Topic reviewed by Waiz Wasey, MD, Board-certified sleep medicine physician
Def: chronic neurological dz sharing PSG and many clinical features with NT1
Cataplexy absent, CSF hypocretin-1 not proven low
Clinical presentation similar to NT1 but without cataplexy
Age of onset and sex distribution mirror NT1
Pathophysiology
Unclear
~45% HLA-DQB1*06:02 positive
Dx criteria (ICSD-3, all required)
- Daily irrepressible need to sleep or daytime lapses into sleep for ≥3 months
- MSLT: MSL ≤8 min and ≥2 SOREMPs
A SOREMP (REM within 15 min) on preceding PSG can replace 1 MSLT SOREMP - Cataplexy absent
- CSF hypocretin-1 not measured, or >110 pg/mL or >1/3 of normal mean with same assay
- Not better explained by insufficient sleep, OSA, delayed sleep phase, meds or substance withdrawal
If CSF hypocretin-1 later found <110 pg/mL or cataplexy develops, dx becomes NT1
Dx of exclusion, must rule out mimics
Differential dx
- Insufficient sleep syndrome: very common, can cause multiple SOREMPs on PSG/MSLT
- IH: also defined by MSLT and a dx of exclusion
- Other sleep d/o (OSA, PLMS, shift work, circadian d/o) can cause EDS and early REM
- Psych d/o, drug misuse, chronic fatigue syndrome can cause EDS, often separated by PSG criteria
Treatment
Similar to NT1, minus cataplexy tx
US: sodium oxybate, low-sodium oxybate, pitolisant and solriamfetol FDA approved for EDS in narcolepsy (NT1 and NT2)
- Oxford Handbook of Sleep Medicine 2022