Narcolepsy with cataplexy patients stricken with chronic pain
MedWire News: Patients who have narcolepsy with cataplexy (NC) experience significantly more chronic pain than the general population, say European researchers who found physicians underestimated pain and its impact on quality of life (QoL).
It is thought that deficiency in hypocretin, which may play a role in nociceptive processing, is associated with the development of NC. Nevertheless, there have been no studies of pain in NC patients, aside from those reporting higher headache frequencies than among controls.
Yves Dauvilliers, from Hôpital Gui de Chauliac in Montpellier, France, and colleagues therefore used face-to-face interviews and questionnaires to assess the presence and frequency of pain, narcolepsy symptoms, and QoL in 67 patients with NC, 67 age- and gender-matched healthy controls, and each patient's physician and partner/friend, from four European countries.
Pain was reported significantly more frequently by NC patients than controls, with 32.8% of NC patients and 17.9% of controls reporting pain at least monthly and 27.3% and 6.0%, respectively, reporting pain at least daily.
The reporting of pain at least monthly was well matched between patients and partners/friends, at 32.8% and 29.9%, respectively. However, physicians significantly underestimated pain, reporting it in only 10.5% of cases.
Patients and their partners/friends also had well-matched responses on the impact of chronic pain on the patient's QoL, at a score of 7.27 and 6.59, respectively, on a 10-point weighting scale. Again, physicians significantly underestimated the impact of pain on QoL, at a score of 2.32. Interestingly, the patients' perception of the impact of chronic pain on QoL was greater than that seen in controls, who had a score of 4.33.
There were marked variations between patients and controls on the location of chronic pain, with just 9.0% of NC patients complaining of headache, compared with 25.0% of controls, the team notes in the journal Sleep Medicine. Most patients and controls reported pain in the neck or back, but nearly a third of patients reported pain in the lower leg/calf, compared with none of the controls.
Regression analysis indicated that the main determinants of pain in NC were mood disorder and sleep quantity, with 14.7% of the percentage variance accounted for by mood disorders, 6.9% by sleep quantity, and 22.4% by mood disorders plus sleep quantity. In turn, chronic pain had a significant impact on sleep quantity, depression, and QoL.
"Our study is the first investigation of pain in NC showing its presence in one-third of patients resulting in a significant impact on QoL compared with controls," says the team. "The frequency and impact of pain is significantly underestimated by physicians. The findings call for improved attention in the assessment and treatment of pain in NC patients."
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By Liam Davenport