Olfactory dysfunction in narcolepsy with and without cataplexy.
BACKGROUND
Not only patients in whom REM behavior disorder (RBD) is associated with narcolepsy, but also those with narcolepsy alone are reported to have olfactory dysfunction. We investigated if hyposmia is specific to narcolepsy with cataplexy (N-C) or if narcolepsy without cataplexy (NwC) is also associated with olfactory dysfunction.


METHODS
We studied olfactory function in two groups of patients: N-C group (n=66, 26 men and 40 women; mean age 41+/-18 years), and NwC group (n=17, 7 men and 10 women; mean age 46+/-20 years). As a control group we used published normative data for particular smell tests.


RESULTS
Both patients with N-C and patients suffering from NwC had a significantly higher olfactory threshold (N-C group, p<0.0001; NwC group, p<0.0001) and impaired odor identification (N-C group, p<0.0001; NwC group, p<0.0001). Our results show for the first time that narcolepsy without cataplexy, where the majority of cases have normal CSF hypocretin levels, is associated with olfactory dysfunction.


CONCLUSIONS
It appears that also a partial loss of hypothalamic hypocretin neurons without a clear CSF level decrease can affect smell projection.
Department of Neurology, 1st Faculty of Medicine, Charles University, Prague, Czech Republic. vankjit@seznam.cz
Jitka
J
Buskova
Jan
J
Klaschka
Karel
K
Sonka
Sona
S
Nevsimalova
D000328:Adult; D000368:Aged; D002385:Cataplexy / Q000175:diagnosis* / Q000503:physiopathology; D005260:Female; D006801:Humans; D007031:Hypothalamus / Q000503:physiopathology; D047908:Intracellular Signaling Peptides and Proteins / Q000134:cerebrospinal fluid; D008297:Male; D008875:Middle Aged; D009290:Narcolepsy / Q000175:diagnosis* / Q000503:physiopathology; D009474:Neurons / Q000502:physiology; D009479:Neuropeptides / Q000134:cerebrospinal fluid; D009812:Odorants; D000857:Olfaction Disorders / Q000175:diagnosis* / Q000503:physiopathology; D000068797:Orexins; D010626:Phenylethyl Alcohol; D012684:Sensory Thresholds / Q000502:physiology; D055815:Young Adult
D047908:Intracellular Signaling Peptides and Proteins; D009479:Neuropeptides; D000068797:Orexins; D010626:Phenylethyl Alcohol