Diagnostic delay and its causes in narcolepsy type 1 in japan : with special emphasis on cataplexy

Introduction Although narcolepsy type 1 is characterized by the pathognomonic symptom of cataplexy, it has been reported that there is long diagnostic delay in various countries. However, the causes of this delay have not been studied enough except for European counties. Japan is in a unique position in that all the people have public medical insurance coverage that allows them to have unlimited direct access to any medical specialists, therefore, once the patients experienced cataplexy, theoretically they could consult their symptom to sleep specialists with no financial burden. Under this condition, this study aims at characterizing the diagnostic delay and its causes in patients with narcolepsy type 1, and investigating whether cataplexy contributes to the accelerating the diagnostic process. Methods This retrospective study dealt with consecutive 45 patients (20 men/ 25 women) with narcolepsy type 1, whose diagnosis was made from April 2006 to September 2022 based on the PSG/MSLT criteria of the International Classification of Sleep Disorders, 3rd edition. We performed the chart review to retrieve demographic and clinical information, and the diagnostic process including the stage before coming to our sleep clinic. Results The diagnostic delay was 13.7±11.9 years (range 0.5-47 years, median 9.0 years). Cataplexy was the first manifestation in 9 out of 45 (20.0%), and excessive daytime sleepiness (EDS) and cataplexy occurred almost at the same time in 11(24.4%) patients. 24 (53.3%) patients considered cataplexy disturbing and/or of pathological nature, but for the remaining 21 patients, cataplexy was a kind of habit until EDS became problematic for their daily life. Seven (15.6%) patients had been diagnosed as having epilepsy, and the first medical contact of 4 patients was emergency room visit due to cataplexy leading to the diagnoses of hyperventilation syndrome, transient ischemic attack, and consciousness loss attack of unknown origin. Conclusion There was substantial diagnostic delay in patients with narcolepsy type 1, and cataplexy did not seem to be properly evaluated in Japan. Support (if any)