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SOURCE

Source: Dopp JM, Phillips BG. Sleep–wake disorders. In: DiPiro JT, Talbert RL, Yee GC, Matzke GR, Wells BG, Posey LM, eds. Pharmacotherapy: A Pathophysiologic Approach. 10th ed. New York, NY: McGraw-Hill; 2017. http://accesspharmacy.mhmedical.com/content.aspx?bookid=1861&sectionid=134128126. Accessed March 27, 2017.

DEFINITION

  • Sleep disorder characterized by excessive sleepiness and sleep attacks at inappropriate times.

ETIOLOGY

  • Precise cause unknown.

  • Genetic component (3% of patients have first-degree relative with disorder).

Possible environmental influences.

PATHOPHYSIOLOGY

  • The hypocretin/orexin neurotransmitter system may be involved. Autoimmune process may cause destruction of hypocretin-producing cells.

EPIDEMIOLOGY

  • Affects 0.03–0.06% of adult Americans.

  • Incidence may be higher in men than women.

  • Usually occurs in second decade of life and increases in severity through third and fourth decades.

  • Can occur in children and adolescents.

RISK FACTORS

  • Family history of narcolepsy.

  • Head injury.

  • Obesity.

  • History of meningitis or encephalitis.

CLINICAL PRESENTATION

SIGNS AND SYMPTOMS

  • Complaints of:

    • Excessive daytime sleepiness.

    • Sleep attacks that last up to 30 min.

    • Fatigue.

    • Impaired performance.

    • Disturbed nighttime sleep.

  • Multiple arousals during the night.

DIAGNOSIS

MEANS OF CONFIRMATION AND DIAGNOSIS

  • Essential features include.

    • Sleep attacks.

    • Cataplexy (sudden bilateral loss of muscle tone with collapse, often precipitated by emotional situations)

    • Hypnagogic hallucinations before sleep or during a sleep attack.

    • Sleep paralysis (flaccid muscles with full consciousness while falling or waking from sleep)

  • Sleep study demonstrating abrupt transition into REM sleep necessary for diagnosis.

DESIRED OUTCOMES

  • Maximize alertness during waking hours.

  • Improve quality of life.

TREATMENT: NONPHARMACOLOGIC THERAPY

  • Encourage good sleep hygiene.

  • Recommend two or more brief daytime naps daily; as little as 15 min may be beneficial.

TREATMENT: PHARMACOLOGIC THERAPY

  • Pharmacotherapy focuses on excessive daytime sleepiness and cataplexy (Table 1).

  • Excessive daytime somnolence.

    • Modafinil 200 mg each morning standard treatment.

      • No evidence of tolerance or withdrawal after abrupt discontinuation.

      • Side effects include:

        • Headache.

        • Nausea.

        • Nervousness.

        • Insomnia.

    • Armodafinil (the active R-isomer of modafinil) is also available.

    • Amphetamines and methylphenidate have higher likelihood of abuse and tolerance.

      • Side effects include:

        • Insomnia.

        • Hypertension.

        • Palpitations.

        • Irritability.

    • Selegiline may also be beneficial.

  • Cataplexy.

    • Most effective treatments:

      • Imipramine.

      • Protriptyline.

      • Nortriptyline.

      • Fluoxetine.

      • Venlafaxine.

    • Selegiline may also improve cataplexy.

  • Sodium oxybate (γ-hydroxybutyrate; potent sedative-hypnotic) improves excessive daytime sleepiness and decreases episodes of sleep paralysis, cataplexy, and hypnagogic hallucinations.

    • Taken at bedtime and repeated 2.5–4 hours later.

    • Side effects include:

      • Nausea.

      • Somnolence.

      • Confusion.

      • Dizziness.

      • Incontinence.

TABLE 1.abcPharmacotherapy of Narcolepsy

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