Nejm 1990;323:389

Cause: Genetic in 15%; autosomal dominant; associated with HLA-DR2 in 100%

Pathophys:Drop directly into REM sleep, which causes paralysis, dreams, and loss of postural tone, all of which can also occur inappropriately when awake

Males and females equally affected; prevalence = 1-10/10 000 population; incidence increased × 60 in other family members; associated with SIDS families (Nejm 1978;299:969)

Sx:

Positive family history; onset usually in teens, 80% by age 30 yr, all <40 yr

Periodic inappropriate drowsiness 30 sec to 15 min, awake refreshed

Cataplexy: REM-type episodic loss of postural tone precipitated by excitement, laughter, surprise, nostalgia; lasts usually <1 min; 30% have when 1st present, 50% have eventually

Hypnagogic hallucinations: vivid dreams at onset of, or coming out of sleep

Sleep paralysis (60%): can't move as going into sleep or coming out but latter not diagnostic; lasts up to 10 min

Onset usually between ages 15 and 35 yr; benign usually, don't progress after 1st 3-4 yr

Accidents, esp with cars; secondary psych problems, esp depression

r/o familial sleep paralysis on awakening (benign), sleep apnea hypersomnolence

Lab:Noninv:EEG shows immediate REM sleep or at least slow wave sleep very abbreviated (1-2 min); not true in all narcoleptics, and amphetamines can mask

Rx:

Nap 15-20 min at least 1-3/day

1st:

• Methylphenidate (Ritalin) up to 200 mg qd; must give drug holidays 1/12 mo or increase doses to levels that cause severe dependence; worse during these holidays

2nd:

• Amphetamines like methamphetamine 10-60 mg qd, or dextroamphetamine 5-50 mg qd

Others:

• Modafinil (Provigil) (Med Let 1999;41:30) 200-400 mg po qd in am; many drug interactons; comparable to 2 cups of coffee?; also used w moderate success in shift workers (Nejm 2005;353:476); $150/mo
• Imipramine or desipramine 25 mg tid for cataplexy (decreases REM), but beware of increased BP when used with amphetamines

of cataplexy: gamma hydroxybutyrate (Xyrem) (Med Let 2002;44:103) po hs and 2-4 h later; date-rape drug, so schedule III and special rules