conversion was explored from medical documentation of neurologically followed-up patients and structured interview, as well as using information provided by general practitioners.
We were able to assess the development in 34 of these patients ( 26 males, 8 females). Results: The median age of iRBD symptom onset was 62 (41- 83) years, the median age at iRBD diagnosis was 67 (46- 83) years and the median follow-up was 5 (1-14) years.
Eleven (32.4%) patients displayed symptoms indicating phenoconversion into the following subgroups: Parkinson's disease ( four patients), Lewy body dementia ( three patients), multiple system atrophy ( one patient) and dementia which was not further specified ( three patients). Four patients displaying mild extrapyramidal symptoms did not meet Parkinsonian syndrome criteria.
The ratio of patients who developed a defined neurodegenerative disease within 5 years from the iRBD symptom onset was 20.6% (95% CI 10.4- 36.8%). The median latency of phenoconversion patients with conversion was 5 (1- 27) years.
Conclusion: The iRBD phenoconversion in our patient population is similar to that of other studied cohorts, suggesting that also in the Central European predominantly Slavic population, iRBD can be considered as the initial stage of neurodegeneration with pathological alpha synuclein deposition