Name
NARCOLEPSY
DESCRIPTION
DETAIL
CAUSES β’ Unknown; associated with loss of the neurotransmitter hypocretin-1 in CNS β’ Possible involvement of the immune system β’ 75% of narcoleptic patients - no detectable hypocretin in CSF -------------------------------------------------------------------------- DIFFERENTIAL DIAGNOSIS EDS present in 4% of population, most are not narcolepsy, causes include: β’ Sleep apnea syndromes - 40-50% of those with excessive somnolence β’ Epileptic seizures and syncope β’ Idiopathic CNS hypersomnolence - 5-10% of those with excessive somnolence β’ Nocturnal myoclonus β’ Psychomotor seizures β’ Abuse of sedative drugs β’ Clinical diagnosis possible if cataplexy presentLABORATORY TEST: NONE SPECIAL TESTS . Nighttime polysomnography - monitoring of patients in a sleep laboratory will usually document fragmented sleep with a normal amount of REM sleep but a pattern of sleep onset REM. Polysomnography rules out other causes of excessive daytime sleepiness including sleep apnea syndromes and nocturnal myoclonus. . Multiple sleep latency test (MSLT) - begins at least 90 minutes after nighttime test. Patient is monitored during 4-5 naps taken at two-hour intervals. The rapidity of sleep onset and type of sleep pattern are documented. A supportive test includes a mean sleep latency (time to fall asleep) of five minutes or less and at least two sleep-onset REM periods. Sensitivity 77%, specificity 97%, PPV 73%. . HLA typing in ambiguous cases DIAGNOSTIC PROCEDURES . REM periods during MSLT . Diagnostic criteria - B and C, or A and D and E and G . A. Excessive sleepiness . B. Recurrent lapses into sleep daily for . 3 months . C. Cataplexy . D. Associated features: sleep paralysis, hypnagogic hallucinations, disrupted sleep . E. Multiple sleep latency test abnormalities as described . F. Biologic markers . G. Absence of medical or psychiatric disorder . H. CSF hypocretin-1 level low - 99% specificity, 87% sensitivity; useful in children unable to do MSLT
TYPENOTES
RISK FACTORS: Head trauma, CNS infectious disease, Anesthesia, Family historyGENERAL MEASURES β’ Usually managed with medication β’ Regularly scheduled time for naps may help in mild cases β’ Regular sleep-wake schedule ACTIVITY Exercise can sometimes decrease the number of sleep attacks. Seek to achieve optimal physical fi tness. DIET No special diet, avoid alcohol PATIENT EDUCATION β’ Symptoms can spontaneously improve or worsen DRUG(S) OF CHOICE . Excessive daytime sleepiness . Non-amphetamines: - Modafinil (Provigil) 200 or 400 mg/day; structurally distinct from amphetamines. Start with 100 mg and increase over 3-4 days. - Selegiline - selective MAO-B inhibitor, 20-40 mg/day divided AM and noon; anticataplectic and effective for excessive daytime sleepiness . Amphetamines: - Methylphenidate (Ritalin) initial dose 30 mg/day divided 2-3/day; maximum dose 100 mg/day - Pemoline (Cylert) - longer half life 8-10 hours; initial dose 37.5 mg/day divided AM and noon; maximum dose 150 mg/day. Monitor liver function studies 4 weeks after start and then once a year. - Dextroamphetamine initial dose 15 mg/day divided 2-3/day; maximum dose 100 mg/day - Combination of long and short acting - pemoline plus single or multiple doses of methylphenidate . Auxiliary symptoms (cataplexy, hypnagogic hallucination, sleep paralysis) - antidepressants suppress REM sleep . Imipramine 75-150 mg/day . Protriptyline 10-40 mg/day . Clomipramine 150-250 mg/day . Fluoxetine 20-60 mg/day . Sodium oxybate (Xyrem) - 6-9 gm/day po in 2 equal doses for cataplexy. Beginning dose is 4.5gm/day. ALTERNATIVE DRUGS . Excessive daytime sleepiness: . Propranolol 280-480 mg/day, good for patients during withdrawal from stimulants or patients with hypertension . Dextroamphetamines 5-60 mg/day . L-Tyrosine 64-120 mg/day . Ancillary symptoms . Gamma-hydroxybutyrate 5.25-6.75 g during sleep, has little effect on sleep architecture of REM sleep but increases slow-wave sleep. Also has mild effect on excessive daytime sleepiness without tolerance development. Gamma-hydroxybutyrate can increase sleep walking by increasing slow-wave sleep. . Codeine 150 mg/day . Triazolam 0.25 mg improves nocturnal sleep quality PATIENT MONITORING β’ Frequent blood pressure checks β’ Followup every 6 months POSSIBLE COMPLICATIONS N/A EXPECTED COURSE/PROGNOSIS β’ Life-long disease β’ Symptoms can worsen with aging β’ In women, symptoms can improve after menopause
RELATED DISEASE
Not Available Disease
DISEASE
INVESTIGATION
CSF EXAMINATION, HLA TYPING
[NARCOLEPSY]