Swiss Narcolepsy Scale

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