Author Affiliations: Department of Neurology, Mayo Clinic, Center for Sleep Medicine, Rochester, Minnesota.
We appreciate Tezer et al describing an additional patient with RBD associated with neuronal VGKC complex autoimmunity. Their report confirms the difficulties of recording nocturnal REM sleep in patients manifesting profound insomnia. In our full series, we were able to confirm polysomnographically the presence of RBD in 4 of 8 patients in whom it was suspected clinically, 1 only after a second PSG.1 We agree that extending a PSG into the morning might increase the probability of obtaining REM sleep. However, Tezer et al state that phasic electromyographic activity was noted in their patient during the short period of REM sleep recorded at night. Together with the history of dream-enactment behaviors, this fulfills formal criteria for RBD2 and recording the abnormal behaviors was not essential for diagnosis.
Cornelius JR, Pittock SJ, McKeon A, Lennon VA, Aston PA, Josephs KA, Tippmann-Peikert M, Silber MH. Daytime Polysomnography Recording in LIG1 -Related Limbic Encephalitis—Reply. Arch Neurol. 2012;69(1):145-146. doi:10.1001/archneur.69.1.146