Background: Hyposmia and isolated REM sleep behavior disorder are well-established features of prodromal Parkinson's disease (PD).Objectives: The objective of the present study was to evaluate whether taste loss (reported in PD and possibly suggesting brain stem involvement) is present at the isolated REM sleep behavior disorder stage. Methods: We assessed taste function using the Taste Strip Test (evaluating 4 concentrations of bitter, sweet, sour, and salty) in 44 participants with isolated REM sleep behavior disorder, 19 with PD, and 29 controls. All participants underwent video-polysomnography, standardized questionnaires, and clinical examination, including olfactory assessment.Results: Participants with isolated REM sleep behavior disorder and PD had lower taste scores than controls. There was no difference between isolated REM sleep behavior disorder and PD cohorts, nor was there any correlation between taste and olfaction, age, disease duration, cognition, or autonomic function. Conclusion:This study demonstrates for the first time the presence of taste impairment in isolated REM sleep behavior disorder that is independent of olfactory dysfunction and comparable to participants with PD.

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Study objectives To evaluate sleep, sleepiness and excessive need for sleep in patients with craniopharyngioma (a suprasellar tumor which can affect sleep-wake systems). Methods A retrospective study of all adult craniopharyngioma patients referred to the sleep clinic, who received a sleep interview, nocturnal polysomnography, multiple sleep latency tests (MSLT) and 18-hour bed rest polysomnography. Their sleep measurements were compared with those of age- and sex-matched healthy controls. Results Of 54 patients screened with craniopharyngioma, 42 were analyzed, 80% of whom complained of excessive daytime sleepiness. Sleep testing revealed that 6 (14.3%) of them had secondary narcolepsy (including one with cataplexy), and 11 (26.2%) had central hypersomnia associated with a medical disorder. Compared with controls, patients were more frequently obese, had a shorter mean sleep latency on MSLT and slept longer on the first night. There was a non-significant trend for patients with (vs. without) narcolepsy and hypersomnia to be younger, to have a higher body mass index, to be more likely to have received radiation therapy and to have more severe damage to the hypothalamus after surgery. Treatment with stimulants (modafinil, pitolisant and methylphenidate) was beneficial in 9/10 patients. Conclusion Nearly half of the patients with craniopharyngioma and sleep disorders have a central disorder of hypersomnolence (narcolepsy and hypersomnia), which should be investigated and lead to considerations beyond sleep apnea syndrome in these obese patients.