How do neurological and psychiatric signs and symptoms which are indicative of lewy body disease appear in apparent idiopathic rem sleep behavior disorder? – A descriptive study in the clinical setting

Abstract

Introduction There has been accumulating evidence that idiopathic RBD (iRBD) could be pre-motor or pre-dementing state of Levy body disease (LBD) (Parkinson’s disease (PD) and dementia with Lewy bodies). Since the transition from apparent iRBD to full-blown LBD is considered gradual development, various symptoms and signs could appear in this process. This observational study outlines when and how neurological and psychiatric signs and symptoms appeared in our patients with apparent iRBD. Materials and methods We retrospectively reviewed the sleep clinic records of consecutive 19 polysomnographically confirmed iRBD patients who made the first consultation from December 2005 to December 2009 with successful continual follow-up period (once per 1–3 months) up to June 2013. One patient who had end-stage renal disease under hemodialysis was excluded. 18 patients (15 men and 3 women, 66.4 ± 6.5 years of age at the first clinic visit, 71.7 ± 6.6 at the last clinic visit) were analyzed. 16 out of the18 patients underwent myocardial 123I-MIBG scintigraphy within two months from the first clinic visit, the result of which was taken into consideration whether it helps to predict the later development into LBD. Results The follow-up duration was 5.2 ± 1.2 years (range 3.5–7.5). The onset age of iRBD was 59.8 ± 6.9 years old and the duration from the onset to the first clinic visit was 6.6 ± 4.7 years (range 2–19), therefore, our patients have been suffering from RBD for 11.8 ± 5.3 years (range 6.5–26). Seven out of 18 patients (38.9%) showed muscle rigidity at the 7.8 ± 4.6 years from the onset of iRBD, and 2 of them fulfilled the British Brain Bank Criteria of PD at 4.2 years and 1 year respectively after the appearance of rigidity. About the remaining 5 patients with muscle rigidity, 4 of them also showed other symptoms (temporary depressive episodes in 2, mild cognitive impairment in 1, and episodic decreased activity [bedridden all day] continuing a few weeks in 1. All of the 7 patients with rigidity had showed decreased 123I-MIBG uptake. One patient is overall anxious with the past depressive episode (after the onset of RBD), and one started to experience visual hallucination at night which was clearly differentiated from RBD behaviors. Eight out of 18 patients (44.4%) still remained as apparent iRBD at 12.0 ± 4.0 years after the onset of iRBD, however, 7 patients of this group had 123I-MIBG scintigraphy and all but one had showed decreased uptake. The last one patient revealed to be possible multiple system atrophy, of whom 123I-MIBG uptake was within normal limits. In this woman, mild cerebellar signs appeared at the 3.6 years from the onset of iRBD and it took another 2.3 years to have this diagnosis. Conclusion Our results strongly support that iRBD is a predictor of LBD, but neurological and psychiatric signs and symptoms in iRBD which are indicative of LBD seem to appear in a long time span with various severities and combinations. It is still difficult to expect when and what will be overt in the daily clinical settings. Acknowledgement We thank Keiichi Marumoto and Youko Uozumi for their technical support for performing PSG.