Making the Narcolepsy Diagnosis

A complete clinical interview, including assessment for all 5 narcolepsy symptoms (CHESS: Cataplexy, Hallucinations, Excessive daytime sleepiness, Sleep paralysis, Sleep disruption), is important to the differential diagnosis and provides clinical context when evaluating the results of sleep laboratory testing.^1-4 Including the patient's spouse, bed partner, or another family member during the clinical interview can be helpful to corroborate or refute the patient’s report of sleepiness or to uncover cataplexy.^5,6

Sleep laboratory testing, consisting of overnight polysomnography (PSG) followed by a multiple sleep latency test (MSLT), should be performed if narcolepsy is suspected.¹ Sleep laboratory testing should be performed under appropriate conditions using standardized techniques and should be interpreted within the clinical context of the patient’s history and symptoms.¹

• Home Sleep Apnea Testing (HSAT) cannot detect narcolepsy and is not recommended if narcolepsy is suspected^7,8

Assessment of cerebrospinal fluid (CSF) hypocretin-1 levels is another objective test that can confirm a narcolepsy type 1 diagnosis.¹ However, CSF hypocretin-1 levels typically are not obtained in clinical practice.⁹ An assay is now commercially available.Hypocretin deficiency in patients with excessive daytime sleepiness is considered diagnostic for narcolepsy type 1 in the ICSD-3¹ and for narcolepsy in the DSM‑5.^1,10 Hypocretin deficiency is generally defined as CSF hypocretin-1 levels ≤110 pg/mL or <1/3 (≤1/3 in DSM‑5) of mean values obtained using the same assay in healthy subjects.^1,10