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Related Concept Videos

Narcolepsy01:07

Narcolepsy

Narcolepsy is a chronic sleep disorder characterized by pervasive, uncontrolled sleepiness and other sleep disturbances. One of its hallmark symptoms is an abrupt transition to REM sleep upon falling asleep, which causes symptoms typically associated with this phase to occur unexpectedly during wakefulness. These include the following symptoms, which typically last from a minute or two to half an hour.
Sleep-Wake Cycles01:24

Sleep-Wake Cycles

Sleep is an essential physiological process vital to maintaining overall well-being. The reticular activating system (RAS), a network of neurons in the brainstem, regulates wakefulness and sleep. While it may seem passive, sleep consists of distinct cycles, each with its unique characteristics and functions. Two key sleep phases are non-rapid eye movement (NREM) and  rapid eye movement (REM).
NREM Sleep
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Olfactory Receptors: Location and Structure01:03

Olfactory Receptors: Location and Structure

The process of olfaction, also known as the sense of smell, is a sophisticated chemical response system. The specialized sensory neurons that facilitate this process, known as olfactory receptor neurons, are situated in an upper segment of the nasal cavity, known as the olfactory epithelium. Olfactory sensory neurons are bipolar, with their dendrites extending from the epithelium's apex into the mucus that lines the nasal cavity. Airborne molecules, when inhaled, traverse the olfactory...
Olfaction01:25

Olfaction

The sense of smell is achieved through the activities of the olfactory system. It starts when an airborne odorant enters the nasal cavity and reaches olfactory epithelium (OE). The OE is protected by a thin layer of mucus, which also serves the purpose of dissolving more complex compounds into simpler chemical odorants. The size of the OE and the density of sensory neurons varies among species; in humans, the OE is only about 9-10 cm2.
The olfactory receptors are embedded in the cilia of the...
Physiology of Smell and Olfactory Pathway01:20

Physiology of Smell and Olfactory Pathway

Humans detect odors with the help of specialized cells located in the upper part of the nasal cavity, called olfactory receptor neurons (ORNs). ORNs possess hair-like structures called cilia, which are receptive to sensations from the inhaled air. When an odorant molecule binds to a specific receptor on the cell of the cilia, it leads to a series of events that ultimately cause the ORN to send electrical signals to the olfactory bulb in the brain through the olfactory nerves.
The olfactory...
Sleep Apnea01:21

Sleep Apnea

Sleep apnea is a condition where breathing stops intermittently during sleep, often leading to significant health issues. Each episode can last from 10 to 20 seconds or more and is frequently accompanied by a brief arousal from sleep. This disturbance, largely unnoticed by the individual, can lead to severe daytime fatigue. Commonly, individuals seek help after being informed by their partners about loud snoring and noticeable breathing pauses during sleep.
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Olfactory Neurons Obtained through Nasal Biopsy Combined with Laser-Capture Microdissection: A Potential Approach to Study Treatment Response in Mental Disorders
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Olfactory dysfunction in narcolepsy with cataplexy.

Sophie Bayard1, Giuseppe Plazzi, Francesca Poli

  • 1Department of Neurology, Hôpital-Gui-de Chauliac, CHU Montpellier, National Reference Network for Narcolepsy, Inserm U888, France.

Sleep Medicine
|September 7, 2010
PubMed
Summary
This summary is machine-generated.

Narcolepsy-cataplexy (NC) is linked to olfactory dysfunction in a significant portion of patients. This study found that about a quarter of NC patients experience mild to moderate smell impairment.

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Area of Science:

  • Neuroscience
  • Sleep Medicine
  • Olfactory Research

Background:

  • Narcolepsy-cataplexy (NC) results from hypocretin neuron loss.
  • Hypocretin plays a role in olfactory function.
  • Previous studies on NC and olfactory dysfunction were limited by small sample sizes.

Purpose of the Study:

  • To investigate olfactory performance in a large cohort of narcolepsy-cataplexy patients.
  • To compare olfactory function in NC patients versus healthy controls.
  • To determine the prevalence and characteristics of olfactory dysfunction in NC.

Main Methods:

  • Recruited 130 NC patients from French and Italian sleep disorder centers.
  • Administered standardized olfactory tests: Sniffin' Sticks (France) and Brief Smell Identification (Italy).
  • Compared olfactory test scores between NC patients and 129 age- and gender-matched healthy controls.

Main Results:

  • Olfactory deficit was more prevalent in NC patients (23.8%) than controls (13.9%).
  • Significant olfactory identification deficits were noted in Italian NC patients.
  • NC patients showed lower discrimination and global olfactory performance on the Sniffin' Sticks test, with 6.4% experiencing moderate hyposmia and 22.2% mild hyposmia.

Conclusions:

  • Narcolepsy-cataplexy is associated with olfactory dysfunction in approximately 25% of patients.
  • The observed olfactory impairment is generally mild to moderate.
  • Factors like age at onset or disease severity did not significantly impact olfactory performance, except for tobacco smoking.