What are the diagnostic criteria and treatment options for narcolepsy?

Narcolepsy Diagnosis and Treatment

The diagnosis of narcolepsy requires documentation of excessive daytime sleepiness plus either cataplexy, cerebrospinal fluid hypocretin deficiency, or specific sleep study findings showing sleep-onset REM periods, with treatment primarily consisting of modafinil for excessive sleepiness and sodium oxybate for cataplexy. 1

Diagnostic Criteria

Clinical Symptoms

• Excessive daytime sleepiness (EDS) - essential for diagnosis
• Cataplexy (sudden loss of muscle tone triggered by emotions)
• Sleep paralysis
• Hypnagogic/hypnopompic hallucinations
• Disrupted nocturnal sleep

Objective Testing

1. Polysomnography (PSG) - overnight sleep study to:

   • Rule out other sleep disorders
   • Document sleep latency
   • Identify sleep-onset REM periods (SOREMPs)

2. Multiple Sleep Latency Test (MSLT) - daytime nap study showing:

   • Mean sleep latency ≤8 minutes (indicates pathological sleepiness)
   • ≥2 sleep-onset REM periods 1, 2

3. Cerebrospinal fluid (CSF) testing:

   • Hypocretin-1 levels <110 pg/mL confirm narcolepsy type 1 1

Narcolepsy Classification

• Type 1 Narcolepsy: EDS plus cataplexy and/or CSF hypocretin deficiency
• Type 2 Narcolepsy: EDS without cataplexy and normal/unknown CSF hypocretin levels 2

Treatment Options

Pharmacologic Management

For Excessive Daytime Sleepiness:

1. Modafinil (first-line):

   • Starting dose: 100mg daily (elderly patients)
   • Typical dose: 200-400mg daily
   • FDA-approved for narcolepsy with demonstrated efficacy in improving wakefulness 1, 3

2. Sodium oxybate:

   • FDA-approved for both cataplexy and EDS in narcolepsy patients ≥7 years old
   • Improves multiple symptoms including disrupted nocturnal sleep 1, 4

For Cataplexy:

1. Sodium oxybate (first-line) 1, 4
2. Antidepressants (alternatives):
   • Tricyclic antidepressants (TCAs)
   • Selective serotonin reuptake inhibitors (SSRIs)
   • Serotonin-norepinephrine reuptake inhibitors (SNRIs) 1, 5

Non-Pharmacologic Management

• Regular sleep-wake schedule
• Scheduled daytime naps (typically two short naps daily)
• Avoidance of sleep deprivation
• Avoidance of alcohol and heavy meals
• Regular exercise 1, 5

Follow-up and Monitoring

• Regular assessment using Epworth Sleepiness Scale
• Monitoring medication efficacy and side effects
• Evaluation of symptom exacerbation
• Occupational counseling (avoid shift work, driving jobs, positions requiring sustained attention) 1

Special Considerations

• Children may present with atypical features including more prominent motor manifestations during sleep
• Elderly patients require careful evaluation of medication regimens to prevent hypersomnia due to polypharmacy
• Untreated narcolepsy significantly impacts quality of life, causing depression, social withdrawal, and increased accident risk 1

Referral Guidelines

• Refer to sleep specialists when:
  • Narcolepsy is suspected
  • Cause of sleepiness is unknown
  • Patient is unresponsive to initial therapy 1

Ongoing management often requires collaboration between sleep medicine specialists, neurologists, and primary care physicians, as narcolepsy is typically a lifelong disorder requiring continuous care 1, 5.