Neurology · Year 3 · from Neurology

Case 2: Narcolepsy Type 1

Patient Demographics

• Age: 22 years old
• Sex: Female
• Occupation: College student

Chief Complaint

"I keep falling asleep in class, and sometimes when I laugh really hard, my knees buckle and I collapse."

History of Present Illness

Ms. Jennifer Martinez is a 22-year-old college student referred for evaluation of excessive daytime sleepiness and "spells." She has experienced overwhelming sleepiness since age 16, initially attributed to being a "typical teenager." Despite sleeping 8-9 hours at night, she experiences irresistible sleep attacks 2-3 times daily. She has fallen asleep during exams, while eating dinner, and during conversations. More concerning, since age 17, she has experienced episodes where her muscles suddenly go weak. These episodes are triggered by strong emotions, particularly laughter. She describes her knees buckling, her jaw going slack, and sometimes collapsing to the ground. She remains fully conscious during these episodes, which last 30 seconds to 2 minutes. She also reports vivid, sometimes frightening hallucinations as she falls asleep (seeing people in her room) and occasional episodes of being unable to move when waking up.

Sleep History

• Nighttime sleep: 8-9 hours but fragmented, wakes 2-3 times
• Naps: Takes 1-2 naps daily, 15-30 minutes, refreshing
• Sleep paralysis: 2-3 times per month
• Hypnagogic hallucinations: Weekly

Past Medical History

• No significant medical history
• No prior sleep studies
• No psychiatric diagnosis

Medications

• None currently
• Tried caffeine pills with minimal benefit

Family History

• No known sleep disorders
• No autoimmune diseases

Social History

• College junior, struggling academically due to sleepiness
• Non-smoker
• Rare alcohol use (makes symptoms worse)
• Single, lives in dormitory

Neurological Examination

• General: Alert, appropriate, yawns frequently during interview
• Mental Status: Normal
• Cranial Nerves: Intact
• Motor: Normal strength throughout; during discussion of funny videos on her phone, examiner observes transient jaw drop and neck flexion for ~30 seconds - patient remains conscious and can speak (slurred) during episode
• Sensory: Normal
• Reflexes: 2+ throughout
• Coordination: Normal

Clinical Image

Image: Illustration depicting the classic tetrad of narcolepsy symptoms: excessive daytime sleepiness, cataplexy, sleep paralysis, and hypnagogic hallucinations, plus disrupted nocturnal sleep.

Image Source: Wikimedia Commons Attribution: Medical illustration, Educational Use URL: https://commons.wikimedia.org/wiki/File:Narcolepsy_symptoms.png

Diagnostic Studies

Epworth Sleepiness Scale: 19/24 (severely elevated)

Polysomnography (overnight):

• Total sleep time: 412 minutes
• Sleep efficiency: 82%
• Sleep latency: 3 minutes (short)
• REM latency: 8 minutes (very short; normal >90 minutes)
• AHI: 2 (no significant sleep apnea)
• PLMI: 4 (no significant periodic limb movements)

Multiple Sleep Latency Test (MSLT) - Following Day:

• Five nap opportunities at 2-hour intervals

MSLT Results:

• Mean sleep latency: 1.8 minutes (normal >8 minutes)
• Sleep-onset REM periods (SOREMPs): 4 (need ≥2 for diagnosis)

HLA Typing: DQB1*06:02 positive (associated with narcolepsy, but not diagnostic alone)

Assessment and Diagnosis

Narcolepsy Type 1 (with cataplexy)

Diagnostic Criteria Met:

1. Excessive daytime sleepiness for >3 months
2. Cataplexy (clearly witnessed during examination)
3. MSLT: Mean sleep latency <8 minutes with ≥2 SOREMPs
4. (CSF orexin/hypocretin not required when cataplexy is unequivocal, but would be low if measured)

Classic Pentad of Narcolepsy

Management Plan

Pharmacologic Treatment:

For Excessive Daytime Sleepiness:

• Modafinil 100 mg every morning, titrate to 200 mg if needed
• If inadequate: can add afternoon dose or switch to armodafinil
• Alternative: methylphenidate or amphetamine salts if modafinil insufficient

For Cataplexy:

• Sodium oxybate (Xyrem) - First-line for cataplexy
• Start 4.5 g nightly divided into two doses (at bedtime and 2.5-4 hours later)
• Titrate up as tolerated
• Also improves EDS and consolidates sleep
• Schedule III controlled substance - prescribed through REMS program
• Counsel on side effects: sedation, respiratory depression (avoid with other CNS depressants), abuse potential

Alternative for cataplexy if sodium oxybate not tolerated:

• Venlafaxine (SNRI) - suppresses REM, reduces cataplexy
• Clomipramine (TCA)

Lifestyle Modifications:

• Scheduled short naps (15-20 minutes) 1-2 times daily
• Regular sleep-wake schedule
• Avoid alcohol (worsens symptoms and dangerous with sodium oxybate)
• Avoid driving until symptoms controlled

Safety Counseling:

• Do not drive or operate machinery until sleepiness controlled
• Avoid swimming alone, heights, other high-risk situations
• Medical alert bracelet recommended

Accommodations:

• Letter provided for university disability services requesting:
• Extended time for exams
• Permission to take scheduled rest breaks
• Note-taking assistance

Follow-Up (8 weeks later)

Response to Treatment:

• Modafinil 200 mg daily: Significant improvement in daytime alertness
• Sodium oxybate 6 g nightly: Cataplexy episodes reduced from daily to 1-2 per month
• Sleep paralysis and hypnagogic hallucinations improved
• Epworth: 9 (normalized from 19)

Academic Performance: Improved, passing all courses

Teaching Points

1. Narcolepsy Type 1 = with cataplexy; Type 2 = without cataplexy

1. Cataplexy is pathognomonic for narcolepsy Type 1:

• Sudden, bilateral loss of muscle tone
• Triggered by strong emotion (especially laughter)
• Consciousness preserved
• Lasts seconds to minutes

1. MSLT diagnostic criteria:

• Mean sleep latency <8 minutes
• ≥2 sleep-onset REM periods (SOREMPs)

1. Pathophysiology: Narcolepsy Type 1 results from autoimmune destruction of orexin/hypocretin-producing neurons in the hypothalamus

1. Treatment:

• Sleepiness: Modafinil (first-line), stimulants (second-line)
• Cataplexy: Sodium oxybate (first-line), SNRIs, TCAs

1. Sodium oxybate treats multiple symptoms (EDS, cataplexy, disrupted sleep) but requires careful counseling about risks

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