High pain frequency in narcolepsy with cataplexy

Background: Narcolepsy with cataplexy (NC) is caused by the loss of hypocretin neurons. Recent studies highlighted the roles for hypocretins in the modulation of nociceptive transmission. The aims of the present multicenter case-control study were to look at the frequency of pain in NC and to study the determinants and impact of pain on narcolepsy symptoms and quality of life (QoL). Methods: Sixty-seven adult patients with NC, together with their physician, partner/friend, and sex- and age-matched normal controls underwent a face-to-face interview and completed questionnaires on the presence and frequency of pain, narcolepsy symptoms and QoL (Short-Form 36-item score, Functional Outcomes of Sleep Questionnaire, Medical Outcomes Study, Fatigue Severity Scale, and Beck Depression Inventory). Results: One-third (32.8%) of NC patients experienced pain at least monthly, with a significantly higher frequency and impact than controls (17.9%) and independent of the patients' narcolepsy medication. The reporting of pain was well matched between patients and partners/friends but significant differences were observed between patients and physicians, with physicians significantly underestimating its frequency and impact. The location of chronic pain varies within subjects with differences between NC and controls. We pinpointed that sleep quantity and depression were determinants for pain, and chronic pain had significant impact on sleep quantity, depression and QoL in NC. Conclusion: We report, for the first time, evidence that chronic pain is significantly more common and disabling in NC compared to the general population. The findings call for improved attention to assessment and treatment of pain in the follow-up of NC. (C) 2011 Elsevier B.V. All rights reserved.