The exact cause of narcolepsy is unknown. It is considered that genetic factors play an important role. Often the triggering factor may be an infection that causes damage to brain cells involved in maintaining the nictemeral rythm.
Narcolepsy Causes – Normal sleep compared with that of those who suffer from narcolepsy
There are significant differences between physiological sleep, the normal sleep and narcolepsy related one. Common people get through a phase called non-REM (rapid eye movement without – also known movements of REM) in the first phase of the sleep. Now, the brain activity decreases significantly. After 1 or 2 hours of non-REM sleep, REM sleep stage is characterized by increased brain activity. This stage of sleep is when dreams occur.
Pacients with narcolepsy don’t experience the non-REM phase, such as was normal. Moreover, the REM sleep can happen anytime during the day. Accompanying physical manifestations of normal REM phase occur not (sleep paralysis, decreased muscle tone, the appearance of dreams) at this stage, but at different moments during the non-REM sleep, in people who suffer from narcolepsy.
Narcolepsy Causes – Role of brain chemical mediators
Hypocretin is an important chemical mediator that regulates sleep-wake rhythm and time of occurrence of REM sleep periods. In narcolepsy, producing cells are destroyed, which causes a low level of hypocretin in persons suffering from narcolepsy. The exact cause of the destruction of these cells is unknown, but suspected it would be an infection with an abnormal immune response that would form the basis for cellular alterations. Furthermore, certain genetic markers are more common in narcolepsy, which is why the relatives of those who suffer from narcolepsy have a significantly higher risk of developing the disease than other persons.
Research has not determined yet whether genetic or immune responses are the main culprits for destroying cells that produce hypocretin and that the causative agents have the highest contribution in the development of narcolepsy. Hypocretin is abundant in the cerebrospinal fluid (CSF) of persons not suffering from narcolepsy; patients with narcolepsy, on the other hand, have a very low hypocretin level.
Narcolepsy Diagnosis – Exam and criteria:
When assessing a patient with narcolepsy is likely that he will fall asleep while a clinical examination is being performed, or when the medical examiner is talking. Besides the main symptoms of the disorder, a number of other symptoms can occur, such as: continued fatigue, low energy, their arms and legs feel weak, people may have depression, difficulties to concentrate, lack of appetite, problems with alcohol. Patients with narcolepsy may have serious emotional and social integration problems; these problems can be exaggerated by the entourage that often doesn’t understand the situation.
Sleep attacks are essential in confirming the narcolepsy diagnosis if they occur daily for at least 3 months. Moreover, other signs of narcolepsy are:
- Cataplexy (episodes of sudden, bilateral and reversible loss of muscle tone, whose appearance can be precipitated by strong emotions)
- Hallucinations which appear during the transition from the waking to sleep
- Sleep-paralysis. Some specialists diagnose narcolepsy without other symptoms, but in the presence of excessive daytime sleepiness, associated with one or more periods of REM sleep early, during the SLT (sleep latency test).
Note that these symptoms should not be provoked by the use of a substance or a drug; also the symptoms are not relevant if the person has a preexisting medical condition.
Narcolepsy Diagnosis – Differential Diagnosis
Narcolepsy should be differentiated from:
- Normal variations in sleep- in the afternoon, it appears an increase physiological sleepiness and if it does, the individual knows and can “fight” against it;
- Lack of sleep – no matter the reason that caused the lack of sleep, it can cause daytime drowsiness and even hallucinations, so you should insist on finding out what is the sleep-wake rhythm.
- Primary hypersomnia – they do not have hallucinatory phenomena, sleep paralysis and cataplexy, and neither this state of paroxysmal need to sleep anywhere and anyway; Sleep-disorder breathing-related – breathing pauses and tiring sleep occur here, but without other symptoms;
- Major depressive disorder – the individual tends to sleep all the time and to have very intense dreams, but shows a continuous sleep at night, not fragmented as in narcolepsy;
- The use of or abstinence from certain chemicals, drugs: interrupting the treatment with stimulants can lead to excessive sleepiness (reserpin, metidopa, etc.).
Narcolepsy Diagnosis – Evolution and prognosis:
The main symptom in narcolepsy, excessive sleepiness, is more common in teenagers, but a careful search may reveal signs at an earlier age (school, preschool). Their emergence into adulthood is very rare. Often, social factors and mental stress or sleep-wake rhythm disorders can be the forerunners of the disease symptoms; it is also known that drowsiness is not always first. Cataplexy may appear in the early stages of the disease and can occur in the same time with drowsiness, or often in weeks, months or even years after the first symptoms. Hallucinations and sleep paralysis related to sleep may not even appear.