How should we deal with the possible development into lewy body diseases from idiopathic REM sleep behavior disorder in the real world clinical practice?

It has been well established that apparent idiopathic REM sleep behavior disorder (iRBD) evolves mostly into Lewy body diseases (LBD) (Parkinson’s disease (PD) and dementia with Lewy bodies ). Therefore, in clinical practice we have to keep a watch on its early signs and symptoms as well as to treat REM sleep related behaviors. This study describes our experience in following up iRBD patients in the daily clinical setting, some of whom actually developed additional neurological and psychiatric signs and symptoms. We retrospectively reviewed the sleep clinic records of consecutive 30 polysomnographically confirmed iRBD patients who made the first consultation in the four year time period from December 2005. Four patients who were lost within one year after the first consultation were excluded. 26 patients (21 men and 5 women, 67.3} 5.9 years of age at the first clinic visit) were analyzed whose follow-up duration was 4.6}1.6 years (range 1–7.5 years). We found out that we had informed the possibility of future development in other neurodegenerative diseases in 24 patients (92.3%) after they completed diagnostic polysomnography and other investigations to rule out comorbid neurological diseases when they were discharged from hospital. However, the way of transmission was modified for each patient and mostly about PD, which later caused some confusion in the patients who developed psychiatric rather than motor symptoms. Two patients were not informed about this possibility because they were full of anxiety at that time. 16 out of 26 patients (61.5%) always came to the clinic alone and their RBD severity under treatment did not differ from that of the remaining 10 patients who were accompanied by their family members. Solo visit generally did not interfere with our comprehension of the actual state of RBD by the use of questionnaire for RBD severity index, nor with the assessment of motor function, but gradual intermittent intrusion of visual hallucination was difficult to be perceived until family members came up. 18 out of 26 patients (69.2%) continued to pay a regular visit (once per 1–3 months) up to the present (June 2013), and what symptoms and signs appeared to them chronologically will be presented in the other paper of our group. In respect of development into LBD from iRBD, what we should focus on includes close communication with the patients as well as family members. It should be warranted to seek for good predictors for the future LBD in tandem with developing educational materials addressing this issue. We thank Kei-Ichi Marumoto and Yoko Uozumi for their technical support for performing PSG.