Exploration of cardiac sympathetic adrenergic nerve activity in narcolepsy

Abstract Objective To compare cardiac sympathetic adrenergic nerve activity in patients with narcolepsy type 1 (NT1) and controls using 123 I-MIBG myocardial scintigraphy, and to determine the clinical and neurophysiological variables associated with 123 I-MIBG scintigraphy results in NT1. Methods Fifty-six NT1 patients and 91 controls without neurological diseases underwent a cardiac scintigraphy. MIBG uptake was quantified by delayed heart/mediastinum (H/M) ratio. Clinical, neurophysiological and biological determinants of a low H/M were assessed in NT1. Results MIBG uptake did not differ between NT1 and controls in crude and adjusted associations. Five patients had low MIBG uptake ( Conclusion A direct measure of the heart adrenergic nerve activity revealed no sympathetic denervation in NT1. Significance Our results indicate normal cardiac sympathetic innervation in NT1. However, few patients with low MIBG uptake also presented CV comorbidities and REM sleep motor deregulation, potentially at high CV risk, requiring a careful follow-up.