title: Challenges in diagnosing narcolepsy without cataplexy: a consensus statement.
abstract: BACKGROUND
  Diagnosing narcolepsy without cataplexy is often a challenge as the symptoms are nonspecific, current diagnostic tests are limited, and there are no useful biomarkers. In this report, we review the clinical and physiological aspects of narcolepsy without cataplexy, the limitations of available diagnostic procedures, and the differential diagnoses, and we propose an approach for more accurate diagnosis of narcolepsy without cataplexy.
  
  
  METHODS
  A group of clinician-scientists experienced in narcolepsy reviewed the literature and convened to discuss current diagnostic tools, and to map out directions for research that should lead to a better understanding and more accurate diagnosis of narcolepsy without cataplexy.
  
  
  CONCLUSIONS
  To aid in the identification of narcolepsy without cataplexy, we review key indicators of narcolepsy and present a diagnostic algorithm. A detailed clinical history is mainly helpful to rule out other possible causes of chronic sleepiness. The multiple sleep latency test remains the most important measure, and prior sleep deprivation, shift work, or circadian disorders should be excluded by actigraphy or sleep logs. A short REM sleep latency (≤ 15 minutes) on polysomnography can aid in the diagnosis of narcolepsy without cataplexy, although sensitivity is low. Finally, measurement of hypocretin levels can helpful, as levels are low to intermediate in 10% to 30% of narcolepsy without cataplexy patients.
authors.affiliation: Department of Neurology, University Hospital Zurich, Zurich, Switzerland ; Department of Neurology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA.
authors.forename: Christian R
authors.initials: CR
authors.lastname: Baumann
authors.affiliation: Stanford Center for Sleep Sciences, Stanford University, Stanford, CA.
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Mignot
authors.affiliation: Department of Neurology, Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: Gert Jan
authors.initials: GJ
authors.lastname: Lammers
authors.affiliation: Department of Neurology, Radboud University Medical Center, Nijmegen, The Netherlands.
authors.forename: Sebastiaan
authors.initials: S
authors.lastname: Overeem
authors.affiliation: Hôpital Pitié-Salpêtrière, Pierre and Marie Curie University, Paris, France.
authors.forename: Isabelle
authors.initials: I
authors.lastname: Arnulf
authors.affiliation: Department of Neurology and Program in Sleep, Emory University School of Medicine, Atlanta.
authors.forename: David
authors.initials: D
authors.lastname: Rye
authors.affiliation: National Reference Network for Orphan Diseases (Narcolepsy), Department of Neurology, Hôpital Gui de Chauliac, CHU Montpellier, INSERM U1061, France.
authors.forename: Yves
authors.initials: Y
authors.lastname: Dauvilliers
authors.affiliation: Tokyo Metropolitan Institute of Sleep Science, Tokyo, Japan.
authors.forename: Makoto
authors.initials: M
authors.lastname: Honda
authors.affiliation: Sleep Medicine Children's National Med Center, Washington, DC.
authors.forename: Judith A
authors.initials: JA
authors.lastname: Owens
authors.affiliation: Department of Biomedical and Neuromotor Neurological Sciences, University of Bologna, and IRCCS Istituto delle Scienze Neurologiche, Bologna, Italy.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Plazzi
authors.affiliation: Department of Neurology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA.
authors.forename: Thomas E
authors.initials: TE
authors.lastname: Scammell
mesh_terms: D056044:Actigraphy; D000328:Adult; D015415:Biomarkers / Q000032:analysis; D035843:Biomedical Research / Q000639:trends; D002648:Child; D032921:Consensus; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000134:cerebrospinal fluid; D008297:Male; D009290:Narcolepsy / Q000134:cerebrospinal fluid / Q000175:diagnosis* / Q000235:genetics / Q000503:physiopathology; D009479:Neuropeptides / Q000134:cerebrospinal fluid; D000068797:Orexins; D017286:Polysomnography; D057566:Self Report; D012892:Sleep Deprivation / Q000175:diagnosis; D012894:Sleep Stages / Q000502:physiology
chemical_list: D015415:Biomarkers; D047908:Intracellular Signaling Peptides and Proteins; D009479:Neuropeptides; D000068797:Orexins
keywords: insomnia; multiple sleep latency test; narcolepsy; polysomnography