Narcolepsy and Cataplexy

Narcolepsy is a chronic neurological condition producing disruption to the normal sleep pattern, which produces excessive sleepiness; may occur with or without cataplexy
Cataplexy is a sudden loss of muscle tone and power in response to strong emotion - it always and only occurs as part of narcolepsy

Aetiology

  • Equal sex incidence
  • Age of onset is typically around adolescence; a smaller number of cases presents at around 35 years

Pathophysiology

  • Caused by abnormalities of the brain neurotransmitter hypocretin (orexin), which is a regulator of sleep

Consequences

  • Frequently unrecognised, typical delay of 10 years between onset and diagnosis
  • Can lead to impairment of social and academic performance

Clinical presentation

  • Daytime sleepiness
    • Involuntary somnolence during eating/talking
    • May be severe, and impossible to resist
  • Cataplexy - loss of muscle tone, triggered by emotion
  • Hypnagogic hallucinations - hallucinations occurring at sleep onset
  • Sleep paralysis - unable to move upon falling asleep or awakening with retained consciousness
  • REM sleep behavior disorder (RBD) - 7-36% of patients with RBD have narcolepsy

Investigations

  • Overnight polysomnography
  • Multiple sleep latency test

Management

  • Patients must cease driving on diagnosis and inform the DVLA
    • Driving is allowed once satisfactory control of symptoms has been achieved

Non-drug treatment

Excessive daytime sleepiness
  • Good sleep hygiene
  • Strategic daytime naps
  • Regular exercise
  • Education
Cataplexy
  • Support and information for the patient and their family

Drug treatment

  • Modafinil dexamfetamine and methylphenidate are used to treat EDS
  • Tricyclic antidepressants, particularly clomipramine, or SSRIs can improve cataplexy
  • Sodium oxybate is also used