What is central hypoventilation syndrome?
Central hypoventilation syndrome, sometimes referred to as Ondine’s curse, is an inability of the brain to detect changes in carbon dioxide levels in the body during sleep. The human body determines the amount of oxygen it needs by monitoring how much carbon dioxide is in the blood. If the body detects too much carbon dioxide, it will increase the breathing rate; too little and it will reduce the breathing rate.
Central hypoventilation syndrome prevents the body from detecting increased carbon dioxide levels, meaning that it will not increase the breathing rate. The lack of necessary breathing can result in hypoxemia (a low level of oxygen in the blood). Symptoms of hypoxemia can include confusion, shortness of breath, bluish skin tone and purpling of the lips The condition can be fatal if left untreated.
Central hypoventilation syndrome can be classified as congenital-or present at birth (CCHS), late-onset congenital (LO-CCHS), or acquired (ACHS). Classification determines when the condition first appears. It is estimated that 1 in 200,000 infants are born with the genetic mutation that causes congenital central hypoventilation syndrome (CCHS). Late-onset central hypoventilation syndrome and acquired central hypoventilation syndrome are much more rare.
What are the causes of congenital central hypoventilation syndrome?
Central hypoventilation syndrome is caused by certain receptors in the brain failing to recognize changes in carbon dioxide levels during sleep, leading to a low breathing rate and low blood concentration of oxygen.
Central hypoventilation syndrome can be caused by numerous conditions. The most common of these is congenital central hypoventilation syndrome, which is due to a rare mutation known as PHOX2B, which often occurs spontaneously and is not inherited. The genetic mutation may also occur later in life, causing late-onset central hypoventilation syndrome.
Other causes of central hypoventilation syndrome include:
- Rapid-onset obesity with hypothalamic dysfunction, hypoventilation, and autonomic dysregulation (ROHHAD), which affects the hypothalamus in the brain
- Spinal cord surgery or brainstem tumors, which can result in acquired central hypoventilation syndrome
What are the symptoms of central hypoventilation syndrome?
Central hypoventilation syndrome symptoms mostly relate to the low levels of oxygen in the blood.
These include:
- Shallow breathing during sleep
- Bluish skin discoloration during sleep in the fingers and/or toes
- Seizures during sleep
- Heart abnormalities
- Cognitive difficulties, or difficulty thinking or completing basic tasks
Congenital central hypoventilation syndrome in particular can also be associated with other disorders, including Hirschsprung disease.
How is central hypoventilation syndrome diagnosed?
In a newborn, congenital central hypoventilation syndrome can be identified with a sleep study known as polysomnography, which can register an abnormally high level of carbon dioxide in the blood during sleep.
A chromosomal or genetic test can confirm the characteristic mutation PHOX2B to make a congenital central hypoventilation syndrome diagnosis.
Imaging tests can help identify nerve-damaging injuries and tumors associated with acquired central hypoventilation syndrome.
What is the treatment for congenital central hypoventilation syndrome?
The treatment for congenital central hypoventilation syndrome involves beathing support during sleep, often through the assistance of a mechanical ventilator. In same cases, this type of breathing support may be necessary during waking hours as well.
Diaphragmatic pacing, which involves placing a pacemaker lead on the phrenic nerve to regulate breathing, can eliminate the need for other, more inconvenient mechanical ventilation for some people.