Sleep disorders and Central Sleep Apnea Syndrome, CSAS


A sleep disorder caused by brain injury appears to be more common than was thought until recently.


Sleep is necessary to be able to remain concentrated and maintain thinking ability. Proper treatment of sleep disorders after brain injury usually leads to improvement with regard to cognitive and psychological problems and improvement of energy or work performance. A well-treated sleep disorder can also reduce headaches and depression, if present, and prevent serious physical complications.


40-65% of people with traumatic brain injury complain of insomnia. Studies show that sleep disturbances occur three times more often in people with traumatic brain injuries than in healthy people. Also in people with stroke / brain hemorrhage or infarction sleep disorders may occur. It is estimated that 60% of people with stroke have a sleep disorder. In particular, people with brainstem infarction or brain stem bleeding are known to develop sleep disorders. Also in neurodegenerative diseases, such as Parkinson's disease, sleep disorders occur.


Many people with brain injury do get sleep medication to correct their problem falling asleep but are not set to the appropriate sleep-wake schedule. Sleep medications can even worsen an undiagnosed and untreated sleep disorder, such as CSAS. We therefore call for a proper diagnosis if a person with brain injury continues to complain about sleep problems. See for example this wikipedia site.


Doctors diagnose a problem sleeping as a sleep disorder in case the patient did not sleep well for more than a month and experiences problems with this during daytime.


Sleep disturbances


In general, sleep disorders are classified into dyssomnias and parasomnias.


Dyssomnia is related to the duration, the quality and the time of the sleep:

  • Sleep-wake disorders including narcolepsy with sleep attacks during the day that cannot be resisted. Also, sudden muscular weakness seizures may occur then.
  • Restless legs syndrome RLS. Anxiety or cramps or short-term shocks in the legs, even without the person being aware of it. And Periodic Limb Movement Disorder (PLMD).
  • Difficulty falling asleep, waking up too early and not being able to fall asleep again, frequently awake.
  • Circadian rhythm sleep disorder (CSRD): problems with the sleep-wake rhythm, and the time at which one can fall asleep. For example, the "delayed sleep phase syndrome."
  • Apnea Syndrome: CSAS, OSAS or mixed picture. See paragraph below.


Parasomnia is associated with abnormal symptoms or behaviors during sleep:

  • Many movements during sleep, such as sleepwalking (somnambulism)
  • Night terrors (pavor nocturnus)
  • Sleep Behavior Disorder RBD = REM Sleep Conduct Disorder, which i.a. is seen in Parkinson's disease.
  • Teeth grinding (bruxism) can occur in Parkinson’s and Huntington’s disease
  • Talking during sleep. (somniloquy)


Central Sleep Apnea Syndrome after brain injury


The respiratory center in the brains controls the breathing frequency and volume of the lung capacity. Normally, the brains respond to an increase of carbon dioxide and reduction of oxygen, after which the signal is given to the respiratory muscles to breathe. In people with brain injury this may be disturbed. In particular in people who have brain stem injury.

But also people who had oxygen deficiency as the cause of the brain damage are vulnerable to this disease. Also, patients with multi-system atrophy (MSA), and Parkinson's disease may have it (unnoticed).


CSAS = Central Sleep Apnea Syndrome, (central means: from the brains) is a sleep breathing disorder from the brains. The brains give insufficient or no signals to the breathing muscles to ensure that the person breathes during sleep. A characteristic phenomenon is the very great difficulty falling asleep, which can take hours. Out of a survival reflex, the person wakes up at the moments that there is no breathing. In case this occurs frequently during a night then the person is very tired when it's time to get up.


CSAS, Central Sleep Apnea Syndrome occurs in combination with OSAS Obstructive Sleep Apnea Syndrome, but it also occurs without OSAS.


OSAS can occur because the muscles relax during sleep. This causes the soft tissue in the throat to obstruct breathing. Usually it is accompanied by loud snoring. For more information, see here.


The difference of CSAS with OSAS is that CSAS is not accompanied by snoring. The breathing may slow down to a very low frequency, for example, two to three times per minute, where twelve to sixteen times is a normal frequency. Breathing can finally stop completely.

If a person is not breathing adequately this is called hypoventilation. Hypoventilation creates a hypercapnia; an accumulation of carbon dioxide (CO2 or carbonic dioxide), which is exhaled in normal breathing but is not exhaled by the low breathing frequency. Carbon dioxide is a waste product of respiration and can cause problems if it is insufficiently dissipated. Sleep Medications can even increase the carbon dioxide accumulation or hypercapnia. Therefore, a proper diagnosis is very important.


Symptoms of CSAS


  • Sleep problems: often waking up, restless sleeping and not getting into a deep sleep
  • Difficulty getting to sleep
  • Drowsiness or severe daytime fatigue
  • Recurrent headaches upon awakening
  • Not feel fully recovered upon awakening
  • Frequent urination during the night
  • Hypoventilation and consequently possibly hypercapnia (see below)
  • Physical symptoms in the long term that often previously seemed inexplicable (see below)


Hypoventilation and hypercapnia


Hypoventilation is the reverse of hyperventilation.

Breathing is ineffective.

In the case of hyperventilation, breathing is too rapid and carbon dioxide is too low (hypocapnia), and in the case of hypoventilation, breathing is too slow or breathing stops and too high value of carbon dioxide (hypercapnia).


Normally an increasing carbon dioxide level gives a stimulus to respiration. For example, just try to stay underwater in the pool. The stimulus that makes you want to go up for air is the same stimulus that makes you desperate for oxygen and makes you start breathing faster.

In humans with brain injury, it happens that the stimulus from the brains disappears during sleep. The brains of people with brain injuries gradually get accustomed to the high carbon dioxide levels. 

This leads to acidification of the blood, and drowsiness.


Hypercapnia can also be seen as a complication for COPD. Here we see an inability to breathe out in the right way so that air remains in the lungs, and less carbon dioxide (CO2) is exhaled. COPD is short for Chronic Obstructive Pulmonary Disease.


Dangers of Hypercapnia


Hypercapnia leads to headaches, increased blood pressure and heart palpitations.

It can cause muscle twitching (myoclonus and tremor), confusion, lethargy, seizures, drowsiness and consciousness falls, and ultimately coma or death.


In brain injury patients with hypercapnia, we see impaired motor skills, depression and memory disorders and nerve pain with pieces of numb spots on the skin or even scratchy pieces as if ants are running over the skin (neuropathy with paraesthesia).


Treatment of nocturnal respiratory arrest and increased carbon dioxide


Diagnosing CSAS with hypercapnia can only be done in a hospital. The general practitioner can refer to a lung specialist. The lung specialist will refer to a center for Home Artificial respiration.

A research can be done at home, a sleep registration often with a TOSCA measurement.

A TOSCA measurement uses a sensor that is placed overnight on the forehead and measures the carbonic acid gases through the skin. (transcutaneous).

On the basis of these measurements at home it is decided to take a patient to a center for home artificial respiration.


If a diagnosis Central Sleep Apnea / CSAS with nocturnal respiratory arrest, and increase in carbon dioxide (hypercapnia) is made, the patient is adjusted to a BiPAP machine.


By means of this machine the breathing occurs by a nose cap which regulates both the inhalation and the exhalation. When the patient is properly adjusted to the machine he or she can learn to use the machine and can then be ventilated at home during the night.


A BiBAP Machine



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