Narcolepsy is a condition that can be difficult to diagnose. On average, getting a narcolepsy diagnosis can take 10 years. Some estimates suggest 60 percent of those with narcolepsy are incorrectly diagnosed in that period of time, so a reappraisal of symptoms is important. There are only a few diagnostic tools currently used to identify narcolepsy. One in particular, the Swiss Narcolepsy Scale (SNS), has shown promise as being accurate and easy to administer.
The Swiss Narcolepsy Scale is one of the screening tools used to determine whether someone has narcolepsy. It is patient-administered, which means it is given to a person experiencing narcolepsy symptoms to fill out. It will later be reviewed by a doctor.
The scale consists of five questions about various clinical features of narcolepsy that can be answered as a numerical value, from one to five. Three of the questions have to do with excessive daytime sleepiness (hypersomnia). Two questions concern cataplexy, a condition where muscles weaken or become paralyzed (such as weak knees, buckling of the knees, or sagging of the jaw) in response to strong emotion. A negative score is indicative of a diagnosis of narcolepsy, while a positive score suggests another of the central disorders of hypersomnolence — such as sleep apnea.
Research has shown the Swiss Narcolepsy Scale has a high specificity rate, higher than other screening tests for narcolepsy. One study, by Christian Sturzenegger and Christian Bauman published in Clinical and Translational Neuroscience, found the SNS had around 89 percent accuracy in distinguishing between people with narcolepsy and those without narcolepsy.
Two other common screening scales, the Epworth Sleepiness Scale (ESS) and the Ullanlinna Narcolepsy Scale (UNS), were found in the same study to be less accurate. The ESS is a longer test, with eight questions instead of five. It determines a rate of daytime sleepiness, which is only one part of narcolepsy. While the ESS is still valuable as an initial test, the SNS can be used to distinguish further between narcolepsy and other sleeping problems.
The UNS consists of 11 questions. It is calculated through a point scale on each question, with higher scores being indicative of narcolepsy. The UNS is a useful tool, but some studies indicate it is not particularly specific in distinguishing between diagnoses.
The Swiss Narcolepsy Scale is not without its disadvantages. For example, it’s only useful to diagnose narcolepsy type 1 — narcolepsy with cataplexy. It’s also graded on a sometimes confusing scale, where negative numbers indicate narcolepsy. (A narcolepsy screener app is available to help score the test, if needed.) However, the SNS can still rule out other sleep disorders with similar symptoms.
Other tests can be performed when an SNS score shows signs of narcolepsy. As mentioned before, a high score on the ESS indicates some kind of sleep problem. Both the ESS and the SNS can be administered at the same time, or the SNS can be used as a follow-up. If you have taken the ESS or the SNS on your own and the scores indicate a possible problem, it is important to see a neurologist or sleep specialist who has experience in narcolepsy.
Your health care provider can order other tests to determine if you have narcolepsy. An overnight sleep test in a lab measures your brainwaves, heartbeat, and other vital signs. A multiple sleep latency test (MSLT) measures your ability to fall asleep in the daytime. The American Academy of Sleep Medicine’s Find A Sleep Facility Near You feature can help you locate a sleep lab.
The SNS can be a first line of testing if you have symptoms of narcolepsy or a further test if you already had a high score on the ESS. If you see a neurologist about sleep issues and you have not already taken these tests, both the SNS and the ESS will likely be administered.
A sleep disorder like narcolepsy can be frustrating, and the fact that there is no definitive test for diagnosis can be more frustrating. The tests that are available can work together to give you an overall diagnosis, and once you have a diagnosis, you can be treated accurately.
Have you taken the Swiss Narcolepsy Scale? Which tests helped you toward a diagnosis? Comment below or start a new conversation on MyNarcolepsyTeam.