Narcolepsy is an important clinical manifestation of many sleep disorders, and serious cases can fall asleep regardless of time and place, which can have a great impact on the work and life of patients and even lead to accidents that endanger the safety of others and themselves. In recent years, it has been found that the incidence of traffic accidents related to drowsiness is comparable to that caused by drunk driving, but has not yet attracted attention. Clinical experience in China has shown that excessive sleepiness is one of the main reasons for patients to visit sleep centers. Accurate and comprehensive evaluation of the severity of narcolepsy, finding the causes of narcolepsy, selecting appropriate treatment plans, and systematically assessing the effects of treatment are important issues to be addressed in the clinical practice of sleep medicine.
Epidemiology
The population prevalence of narcolepsy ranged from 0.5% to 35.8% (Table 1), with most reports ranging from 5% to 15%, and the reasons for the wide variation were related to the population surveyed and the questionnaires used. The prevalence of drowsiness was higher among frequent shift workers, the elderly, adolescents, and females. In addition, with the accelerated pace of life and changes in lifestyle, the incidence of narcolepsy has increased. Although there are many causes of narcolepsy, sleep breathing disorder is the most important cause of daytime sleepiness in sleep centers in Europe and the United States (Table 1), accounting for 75%; episodic sleeping sickness is the next most important cause, accounting for 20%, and the remaining 5% include leg movement syndrome. Sleep breathing disorders, especially sleep apnea hypoventilation (OSAHS) and upper airway resistance syndrome, accounted for the first 80% of the patients treated in our hospital, while episodic sleeping sickness accounted for about 12%, and primary sleepiness and periodic leg movement syndrome could also be seen.
Table 1 Causes of daytime sleepiness
Internal causes External causes Biological rhythm disorders Other
Episodic sleep disorder Poor sleep habits Jet lag Depression
Periodic sleepiness Environmental factors Shift work Alcohol addiction
Primary narcolepsy Sleep deprivation Irregular sleep Parkinson’s disease
Post-traumatic drowsiness Sedative sleeping pills Delayed sleep phase
Legerdemain syndrome Alcohol consumption
SAHS
Evaluation of daytime sleepiness
Factors associated with daytime sleepiness include: length of sleep, quality of sleep, influence of circadian rhythms, medications and underlying diseases. After subjective and objective evaluations, together with detailed history taking, the severity of somnolence can be clarified, the cause of somnolence can be searched for and the effect of treatment can be initially assessed.
I History taking
History taking mainly includes medical history taking and comprehensive physical examination. When taking medical history, the following aspects should be noted. One, is the patient excessively sleepy during the day? Setting a specific environment, such as a meeting, a car ride, or a lecture can help to understand the patient’s daytime sleepiness. Many salivary patients often do not present to the clinic with excessive sleep, but complain of easy fatigue, low energy, memory loss, and depressed mood, etc., which should be distinguished. Second, is the excessive sleep complained by the patient an abnormal phenomenon? Individuals vary greatly in the amount of sleep they need, so you should ask the patient how long they sleep to keep their energy and mental clarity during the day. Some people have short sleep time but it does not affect their daytime work and life, so it may not be a pathological phenomenon. Third, the length of the illness, episodic or persistent. Fourth, how are the sleep habits? The main considerations are sleep duration, sleep-wake rhythm, work schedule, short daytime sleep, sleep environment, eating habits and medication history. V. What are the accompanying symptoms? It is helpful to know the concomitant symptoms of narcolepsy to clarify the etiology (Table 3). Since many pathologies in sleep are not conscious by the patient, their family members or spouse can often provide a more objective history, and their cooperation should be obtained; taking a history often requires the help of the patient’s family to complete. For example, for patients with suspected sleep apnea hypoventilation syndrome, family members can be asked: 1. Is the snoring audible in the next room? Is the snoring unevenly high and low? If necessary, simulate the patient’s snoring sound. 2, Does the patient have frequent intervals of breathing while sleeping? 3, Is the patient sleepy during the day, such as when watching TV, in meetings, or riding in the car. Systematic history taking is best accomplished with the aid of a more reasonably designed questionnaire. Physical examination often has no characteristic positive findings, and those with severe narcolepsy are unresponsive and have poor memory at the time of consultation, and can even doze off during the consultation. In addition to the routine examination, the upper airway and neurological system should be the focus of examination in patients with narcolepsy.
Table 2 Clinical differential diagnosis of daytime narcolepsy
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1, Is there a transient decompensation (Cataplexy) such as falling, kneeling, etc. occurring? If yes, it may be episodic sleepiness
2, Do you snore during sleep? Is the snoring unevenly high and low? If yes, it may be combined with sleep apnea
3, Is there any leg kicking movement during sleep? If yes, leg movement syndrome should be suspected
4, Is there any history of taking excitatory or sedative drugs? If yes, consider drug effects or addiction
5, Do you sleep significantly longer on weekends than usual? If so, sleep deprivation should be suspected.
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II Subjective test
Retrospective investigations are mainly performed by specially designed questionnaires [2], the following are commonly used: 1, sleep diaries and recording forms, which provide a preliminary understanding of the time of falling asleep and the length of sleep, 2, Stanford Sleep Study Scale (SSS), 3, Epworth Sleep Study Scale (ESS) (Table 3). One of the more applied is the ESS, which is designed to detect sleepiness in different environments. The evaluation results correlated well with multiple measurements of nap sleep latency, with a reliability of 0.81 for repeated test results in the same patient and a correlation of 0.74 for results rated by the testers themselves and their families. patients with episodic sleeping sickness and primary narcolepsy (both ESS scores >12) were compared with normal subjects (both ESS scores