Narcolepsy in Adult Patients: Clinical Insights

The American Academy of Sleep Medicine (AASM) recommends assessing excessive daytime sleepiness (EDS) with a validated scale at every patient visit and documenting any change from baseline.^1,2 Regular assessment of cataplexy is also important, as it may develop and evolve over the course of the disorder.^3-5

Daytime sleepiness severity can be subjectively quantified with one of many validated scales, such as the Epworth Sleepiness Scale (ESS), which measures adult patients’ perceived likelihood of falling asleep in 8 common daily situations, such as sitting and reading or sitting quietly after lunch.^6,7 The maximum score on the ESS is 24, with higher scores reflecting a higher chance of falling asleep; ESS scores >10 indicate EDS, and scores ≥16 indicate severe EDS.⁶

The Functional Outcomes of Sleep Questionnaire, Short Form (FOSQ-10) is also a validated self-assessment of EDS in adult patients aged 20 to 60 years. It is a 10-item questionnaire that assesses the impact of EDS on daily activities across 5 domains (general productivity, activity level, vigilance, social outcomes, and intimacy and sexual relationships) and also assesses changes with treatment. On the FOSQ-10, lower scores indicate greater functional impairment (total scores range from 5-20).^8,9

EDS can also be quantified objectively by a Multiple Sleep Latency Test (MSLT; performed in accordance with current recommended protocols), which measures the physiologic propensity of patients to fall asleep in quiet situations. Because there is not always correlation between subjective and objective measures, they must be interpreted in concert with appropriate clinical judgment.⁶

The Narcolepsy Severity Scale (NSS) is a validated, 15-item self-assessment that evaluates the frequency, severity, and impact of the 5 main narcolepsy symptoms—EDS, cataplexy, hypnagogic hallucinations, sleep paralysis, and disrupted nighttime sleep—in adult patients. Higher scores indicate more severe symptoms. The NSS is intended for monitoring symptom severity in patients with narcolepsy type 1, rather than as a diagnostic tool.¹⁰

The clinical interview is an important aspect of evaluating EDS, cataplexy, and any potential additional symptoms associated with narcolepsy.^6,11 Following best practices for clinical interviews in patients with narcolepsy may be helpful in evaluating more subtle manifestations of symptoms, as well as the impact of symptoms on the patient.⁶

The scales described above are also included in Clinical Resources, along with additional tools and resources.