We describe a 22 years old caucasian male who received 7 years ago a diagnosis of Narcolepsy type 1 (NT1) in our Sleep Medicine unit in Lugano, corroborated by undetectable CSF orexin levels, positive HLA DQB1*0602 allele, and generalized cataplexy.
The first video-polysomnography (PSG) showed a low sleep efficiency, and a normal breathing pattern. A brain magnetic resonance (MRI) with contrast was normal. A combined treatment with Sodium Oxybate (SO), and Venlafaxine was started with a long period of benefit.
After 7 years, a progressively relapse of daytime sleepiness appeared. In the meantime, the BMI had increased from 22.8 kg/m2 to 25 kg/m2. Repeated PSG disclosed a new severe central sleep apnea (CSA) with Cheyne-Stokes breathing (CSB). A full neurological and cardiological evaluation including blood examinations and cerebral MRI, were normal. The patient denied the use of opioids or other substances. With the hypothesis of sodium oxybate (SO)-induced CSA-CSB , we decided for its gradual withdrawal.
A new PSG, performed 8 weeks after complete withdrawal of SO did not show any improvement of CSB. We hypothesized that the breathing disorder was linked to a Narcolepsy-related hypothalamic dysfunction, although the patient had no nocturnal hypercapnia and had no endocrinological abnormalities indicative of a dysfunction of the hypothalamo/hypophysis axis.
A successful treatment with auto-Servo-Ventilation was established by manual titration under PSG monitoring, and showed to be well tolerated and effective on the CSA and sleepiness. Clinical course was favourable.
We report the first case of overlap between NT1 and idiopathic CSA-CSB described in the literature.
In our opinion, CSA-CSB could be a consequence of NT1, or could even be considered a specific dimension of NT1 itself, based on the wide influence of orexine on breathing regulation. Further controlled studies are needed to test this hypothesis.

Case report by Prof. Dr med Silvia Miano
Sleep Medicine Unit, Neurocenter of Southern
Switzerland, Ospedale Civico, Lugano
Faculty of Biomedical Sciences, Università della
Svizzera Italiana, Lugano, Switzerland

In courtesy of the patient, who kindly agreed to the publication of the case