Insights into REM Sleep Behavior Disorder Pathophysiology in Brainstem-Predominant Lewy Body Disease
Background and purpose—Rapid eye movement (REM) sleep behavior disorder (RBD) is a
parasomnia reflecting changes in the brain, but which specific neuronal networks are involved in
human RBD pathogenesis has not yet been determined. To date, only one case of idiopathic RBD
has undergone autopsy, in which “incidental Lewy body disease” was found. Due to the severe
neuronal loss and gliosis in the substantia nigra (SN) and locus ceruleus (LC) in this case,
degeneration of brainstem monoaminergic neurons was postulated as the underlying substrate for
RBD. Additional cases of idiopathic RBD with neuropathologic examination may help clarify which
key brainstem structures are involved.
Patient and methods—Case report with neuropathologic analysis.
Results—A man with polysomnographically proven RBD (onset age 57 years), but no other
neurologic signs or symptoms, underwent neuropathologic examination upon his death at age 72.
Histopathologic analysis showed Lewy body disease, but no significant neuronal loss or gliosis was
present in the SN or LC.
Conclusions—This case represents another example of Lewy body disease associated with RBD.
The minimal degenerative changes in the SN and LC call into question the role of these nuclei in
RBD, at least in our case. We suggest additional cases of idiopathic RBD undergo neuropathologic
analyses to better delineate the neurologic substrate of this intriguing parasomnia.