The Swiss Narcolepsy Scale (SNS) is a brief subjective questionnaire that screens for the occurrence of several behavioral symptoms that may be associated with narcolepsy with cataplexy.1
Features of the SNS
- Purpose:
Designed to screen for a symptom profile that might be suggestive of narcolepsy with cataplexy1
- Population:
Patients with EDS in whom the clinician may want to screen for potential narcolepsy with cataplexy2
- Assessments:
Measures frequency of 5 potential symptoms1:
Q1 – Inability to fall asleep
Q2 – Feeling bad or not well rested in the morning
Q3 – Taking a nap during the day
Q4 – Weak knees/buckling of the knees during emotions such as laughing, happiness, or anger
Q5 – Sagging of the jaw during emotions such as laughing, happiness, or anger - Method:
Patient self-report1
- Time required:
Consists of 5 questions and takes only a few minutes to complete1
- Scoring:
Frequency for each behavioral complaint is rated on a 5-point scale, from 1, indicating “never,” to 5, indicating “almost always.” Each question is weighted by a positive or negative factor, with the score calculated using the following validated equation: (6×Q1 + 9×Q2 – 5×Q3 – 11×Q4 – 13×Q5 +20).1,2
- Interpretation:
An SNS score <0 is suggestive of narcolepsy with cataplexy.1,2
- Validation:
In one study of patients with narcolepsy with cataplexy, an SNS score <0 was shown to have a sensitivity of 96% and specificity of 98%.2
A narcolepsy diagnosis should be established by a sleep specialist with a clinical interview and a nighttime polysomnogram (PSG) followed by a multiple sleep latency test (MSLT). A consistent sleep-wake schedule, including a minimum of 7 hours in bed, should be established for at least 1 week prior to MSLT and PSG, and documented by a sleep log or actigraphy.3