Narcolepsy

Narcolepsy is a rare chronic neurological disorder that affects the brain’s ability to regulate the sleep–wake cycle. Type 1 narcolepsy is caused by reduced production of a substance called hypocretin (or orexin), produced by specialised neurons in the hypothalamus and responsible for alertness (the state of wakefulness). This loss is most often autoimmune in origin. The pathophysiology of type 2 narcolepsy is less well understood: hypocretin levels in the cerebrospinal fluid are normal, and the mechanisms involved have not yet been clearly established.

Narcolepsy frequently begins during childhood or adolescence, with an initial peak between the ages of 10 and 15, followed by a second peak around the ages of 30 to 35. Diagnosis is often delayed by several years because of atypical presentations in children.

Narcolepsy manifests through four main symptoms (the “tetrad”):

•  Excessive daytime sleepiness (EDS): an irresistible urge to sleep during the day, even after a full night’s sleep, generally manifesting as falling asleep and sleep attacks that occur suddenly during the day, during less stimulating activities (while travelling by car/on public transport, in class during lessons, on the sofa while watching TV, etc.). In children, this may also manifest as irritability, hyperactivity or difficulty concentrating.

•  Cataplexy: sudden and brief loss of muscle tone, generally triggered by a positive emotion (laughter, surprise, etc.). It may be partial (drooping of the head, weakness in the arms, buckling of the legs) or complete. It is characteristic of type 1 narcolepsy.

•  Hypnagogic/hypnopompic hallucinations: visual or auditory hallucinations occurring when falling asleep or waking up; they can be frightening.

•  Sleep paralysis: inability to move for a few seconds to a few minutes during the transition from sleep to wakefulness. This paralysis can cause anxiety, but it always resolves after a few seconds/minutes.

Associated symptoms are common: weight gain, behavioural disorders (aggressiveness, anxiety, automatic behaviours), depression and precocious puberty.

If narcolepsy is suspected, patients will be offered a consultation at the Sleep Clinic to undergo a complete medical history, a neurological examination and blood tests (routine tests, thyroid function tests, serology and HLA typing). Measures to ensure good sleep hygiene and a sleep diary will be implemented for at least 4 weeks before the remainder of the complementary assessment is carried out. Medications that may influence the tests will also be discontinued beforehand. 

The diagnostic assessment takes place over 3 days of hospitalisation in our unit. 

• This will be preceded by actigraphy (a “kind of smart watch”), to be worn at home for 2 weeks before the sleep test

The sleep test takes place in several stages:

• Standard polysomnography (PSG) over 2 nights.
• A daytime multiple sleep latency test (MSLT): 4 to 5 scheduled naps at 2-hour intervals.
• Continuous recording over 24 hours to document a total sleep time of ≥ 660 minutes (11 hours).
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Other examinations will also be arranged on an outpatient basis (optional):

• A neuropsychological assessment
• A brain MRI
• An Endocrinology consultation may also be offered depending on the hormonal assessment 

In certain cases, a lumbar puncture may be proposed at a later stage to measure the hypocretin level in the cerebrospinal fluid and confirm or rule out a diagnosis of type 1 narcolepsy.

What treatments are available?

There is currently no curative treatment. Treatments are symptomatic and aim to improve quality of life.

Non-medication measures:

• Regular sleep schedule
• Scheduled daytime naps (1–2 naps of 20 minutes)
• Regular physical activity
• Educational or occupational adjustments (additional time during examinations, adapted schedules, justified absences)

Medication treatments (prescription-only and requiring specialist follow-up):

•  Modafinil (Provigil): first-line treatment for excessive daytime sleepiness

•  Pitolisant (Wakix): an alternative, effective against sleepiness and cataplexy

• Sodium oxybate (Xyrem): for moderate to severe forms with cataplexy and sleep fragmentation.

•  Other options: methylphenidate or venlafaxine, depending on the situation

Treatments are reimbursed in Belgium subject to INAMI conditions (confirmed diagnosis and clinical criteria)

Other professionals may be involved in your care pathway, including:

• Neuropsychologists and psychologists: Comprehensive neuropsychological assessment of cognitive functions. Assessment of comorbidities such as attention deficit hyperactivity disorder, both at diagnosis and during treatment. Psychoeducation and support regarding the impact of the condition on schooling/work, self-esteem and social life.

• Endocrinology : hormonal disorders, diabetes

• Gastroenterology and hepatology  : overweight clinic

• ENT and Pneumology: Management of sleep apnea

School/Work: Medical certificate to put reasonable accommodations in place. Coordination with the PMS Centre if necessary.