Narcolepsy is considered a homogeneous clinical entity when excessive daytime sleepiness and cataplexy are present. Cataplexy is a polymerphic symptom that can be very mild and is thus subjectively defined. The Multiple Sleep Latency Test (MSLT) is widely used as a diagnostic test for narcolepsy. A short mean sleep latency and multiple sleep onset REM periods (SOREMPs) are typically observed in narcoleptic patients. The discovery of a tight association of narcolepsy with HLA class II antigens offers a unique opportunity to explore the respective value of the MSLT or of the presence of clear-cut cataplexy in defining an etiologically homogeneous group of narcoleptic patients. In this study, we carried out HLA typing for DR15(DR2) and DQB1*0602 in 188 narcoleptic patients with cataplexy in three ethnic groups (24 Asians, 61 Blacks, and 163 Caucasians). These results confirm the importance of DQB1*0602 typing rather than DR15 (DR2) typing in Black narcoleptic patients and demonstrate that the presence of clear-cut cataplexy is a better predictor for DQB1*0602 positivity than the presence of abnormal MSLT results.
Two unusual cases of large aneurysms, one located in the native right coronary artery and the other in a saphenous vein graft, are reported. Their size and mode of presentation as asymptomatic paracardiac masses on chest x- ray films make them unique. It is proposed that these entities be considered as part of the differential diagnosis of paracardiac masses.